Homework on Mining and Proof of Work - Questions

Blockchain and Bitcoin 101
#4219

  1. If the miners do not follow the rules, they will not receive the block reward and the tx fees…meaning they will lose money on the electricity they paid for.

  2. Any changes to a previously added block will change the hash for that block, which also changes the hash for the following block…thereby breaking the “chain”.

  3. If there is a large number of miners, the target lowers making it harder for the miners to guess the nonce and “win” the block

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#4220

  1. To create incentive for honest mining and ensure that there was investment from the miner

  2. After changing a block they would need to remine all the blocks thereafter and catch up to the current block making it virtually impossible

  3. With the use of target that is adjusted according to the amount of hash rate that is currently mining.

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#4221
  1. They are incentivized to follow the rules and have skin in the game.
  2. Because the you would have to find the chain of hashes, nonces and tx lists of all previous hashes which is very expensive, takes a lot of time while mining new nonces would be more profitable and quicker.
  3. As there are more miners in the network, the target will be set lower and thus finding the nonce will be more difficult to find.
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#4222
  1. Why is it important to make sure that miners spend money (on electricity) while mining? Spending money incentivizes Miners to play by the rules or risk losing money.
  2. Why would it be very difficult for someone to go back change a previously added block? Because changing a previously added block would fracture the links between successive blocks. It would take thousands of years to catch up with newly appended blocks.
  3. How does the network regulate mining difficulty? By using an inverse relationship between the number of miners mining and the target. The more miners that are mining (hash power), the lower the target hash, and thus the greater the difficulty of achieving the correct target, and vice versa.
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#4223
  1. Why is it important to make sure that miners spend money (on electricity) while mining? It incentivizes them to still to the rules.
  2. Why would it be very difficult for someone to go back change a previously added block? Because it would affect all other blocks created from the altered block which would then have to be re-mined.
  3. How does the network regulate mining difficulty? It regulates mining by basing difficulty on the number of miners on the network and setting the target accordingly. More miners lower target.
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#4224

  1. Forcing the miners to prove that they’ve worked (to append their blcok, i.e. to add their unconfirmed transaction --mempool-- list to the blockchain) incentivizes them to recoup their losses with the block reward and tx fees that come from an accepted block (i.e. a block having hash [data+prev hash + nonce] < target)

  2. when attempting to re-write any block in the block chain, the future remainder of the chain will be invalidated (thus shortened) because the hash of the altered data will no longer feed into the prev hash portion of the succeeding block, thus the hash of the succeeding block will also not fit into ITS succeeding block, i.e. because the hash function is essentially taking nested inputs, there’s no changing any input without an avalanche effect taking over the resulting hashes (let alone the fact that all newly created blocks created since the attempt to alter a block will ALSO have to be rehashed, making the entire rest of the chain difficult to mine FAST ENOUGH to rewrite its history)

  3. the network sets target difficulty dynamically according to how much mining power (in Terahashes/sec) there is in order to have keep blocks appending about every 10 minutes; more power yields more difficult targets and vice versa

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#4225

  1. It is important to make sure that miners spend money (on electricity) while mining as to ensure the Security of the Network through Proof of Work Consensus, which requires the usage / purchase of Electricity upfront to solve “Crypto-Puzzle” inspiring Incentives.

  2. It would be very difficult for someone to go back change a previously added block because it would take an enormouse amount of cpu power ; data ; electricity to construct a new cryptographic puzzle ; block fast enough to alter all Transactions blocked and confirmed on the Network.

  3. The network regulates mining difficulty by the Level of the Target #. Target Number Low = High Difficulty ; Target Number High = Low Difficulty.

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#4226

1. Why is it important to make sure that miners spend money (on electricity) while mining?
In order to incentivize good behavior and push them to work for block rewards and transaction fees.

2. Why would it be very difficult for someone to go back change a previously added block?
Reguessing nonces and rehashing would take thousands of years because they would have to keep up with the current hashrate which they cannot overcome.

3. How does the network regulate mining difficulty?
If hashrate is higher, the target nonce is lower which increases the difficulty to guess the correct target nonce.

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#4227
  1. to make sure that they are honest. if they are paying a lot for electricity they are going to make sure they paid. if you dont play by the rules it will be obvious and blockchain wouldnt accept it. and you would have to start all over.
  2. if you go back and change something the hash will change and blockchain wouldnt accept it.
  3. you have to guess a random number (nance) and it has to be lower than the target and the more miners are mining the more diffcult.
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#4228

Homework on Mining and Proof of Work - Questions

  1. Why is it important to make sure that miners spend money (on electricity) while mining?
  • So that they have “skin in the game”, which deters them from trying to double spend.
  1. Why would it be very difficult for someone to go back change a previously added block?
  • Because it would take an extremely large amount of money and hashing power.
  1. How does the network regulate mining difficulty?
  • It changes the difficulty based on how fast the previous blocks were mined. If blocks are mined too fast, it will increase the difficulty by adjusting the target value lower, and vice versa if blocks are mined too slow.
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#4229
  1. Its important to make sure miners spend money while mining because when a miner is successful in solving the cryptographic puzzle, they receive the block rewards and transaction fees of each block that they mined. By spending money upfront in electricity, they show their PoW.
  2. Its very difficult for someone to go back and change a previously added block because it will then the links of all of the blocks in front of it will be broken, which makes it difficult to re-create all the blocks that were broken. It could take a very long time fixing those broken links, which would waste a long time and making it not worth the time.
  3. The network regulates mining difficulty by how low the target number making the difficulty level high. So, the more miners on the network, the lower the target number would be.
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#4230
  1. The longest blockchain is always the valid one and it is created by spending money so they loose money if they are dishonest and it is almost impossible to hack.
  2. If anything is changed in a previously added block it would break the link to the next and the following blocks until present block and due to the fact that the longest chain prevails it is very difficult to do.
  3. The newtork regulates mining difficulty by adapting the target. The lower the target is the more difficult to guess the nonce. The protocol rates this difficulty to keep the blocks 10 min away based on the competition (amount of miners) there is at the moment.
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#4231
  1. The fact that mining is an expensive operation is essential to the proof of work system, by spending money miners are incentivized to follow the rules or else they will waste money mining blocks that will not be accepted by the network.
  2. It would be very difficult because it would change all the blocks linked to it, therefore that person would have to work at an unrealistic pace to catch up with the rest of the miners as they remine the blocks they changed, as well as mining the most recent blocks.
  3. The network regulates mining difficulty by changing the difficulty of the puzzles based on how many miners are operating. This is done with the setting of targets, and as the target get lower the difficulty of the puzzle is raised.
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#4232
  1. Why is it important to make sure that miners spend money (on electricity) while mining?
    So that they’re fully invested in the process.
  2. Why would it be very difficult for someone to go back change a previously added block?
    The amount of compute power necessary to go back, modify a transaction on a block, and regenerate the chain that now has new added blocks will be absurdly high. Also, this amount of compute power will likely result in big profits on standard mining due to the built-in incentives.
  3. How does the network regulate mining difficulty?
    Depending on the compute capacity of active miners, the network regulates the mining difficulty to attract miners and/or make sure current miners are fully invested. For example, if there are many miners, difficulty is increased my adjusting the nonce to a lower number which will require miners to spend more compute power (larger network -> more compute power -> less incentives).
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#4233

Homework on Mining and Proof of Work - Questions

  1. Why is it important to make sure that miners spend money (on electricity) while mining?
    To keep them honest and incentivise miners tp follow protocol.
  2. Why would it be very difficult for someone to go back change a previously added block?
    Block chain continuously moves forward if you change a previous block every block there on will be deemed invalid in that chain and will need to be re-mined.
  3. How does the network regulate mining difficulty?
    By adjusting the mining target(nonce), the more miners are in the network, the lower this number is, the more difficult it is to guess the nonce.
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#4234
  1. it is made to incentivise miners to play by the rules by forcing them to spend money before they get profit.
  2. It would require enormous amount of electricity and computing power but also, while someone tries to change some past block others already create new block which that person would have to recreate and it is practically impossible.
  3. the more miners are in the network the lower the target which they have to guess
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#4235

  1. It is important for miners to spend money on electricity as it is part of their incentive, they have to spend money to make money. If they don’t do what they are supposed to they wont get compensated and lose the money they spent on electricity.

  2. It is difficult to change a previously added block as it would change the hash for the most recent block and would require you to resolve the prev hash, tx list, and nonce.

  3. The network regulates mining difficulty by more hashing power connected will lower the target. Causing it to be more difficult to solve.

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#4236

  1. It functions as an incentive for the miners to make their money back via mining.

  2. If one were to change the previous block, he would need to re-mine it (which would take a long time by oneself), then would need to play catch up with all the other miners who are constantly mining new blocks. And the longest chain will always win.

  3. The higher the difficulty (the more people mining on the network) the lower the target, which makes it much harder to mine. The more electricity is required to be spent

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#4237

1 - Why is it important to make sure that miners spend money (on electricity) while mining?

It is important that the miners spend electricity during the protocol because it is precisely thanks to this electricity that they can enter into competition to calculate the golden nonce, that is to say a random number always lower but approaching the more of the target hash. Clarification that the hash refers to three criteria:

1 - Data or number of transactions contained in the current block.
2 - The hash of the current block.
3 - The hash of the previous block.

So, the target hash here is not the set of mathematical operations (SHA 256 algorithm) allowing the calculation of a set of nonces or random number until a minor or a set of Asic finds the target, but the result from the target difficulty (changing every 2016 blocks or around 15 days) approaching as closely as possible but not equal to what is called the Golden nonce, and which corresponds to the random number solving the mathematical game through a set of computation (hash) of prior nonce.

To put it simply, the goal of is to get as close as possible to the random number representing the target towards which the difficulty tends.

2 - Why would it be very difficult for someone to go back change a previously added block?

The Blockchain or the BTC block chain issued its first block on January 3, 2009, it would have been easy to break the first chains and try to create a ddos ​​attack at 51 percent of the computing power to take control of the last one. block accept by consensus and integrate into the block chain in order to change the hash of the header and therefore change what was the target, which would have had the effect of changing all the hashes, not only of the last block, but also all the preceding until the last, which will destroy the immutability of the network, and therefore its security, in short the network will be dead before having had time to be born. This is why the first blocks had to be mined on a set of private clients / nodes that all knew each other. At

Today the size of the block chain is so considerable that the energy required to catch up with the last block is almost impossible, i.e. it is statistically more than very unlikely without being impossible to catch up and therefore to hack the last block issued, due to the size of the BTC blochain which is enormous today. Moreover, the cost of such an attack, the more than satisfactory decentralization of mining farms as well as their number excludes for the moment the possibility of taking control of the network.

3 - How does the network regulate mining difficulty?

The more the miners are numerous to mine and therefore to secure the network, the more the difficulty of the resolution games increases. Conversely, the fewer there are, the more the difficulty decreases which facilitates the chances of each miner to mine a block. This difficulty is regulated every 15 days, ie every 2016 blocks.

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#4238
  1. Why is it important to make sure that miners spend money (on electricity) while mining?
    • The electricity spent is basically an insurance that the miner sticks to the rules. That way the get incentivised by transaction fees and inflation. However, if they decided to cheat then their block would not get validated and all the spent electricity would be lost. It is further, more profitable to use the computing power to stick to the rules and earn fees than trying to use the same computing power to cheat.
  2. Why would it be very difficult for someone to go back change a previously added block?
    • For each added block a cryptographic puzzle has to be solved which involsed finding a random number lower than the hash key. If someone no went back and tried to change something, the hash would change and they would have to find a new random number. In addition however, all the future hashes would be changed as well in form of a chain reaction and all subsequent blocks would have to be remined as well. At the same time, the network keeps adding new blocks making it almost impossible to change a previously added block.
  3. How does the network regulate mining difficulty?
    • The more miner are on the network the faster the random number would be found. This makes the network less securel In order to prevent this from happening the average solving time of the puzzle is set to 10 minutes. If the average solving time drops below 10 minutes the random number is lowered making the puzzle harder to solve. In turn, if there are less miners and the average solving time goes above 10 minutes, the random number is increased, making the puzzle easier to solve.
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