Bitcoin: What’s the Math? | by Serena McDonnell | Towards

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What are the impediment of Bitcoin as a Transaction Currency?
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While it was made as a methods for doing electronic, distributed exchanges, the idea isn't versatile at this stage. It relies a great deal upon confirmation of-work, which happens to be a strategy used to affirm that an arrangement came to fruition.
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The benefit of using this technique is that proprietors on the Bitcoin framework don't need to know or even have faith in each other. Neither do they rely on a last gathering as the fundamental force that has an extreme state over an exchange? The procedure's advantages are accessible for speed, in any case. The Bitcoin framework can just oversee seven exchanges for every second.
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Considerably more unequivocally, every ten mins, a clump of exchanges (alluded to for discourage of activities, along these lines, "square" chain) is affirmed. The issue, in any case, is the bunch is sufficiently enormous to fit a great deal of exchanges. In the event that, for example, you head over Starbucks, and you make a purchase with Bitcoin, in the most ideal situation, your espresso purchase is put into the following cluster. It's checked under ten minutes if Starbucks is sufficient just to remember one confirmation (there are chances associated with just tolerating one affirmation, however we won't get into that in this occurrence).
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On the other side, if there's a broad rundown of exchanges in front of you, your coffee exchange probably won't get by into that next group. What winds up happening would be that your buy gets lined set up for another shipment. The line which the exchange is persistently holding up in is known as the mempool. Presently you've to hold up an extra ten minutes after the earlier cluster of exchanges is finished; i.e., you've to wait for as much as twenty minutes. And still, at the end of the day, there's just no assurance. Maybe, at this point, you discover the point and unquestionably will see unequivocally how troubling it will become to buy a mug of coffee with Bitcoin.
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On the off chance that you exchange on each brought together trade, in spite of the fact that, you could be imagining that Bitcoin speeds are close moment that is a deception. On brought together trades, all the bitcoin is kept in one area. The Bitcoin of yours and mine are aggregate. The trade deals with a database that gives and takes away a history on the Bitcoin you own, subject to each exchange. That is the explanation. Bitcoin maximalists contend that you don't genuinely have your Bitcoin except if it is in your wallet; on the off chance that it lays on a trade, you're represented by chance. The exchange may vanish one day with the entirety of your coins, or perhaps only level out decline to furnish you with the coins you purchased.
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As a retail establishment of worth, Bitcoin has a few great properties. In the first place, it could be had and effectively put away. In contrast to gold, Bitcoin might be put away for a USB stick, regardless of the amount you have. Gold occupies genuine physical room, and holding extensive measures of it can get obvious. Bitcoin likewise offers a fixed cost. Altogether, there'll be close to twenty-one million Bitcoin promptly accessible to the world.
Think about Bitcoin exchange
How Are BITCOIN TRANSACTIONS Processed?
The Bitcoin (BSV) blockchain supports an open record that will keep a background marked by the majority of the exchanges that occurred. Each hub on the framework has a total message of the bookkeeping. Mining will be where extra exchanges between individuals are checked and placed into the Bitcoin (BSV) open record and the way the blockchain is made sure about. Along these lines, blockchain mining will be where fresh out of the box new Bitcoin (BSV) coins are printed and furthermore brought into the current flowing flexibly.
How Does Mining Work?
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Mining is a fundamental segment that empowers the Bitcoin (BSV) blockchain to work being a decentralized shared framework with zero outsider focal position. In expansive phrasing, exchanges become brought into the blockchain by hubs when one specific social gathering coordinates a Bitcoin to another. Excavators run a particular programming bundle to record the squares upon the Bitcoin (BSV) blockchain.
Hubs are the establishment of the blockchain. A hub is a digger that joins towards the Bitcoin (BSV) framework to reveal obstructs in addition to process exchanges. Hubs talk with each other by transmitting data inside the conveyed framework with the Bitcoin (BSV) distributed procedure. All system hubs get the arrangements at that point affirm the legitimacy of theirs.
What occurs after?
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An excavator gathers exchanges from the brain pool, independently hashes them, presently amasses them inside an impede. After the exchanges get hashed, the hashes are organized straight into a Merkle Tree (or perhaps a hash tree).
A Merkle Tree is made by orchestrating the distinctive exchange hashes into sets at that point hashing them by and by. The yield is organized into sets and hashed again then over and again, until "the top piece of the tree" is secured. The zenith of the tree is known as a root hash or perhaps Merkle root. Its one hash that presents the entirety of the earlier blends utilized in its age.
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The square's coming up next: is controlled by header
Mining a square is troublesome in light of the fact that the SHA 256 hash of a square's header ought to be not exactly or maybe equivalent to the objective with the square to be recognized by the framework. Diggers consistently hash the square header in, by emphasizing through the nonce until one inside the framework excavator makes a legitimate block hash.
At the point when found, the originator hub is going to communicate the square on the Bitcoin people group. Different hubs look at to discover if the hash is certifiable and, hence, tack the square into a duplicate of theirs of the blockchain. Therefore, they've up record after that begin dealing with mining another square.
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Blockchain Rewards
The underlying advance in blockchain mining is including a coinbase exchange, e.g., an unmistakable sort of bitcoin exchange that can simply be created by a digger. This exchange doesn't have any sources of info, and there's an individual comprised of each fresh out of the plastic new impede mined on the Bitcoin (BSV) people group. Any exchange and square rewards expenses got together by the digger are presented this exchange as pay for finding the new square.
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What are the impediment of Bitcoin as a Transaction Currency?
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While it was made as a methods for doing electronic, distributed exchanges, the idea isn't versatile at this stage. It relies a great deal upon confirmation of-work, which happens to be a strategy used to affirm that an arrangement came to fruition.
The benefit of using this technique is that proprietors on the Bitcoin framework don't need to know or even have faith in each other. Neither do they rely on a last gathering as the fundamental force that has an extreme state over an exchange? The procedure's advantages are accessible for speed, in any case. The Bitcoin framework can just oversee seven exchanges for every second.
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Considerably more unequivocally, every ten mins, a clump of exchanges (alluded to for discourage of activities, along these lines, "square" chain) is affirmed. The issue, in any case, is the bunch is sufficiently enormous to fit a great deal of exchanges. In the event that, for example, you head over Starbucks, and you make a purchase with Bitcoin, in the most ideal situation, your espresso purchase is put into the following cluster. It's checked under ten minutes if Starbucks is sufficient just to remember one confirmation (there are chances associated with just tolerating one affirmation, however we won't get into that in this occurrence).
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On the other side, if there's a broad rundown of exchanges in front of you, your coffee exchange probably won't get by into that next group. What winds up happening would be that your buy gets lined set up for another shipment. The line which the exchange is persistently holding up in is known as the mempool. Presently you've to hold up an extra ten minutes after the earlier cluster of exchanges is finished; i.e., you've to wait for as much as twenty minutes. And still, at the end of the day, there's just no assurance. Maybe, at this point, you discover the point and unquestionably will see unequivocally how troubling it will become to buy a mug of coffee with Bitcoin.
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On the off chance that you exchange on each brought together trade, in spite of the fact that, you could be imagining that Bitcoin speeds are close moment that is a deception. On brought together trades, all the bitcoin is kept in one area. The Bitcoin of yours and mine are aggregate. The trade deals with a database that gives and takes away a history on the Bitcoin you own, subject to each exchange. That is the explanation. Bitcoin maximalists contend that you don't genuinely have your Bitcoin except if it is in your wallet; on the off chance that it lays on a trade, you're represented by chance. The exchange may vanish one day with the entirety of your coins, or perhaps only level out decline to furnish you with the coins you purchased.
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As a retail establishment of worth, Bitcoin has a few great properties. In the first place, it could be had and effectively put away. In contrast to gold, Bitcoin might be put away for a USB stick, regardless of the amount you have. Gold occupies genuine physical room, and holding extensive measures of it can get obvious. Bitcoin likewise offers a fixed cost. Altogether, there'll be close to twenty-one million Bitcoin promptly accessible to the world.
Think about Bitcoin exchange
How Are BITCOIN TRANSACTIONS Processed?
The Bitcoin (BSV) blockchain supports an open record that will keep a background marked by the majority of the exchanges that occurred. Each hub on the framework has a total message of the bookkeeping. Mining will be where extra exchanges between individuals are checked and placed into the Bitcoin (BSV) open record and the way the blockchain is made sure about. Along these lines, blockchain mining will be where fresh out of the box new Bitcoin (BSV) coins are printed and furthermore brought into the current flowing flexibly.
How Does Mining Work?
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Mining is a fundamental segment that empowers the Bitcoin (BSV) blockchain to work being a decentralized shared framework with zero outsider focal position. In expansive phrasing, exchanges become brought into the blockchain by hubs when one specific social gathering coordinates a Bitcoin to another. Excavators run a particular programming bundle to record the squares upon the Bitcoin (BSV) blockchain.
Hubs are the establishment of the blockchain. A hub is a digger that joins towards the Bitcoin (BSV) framework to reveal obstructs in addition to process exchanges. Hubs talk with each other by transmitting data inside the conveyed framework with the Bitcoin (BSV) distributed procedure. All system hubs get the arrangements at that point affirm the legitimacy of theirs.
What occurs after?
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An excavator gathers exchanges from the brain pool, independently hashes them, presently amasses them inside an impede. After the exchanges get hashed, the hashes are organized straight into a Merkle Tree (or perhaps a hash tree).
A Merkle Tree is made by orchestrating the distinctive exchange hashes into sets at that point hashing them by and by. The yield is organized into sets and hashed again then over and again, until "the top piece of the tree" is secured. The zenith of the tree is known as a root hash or perhaps Merkle root. Its one hash that presents the entirety of the earlier blends utilized in its age.
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The square's coming up next: is controlled by header
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Mining a square is troublesome in light of the fact that the SHA 256 hash of a square's header ought to be not exactly or maybe equivalent to the objective with the square to be recognized by the framework. Diggers consistently hash the square header in, by emphasizing through the nonce until one inside the framework excavator makes a legitimate block hash.
At the point when found, the originator hub is going to communicate the square on the Bitcoin people group. Different hubs look at to discover if the hash is certifiable and, hence, tack the square into a duplicate of theirs of the blockchain. Therefore, they've up record after that begin dealing with mining another square.
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Blockchain Rewards
The underlying advance in blockchain mining is including a coinbase exchange, e.g., an unmistakable sort of bitcoin exchange that can simply be created by a digger. This exchange doesn't have any sources of info, and there's an individual comprised of each fresh out of the plastic new impede mined on the Bitcoin (BSV) people group. Any exchange and square rewards expenses got together by the digger are presented this exchange as pay for finding the new square.
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What are the impediment of Bitcoin as a Transaction Currency?
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While it was made as a methods for doing electronic, distributed exchanges, the idea isn't versatile at this stage. It relies a great deal upon confirmation of-work, which happens to be a strategy used to affirm that an arrangement came to fruition.
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The benefit of using this technique is that proprietors on the Bitcoin framework don't need to know or even have faith in each other. Neither do they rely on a last gathering as the fundamental force that has an extreme state over an exchange? The procedure's advantages are accessible for speed, in any case. The Bitcoin framework can just oversee seven exchanges for every second.
Considerably more unequivocally, every ten mins, a clump of exchanges (alluded to for discourage of activities, along these lines, "square" chain) is affirmed. The issue, in any case, is the bunch is sufficiently enormous to fit a great deal of exchanges. In the event that, for example, you head over Starbucks, and you make a purchase with Bitcoin, in the most ideal situation, your espresso purchase is put into the following cluster. It's checked under ten minutes if Starbucks is sufficient just to remember one confirmation (there are chances associated with just tolerating one affirmation, however we won't get into that in this occurrence).
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On the other side, if there's a broad rundown of exchanges in front of you, your coffee exchange probably won't get by into that next group. What winds up happening would be that your buy gets lined set up for another shipment. The line which the exchange is persistently holding up in is known as the mempool. Presently you've to hold up an extra ten minutes after the earlier cluster of exchanges is finished; i.e., you've to wait for as much as twenty minutes. And still, at the end of the day, there's just no assurance. Maybe, at this point, you discover the point and unquestionably will see unequivocally how troubling it will become to buy a mug of coffee with Bitcoin.
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On the off chance that you exchange on each brought together trade, in spite of the fact that, you could be imagining that Bitcoin speeds are close moment that is a deception. On brought together trades, all the bitcoin is kept in one area. The Bitcoin of yours and mine are aggregate. The trade deals with a database that gives and takes away a history on the Bitcoin you own, subject to each exchange. That is the explanation. Bitcoin maximalists contend that you don't genuinely have your Bitcoin except if it is in your wallet; on the off chance that it lays on a trade, you're represented by chance. The exchange may vanish one day with the entirety of your coins, or perhaps only level out decline to furnish you with the coins you purchased.
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As a retail establishment of worth, Bitcoin has a few great properties. In the first place, it could be had and effectively put away. In contrast to gold, Bitcoin might be put away for a USB stick, regardless of the amount you have. Gold occupies genuine physical room, and holding extensive measures of it can get obvious. Bitcoin likewise offers a fixed cost. Altogether, there'll be close to twenty-one million Bitcoin promptly accessible to the world.
Think about Bitcoin exchange
How Are BITCOIN TRANSACTIONS Processed?
The Bitcoin (BSV) blockchain supports an open record that will keep a background marked by the majority of the exchanges that occurred. Each hub on the framework has a total message of the bookkeeping. Mining will be where extra exchanges between individuals are checked and placed into the Bitcoin (BSV) open record and the way the blockchain is made sure about. Along these lines, blockchain mining will be where fresh out of the box new Bitcoin (BSV) coins are printed and furthermore brought into the current flowing flexibly.
How Does Mining Work?
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Mining is a fundamental segment that empowers the Bitcoin (BSV) blockchain to work being a decentralized shared framework with zero outsider focal position. In expansive phrasing, exchanges become brought into the blockchain by hubs when one specific social gathering coordinates a Bitcoin to another. Excavators run a particular programming bundle to record the squares upon the Bitcoin (BSV) blockchain.
Hubs are the establishment of the blockchain. A hub is a digger that joins towards the Bitcoin (BSV) framework to reveal obstructs in addition to process exchanges. Hubs talk with each other by transmitting data inside the conveyed framework with the Bitcoin (BSV) distributed procedure. All system hubs get the arrangements at that point affirm the legitimacy of theirs.
What occurs after?
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An excavator gathers exchanges from the brain pool, independently hashes them, presently amasses them inside an impede. After the exchanges get hashed, the hashes are organized straight into a Merkle Tree (or perhaps a hash tree).
A Merkle Tree is made by orchestrating the distinctive exchange hashes into sets at that point hashing them by and by. The yield is organized into sets and hashed again then over and again, until "the top piece of the tree" is secured. The zenith of the tree is known as a root hash or perhaps Merkle root. Its one hash that presents the entirety of the earlier blends utilized in its age.
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The square's coming up next: is controlled by header
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Mining a square is troublesome in light of the fact that the SHA 256 hash of a square's header ought to be not exactly or maybe equivalent to the objective with the square to be recognized by the framework. Diggers consistently hash the square header in, by emphasizing through the nonce until one inside the framework excavator makes a legitimate block hash.
At the point when found, the originator hub is going to communicate the square on the Bitcoin people group. Different hubs look at to discover if the hash is certifiable and, hence, tack the square into a duplicate of theirs of the blockchain. Therefore, they've up record after that begin dealing with mining another square.
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Blockchain Rewards
The underlying advance in blockchain mining is including a coinbase exchange, e.g., an unmistakable sort of bitcoin exchange that can simply be created by a digger. This exchange doesn't have any sources of info, and there's an individual comprised of each fresh out of the plastic new impede mined on the Bitcoin (BSV) people group. Any exchange and square rewards expenses got together by the digger are presented this exchange as pay for finding the new square.
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What are the impediment of Bitcoin as a Transaction Currency?
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While it was made as a methods for doing electronic, distributed exchanges, the idea isn't versatile at this stage. It relies a great deal upon confirmation of-work, which happens to be a strategy used to affirm that an arrangement came to fruition.
bitcoin customer care number ⑧③③~⑤④⓪~⓪ ⑨①⓪
The benefit of using this technique is that proprietors on the Bitcoin framework don't need to know or even have faith in each other. Neither do they rely on a last gathering as the fundamental force that has an extreme state over an exchange? The procedure's advantages are accessible for speed, in any case. The Bitcoin framework can just oversee seven exchanges for every second.
bitcoin customer care number ⑧③③~⑤④⓪~⓪ ⑨①⓪
Considerably more unequivocally, every ten mins, a clump of exchanges (alluded to for discourage of activities, along these lines, "square" chain) is affirmed. The issue, in any case, is the bunch is sufficiently enormous to fit a great deal of exchanges. In the event that, for example, you head over Starbucks, and you make a purchase with Bitcoin, in the most ideal situation, your espresso purchase is put into the following cluster. It's checked under ten minutes if Starbucks is sufficient just to remember one confirmation (there are chances associated with just tolerating one affirmation, however we won't get into that in this occurrence).
bitcoin customer care number ⑧③③~⑤④⓪~⓪ ⑨①⓪
On the other side, if there's a broad rundown of exchanges in front of you, your coffee exchange probably won't get by into that next group. What winds up happening would be that your buy gets lined set up for another shipment. The line which the exchange is persistently holding up in is known as the mempool. Presently you've to hold up an extra ten minutes after the earlier cluster of exchanges is finished; i.e., you've to wait for as much as twenty minutes. And still, at the end of the day, there's just no assurance. Maybe, at this point, you discover the point and unquestionably will see unequivocally how troubling it will become to buy a mug of coffee with Bitcoin.
bitcoin customer care number ⑧③③~⑤④⓪~⓪ ⑨①⓪
On the off chance that you exchange on each brought together trade, in spite of the fact that, you could be imagining that Bitcoin speeds are close moment that is a deception. On brought together trades, all the bitcoin is kept in one area. The Bitcoin of yours and mine are aggregate. The trade deals with a database that gives and takes away a history on the Bitcoin you own, subject to each exchange. That is the explanation. Bitcoin maximalists contend that you don't genuinely have your Bitcoin except if it is in your wallet; on the off chance that it lays on a trade, you're represented by chance. The exchange may vanish one day with the entirety of your coins, or perhaps only level out decline to furnish you with the coins you purchased.
bitcoin customer care number ⑧③③~⑤④⓪~⓪ ⑨①⓪
As a retail establishment of worth, Bitcoin has a few great properties. In the first place, it could be had and effectively put away. In contrast to gold, Bitcoin might be put away for a USB stick, regardless of the amount you have. Gold occupies genuine physical room, and holding extensive measures of it can get obvious. Bitcoin likewise offers a fixed cost. Altogether, there'll be close to twenty-one million Bitcoin promptly accessible to the world.
Think about Bitcoin exchange
How Are BITCOIN TRANSACTIONS Processed?
The Bitcoin (BSV) blockchain supports an open record that will keep a background marked by the majority of the exchanges that occurred. Each hub on the framework has a total message of the bookkeeping. Mining will be where extra exchanges between individuals are checked and placed into the Bitcoin (BSV) open record and the way the blockchain is made sure about. Along these lines, blockchain mining will be where fresh out of the box new Bitcoin (BSV) coins are printed and furthermore brought into the current flowing flexibly.
How Does Mining Work?
Mining is a fundamental segment that empowers the Bitcoin (BSV) blockchain to work being a decentralized shared framework with zero outsider focal position. In expansive phrasing, exchanges become brought into the blockchain by hubs when one specific social gathering coordinates a Bitcoin to another. Excavators run a particular programming bundle to record the squares upon the Bitcoin (BSV) blockchain.
Hubs are the establishment of the blockchain. A hub is a digger that joins towards the Bitcoin (BSV) framework to reveal obstructs in addition to process exchanges. Hubs talk with each other by transmitting data inside the conveyed framework with the Bitcoin (BSV) distributed procedure. All system hubs get the arrangements at that point affirm the legitimacy of theirs.
What occurs after?
bitcoin customer care number ⑧③③~⑤④⓪~⓪ ⑨①⓪
An excavator gathers exchanges from the brain pool, independently hashes them, presently amasses them inside an impede. After the exchanges get hashed, the hashes are organized straight into a Merkle Tree (or perhaps a hash tree).
A Merkle Tree is made by orchestrating the distinctive exchange hashes into sets at that point hashing them by and by. The yield is organized into sets and hashed again then over and again, until "the top piece of the tree" is secured. The zenith of the tree is known as a root hash or perhaps Merkle root. Its one hash that presents the entirety of the earlier blends utilized in its age.
bitcoin customer care number ⑧③③~⑤④⓪~⓪ ⑨①⓪
The square's coming up next: is controlled by header
bitcoin customer care number ⑧③③~⑤④⓪~⓪ ⑨①⓪
Mining a square is troublesome in light of the fact that the SHA 256 hash of a square's header ought to be not exactly or maybe equivalent to the objective with the square to be recognized by the framework. Diggers consistently hash the square header in, by emphasizing through the nonce until one inside the framework excavator makes a legitimate block hash.
At the point when found, the originator hub is going to communicate the square on the Bitcoin people group. Different hubs look at to discover if the hash is certifiable and, hence, tack the square into a duplicate of theirs of the blockchain. Therefore, they've up record after that begin dealing with mining another square.
bitcoin customer care number ⑧③③~⑤④⓪~⓪ ⑨①⓪
Blockchain Rewards
The underlying advance in blockchain mining is including a coinbase exchange, e.g., an unmistakable sort of bitcoin exchange that can simply be created by a digger. This exchange doesn't have any sources of info, and there's an individual comprised of each fresh out of the plastic new impede mined on the Bitcoin (BSV) people group. Any exchange and square rewards expenses got together by the digger are presented this exchange as pay for finding the new square.
Bitcoin support number.
Bitcoin technical support number.
Bitcoin helpline number.
Bitcoin toll free number.
Bitcoin customer care number.
Bitcoin customer service.
bitcoin customer care number ⑧③③~⑤④⓪~⓪ ⑨①⓪
submitted by SpareEbb7035 to u/SpareEbb7035 [link] [comments]

Looking for Technical Information about Mining Pools

I'm doing research on how exactly bitcoins are mined, and I'm looking for detailed information about how mining pools work - i.e. what exactly is the pool server telling each participating miner to do.
It's so far my understanding that, when Bitcoins are mined, the following steps take place:
  1. Transactions from the mempool are selected for a new block; this may or may not be all the transactions in said mempool. A coinable transaction - which consists of the miner's wallet's address and other arbitrary data - that will help create new Bitcoin will also be added to the new block.
  2. All of said transactions are hashed together into a Merkle Root. The hashing algorithm is Double SHA-256.
  3. A block header is formed for the new block. Said block header consists of a Version, the Block Hash of the Previous Block in the Blockchain, said Merkle Root from earlier, a timestamp in UTC, the target, and a nonce - which is 32 bits long and can be any value from 0x00000000 to 0xFFFFFFFF (a total of 4,294,967,296 nonce values in total).
  4. The nonce value is set to 0x00000000, and said block header is double hashed to get the Block Hash of the current block; and if said Block Hash starts with a certain number of zeroes (depending on the difficulty), the miner sends the block to the Bitcoin Network, the block successfully added to the blockchain and the miner is awarded with newly created bitcoin.
  5. But if said Block Hash does not start with the required number of zeroes, said block will not be accepted by the network, and the miner Double Hashes the block again, but with a different nonce value; but if none of the 4,294,967,296 nonce values yields a Block Hash with the required number of zeroes, it will be impossible to add the block to the network - and in that case, the miner will either need to change the timestamp and try all 4,294,967,296 nonce values again, or the miner will need to start all over again and compose a new block with a different set of transactions (either a different coinable transaction, a different set of transactions from the mempool, or both).
Now, what I'm trying to figure out is what exactly each miner is doing differently in a mining pool, and if it is different depending on the pool.
One thing I've read is that a mining pool gives each participating miner a different set of transactions from the mempool.
I've also read that, because the most sophisticated miners can try all 4,294,967,296 nonce values in less than a fraction of a second, and since the timestamp can only be updated every second, the coinbase transaction is used as a "second nonce" (although, it is my understanding that, being part of a transaction, if this "extra nonce" is changed, all the transactions need to be double hashed into a new Merkle Root); and I may have read someplace that miners could also be given the same set of transactions from the mempool, but are each told to use a different set of "extra nonce" values for the coinbase transaction.
Is there anything else that pools tell miners to do differently? Is each pool different in the instructions it gives to the participating miners? Did I get anything wrong?
I want to make sure I have a full technical understanding of what mining pools are doing to mine bitcoin.
submitted by sparky77734 to Bitcoin [link] [comments]

Bitcoin (BTC)A Peer-to-Peer Electronic Cash System.

Bitcoin (BTC)A Peer-to-Peer Electronic Cash System.
  • Bitcoin (BTC) is a peer-to-peer cryptocurrency that aims to function as a means of exchange that is independent of any central authority. BTC can be transferred electronically in a secure, verifiable, and immutable way.
  • Launched in 2009, BTC is the first virtual currency to solve the double-spending issue by timestamping transactions before broadcasting them to all of the nodes in the Bitcoin network. The Bitcoin Protocol offered a solution to the Byzantine Generals’ Problem with a blockchain network structure, a notion first created by Stuart Haber and W. Scott Stornetta in 1991.
  • Bitcoin’s whitepaper was published pseudonymously in 2008 by an individual, or a group, with the pseudonym “Satoshi Nakamoto”, whose underlying identity has still not been verified.
  • The Bitcoin protocol uses an SHA-256d-based Proof-of-Work (PoW) algorithm to reach network consensus. Its network has a target block time of 10 minutes and a maximum supply of 21 million tokens, with a decaying token emission rate. To prevent fluctuation of the block time, the network’s block difficulty is re-adjusted through an algorithm based on the past 2016 block times.
  • With a block size limit capped at 1 megabyte, the Bitcoin Protocol has supported both the Lightning Network, a second-layer infrastructure for payment channels, and Segregated Witness, a soft-fork to increase the number of transactions on a block, as solutions to network scalability.

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1. What is Bitcoin (BTC)?

  • Bitcoin is a peer-to-peer cryptocurrency that aims to function as a means of exchange and is independent of any central authority. Bitcoins are transferred electronically in a secure, verifiable, and immutable way.
  • Network validators, whom are often referred to as miners, participate in the SHA-256d-based Proof-of-Work consensus mechanism to determine the next global state of the blockchain.
  • The Bitcoin protocol has a target block time of 10 minutes, and a maximum supply of 21 million tokens. The only way new bitcoins can be produced is when a block producer generates a new valid block.
  • The protocol has a token emission rate that halves every 210,000 blocks, or approximately every 4 years.
  • Unlike public blockchain infrastructures supporting the development of decentralized applications (Ethereum), the Bitcoin protocol is primarily used only for payments, and has only very limited support for smart contract-like functionalities (Bitcoin “Script” is mostly used to create certain conditions before bitcoins are used to be spent).

2. Bitcoin’s core features

For a more beginner’s introduction to Bitcoin, please visit Binance Academy’s guide to Bitcoin.

Unspent Transaction Output (UTXO) model

A UTXO transaction works like cash payment between two parties: Alice gives money to Bob and receives change (i.e., unspent amount). In comparison, blockchains like Ethereum rely on the account model.
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Nakamoto consensus

In the Bitcoin network, anyone can join the network and become a bookkeeping service provider i.e., a validator. All validators are allowed in the race to become the block producer for the next block, yet only the first to complete a computationally heavy task will win. This feature is called Proof of Work (PoW).
The probability of any single validator to finish the task first is equal to the percentage of the total network computation power, or hash power, the validator has. For instance, a validator with 5% of the total network computation power will have a 5% chance of completing the task first, and therefore becoming the next block producer.
Since anyone can join the race, competition is prone to increase. In the early days, Bitcoin mining was mostly done by personal computer CPUs.
As of today, Bitcoin validators, or miners, have opted for dedicated and more powerful devices such as machines based on Application-Specific Integrated Circuit (“ASIC”).
Proof of Work secures the network as block producers must have spent resources external to the network (i.e., money to pay electricity), and can provide proof to other participants that they did so.
With various miners competing for block rewards, it becomes difficult for one single malicious party to gain network majority (defined as more than 51% of the network’s hash power in the Nakamoto consensus mechanism). The ability to rearrange transactions via 51% attacks indicates another feature of the Nakamoto consensus: the finality of transactions is only probabilistic.
Once a block is produced, it is then propagated by the block producer to all other validators to check on the validity of all transactions in that block. The block producer will receive rewards in the network’s native currency (i.e., bitcoin) as all validators approve the block and update their ledgers.

The blockchain

Block production

The Bitcoin protocol utilizes the Merkle tree data structure in order to organize hashes of numerous individual transactions into each block. This concept is named after Ralph Merkle, who patented it in 1979.
With the use of a Merkle tree, though each block might contain thousands of transactions, it will have the ability to combine all of their hashes and condense them into one, allowing efficient and secure verification of this group of transactions. This single hash called is a Merkle root, which is stored in the Block Header of a block. The Block Header also stores other meta information of a block, such as a hash of the previous Block Header, which enables blocks to be associated in a chain-like structure (hence the name “blockchain”).
An illustration of block production in the Bitcoin Protocol is demonstrated below.

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Block time and mining difficulty

Block time is the period required to create the next block in a network. As mentioned above, the node who solves the computationally intensive task will be allowed to produce the next block. Therefore, block time is directly correlated to the amount of time it takes for a node to find a solution to the task. The Bitcoin protocol sets a target block time of 10 minutes, and attempts to achieve this by introducing a variable named mining difficulty.
Mining difficulty refers to how difficult it is for the node to solve the computationally intensive task. If the network sets a high difficulty for the task, while miners have low computational power, which is often referred to as “hashrate”, it would statistically take longer for the nodes to get an answer for the task. If the difficulty is low, but miners have rather strong computational power, statistically, some nodes will be able to solve the task quickly.
Therefore, the 10 minute target block time is achieved by constantly and automatically adjusting the mining difficulty according to how much computational power there is amongst the nodes. The average block time of the network is evaluated after a certain number of blocks, and if it is greater than the expected block time, the difficulty level will decrease; if it is less than the expected block time, the difficulty level will increase.

What are orphan blocks?

In a PoW blockchain network, if the block time is too low, it would increase the likelihood of nodes producingorphan blocks, for which they would receive no reward. Orphan blocks are produced by nodes who solved the task but did not broadcast their results to the whole network the quickest due to network latency.
It takes time for a message to travel through a network, and it is entirely possible for 2 nodes to complete the task and start to broadcast their results to the network at roughly the same time, while one’s messages are received by all other nodes earlier as the node has low latency.
Imagine there is a network latency of 1 minute and a target block time of 2 minutes. A node could solve the task in around 1 minute but his message would take 1 minute to reach the rest of the nodes that are still working on the solution. While his message travels through the network, all the work done by all other nodes during that 1 minute, even if these nodes also complete the task, would go to waste. In this case, 50% of the computational power contributed to the network is wasted.
The percentage of wasted computational power would proportionally decrease if the mining difficulty were higher, as it would statistically take longer for miners to complete the task. In other words, if the mining difficulty, and therefore targeted block time is low, miners with powerful and often centralized mining facilities would get a higher chance of becoming the block producer, while the participation of weaker miners would become in vain. This introduces possible centralization and weakens the overall security of the network.
However, given a limited amount of transactions that can be stored in a block, making the block time too longwould decrease the number of transactions the network can process per second, negatively affecting network scalability.

3. Bitcoin’s additional features

Segregated Witness (SegWit)

Segregated Witness, often abbreviated as SegWit, is a protocol upgrade proposal that went live in August 2017.
SegWit separates witness signatures from transaction-related data. Witness signatures in legacy Bitcoin blocks often take more than 50% of the block size. By removing witness signatures from the transaction block, this protocol upgrade effectively increases the number of transactions that can be stored in a single block, enabling the network to handle more transactions per second. As a result, SegWit increases the scalability of Nakamoto consensus-based blockchain networks like Bitcoin and Litecoin.
SegWit also makes transactions cheaper. Since transaction fees are derived from how much data is being processed by the block producer, the more transactions that can be stored in a 1MB block, the cheaper individual transactions become.
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The legacy Bitcoin block has a block size limit of 1 megabyte, and any change on the block size would require a network hard-fork. On August 1st 2017, the first hard-fork occurred, leading to the creation of Bitcoin Cash (“BCH”), which introduced an 8 megabyte block size limit.
Conversely, Segregated Witness was a soft-fork: it never changed the transaction block size limit of the network. Instead, it added an extended block with an upper limit of 3 megabytes, which contains solely witness signatures, to the 1 megabyte block that contains only transaction data. This new block type can be processed even by nodes that have not completed the SegWit protocol upgrade.
Furthermore, the separation of witness signatures from transaction data solves the malleability issue with the original Bitcoin protocol. Without Segregated Witness, these signatures could be altered before the block is validated by miners. Indeed, alterations can be done in such a way that if the system does a mathematical check, the signature would still be valid. However, since the values in the signature are changed, the two signatures would create vastly different hash values.
For instance, if a witness signature states “6,” it has a mathematical value of 6, and would create a hash value of 12345. However, if the witness signature were changed to “06”, it would maintain a mathematical value of 6 while creating a (faulty) hash value of 67890.
Since the mathematical values are the same, the altered signature remains a valid signature. This would create a bookkeeping issue, as transactions in Nakamoto consensus-based blockchain networks are documented with these hash values, or transaction IDs. Effectively, one can alter a transaction ID to a new one, and the new ID can still be valid.
This can create many issues, as illustrated in the below example:
  1. Alice sends Bob 1 BTC, and Bob sends Merchant Carol this 1 BTC for some goods.
  2. Bob sends Carols this 1 BTC, while the transaction from Alice to Bob is not yet validated. Carol sees this incoming transaction of 1 BTC to him, and immediately ships goods to B.
  3. At the moment, the transaction from Alice to Bob is still not confirmed by the network, and Bob can change the witness signature, therefore changing this transaction ID from 12345 to 67890.
  4. Now Carol will not receive his 1 BTC, as the network looks for transaction 12345 to ensure that Bob’s wallet balance is valid.
  5. As this particular transaction ID changed from 12345 to 67890, the transaction from Bob to Carol will fail, and Bob will get his goods while still holding his BTC.
With the Segregated Witness upgrade, such instances can not happen again. This is because the witness signatures are moved outside of the transaction block into an extended block, and altering the witness signature won’t affect the transaction ID.
Since the transaction malleability issue is fixed, Segregated Witness also enables the proper functioning of second-layer scalability solutions on the Bitcoin protocol, such as the Lightning Network.

Lightning Network

Lightning Network is a second-layer micropayment solution for scalability.
Specifically, Lightning Network aims to enable near-instant and low-cost payments between merchants and customers that wish to use bitcoins.
Lightning Network was conceptualized in a whitepaper by Joseph Poon and Thaddeus Dryja in 2015. Since then, it has been implemented by multiple companies. The most prominent of them include Blockstream, Lightning Labs, and ACINQ.
A list of curated resources relevant to Lightning Network can be found here.
In the Lightning Network, if a customer wishes to transact with a merchant, both of them need to open a payment channel, which operates off the Bitcoin blockchain (i.e., off-chain vs. on-chain). None of the transaction details from this payment channel are recorded on the blockchain, and only when the channel is closed will the end result of both party’s wallet balances be updated to the blockchain. The blockchain only serves as a settlement layer for Lightning transactions.
Since all transactions done via the payment channel are conducted independently of the Nakamoto consensus, both parties involved in transactions do not need to wait for network confirmation on transactions. Instead, transacting parties would pay transaction fees to Bitcoin miners only when they decide to close the channel.
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One limitation to the Lightning Network is that it requires a person to be online to receive transactions attributing towards him. Another limitation in user experience could be that one needs to lock up some funds every time he wishes to open a payment channel, and is only able to use that fund within the channel.
However, this does not mean he needs to create new channels every time he wishes to transact with a different person on the Lightning Network. If Alice wants to send money to Carol, but they do not have a payment channel open, they can ask Bob, who has payment channels open to both Alice and Carol, to help make that transaction. Alice will be able to send funds to Bob, and Bob to Carol. Hence, the number of “payment hubs” (i.e., Bob in the previous example) correlates with both the convenience and the usability of the Lightning Network for real-world applications.

Schnorr Signature upgrade proposal

Elliptic Curve Digital Signature Algorithm (“ECDSA”) signatures are used to sign transactions on the Bitcoin blockchain.
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However, many developers now advocate for replacing ECDSA with Schnorr Signature. Once Schnorr Signatures are implemented, multiple parties can collaborate in producing a signature that is valid for the sum of their public keys.
This would primarily be beneficial for network scalability. When multiple addresses were to conduct transactions to a single address, each transaction would require their own signature. With Schnorr Signature, all these signatures would be combined into one. As a result, the network would be able to store more transactions in a single block.
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The reduced size in signatures implies a reduced cost on transaction fees. The group of senders can split the transaction fees for that one group signature, instead of paying for one personal signature individually.
Schnorr Signature also improves network privacy and token fungibility. A third-party observer will not be able to detect if a user is sending a multi-signature transaction, since the signature will be in the same format as a single-signature transaction.

4. Economics and supply distribution

The Bitcoin protocol utilizes the Nakamoto consensus, and nodes validate blocks via Proof-of-Work mining. The bitcoin token was not pre-mined, and has a maximum supply of 21 million. The initial reward for a block was 50 BTC per block. Block mining rewards halve every 210,000 blocks. Since the average time for block production on the blockchain is 10 minutes, it implies that the block reward halving events will approximately take place every 4 years.
As of May 12th 2020, the block mining rewards are 6.25 BTC per block. Transaction fees also represent a minor revenue stream for miners.
submitted by D-platform to u/D-platform [link] [comments]

TKEYSPACE — blockchain in your mobile

TKEYSPACE — blockchain in your mobile

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Someone says that the blockchain in the phone is marketing. This is possible for most applications, but not for Tkeycoin. Today we will talk about how the blockchain works in the TkeySpace app.
Who else is not in the topic, TkeySpace is a financial application for decentralized and efficient management of various cryptocurrencies, based on a distributed architecture without using a client-server.
In simple words, it is a blockchain in the user’s mobile device that excludes hacking and hacker attacks, and all data is encrypted using modern cryptographic methods.
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Blockchain

Let’s start with the most important thing — the blockchain works on the principles of P2P networks, when there is no central server and each device is both a server and a client, such an organization allows you to maintain the network performance with any number and any combination of available nodes.
For example, there are 12 machines in the network, and anyone can contact anyone. As a client (resource consumer), each of these machines can send requests for the provision of some resources to other machines within this network and receive them. As a server, each machine must process requests from other machines in the network, send what was requested, and perform some auxiliary and administrative functions.
With traditional client-server systems, we can get a completely disabled social network, messenger, or another service, given that we rely on a centralized infrastructure — we have a very specific number of points of failure. If the main data center is damaged due to an earthquake or any other event, access to information will be slowed down or completely disabled.
With a P2P solution, the failure of one network member does not affect the network operation in any way. P2P networks can easily switch to offline mode when the channel is broken — in which it will exist completely independently and without any interaction.
Instead of storing information in a single central point, as traditional recording methods do, multiple copies of the same data are stored in different locations and on different devices on the network, such as computers or mobile devices.

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This means that even if one storage point is damaged or lost, multiple copies remain secure in other locations. Similarly, if one part of the information is changed without the consent of the rightful owners, there are many other copies where the information is correct, which makes the false record invalid.
The information recorded in the blockchain can take any form, whether it is a transfer of money, ownership, transaction, someone’s identity, an agreement between two parties, or even how much electricity a light bulb used.
However, this requires confirmation from multiple devices, such as nodes in the network. Once an agreement, otherwise known as consensus, is reached between these devices to store something on the blockchain — it can’t be challenged, deleted, or changed.
The technology also allows you to perform a truly huge amount of computing in a relatively short time, which even on supercomputers would require, depending on the complexity of the task, many years or even centuries of work. This performance is achieved because a certain global task is divided into a large number of blocks, which are simultaneously performed by hundreds of thousands of devices participating in the project.

P2P messaging and syncing in TkeySpace

TkeySpace is a node of the TKEY network and other supported networks. when you launch the app, your mobile node connects to an extensive network of supported blockchains, syncs with full nodes to validate transactions and incoming information between nodes, so the nodes organize a graph of connections between them.
You can always check the node information in the TkeySpace app in the ⚙ Settings Contact and peer info App Status;

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TkeySpace creates initiating connections to servers registered in the blockchain Protocol as the main ones, from these servers it gets the addresses of nodes to which it can join, in turn, the nodes to which the connection occurred share information about other nodes.

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TkeySpace sends network messages to nodes from supported blockchains in the app to get up-to-date data from the network.
The Protocol uses data structures for communication between nodes, such as block propagation over the network, so before network messages are read, nodes check the “magic number”, check the first bytes, and determine the type of data structure. In the blockchain, the “magic number” is the network ID used to filter messages and block traffic from other p2p networks.
Magic numbers are used in computer science, both for files and protocols. They identify the type of file/data structure. A program that receives such a file/data structure can check the magic number and immediately find out the intended type of this file/data structure.
The first message that your node sends is called a Version Message. In response, the node waits for a Verack message to establish a connection between other peers. The exchange of such messages is called a “handshake”.

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After the “handshake” is set, TkeySpace will start connecting to other nodes in the network to determine the last block at the end of the required blockchain. At this point — nodes request information about blocks they know using GetBlock messages — in response, your node receives an inv (Inventory Message) from another node with the information that it has the information that was requested by the TkeySpace node.
In response to the received message, inv — TkeySpace sends a GetData message containing a list of blocks starting immediately after the last known hash.

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Loading and storing blocks

After exchanging messages, the block information is loaded and transactions are uploaded to your node. To avoid storing tons of information and optimize hard disk space and data processing speed, we use RDBMS — PostgreSQL in full nodes (local computer wallet).
In the TkeySpace mobile app, we use SQLite, and validation takes place by uploading block headers through the Merkle Tree, using the bloom filter — this allows you to optimize the storage of your mobile device as much as possible.
The block header includes its hash, the hash of the previous block, transaction hashes, and additional service information.
Block headers in the Tkeycoin network=84 bytes due to the extension of parameters to support nChains, which will soon be launched in “combat” mode. The titles of the Bitcoin block, Dash, Litecoin=80 bytes.

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And so, let’s continue — application nodes receive information from the blockchain by uploading block headers, all data is synchronized using the Merkle Tree, or rather your node receives and validates information from the Merkle root.
The hash tree was developed in 1979 by Ralph Merkle and named in his honor. The structure of the system has received this name also because it resembles a tree.
The Merkle tree is a complete binary tree with leaf vertexes containing hashes from data blocks, and inner vertexes containing hashes from adding values in child vertexes. The root node of the tree contains a hash from the entire data set, meaning the hash tree is a unidirectional hash function. The Merkle tree is used for the efficient storage of transactions in the cryptocurrency blockchain. It allows you to get a “fingerprint” of all transactions in the block, as well as effectively verify transactions.

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Hash trees have an advantage over hash chains or hash functions. When using hash trees, it is much less expensive to prove that a certain block of data belongs to a set. Since different blocks are often independent data, such as transactions or parts of files, we are interested in being able to check only one block without recalculating the hashes for the other nodes in the tree.
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The Merkle Tree scheme allows you to check whether the hash value of a particular transaction is included in Merkle Root, without having all the other transactions in the block. So by having the transaction, block header, and Merkle Branch for that transaction requested from the full node, the digital wallet can make sure that the transaction was confirmed in a specific block.

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The Merkle tree, which is used to prove that a transaction is included in a block, is also very well scaled. Because each new “layer” added to the tree doubles the total number of “leaves” it can represent. You don’t need a deep tree to compactly prove transaction inclusion, even among blocks with millions of transactions.

Statistical constants and nChains

To support the Tkeycoin cryptocurrency, the TkeySpace application uses additional statistical constants to prevent serialization of Merkle tree hashes, which provides an additional layer of security.
Also, for Tkeycoin, support for multi-chains (nChains) is already included in the TkeySpace app, which will allow you to use the app in the future with most of the features of the TKEY Protocol, including instant transactions.

The Bloom Filter

An additional level of privacy is provided by the bloom filter — which is a probabilistic data structure that allows you to check whether an element belongs to a set.

https://preview.redd.it/7ejkvi82stx41.png?width=374&format=png&auto=webp&s=ed75cd056949fc3a2bcf48b4d7ea78d3dc6d81f3
The bloom filter looks for whether a particular transaction is linked to Alice, not whether Alice has a specific cryptocurrency. In this way, transactions and received IDs are analyzed through a bloom filter. When “Alice wants to know about transaction X”, an ID is requested for transaction X, which is compared with the filled segments in her bloom filter. If “Yes” is received, the node can get the information and verify the transaction.

https://preview.redd.it/gjpsbss3stx41.png?width=1093&format=png&auto=webp&s=4cdcbc827849d13b7d6f0b7e7ba52e65ddc03a82

HD support

The multi-currency wallet TkeySpace is based on HD (or hierarchical determinism), a privacy-oriented method for generating and managing addresses. Each wallet address is generated from an xPub wallet (or extended public key). The app is completely anonymous — and individual address is generated for each transaction to accept a particular cryptocurrency. Even for low-level programming, using the same address is negative for the system, not to mention your privacy. We recommend that you always use a new address for transactions to ensure the necessary level of privacy and security.
The EXT_PUBLIC_KEY and EXT_SECRET_KEY values for DASH, Bitcoin, and Litecoin are completely identical. Tkeycoin uses its values, as well as other methods for storing transactions and blocks (RDBMS), and of course — nChains.

Secret key

Wallets in the blockchain have public and private keys.
https://preview.redd.it/br9kk8n5stx41.png?width=840&format=png&auto=webp&s=a36e4c619451735469a9cff57654d322467e4fba
Centralized applications usually store users’ private keys on their servers, which makes users’ funds vulnerable to hacker attacks or theft.
A private key is a special combination of characters that provides access to cryptocurrencies stored on the account. Only a person who knows the key can move and spend digital assets.
TkeySpace — stores the encrypted key only on the user’s device and in encrypted form. The encrypted key is displayed as a mnemonic phrase (backup phrase), which is very convenient for users. Unlike complex cryptographic ciphers, the phrase is easy to save or write. A backup keyword provides the maximum level of security.
A mnemonic phrase is 12 or 24 words that are generated using random number entropy. If a phrase consists of 12 words, then the number of possible combinations is 204⁸¹² or 21¹³² — the phrase will have 132 security bits. To restore the wallet, you must enter the mnemonic phrase in strict order, as it was presented after generation.

Result

Now we understand that your application TkeySpace is a node of the blockchain that communicates with other nodes using p2p messages, stores block headers and validate information using the Merkle Tree, verifies transactions, filters information using the bloom filter, and operates completely in a decentralized model. The application code contains all the necessary blockchain settings for communicating with the network, the so-called chain parameters.
TkeySpace is a new generation mobile app. A completely new level of security, easy user-friendly interfaces and all the necessary features that are required to work with cryptocurrency.
submitted by tkeycoin to Tkeycoin_Official [link] [comments]

What is Block Explorer?

What is Block Explorer?

https://preview.redd.it/mnk6p5n98ys41.png?width=3800&format=png&auto=webp&s=eb5c999160e1282f94cf966ea9bbe5ff3192d33c
The term “cryptocurrency” and “blockchain” are widely used in this digital era. Surely by now, you must have a grasp on the area of the topic. But, have you heard of “Block Explorer”? At the end of this article, you would be able to understand not only what block explorer is, but, gain a deeper knowledge on what you are able to do and discover on a block explorer.
Simply put, a blockchain explorer or a block explorer is Google Chrome or Safari, only for cryptocurrencies. But of course, it’s called upon a different name such as Etherscan or Blockchain.com. It is a tool to browse through data which is called blocks in order to retrieve wallet addresses, network hashrate, transaction data and other key information on the blockchain.

How Does It Work?

Similar to internet explorers, each object is displayed in human-readable form just like a web page with a specific URL. For instance, on an internet home page, it displays different websites that cover different topics. Through hyperlinks, users are able to switch from one piece of data to another, within a single click.
Whereas on block explorers, by clicking on the hash of an object, users are able to move to the page that displays its data. So, you are able to switch from looking at a transaction, to looking at the previous transaction which gave this transaction its inputs. Once a miner solves a block, it will be added to the blockchain. Then, all block explorers will update on this particular information in real-time.

What Can I Explore?

Each block displays a summary of the block and its transactions such as the following information:
  1. Block reward, weight, size, version
  2. Estimated transaction volume
  3. Number of transactions on the block
  4. Hash of the current block
  5. Hash of previous and next block
  6. Nonce, Merkle Root
  7. Transaction fees
  8. Total coins that was transacted
  9. Who mined the block
  10. When the block was mined
The data displayed in block explorers are interlinked and well connected to one another.

Let’s Start Exploring

The transparency of blockchain enables you to discover all the data at your fingertips. To start, search for a block explorer that supports the blockchain you’re exploring. For example:
  • Blockhain.com for Bitcoin
  • Blockcypher for Litecoin
  • Etherscan for Ethereum
There are many block explorers that provide a platform to gather data on the respective blockchain. Listed above are just a few. Tell us your favourite block explorer.
submitted by everus-world to u/everus-world [link] [comments]

A radical new way to mine Bitcoin?

I have this crazy idea that I feel could Optimize Solo Mining and make it profitable again, and I'm trying to figure out how to build and program a rig so that I could try this:
It is my understanding that, when a new block is created, the miner first generates a Merkle Root from a Merkle Tree consisting of all the transactions that will be listed in the Block (including the Coinbase Transaction), adds said Merkle Root to the new Block's Header, and then tries to find a number between 0 and 4,294,967,295 (the nonce) that, when combined with the rest of the Block's Header and Hashed will result in a Hash with a certain amount of Zeros. If such a nonce is found, then the block is accepted by the Bitcoin Network, added to the Blockchain, and newly created Bitcoin appears in the Miner's Wallet; but, if none of the nonces work, then a new Merkle Root is generated by changing the Coinbase Transaction (but leaving the other transactions the same as before), and the miner again tests all of the possible nonces to see if any of them will result in the proper hash. And all this goes on and on until the miner finds the right combination of Merkle Root and Nonce that will work with the rest of the Block's Header.
Now, because there are 4,294,967,296 possible nonces, this means that the Miner will Hash bad Merkle Root 4,294,967,296 times; which, if you think about it enough seems like such a waste. However, because there is only 612,772 blocks in the blockchain (as of the typing of this post), this also means that it's quite unlikely that any 2 or more Blocks will share the same Nonce (not impossible, but unlikely).
Hence, my idea is to configure a miner so that, instead of checking all 4,294,967,296 possible nonces, an Artificial Intelligence analyses the Blockchain and guesses the best nonce to try, and the Miner then keeps changing the Merkle Root (leaving the nonce the same) until to hopefully finds a Merkle Root that, when Hashed with the previously chosen nonce and the rest of the Block's Header will produce the appropriate Hash in which the Block will be accepted. This can also be scaled up with work with multiple miners: For example, if you have 8 miners, you can have the AI choose the 8 best nonces to try, assign each of those nonces to a single miner, and each miner keeps trying it assigned nonce with different Merkle Roots until one of the miners finds a combination that works.
submitted by sparky77734 to Bitcoin [link] [comments]

Now that the drama is behind us, Bitcoin Core revisits the work on it's Full Block SPV mode! Please review and test.

Now that the drama is behind us, Bitcoin Core revisits the work on it's Full Block SPV mode! Please review and test. submitted by nopara73 to Bitcoin [link] [comments]

Era Swap Network White Paper

Era Swap Network White Paper

Era Swap Network

White Paper



DISCLAIMER
This Whitepaper is for Era Swap Network. Its purpose is solely to provide prospective community members with information about the Era Swap Ecosystem & Era Swap Network project. This paper is for information purposes only and does not constitute and is not intended to be an offer of securities or any other financial or investment instrument in any jurisdiction.
The Developers disclaim any and all responsibility and liability to any person for any loss or damage whatsoever arising directly or indirectly from (1) reliance on any information contained in this paper, (2) any error, omission or inaccuracy in any such information, or (3) any action resulting therefrom
Digital Assets are extremely high-risk, speculative products. You should be aware of the risks involved and fully consider before participating in Digital assets whether it’s appropriate for you. You should only participate if you are an experienced investor with sophisticated knowledge of financial markets and you fully understand the risks associated with digital assets. We strongly advise you to take independent professional advice before making any investment or participating in any way. You should check what rules and protections apply to your respective jurisdictions before investing or participating in any way. The Creators & community will not compensate you for any losses from trading, investment or participating in any way. You should read whitepaper carefully before participating and consider whether these products are right for you.

TABLE OF CONTENT

· Abstract
· Introduction to Era Swap Network
· Development Overview
· Era Swap Utility Platform
· Alpha-release Development Plan
· Era Swap Network Version 1: Specification
· Bunch Structure: 10
· Converting ES-ERC20 to ES-Na:
· Conclusion:
· Era Swap Ecosystem
· Social Links

Abstract

The early smart contracts of Era Swap Ecosystem like TimeAlly, Newly Released Tokens, Assurance, BetDeEx of Era Swap Ecosystem, are deployed on Ethereum mainnet. These smart contracts are finance-oriented (DeFi), i.e. most of the transactions are about spending or earning of Era Swap tokens which made paying the gas fees in Ether somewhat intuitive to the user (withdrawal charges in bank, paying tax while purchasing burgers) but transactions that are not token oriented like adding a nominee or appointee voting also needs Ether to be charged. As more Era Swap Token Utility platform ideas kept appending to the Era Swap Main Whitepaper, more non-financial transaction situations arise like updating status, sending a message, resolving a dispute and so on. Paying extensively for such actions all day and waiting for the transaction to be included in a block and then waiting for enough block confirmations due to potential chain re-organizations is counter-intuitive to existing free solutions like Facebook, Gmail. This is the main barrier that is stopping Web 3.0 from coming to the mainstream.
As alternatives to Ethereum, there are few other smart contract development platforms that propose their own separate blockchain that features for higher transaction throughput, but they compromise on decentralization for improving transaction speeds. Moreover, the ecosystem tools are most advancing in Ethereum than any other platform due to the massive developer community.
With Era Swap Network, the team aims to achieve scalability, speed and low-cost transactions for Era Swap Ecosystem (which is currently not feasible on Ethereum mainnet), without compromising much on trustless asset security for Era Swap Community users.

Introduction to Era Swap Network

Era Swap Network (ESN) aims to solve the above-mentioned problems faced by Era Swap Ecosystem users by building a side-blockchain on top of Ethereum blockchain using the Plasma Framework.
Era Swap Network leverages the Decentralisation and Security of Ethereum and the Scalability achieved in the side-chain, this solves the distributed blockchain trilema. In most of the other blockchains, blocks are a collection of transactions and all the transactions in one block are mined by a miner in one step. Era Swap Network will consist of Bunches of Blocks of Era Swap Ecosystem Transactions.

Decentralization

Layer 2


Scalable and Secure

A miner mines all the blocks in a bunch consequently and will commit the bunch-root to the ESN Plasma Smart Contract on Ethereum mainnet.

Development Overview
Initially, we will start with a simple Proof-of-Authority (PoA) based consensus of EVM to start the development and testing of Era Swap Ecosystem Smart Contracts as quickly as possible on the test-net. We will call this as an alpha-release of ESN test-net and only internal developers will work with this for developing smart contracts for Era Swap Ecosystem. User’s funds in a Plasma implementation with a simple consensus like PoA are still secured as already committed bunch-roots cannot be reversed.
Eventually, we want to arrive on a more control-decentralized consensus algorithm like Proof-of-Stake (PoS) probably, so that even if the chain operator shuts down their services, a single Era Swap Ecosystem user somewhere in the world can keep the ecosystem alive by running software on their system and similarly more people can join to decentralize the control further. In this PoS version, we will modify the Parity Ethereum client in such a way, that at least 50% of transaction fees collected will go to the Luck Pool of NRT Smart Contract on Ethereum mainnet and rest can be kept by miner of the blocks/bunch of blocks if they wish. After achieving such an implementation, we will release this as a beta version to the community for testing the software on their computers with Kovan ERC20 Era Swaps (Ethereum test-net).

Era Swap Decentralised Ecosystem
Following platforms are to be integrated:
  1. Era Swap Token Contract (adapted ERC20 on Ethereum) The original asset will lie on Ethereum to avoid loss due to any kind of failure in ESN.
  2. Plasma Manager Contract (on Ethereum) To store ESN bunch headers on Ethereum.
  3. Reverse Plasma Manager Contract (on ESN) Bridge to convert ES to ES native and ES native to ES. User deposits ES on Mainnet Plasma, gives proof on ESN and gets ES native credited to their account in a decentralised way.
  4. NRT Manager Contract (on Ethereum or on ESN) If it is possible to send ES from an ESN contract to luck pool of NRT Manager Contract on Ethereum, then it’s ok otherwise, NRT Manager will need to be deployed on ESN for ability to add ES to luck pool.
  5. Era Swap Wallet (React Native App for managing ESs and ES natives) Secure wallet to store multiple private keys in it, mainly for managing ES and ES native, sending ES or ES native, also for quick and easy BuzCafe payments.
  6. TimeAlly (on Ethereum or on ESN) On whichever chain NRT Manager is deployed, TimeAlly would be deployed on the same chain.
  7. Assurance (on Ethereum or on ESN) On whichever chain NRT Manager is deployed, TimeAlly would be deployed on the same chain.
  8. DaySwappers (on ESN) KYC manager for platform. For easily distributing rewards to tree referees.
  9. TimeSwappers (on ESN) Freelance market place with decentralised dispute management.
  10. SwappersWall (on ESN) Decentralised social networking with power tokens.
  11. BuzCafe (on ESN) Listing of shops and finding shops easily and quick payment.
  12. BetDeEx (on ESN) Decentralised Prediction proposals, prediction and results.
  13. DateSwappers (on ESN) Meeting ensured using cryptography.
  14. ComputeEx (on Ethereum / centralised way) Exchange assets.
  15. Era Swap Academy (on ESN / centralised way) Learn. Loop. Leap. How to implement ES Academy is not clear. One idea is if content is constantly being modified, then subscription expired people will only have the hash of old content while new content hash is only available to people who have done Dayswapper KYC and paid for the course. Dayswapper KYC is required because this way people won’t share their private keys to someone else.
  16. Value of Farmers (tbd) The exchange of farming commodities produced by farmers in VoF can be deposited to warehouses where the depositors will get ERC721 equivalent tokens for their commodities (based on unique tagging).
  17. DeGameStation (on ESN) Decentralised Gaming Station. Games in which players take turns can be written in Smart Contract. Games like Chess, Poker, 3 Patti can be developed. Users can come to DeGameStation and join an open game or start a new game and wait for other players to join.

Alpha-release Development Plan
  1. Deploying Parity Node customized according to Era Swap Whitepaper with PoA consensus.
  2. Setting up Plasma Smart Contracts.
  3. Creating a bridge for ERC20 Swap from Ethereum test-net to ESN alpha test-net.

Alpha Version
Era Swap Network Version 1 : Specification
The Version 1 release of ESN plans to fulfill the requirements for political decentralisation and transparency in dApps of Era Swap Ecosystem using Blockchain Technology. After acquiring sufficient number of users, a version 2 construction of ESN will be feasible to enable administrative decentralization, such that the Era Swap Ecosystem will be run and managed by the Era Swap Community and will no longer require the operator to support for it's functioning.
Era Swap Network (ESN) Version 1 will be a separate EVM-compatible sidechain attached to Ethereum blockchain as it’s parent chain. ESN will achieve security through Plasma Framework along with Proof-of-Authority consensus for faster finality. The idea behind plasma framework is to avoid high transaction fees and high transaction confirmation times on Ethereum mainnet by instead doing all the ecosystem transactions off-chain and only post a small information to an Ethereum Smart Contract which would represent hash of plenty of ecosystem transactions. Also, to feature movement of Era Swap Tokens from Ethereum blockchain to ESN using cryptographic proof, reverse plasma of Ethereum on ESN will be implemented.
Also, submitting hash of each ESN blocks to ESN Plasma Smart Contract on Ethereum would force ESN to have a block time equal to or more than Ethereum’s 15 second time as well as it would be very much costly for operator to post lot of hashes to an Ethereum Smart Contract. This is why, merkle root of hashes of bunch of blocks would instead be submitted to ESN Plasma Smart Contact on Ethereum.
Actors involved in the ESN:
  1. Block Producer Nodes Lesser the number of nodes, quicker is the block propagation between block producers which can help quick ecosystem transactions. We find that 7 block producers hosted on different could hosting companies and locations reduces the risk of single point of failure of Era Swap Ecosystem and facilitates 100% uptime of dApps. Block Producer Nodes will also be responsible to post the small information to the Blockchain.
  2. Block Listener Nodes Rest of the nodes will be Block Listeners which will sync new blocks produced by the block producer nodes. Plenty of public block listener nodes would be setup in various regions around the world for shorter ping time to the users of Era Swap Ecosystem. Users would submit their Era Swap Ecosystem transactions to one of these public nodes, which would relay them to rest of the Era Swap Network eventually to the block producer nodes which would finalize a new block including the user transaction.
  3. Bunch Committers This will be an instance in the block producers which will watch for new blocks confirmed on ESN and will calculate bunch merkle roots and will submit it to ESN Plasma Smart Contract. This instance will also post hash of new Ethereum blocks to ESN (after about 10 confirmations) for moving assets between both the blockchain.
  4. Users These will be integrating with dApps which would be connected to some public ESN nodes or they can install a block listner node themselves. They can sign and send transactions to the node which they are connected to and then that node will relay their transactions to block producer nodes who would finalise a block including their transaction.

Bunch Structure

A Bunch Structure in Smart Contract will consist of the following:
• Start Block Number: It is the number of first ESN block in the bunch.
• Bunch Depth: It is Merkle Tree depth of blocks in the bunch. For e.g. If bunch depth is 3, there would be 8 blocks in the bunch and if bunch depth is 10, there would be 1024 blocks in the bunch. Bunch depth of Bunches on ESN Plasma Contract is designed to be variable. During the initial phases of ESN, it would be high, for e.g. 15, to avoid ether expenditure and would be decreased in due course of time.
• Transactions Mega Root: This value is the merkle root of all the transaction roots in the bunch. This is used by Smart Contract to verify that a transaction was sent on the chain.
• Receipts Mega Root: This value is the merkle root of all the receipt roots in the bunch. This is used to verify that the transaction execution was successful.
• Timestamp: This value is the time when the bunch proposal was submitted to the smart contract. After submission, there is a challenge period before it is finalised.

Converting ES-ERC20 to ERC-NA and BACK

On Ethereum Blockchain, the first class cryptocurrency is ETH and rest other tokens managed by smart contracts are second class. On ESN, there is an advancement to have Era Swaps as the first class cryptocurrency. This cryptocurrency will feature better user experience and to differentiate it from the classic ERC20 Era Swaps, it will be called as Era Swap Natives (ES-Na). According to the Era Swap Whitepaper, maximum 9.1 Million ES will exist which will be slowly released in circulation every month.
Era Swaps will exist as ES-ERC20 as well as in form of ES-Na. One of these can be exchanged for the other at 1:1 ratio.
Following is how user will convert ES-ERC20 to ES-Na:
  1. User will give allowance to a Deposit Smart Contract, and following that call deposit method to deposit tokens to the contract.
  2. On transaction confirmation, user will paste the transaction hash on a portal which will generate a Proof of Deposit string for the user. This string is generated by fetching all the transactions in the Ethereum Block and generating a Transaction Patricia Merkle Proof to prove that user’s transaction was indeed included in the block and the Receipts Patricia Merkle Proof to confirm that the user’s transaction was successful.
  3. Using the same portal, user will submit the generated proofs to a Smart Contract on ESN, which would release funds to user. Though, user will have to wait for the Etheruem block roots to be posted to ESN after waiting for confirmations which would take about 3 minutes. Once, it’s done user’s proofs will be accepted and will receive exact amount of ES- Na on ESN.
Following is how user will convert ES-Na to ES-ERC20:
  1. ES-Na being first class cryptocurrency, user will simply send ES-Na to a contract.
  2. User will paste the transaction hash on a portal which will generate a Proof of Deposit for the user. Again ES-Na being first class cryptocurrency, Transaction Patricia Merkle Proof is enough to prove that user’s transaction was indeed included in the block. Another thing which will be generated is the block inclusion proof in the bunch.
  3. User will have to wait for the bunch confirmation to the Plasma Smart Contract and once it’s done, user can send the proof to the Plasma Smart Contract to receive ES-ERC20.

HARD Exit

Since the blocks are produced and transactions are validated by few block producers, it exposes a possibility for fraud by controlling the block producer nodes. Because ESN is based on the Plasma Model, when failure of sidechain occurs or the chain halts, users can hard exit their funds directly from the Plasma Smart Contract on Ethereum by giving a Proof of Holdings.

HOld ES Tokens Swapping with New ES Tokens

The old ES Tokens will be valueless as those tokens will not be accepted in ESN because of NRT (New Released Tokens) and TimeAlly contracts on mainnet which is causing high gas to users, hence reducing interactions. Also, there was an event of theft of Era Swap Tokens and after consensus from majority of holders of Era Swap Tokens; it was decided to create a new contract to reverse the theft to secure the value of Era Swap Tokens of the community. Below is the strategy for swapping tokens:
TimeAlly and TSGAP: Majority of Era Swap Community have participated in TimeAlly Smart Contract in which their tokens are locked for certain period of time until which they cannot move them. Such holders will automatically receive TimeAlly staking of specific durations from the operator during initialization of ESN.
Liquid Tokens: Holders of Liquid Era Swap Tokens have to transfer the old tokens to a specified Ethereum wallet address managed by team. Following that, team will audit the token source of the holder (to eliminate exchange of stolen tokens) and send new tokens back to the wallet address.

Post-Genesis Tokens Return Program

Primary asset holding of Era Swap tokens will exist on Ethereum blockchain as an ERC20 compatible standard due to the highly decentralised nature of the blockchain. Similar to how users deposit tokens to an cryptocurrency exchange for trading and then withdraw the tokens back, users will deposit tokens to ESN Contract to enter Era Swap Ecosystem and they can withdraw it back from ESN Contract for exiting from ecosystem network. The design of the token system will be such that, it will be compatible with the future shift (modification or migration of ESN version 1) to ESN version 2, in which an entirely new blockchain setup might be required.
To manage liquidity, following genesis structure will be followed:

Holder ES-ERC20 ES-Na
Team Wallet 1.17 billion (Circulating Supply) 0
Locked in Smart Contract 7.93 billion (pending NRT releases) 9.1 billion
Though it looks like there are 9.1 * 2 = 18.2 Billion ES, but the cryptographic design secures that at any point in time at least a total of 9.1 billion ES (ES-ERC20 + ES-Na) will be locked. To unlock ES-Na on ESN, an equal amount of ES-ERC20 has to be locked on Ethereum and vice-versa.
9.1 billion ES-ERC20 will be issued by ERC20 smart contract on Ethereum Blockchain, out of which the entire circulating supply (including liquid and TimeAlly holdings) of old ES will be received to a team wallet.
TimeAlly holdings of all users will be converted to ES-Na and distributed on ESN TimeAlly Smart Contract by team to the TimeAlly holders on their same wallet address.
Liquid user holdings will be sent back to the users to the wallet address from which they send back old ES tokens (because some old ES are deposited on exchange wallet address).
ES-Na will be issued in the genesis block to an ESN Manager Smart Contract address. It will manage all the deposits and withdrawals as well as NRT releases.

Attack Vectors


Following are identified risks to be taken care of during the development of ESN:
Network Spamming: Attackers can purchase ES from the exchange and make a lot of transactions between two accounts. This is solved by involving gas fees. A setting of 200 nanoES minimum gas price will be set, which can be changed as per convenience.
DDoS: Attackers can query public nodes for computationally heavy output data. This will overload the public node with requests and genuine requests might get delayed. Block producers RPC is private, so they will continue to produce blocks. To manage user’s denial of service, the provider in dApps needs to be designed in such a way such that many public nodes will be queried simple information (let’s say latest block number) and the one which response quickly to user will be selected.
AWS is down: To minimize this issue due to cloud providers down, there will be enough nodes on multiple cloud providers to ensure at least one block producer is alive.
User deposit double spending: User deposits ES on Ethereum, gets ES-Na on ESN. Then the issue happens that there are re-org on ETH mainnet and the user’s transaction is reversed. Since ETH is not a fixed chain and as per PoW 51% attack can change the blocks. As Ethereum is now enough mature and by statistics forked blocks are at most of height 2. So it is safe to consider 15 confirmations.
Exit Game while smooth functioning: User starts a hard exit directly from Plasma Smart Contract on Ethereum, then spends his funds from the plasma chain too. To counter this, the exit game will be disabled, only when ESN halts, i.e. fails to submit block header within the time the exit game starts. This is because it is difficult to mark user’s funds as spent on ESN.
Vulnerability in Ecosystem Smart Contracts: Using traditional methods to deploy smart contracts results in a situation where if a bug is found later, it is not possible to change the code. Using a proxy construction for every ecosystem smart contract solves this problem, and changing a proxy can be given to a small committee in which 66% of votes are required, this is to prevent a malicious change of code due to compromising of a single account or similar scenario.
ChainID replay attacks: Using old and traditional ways to interact with dApps can cause loss to users, hence every dApp will be audited for the same.

Conclusion

Era Swap Network is an EVM-compatible sidechain attached to the Ethereum blockchain through Plasma Framework. This allows off-chain processing of Era Swap Ecosystem transactions and posting only the hash of the bunch to Ethereum. This greatly reduces the high network fee and confirmation time issues faced by the current Era Swap Ecosystem DApps deployed on Ethereum. Also, having a separate EVM-compatible blockchain tailored to Era Swap Ecosystem improves the user experience to a higher extent. Since by design, Plasma Framework makes the Era Swap Network as secure as the Ethereum Network, user's funds on the network would be secure as well.
We believe Era Swap Network will help scale dApps of Era Swap Ecosystem to onboard the increasing numbers of users.


Era Swap Ecosystem
Era Swap Ecosystem consist of multiple interlinked platforms which is powered by Era swap (ES) token, a decentralized utility token to be used on below utility platforms. Users can access the Platforms through Era Swap Life which is the Single Sign on (SSO) gateway to the one world of Era Swap Ecosystem.
Era Swap Life: https://eraswap.life/
TimeAlly DApp -> Decentralized Token Vesting: https://www.timeally.io/
BetDeEx -> Decentralized prediction platform: https://www.betdeex.com/
Swappers Wall -> Social Time Ledgerise: https://timeswappers.com/swapperswall
TimeSwappers -> Global P2P marketplace: https://timeswappers.com/
BuzCafe -> Connects local P2P outlets: https://buzcafe.com/
DaySwappers -> Unique Affiliate Program: https://dayswappers.com/
Era Swap Academy -> E-mart for skill development: https://eraswap.academy/
Value of Farmers (VOF) -> Farming ecosystem: http://valueoffarmers.org/ coming soon
ComputeEx -> P2P lending and borrowing: https://computeex.net/ coming soon
DateSwappers -> Next gen dating: coming soon
Smart Contract address

Era Swap Token (ES)
https://etherscan.io/address/0xef1344bdf80bef3ff4428d8becec3eea4a2cf574#code

Newly Released Token (NRT) https://etherscan.io/address/0x20ee679d73559e4c4b5e3b3042b61be723828d6c#code

TimeAlly DApp
https://etherscan.io/address/0x5630ee5f247bd6b61991fbb2f117bbeb45990876#code

BetDeEx DApp https://etherscan.io/address/0x42225682113E6Ed3616B36B4A72BbaE376041D7c#code
TSGAP DApp
https://etherscan.io/address/0xbad9af4db5401b7d5e8177a18c1d69c35fc03fd3#code

White Paper
Era Swap Whitepaper: https://eraswaptoken.io/pdf/eraswap_whitepaper.pdf
Era Swap Light Paper: https://eraswaptoken.io/pdf/eraswap_lightpaper.pdf

Howey Test
Howey Test: https://eraswaptoken.io/era-swap-howey-test-letter-august7-2018.php

Era Swap SOCIAL LINKS
Telegram: https://t.me/eraswap
Twitter: https://twitter.com/eraswaptec
Facebook: https://www.facebook.com/eraswap/
Instagram: https://www.instagram.com/eraswap/
BitcoinTalk: https://bitcointalk.org/index.php?topic=5025979.msg45502457
Youtube: https://www.youtube.com/channel/UCGCP4f5DF1W6sbCjS6y3T1g
LinkedIn: https://www.linkedin.com/company/eraswap/
Reddit: https://www.reddit.com/useEraSwap
Medium: https://medium.com/@eraswap
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submitted by EraSwap to u/EraSwap [link] [comments]

Taproot Is Coming: What It Is, and How It Will Benefit Bitcoin

Taproot Is Coming: What It Is, and How It Will Benefit Bitcoin
https://bitcoinmagazine.com/articles/taproot-coming-what-it-and-how-it-will-benefit-bitcoin/
https://preview.redd.it/okiv5un7j1g21.jpg?width=1600&format=pjpg&auto=webp&s=18e4e8bcdd3d8e60c5a28a8ea90f0008ab1f3b91
Bitcoin users may, before long, be able to benefit from a trick called “Taproot.” First proposed by Bitcoin Core contributor and former Blockstream CTO Gregory Maxwell, Taproot would expand on Bitcoin’s smart contract flexibility, while offering more privacy in doing so. Even the most complex smart contracts would, on the blockchain, typically be indistinguishable from regular transactions.
While a big undertaking, this is not just theory. Several of the most prolific Bitcoin Core contributors — including Pieter Wuille, Anthony Towns, Johnson Lau, Jonas Nick, Andrew Poelstra, Tim Ruffing, Rusty Russell and, indeed, Gregory Maxwell — are working on a Schnorr signature proposal that would include Taproot, all in one protocol upgrade.
Here’s what Taproot is and how it works.
P2SH
All bitcoins are essentially “locked up” in scripts: a couple lines of code embedded in a transaction included in the blockchain, that define how the coins can be spent in the next transaction. Spending conditions usually involve providing a signature to prove ownership of the coins. But other, well-known conditions for example include timelocks (coins can only be spent after a specific block height or date) or multisig (coins can only be spent if some number of private keys out of a set of private keys provide signatures).
Different conditions can be mixed and matched, to create complex types of smart contracts. An example of such a contract could be that coins can be spent if both Alice and Bob sign, or if Alice alone signs after a week has passed, or if Bob alone signs while also providing a secret number. Whichever of these three conditions is met first, is how the coins are spent.
Since 2012, scripts (the conditions) are often not publicly visible at first; only the new owner of the coins knows how they can be spent. This is done with a trick called P2SH (pay to script hash), where initially only a hash of the script is included in the blockchain. This seemingly randomly scrambled number holds the coins. When the owner spends the coins, he reveals the whole script as well as the “solution” to the script at the same time. Anyone can then use the initial hash to check that the supplied script was indeed the original script locking up the coins and can immediately conclude that the requirements of the script were met.
Still, when the coins are spent, it’s currently necessary to reveal all the possible conditions that could have been met — including the conditions that weren’t met. This has two main downsides. One, it’s data heavy, especially if there are many conditions. And two, it’s bad for privacy. Everyone learns all the different ways in which funds could have been spent, which can, for example, reveal what kind of wallet was used and perhaps even more.
MAST
MAST (Merkelized Abstract Syntax Tree) is a proposed solution that uses Merkle trees (a decades-old, compact data structure invented by cryptographer Ralph Merkle) to work around these two downsides. In short, all the different conditions under which the funds can be spent are individually hashed (as opposed to combined into a single hash) and included in a Merkle tree, which ultimately produces a single hash: the Merkle root. This Merkle root “locks up” the coins.
The unique benefit is that if any of the data in the Merkle tree is revealed, the Merkle root and some additional data (called the Merkle path) can be used to verify that that specific data was included in the Merkle tree. The rest of the Merkle tree remains hashed and hidden.
With MAST, this means that only the condition that is met needs to be revealed. If, in the initial example above, Alice alone spends the funds after a week, she just reveals that condition (and the Merkle path). No one learns that the money could have also been spent by Alice and Bob together, or by Bob alone if he’d added a secret number. This makes MAST more data efficient than complex P2SH smart contracts and adds privacy to boot.
Yet with Schnorr, Taproot can do even better: a transaction can hide that a MAST-structure existed at all.
Schnorr
The Schnorr signature scheme has long been on the wishlist of many Bitcoin developers and is currently in development to be deployed as a soft fork protocol upgrade. Many cryptographers consider the Schnorr signature scheme to be the best in the field, as its mathematical properties offer a strong level of correctness, it doesn’t suffer from malleability and is relatively fast to verify.
As its best-known benefit in the context of Bitcoin, Schnorr’s “linear math” allows for signature aggregation: several signatures in the same transaction can be combined into one. A similar trick could be applied to multisig transactions. Combining both public keys and signatures into “threshold public keys” and “threshold signatures,” a multisig transaction can be made indistinguishable from any regular transaction.
And the signature scheme can be used in even more interesting ways. For example, it’s possible to use data to “tweak” both a private key and a public key. As a simplified example, a private key and its corresponding public key could be tweaked by multiplying both by two. The “private key x 2” and the “public key x 2” would still correspond, and the “private key x 2” could still sign messages that could be verified with the “public key x 2.” Anyone unaware that the original key pair was tweaked wouldn’t even see any difference; the tweaked keys look like any other key pair.
This is what enables Taproot.
Taproot
Taproot is based on an interesting realization: no matter how complex, almost any MAST-construction could (or should) include a condition that allows all participants to agree on the outcome and simply sign off on a settlement transaction together. In the earlier example, if Bob knows Alice can, by herself, claim all the funds next week, he might as well cooperate with her now to sign off together. (In many typical smart contract setups he would even be penalized if he doesn’t. The complexity really just serves to keep everyone honest.)
Taproot resembles MAST and always includes a condition where all participants can cooperate to spend the funds: the “cooperative close.”
By utilizing Schnorr signatures, this is where it gets interesting.
First off, the cooperative close would utilize Schnorr’s threshold trick to make it look like a regular transaction, from one person to another. So, the public keys of all participants are added together, resulting in the “threshold public key.” Corresponding with this threshold public key, the combination of all participants’ signatures — their “threshold signature” — allows them to spend the funds.
So far so good, but spending the funds as if it were a normal transaction is the only thing they can do — no MAST-like structures yet. That’s where the other Schnorr trick comes in.
All the alternative ways in which the funds can be spent — the non-cooperative outcomes — are this time combined into a different script. This script, then, is hashed and used to tweak the threshold public key. Rather than “public key x 2,” as used in the example earlier, this results in a “threshold public key x script.” (We’re still simplifying.) This “threshold public key x script” corresponds, of course, to a “threshold signature x script.”
Now, if the money is spent cooperatively, all participants combine their signatures into the “threshold signature” and tweak it with the script. The resulting “threshold signature x script” allows them to spend the funds. Yet, and importantly, to the outside world, all this would still just look like a regular public key and a regular signature — a regular transaction.
Only if a cooperative close proves impossible, the threshold public key can be shown for what it really is: tweaked.
In this case, both the original threshold public key and the script are revealed. This proves that the “threshold public key x script” was tweaked with this specific script. So, like the hash in P2SH, the tweak proves to the world that the funds should be spendable if the alternative conditions, as specified in this script, are met. (And, like with P2SH, these conditions are of course immediately met to spend the funds.)
Alternatively, instead of tweaking the threshold public key with script, the threshold public key can be tweaked with a Merkle root of a Merkle tree that includes all the different conditions under which the funds can be spent: a MAST structure. To spend the funds, then, only the spending condition that’s been met needs to be revealed.
As such, Taproot offers all the benefits of MAST, while under normal circumstances no one will ever know that a regular transaction was hiding such a complex smart contract as a fallback.
This is a general outline of the Taproot concept; implementation specifics may vary. For more details, read the original Taproot proposal by Gregory Maxwell or watch this presentation by Pieter Wuille.
https://bitcoinmagazine.com/articles/taproot-coming-what-it-and-how-it-will-benefit-bitcoin/
submitted by FmzQuant to Bitcoin [link] [comments]

12-13 15:04 - 'Read this went the opposite way' (self.Bitcoin) by /u/fukya40 removed from /r/Bitcoin within 38-48min

'''
// Copyright (c) 2008 Satoshi Nakamoto // // Permission is hereby granted, free of charge, to any person obtaining a copy // of this software and associated documentation files (the "Software"), to deal // in the Software without restriction, including without limitation the rights // to use, copy, modify, merge, publish, distribute, sublicense, and/or sell // copies of the Software, and to permit persons to whom the Software is // furnished to do so, subject to the following conditions: // // The above copyright notice and this permission notice shall be included in // all copies or substantial portions of the Software. // // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR // IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, // FITNESS FOR A PARTICULAR PURPOSE, TITLE AND NON-INFRINGEMENT. IN NO EVENT // SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR // OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING // FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS // IN THE SOFTWARE.
class COutPoint; class CInPoint; class CDiskTxPos; class CCoinBase; class CTxIn; class CTxOut; class CTransaction; class CBlock; class CBlockIndex; class CWalletTx; class CKeyItem;
static const unsigned int MAX_SIZE = 0x02000000; static const int64 COIN = 1000000; static const int64 CENT = 10000; static const int64 TRANSACTIONFEE = 1 * CENT; /// change this to a user options setting, optional fee can be zero ///static const unsigned int MINPROOFOFWORK = 40; /// need to decide the right difficulty to start with static const unsigned int MINPROOFOFWORK = 20; /// ridiculously easy for testing
extern map mapBlockIndex; extern const uint256 hashGenesisBlock; extern CBlockIndex* pindexGenesisBlock; extern int nBestHeight; extern CBlockIndex* pindexBest; extern unsigned int nTransactionsUpdated; extern int fGenerateBitcoins;
FILE* OpenBlockFile(unsigned int nFile, unsigned int nBlockPos, const char* pszMode="rb"); FILE* AppendBlockFile(unsigned int& nFileRet); bool AddKey(const CKey& key); vector GenerateNewKey(); bool AddToWallet(const CWalletTx& wtxIn); void ReacceptWalletTransactions(); void RelayWalletTransactions(); bool LoadBlockIndex(bool fAllowNew=true); bool BitcoinMiner(); bool ProcessMessages(CNode* pfrom); bool ProcessMessage(CNode* pfrom, string strCommand, CDataStream& vRecv); bool SendMessages(CNode* pto); int64 CountMoney(); bool CreateTransaction(CScript scriptPubKey, int64 nValue, CWalletTx& txNew); bool SendMoney(CScript scriptPubKey, int64 nValue, CWalletTx& wtxNew);
class CDiskTxPos { public: unsigned int nFile; unsigned int nBlockPos; unsigned int nTxPos;
CDiskTxPos() { SetNull(); }
CDiskTxPos(unsigned int nFileIn, unsigned int nBlockPosIn, unsigned int nTxPosIn) { nFile = nFileIn; nBlockPos = nBlockPosIn; nTxPos = nTxPosIn; }
IMPLEMENT_SERIALIZE( READWRITE(FLATDATA(*this)); ) void SetNull() { nFile = -1; nBlockPos = 0; nTxPos = 0; } bool IsNull() const { return (nFile == -1); }
friend bool operator==(const CDiskTxPos& a, const CDiskTxPos& b) { return (a.nFile == b.nFile && a.nBlockPos == b.nBlockPos && a.nTxPos == b.nTxPos); }
friend bool operator!=(const CDiskTxPos& a, const CDiskTxPos& b) { return !(a == b); }
void print() const { if (IsNull()) printf("null"); else printf("(nFile=%d, nBlockPos=%d, nTxPos=%d)", nFile, nBlockPos, nTxPos); } };
class CInPoint { public: CTransaction* ptx; unsigned int n;
CInPoint() { SetNull(); } CInPoint(CTransaction* ptxIn, unsigned int nIn) { ptx = ptxIn; n = nIn; } void SetNull() { ptx = NULL; n = -1; } bool IsNull() const { return (ptx == NULL && n == -1); } };
class COutPoint { public: uint256 hash; unsigned int n;
COutPoint() { SetNull(); } COutPoint(uint256 hashIn, unsigned int nIn) { hash = hashIn; n = nIn; } IMPLEMENT_SERIALIZE( READWRITE(FLATDATA(*this)); ) void SetNull() { hash = 0; n = -1; } bool IsNull() const { return (hash == 0 && n == -1); }
friend bool operator<(const COutPoint& a, const COutPoint& b) { return (a.hash < b.hash || (a.hash == b.hash && a.n < b.n)); }
friend bool operator==(const COutPoint& a, const COutPoint& b) { return (a.hash == b.hash && a.n == b.n); }
friend bool operator!=(const COutPoint& a, const COutPoint& b) { return !(a == b); }
void print() const { printf("COutPoint(%s, %d)", hash.ToString().substr(0,6).c_str(), n); } };
// // An input of a transaction. It contains the location of the previous // transaction's output that it claims and a signature that matches the // output's public key. // class CTxIn { public: COutPoint prevout; CScript scriptSig;
CTxIn() { }
CTxIn(COutPoint prevoutIn, CScript scriptSigIn) { prevout = prevoutIn; scriptSig = scriptSigIn; }
CTxIn(uint256 hashPrevTx, unsigned int nOut, CScript scriptSigIn) { prevout = COutPoint(hashPrevTx, nOut); scriptSig = scriptSigIn; }
IMPLEMENT_SERIALIZE ( READWRITE(prevout); READWRITE(scriptSig); )
bool IsPrevInMainChain() const { return CTxDB("r").ContainsTx(prevout.hash); }
friend bool operator==(const CTxIn& a, const CTxIn& b) { return (a.prevout == b.prevout && a.scriptSig == b.scriptSig); }
friend bool operator!=(const CTxIn& a, const CTxIn& b) { return !(a == b); }
void print() const { printf("CTxIn("); prevout.print(); if (prevout.IsNull()) { printf(", coinbase %s)\n", HexStr(scriptSig.begin(), scriptSig.end(), false).c_str()); } else { if (scriptSig.size() >= 6) printf(", scriptSig=%02x%02x", scriptSig[4], scriptSig[5]); printf(")\n"); } }
bool IsMine() const; int64 GetDebit() const; };
// // An output of a transaction. It contains the public key that the next input // must be able to sign with to claim it. // class CTxOut { public: int64 nValue; unsigned int nSequence; CScript scriptPubKey;
// disk only CDiskTxPos posNext; //// so far this is only used as a flag, nothing uses the location
public: CTxOut() { nValue = 0; nSequence = UINT_MAX; }
CTxOut(int64 nValueIn, CScript scriptPubKeyIn, int nSequenceIn=UINT_MAX) { nValue = nValueIn; scriptPubKey = scriptPubKeyIn; nSequence = nSequenceIn; }
IMPLEMENT_SERIALIZE ( READWRITE(nValue); READWRITE(nSequence); READWRITE(scriptPubKey); if (nType & SER_DISK) READWRITE(posNext); )
uint256 GetHash() const { return SerializeHash(*this); }
bool IsFinal() const { return (nSequence == UINT_MAX); }
bool IsMine() const { return ::IsMine(scriptPubKey); }
int64 GetCredit() const { if (IsMine()) return nValue; return 0; }
friend bool operator==(const CTxOut& a, const CTxOut& b) { return (a.nValue == b.nValue && a.nSequence == b.nSequence && a.scriptPubKey == b.scriptPubKey); }
friend bool operator!=(const CTxOut& a, const CTxOut& b) { return !(a == b); }
void print() const { if (scriptPubKey.size() >= 6) printf("CTxOut(nValue=%I64d, nSequence=%u, scriptPubKey=%02x%02x, posNext=", nValue, nSequence, scriptPubKey[4], scriptPubKey[5]); posNext.print(); printf(")\n"); } };
// // The basic transaction that is broadcasted on the network and contained in // blocks. A transaction can contain multiple inputs and outputs. // class CTransaction { public: vector vin; vector vout; unsigned int nLockTime;
CTransaction() { SetNull(); }
IMPLEMENT_SERIALIZE ( if (!(nType & SER_GETHASH)) READWRITE(nVersion);
// Set version on stream for writing back same version if (fRead && s.nVersion == -1) s.nVersion = nVersion;
READWRITE(vin); READWRITE(vout); READWRITE(nLockTime); )
void SetNull() { vin.clear(); vout.clear(); nLockTime = 0; }
bool IsNull() const { return (vin.empty() && vout.empty()); }
uint256 GetHash() const { return SerializeHash(*this); }
bool AllPrevInMainChain() const { foreach(const CTxIn& txin, vin) if (!txin.IsPrevInMainChain()) return false; return true; }
bool IsFinal() const { if (nLockTime == 0) return true; if (nLockTime < GetAdjustedTime()) return true; foreach(const CTxOut& txout, vout) if (!txout.IsFinal()) return false; return true; }
bool IsUpdate(const CTransaction& b) const { if (vin.size() != b.vin.size() || vout.size() != b.vout.size()) return false; for (int i = 0; i < vin.size(); i++) if (vin[i].prevout != b.vin[i].prevout) return false;
bool fNewer = false; unsigned int nLowest = UINT_MAX; for (int i = 0; i < vout.size(); i++) { if (vout[i].nSequence != b.vout[i].nSequence) { if (vout[i].nSequence <= nLowest) { fNewer = false; nLowest = vout[i].nSequence; } if (b.vout[i].nSequence < nLowest) { fNewer = true; nLowest = b.vout[i].nSequence; } } } return fNewer; }
bool IsCoinBase() const { return (vin.size() == 1 && vin[0].prevout.IsNull()); }
bool CheckTransaction() const { // Basic checks that don't depend on any context if (vin.empty() || vout.empty()) return false;
// Check for negative values int64 nValueOut = 0; foreach(const CTxOut& txout, vout) { if (txout.nValue < 0) return false; nValueOut += txout.nValue; }
if (IsCoinBase()) { if (vin[0].scriptSig.size() > 100) return false; } else { foreach(const CTxIn& txin, vin) if (txin.prevout.IsNull()) return false; }
return true; }
bool IsMine() const { foreach(const CTxOut& txout, vout) if (txout.IsMine()) return true; return false; }
int64 GetDebit() const { int64 nDebit = 0; foreach(const CTxIn& txin, vin) nDebit += txin.GetDebit(); return nDebit; }
int64 GetCredit() const { int64 nCredit = 0; foreach(const CTxOut& txout, vout) nCredit += txout.GetCredit(); return nCredit; }
int64 GetValueOut() const { int64 nValueOut = 0; foreach(const CTxOut& txout, vout) { if (txout.nValue < 0) throw runtime_error("CTransaction::GetValueOut() : negative value"); nValueOut += txout.nValue; } return nValueOut; }
bool ReadFromDisk(CDiskTxPos pos, FILE** pfileRet=NULL) { CAutoFile filein = OpenBlockFile(pos.nFile, 0, pfileRet ? "rb+" : "rb"); if (!filein) return false;
// Read transaction if (fseek(filein, pos.nTxPos, SEEK_SET) != 0) return false; filein >> *this;
// Return file pointer if (pfileRet) { if (fseek(filein, pos.nTxPos, SEEK_SET) != 0) return false; *pfileRet = filein.release(); } return true; }
friend bool operator==(const CTransaction& a, const CTransaction& b) { return (a.vin == b.vin && a.vout == b.vout && a.nLockTime == b.nLockTime); }
friend bool operator!=(const CTransaction& a, const CTransaction& b) { return !(a == b); }
void print() const { printf("CTransaction(vin.size=%d, vout.size=%d, nLockTime=%d)\n", vin.size(), vout.size(), nLockTime); for (int i = 0; i < vin.size(); i++) { printf(" "); vin[i].print(); } for (int i = 0; i < vout.size(); i++) { printf(" "); vout[i].print(); } }
bool TestDisconnectInputs(CTxDB& txdb, map& mapTestPool) { return DisconnectInputs(txdb, mapTestPool, true); }
bool TestConnectInputs(CTxDB& txdb, map& mapTestPool, bool fMemoryTx, bool fIgnoreDiskConflicts, int64& nFees) { return ConnectInputs(txdb, mapTestPool, CDiskTxPos(1, 1, 1), 0, true, fMemoryTx, fIgnoreDiskConflicts, nFees); }
bool DisconnectInputs(CTxDB& txdb) { static map mapTestPool; return DisconnectInputs(txdb, mapTestPool, false); }
bool ConnectInputs(CTxDB& txdb, CDiskTxPos posThisTx, int nHeight) { static map mapTestPool; int64 nFees; return ConnectInputs(txdb, mapTestPool, posThisTx, nHeight, false, false, false, nFees); }
private: bool DisconnectInputs(CTxDB& txdb, map& mapTestPool, bool fTest); bool ConnectInputs(CTxDB& txdb, map& mapTestPool, CDiskTxPos posThisTx, int nHeight, bool fTest, bool fMemoryTx, bool fIgnoreDiskConflicts, int64& nFees);
public: bool AcceptTransaction(CTxDB& txdb, bool fCheckInputs=true); bool AcceptTransaction() { CTxDB txdb("r"); return AcceptTransaction(txdb); } bool ClientConnectInputs(); };
// // A transaction with a merkle branch linking it to the timechain // class CMerkleTx : public CTransaction { public: uint256 hashBlock; vector vMerkleBranch; int nIndex;
CMerkleTx() { Init(); }
CMerkleTx(const CTransaction& txIn) : CTransaction(txIn) { Init(); }
void Init() { hashBlock = 0; nIndex = -1; }
IMPLEMENT_SERIALIZE ( nSerSize += SerReadWrite(s, (CTransaction)this, nType, nVersion, ser_action); if (!(nType & SER_GETHASH)) READWRITE(nVersion); READWRITE(hashBlock); READWRITE(vMerkleBranch); READWRITE(nIndex); )
int SetMerkleBranch(); int IsInMainChain() const; bool AcceptTransaction(CTxDB& txdb, bool fCheckInputs=true); bool AcceptTransaction() { CTxDB txdb("r"); return AcceptTransaction(txdb); } };
// // A transaction with a bunch of additional info that only the owner cares // about. It includes any unrecorded transactions needed to link it back // to the timechain. // class CWalletTx : public CMerkleTx { public: vector vtxPrev; map mapValue; vector > vOrderForm; unsigned int nTime; char fFromMe; char fSpent;
//// probably need to sign the order info so know it came from payer
CWalletTx() { Init(); }
CWalletTx(const CMerkleTx& txIn) : CMerkleTx(txIn) { Init(); }
CWalletTx(const CTransaction& txIn) : CMerkleTx(txIn) { Init(); }
void Init() { nTime = 0; fFromMe = false; fSpent = false; }
IMPLEMENT_SERIALIZE ( /// would be nice for it to return the version number it reads, maybe use a reference nSerSize += SerReadWrite(s, (CMerkleTx)this, nType, nVersion, ser_action); if (!(nType & SER_GETHASH)) READWRITE(nVersion); READWRITE(vtxPrev); READWRITE(mapValue); READWRITE(vOrderForm); READWRITE(nTime); READWRITE(fFromMe); READWRITE(fSpent); )
bool WriteToDisk() { return CWalletDB().WriteTx(GetHash(), *this); }
void AddSupportingTransactions(CTxDB& txdb); void AddSupportingTransactions() { CTxDB txdb("r"); AddSupportingTransactions(txdb); }
bool AcceptWalletTransaction(CTxDB& txdb, bool fCheckInputs=true); bool AcceptWalletTransaction() { CTxDB txdb("r"); return AcceptWalletTransaction(txdb); }
void RelayWalletTransaction(CTxDB& txdb); void RelayWalletTransaction() { CTxDB txdb("r"); RelayWalletTransaction(txdb); } };
// // Nodes collect new transactions into a block, hash them into a hash tree, // and scan through nonce values to make the block's hash satisfy proof-of-work // requirements. When they solve the proof-of-work, they broadcast the block // to everyone and the block is added to the timechain. The first transaction // in the block is a special one that creates a new coin owned by the creator // of the block. // // Blocks are appended to blk0001.dat files on disk. Their location on disk // is indexed by CBlockIndex objects in memory. // class CBlock { public: // header uint256 hashPrevBlock; uint256 hashMerkleRoot; unsigned int nTime; unsigned int nBits; unsigned int nNonce;
// network and disk vector vtx;
// memory only mutable vector vMerkleTree;
CBlock() { SetNull(); }
IMPLEMENT_SERIALIZE ( if (!(nType & SER_GETHASH)) READWRITE(nVersion); READWRITE(hashPrevBlock); READWRITE(hashMerkleRoot); READWRITE(nTime); READWRITE(nBits); READWRITE(nNonce);
// ConnectBlock depends on vtx being last so it can calculate offset if (!(nType & (SER_GETHASH|SER_BLOCKHEADERONLY))) READWRITE(vtx); else if (fRead) const_cast(this)->vtx.clear(); )
void SetNull() { hashPrevBlock = 0; hashMerkleRoot = 0; nTime = 0; nBits = 0; nNonce = 0; vtx.clear(); vMerkleTree.clear(); }
bool IsNull() const { return (nBits == 0); }
uint256 GetHash() const { return Hash(BEGIN(hashPrevBlock), END(nNonce)); }
uint256 BuildMerkleTree() const { vMerkleTree.clear(); foreach(const CTransaction& tx, vtx) vMerkleTree.push_back(tx.GetHash()); int j = 0; for (int nSize = vtx.size(); nSize > 1; nSize = (nSize + 1) / 2) { for (int i = 0; i < nSize; i += 2) { int i2 = min(i+1, nSize-1); vMerkleTree.push_back(Hash(BEGIN(vMerkleTree[j+i]), END(vMerkleTree[j+i]), BEGIN(vMerkleTree[j+i2]), END(vMerkleTree[j+i2]))); } j += nSize; } return (vMerkleTree.empty() ? 0 : vMerkleTree.back()); }
vector GetMerkleBranch(int nIndex) const { if (vMerkleTree.empty()) BuildMerkleTree(); vector vMerkleBranch; int j = 0; for (int nSize = vtx.size(); nSize > 1; nSize = (nSize + 1) / 2) { int i = min(nIndex1, nSize-1); vMerkleBranch.push_back(vMerkleTree[j+i]); nIndex >>= 1; j += nSize; } return vMerkleBranch; }
static uint256 CheckMerkleBranch(uint256 hash, const vector& vMerkleBranch, int nIndex) { foreach(const uint256& otherside, vMerkleBranch) { if (nIndex & 1) hash = Hash(BEGIN(otherside), END(otherside), BEGIN(hash), END(hash)); else hash = Hash(BEGIN(hash), END(hash), BEGIN(otherside), END(otherside)); nIndex >>= 1; } return hash; }
bool WriteToDisk(bool fWriteTransactions, unsigned int& nFileRet, unsigned int& nBlockPosRet) { // Open history file to append CAutoFile fileout = AppendBlockFile(nFileRet); if (!fileout) return false; if (!fWriteTransactions) fileout.nType |= SER_BLOCKHEADERONLY;
// Write index header unsigned int nSize = fileout.GetSerializeSize(*this); fileout << FLATDATA(pchMessageStart) << nSize;
// Write block nBlockPosRet = ftell(fileout); if (nBlockPosRet == -1) return false; fileout << *this;
return true; }
bool ReadFromDisk(unsigned int nFile, unsigned int nBlockPos, bool fReadTransactions) { SetNull();
// Open history file to read CAutoFile filein = OpenBlockFile(nFile, nBlockPos, "rb"); if (!filein) return false; if (!fReadTransactions) filein.nType |= SER_BLOCKHEADERONLY;
// Read block filein >> *this;
// Check the header if (nBits < MINPROOFOFWORK || GetHash() > (~uint256(0) >> nBits)) return error("CBlock::ReadFromDisk : errors in block header");
return true; }
void print() const { printf("CBlock(hashPrevBlock=%s, hashMerkleRoot=%s, nTime=%u, nBits=%u, nNonce=%u, vtx=%d)\n", hashPrevBlock.ToString().substr(0,6).c_str(), hashMerkleRoot.ToString().substr(0,6).c_str(), nTime, nBits, nNonce, vtx.size()); for (int i = 0; i < vtx.size(); i++) { printf(" "); vtx[i].print(); } printf(" vMerkleTree: "); for (int i = 0; i < vMerkleTree.size(); i++) printf("%s ", vMerkleTree[i].ToString().substr(0,6).c_str()); printf("\n"); }
bool ReadFromDisk(const CBlockIndex* blockindex, bool fReadTransactions); bool TestDisconnectBlock(CTxDB& txdb, map& mapTestPool); bool TestConnectBlock(CTxDB& txdb, map& mapTestPool); bool DisconnectBlock(); bool ConnectBlock(unsigned int nFile, unsigned int nBlockPos, int nHeight); bool AddToBlockIndex(unsigned int nFile, unsigned int nBlockPos, bool fWriteDisk); bool CheckBlock() const; bool AcceptBlock(); };
// // The timechain is a tree shaped structure starting with the // genesis block at the root, with each block potentially having multiple // candidates to be the next block. pprev and pnext link a path through the // main/longest chain. A blockindex may have multiple pprev pointing back // to it, but pnext will only point forward to the longest branch, or will // be null if the block is not part of the longest chain. // class CBlockIndex { public: CBlockIndex* pprev; CBlockIndex* pnext; unsigned int nFile; unsigned int nBlockPos; int nHeight;
CBlockIndex() { pprev = NULL; pnext = NULL; nFile = 0; nBlockPos = 0; nHeight = 0; }
CBlockIndex(unsigned int nFileIn, unsigned int nBlockPosIn) { pprev = NULL; pnext = NULL; nFile = nFileIn; nBlockPos = nBlockPosIn; nHeight = 0; }
bool IsInMainChain() const { return (pnext || this == pindexBest); }
bool EraseBlockFromDisk() { // Open history file CAutoFile fileout = OpenBlockFile(nFile, nBlockPos, "rb+"); if (!fileout) return false;
// Overwrite with empty null block CBlock block; block.SetNull(); fileout << block;
return true; }
bool TestDisconnectBlock(CTxDB& txdb, map& mapTestPool) { CBlock block; if (!block.ReadFromDisk(nFile, nBlockPos, true)) return false; return block.TestDisconnectBlock(txdb, mapTestPool); }
bool TestConnectBlock(CTxDB& txdb, map& mapTestPool) { CBlock block; if (!block.ReadFromDisk(nFile, nBlockPos, true)) return false; return block.TestConnectBlock(txdb, mapTestPool); }
bool DisconnectBlock() { CBlock block; if (!block.ReadFromDisk(nFile, nBlockPos, true)) return false; return block.DisconnectBlock(); }
bool ConnectBlock() { CBlock block; if (!block.ReadFromDisk(nFile, nBlockPos, true)) return false; return block.ConnectBlock(nFile, nBlockPos, nHeight); }
void print() const { printf("CBlockIndex(nprev=%08x, pnext=%08x, nFile=%d, nBlockPos=%d, nHeight=%d)\n", pprev, pnext, nFile, nBlockPos, nHeight); } };
void PrintTimechain();
// // Describes a place in the timechain to another node such that if the // other node doesn't have the same branch, it can find a recent common trunk. // The further back it is, the further before the branch point it may be. // class CBlockLocator { protected: vector vHave; public:
CBlockLocator() { }
explicit CBlockLocator(const CBlockIndex* pindex) { Set(pindex); }
explicit CBlockLocator(uint256 hashBlock) { map::iterator mi = mapBlockIndex.find(hashBlock); if (mi != mapBlockIndex.end()) Set((*mi).second); }
IMPLEMENT_SERIALIZE ( if (!(nType & SER_GETHASH)) READWRITE(nVersion); READWRITE(vHave); )
void Set(const CBlockIndex* pindex) { vHave.clear(); int nStep = 1; while (pindex) { CBlock block; block.ReadFromDisk(pindex, false); vHave.push_back(block.GetHash());
// Exponentially larger steps back for (int i = 0; pindex && i < nStep; i++) pindex = pindex->pprev; if (vHave.size() > 10) nStep *= 2; } }
CBlockIndex* GetBlockIndex() { // Find the first block the caller has in the main chain foreach(const uint256& hash, vHave) { map::iterator mi = mapBlockIndex.find(hash); if (mi != mapBlockIndex.end()) { CBlockIndex* pindex = (*mi).second; if (pindex->IsInMainChain()) return pindex; } } return pindexGenesisBlock; }
uint256 GetBlockHash() { // Find the first block the caller has in the main chain foreach(const uint256& hash, vHave) { map::iterator mi = mapBlockIndex.find(hash); if (mi != mapBlockIndex.end()) { CBlockIndex* pindex = (*mi).second; if (pindex->IsInMainChain()) return hash; } } return hashGenesisBlock; }
int GetHeight() { CBlockIndex* pindex = GetBlockIndex(); if (!pindex) return 0; return pindex->nHeight; } };
extern map mapTransactions; extern map mapWallet; extern vector > vWalletUpdated; extern CCriticalSection cs_mapWallet; extern map, CPrivKey> mapKeys; extern map > mapPubKeys; extern CCriticalSection cs_mapKeys; extern CKey keyUser;
'''
Read this went the opposite way
Go1dfish undelete link
unreddit undelete link
Author: fukya40
submitted by removalbot to removalbot [link] [comments]

Mentor Monday, August 10, 2015: Ask all your bitcoin questions!

Ask (and answer!) away! Here are the general rules:
And don't forget to check out /BitcoinBeginners
You can sort by new to see the latest questions that may not be answered yet.
submitted by BashCoBot to Bitcoin [link] [comments]

Technical: Pay-to-contract and Sign-to-contract

What's this? I don't make a Technical post for a month and now BitPay is censoring the Hong Kong Free Press? Shit I'm sorry, it's all my fault for not posting a Technical post regularly!! Now posting one so that we have a censorship-free Bitcoin universe!
Pay-to-contract and sign-to-contract are actually cryptographic techniques to allow you to embed a commitment in a public key (pay-to-contract) or signature (sign-to-contract). This commitment can be revealed independently of the public key / signature without leaking your private key, and the existence of the commitment does not prevent you from using the public key / signature as a normal pubkey/signature for a normal digital signing algorithm.
Both techniques utilize elliptic curve homomorphism. Let's digress into that a little first.

Elliptic Curve Homomorphism

Let's get an oversimplified view of the maths involved first.
First, we have two "kinds" of things we can compute on.
  1. One kind is "scalars". These are just very large single numbers. Traditionally represented by small letters.
  2. The other kind is "points". These are just pairs of large numbers. Traditionally represented by large letters.
Now, an "Elliptic Curve" is just a special kind of curve with particular mathematical properties. I won't go into those properties, for the very reasonable reason that I don't actually understand them (I'm not a cryptographer, I only play one on reddit!).
If you have an Elliptic Curve, and require that all points you work with are on some Elliptic Curve, then you can do these operations.
  1. Add, subtract, multiply, and divide scalars. Remember, scalars are just very big numbers. So those basic mathematical operations still work on big numbers, they're just big numbers.
  2. "Multiply" a scalar by a point, resulting in a point. This is written as a * B, where a is the scalar and B is a point. This is not just multiplying the scalar to the point coordinates, this is some special Elliptic Curve thing that I don't understand either.
  3. "Add" two points together. This is written as A + B. Again, this is some special Elliptic Curve thing.
The important part is that if you have:
A = a * G B = b * G Q = A + B 
Then:
q = a + b Q = q * G 
That is, if you add together two points that were each derived from multiplying an arbitarry scalar with the same point (G in the above), you get the same result as adding the scalars together first, then multiplying their sum with the same point will yield the same number. Or:
a * G + b * G = (a + b) * G 
And because multiplication is just repeated addition, the same concept applies when multiplying:
a * (b * G) = (a * b) * G = (b * a) * G = b * (a * G) 
Something to note in particular is that there are few operations on points. One operation that's missing is "dividing" a point by a point to yield a scalar. That is, if you have:
A = a * G 
Then, if you know A but don't know the scalar a, you can't do the below:
a = A / G 
You can't get a even if you know both the points A and G.
In Elliptic Curve Cryptography, scalars are used as private keys, while points are used as public keys. This is particularly useful since if you have a private key (scalar), you can derive a public key (point) from it (by multiplying the scalar with a certain standard point, which we call the "generator point", traditionally G). But there is no reverse operation to get the private key from the public key.

Commitments

Let's have another mild digression.
Sometimes, you want to "commit' to something that you want to keep hidden for now. This is actually important in some games and so on. For example, if you are paying a game of Twenty Questions, one player must first write the object they are thinking of, then fold or hide it in such a way that what they wrote is not visible. Then, after the guessing player has asked twenty questions to narrow down what the object is and has revealed what he or she thinks the object being guessed was, the guessee reveals the object by unfodling and showing the paper.
The act of writing down commits you to the specific thing you wrote down. Folding the paper and/or hiding it, err, hides what you wrote down. Later, when you unfold the paper, you reveal your commitment.
The above is the analogy to the development of cryptographic commitments.
  1. First you select some thing --- it could be anything, a song, a random number, a promise to deliver products and services, the real identity of Satoshi Nakamoto.
  2. You commit to it by giving it as input to a one-way function. A one-way function is a function which allows you to get an output from an input, but after you perform that there is no way to reverse it and determine the original input knowing only the final output. Hash functions like SHA are traditionally used as one-way functions. As a one-way function, this hides your original input.
  3. You give the commitment (the output of the one-way function given your original input) to whoever wants you to commit.
  4. Later, when somebody demands to show what you committed to (for example after playing Twenty Questions), you reveal the commitment by giving the original input to the one-way function (i.e. the thing you selected in the first step, which was the thing you wanted to commit to).
  5. Whoever challenged you can verify your commitment by feeding your supposed original input to the same one-way function. If you honestly gave the correct input, then the challenger will get the output that you published above in step 3.

Salting

Now, sometimes there are only a few possible things you can select from. For example, instead of Twenty Questions you might be playing a Coin Toss Guess game.
What we'd do would be that, for example, I am the guesser and you the guessee. You select either "heads" or "tails" and put it in a commitment which you hand over to me. Then, I say "heads" or "tails" and have you reveal your commitment. If I guessed correctly I win, if not you win.
Unfortunately, if we were to just use a one-way function like an SHA hash function, it would be very trivial for me to win. All I would need to do would be to try passing "heads" and "tails" to the one-way function and see which one matches the commitment you gave me. Then I can very easily find out what your committed value was, winning the game consistently. In hacking, this can be made easier by making Rainbow Tables, and is precisely the technique used to derive passwords from password databases containing hashes of the passwords.
The way to solve this is to add a salt. This is basically just a large random number that we prepend (or append, order doesn't matter) to the actual value you want to commit to. This means that not only do I have to feed "heads" or "tails", I also have to guess the large random number (the salt). If the possible space of large random numbers is large enough, this prevents me from being able to peek at your committed data. The salt is sometimes called a blinding factor.

Pay-to-contract

Hiding commitments in pubkeys!
Pay-to-contract allows you to publish a public key, whose private key you can derive, while also being a cryptographic commitment. In particular, your private key is also used to derive a salt.
The key insight here is to realize that "one-way function" is not restricted to hash functions like SHA. The operation below is an example of a one-way function too:
h(a) = a * G 
This results in a point, but once the point (the output) is known, it is not possible to derive the input (the scalar a above). This is of course restricted to having the input be a scalar only, instead of an arbitrary-length message, but you can add a hash function (which can accept an arbitrary-length input) and then make its output (a fixed-length scalar) as the scalar to use.
First, pay-to-contract requires you to have a public and private keypair.
; p is private key P = p * G ; P is now public key 
Then, you have to select a contract. This is just any arbitrary message containing any arbitrary thing (it could be an object for Twenty Questions, or "heads" or "tails" for Coin Toss Guessing). Traditionally, this is symbolized as the small letter s.
In order to have a pay-to-contract public key, you need to compute the below from your public key P (called the internal public key; by analogy the private key p is the internal private key):
Q = P + h(P | s) * G 
"h()" is any convenient hash function, which takes anything of arbitrary length, and outputs a scalar, which you can multiply by G. The syntax "P | s" simply means that you are prepending the point P to the contract s.
The cute thing is that P serves as your salt. Any private key is just an arbitrary random scalar. Multiplying the private key by the generator results in an arbitrary-seeming point. That random point is now your salt, which makes this into a genuine bonafide hiding cryptographic commitment!
Now Q is a point, i.e. a public key. You might be interested in knowing its private key, a scalar. Suppose you postulate the existence of a scalar q such that:
 Q = q * G 
Then you can do the below:
 Q = P + h(P | s) * G Q = p * G + h(P | s) * G Q = (p + h(P | s)) * G 
Then we can conclude that:
 q = p + h(P | s) 
Of note is that somebody else cannot learn the private key q unless they already know the private key p. Knowing the internal public key P is not enough to learn the private key q. Thus, as long as you are the only one who knows the internal private key p, and you keep it secret, then only you can learn the private key q that can be used to sign with the public key Q (that is also a pay-to-contract commitment).
Now Q is supposed to be a commitment, and once somebody else knows Q, they can challenge you to reveal your committed value, the contract s. Revealing the pay-to-contract commitment is done by simply giving the internal public key P (which doubles as the salt) and the committed value contract s.
The challenger then simply computes:
P + h(P | s) * G 
And verifies that it matches the Q you gave before.
Some very important properties are:
  1. If you reveal first, then you still remain in sole control of the private key. This is because revelation only shows the internal public key and the contract, neither of which can be used to learn the internal private key. So you can reveal and sign in any order you want, without precluding the possibility of performing the other operation in the future.
  2. If you sign with the public key Q first, then you do not need to reveal the internal public key P or the contract s. You can compute q simply from the internal private key p and the contract s. You don't even need to pass those in to your signing algorithm, it could just be given the computed q and the message you want to sign!
  3. Anyone verifying your signature using the public key Q is unaware that it is also used as a cryptographic commitment.
Another property is going to blow your mind:
  1. You don't have to know the internal private key p in order to create a commitment pay-to-contract public key Q that commits to a contract s you select.
Remember:
Q = P + h(P | s) * G 
The above equation for Q does not require that you know the internal private key p. All you need to know is the internal public key P. Since public keys are often revealed publicly, you can use somebody else's public key as the internal public key in a pay-to-contract construction.
Of course, you can't sign for Q (you need to know p to compute the private key q) but this is sometimes an interesting use.
The original proposal for pay-to-contract was that a merchant would publish their public key, then a customer would "order" by writing the contract s with what they wanted to buy. Then, the customer would generate the public key Q (committing to s) using the merchant's public key as the internal public key P, then use that in a P2PKH or P2WPKH. Then the customer would reveal the contract s to the merchant, placing their order, and the merchant would now be able to claim the money.
Another general use for pay-to-contract include publishing a commitment on the blockchain without using an OP_RETURN output. Instead, you just move some of your funds to yourself, using your own public key as the internal public key, then selecting a contract s that commits or indicates what you want to anchor onchain. This should be the preferred technique rather than OP_RETURN. For example, colored coin implementations over Bitcoin usually used OP_RETURN, but the new RGB colored coin technique uses pay-to-contract instead, reducing onchain bloat.

Taproot

Pay-to-contract is also used in the nice new Taproot concept.
Briefly, taproot anchors a Merkle tree of scripts. The root of this tree is the contract s committed to. Then, you pay to a SegWit v1 public key, where the public key is the Q pay-to-contract commitment.
When spending a coin paying to a SegWit v1 output with a Taprooted commitment to a set of scripts s, you can do one of two