Homework on Mining and Proof of Work - Questions

Blockchain and Bitcoin 101
#4179
  1. To incentivize them to play by rules
  2. To change a transaction in previous blocks, you’ll have to mine again all the links since that block and catch up with the latest chain version and even go ahead so your version of the chain gets adopted by the network. Such hash power is imposible at the current state, and if would be possible, it would be so much more effective used elsewhere than “wasted” for a transaction of any value.
  3. By decreasing the range of the nonce’s hash value, required to integrate the new block
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#4180

  1. It’s important for them to spend to keep them incentivized. Because they spend up front trying to solve the cryptographic puzzle…they must keep on mining to recoup money and make a profit

  2. Because the hash of each block depends on the hash of previous

  3. By causing the level of the target nonce level to be lower when more miners are involved, making it more difficult and vice versa

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#4181

  1. Spending money on mining ensures integrity in the mining process. This is because the miners must first spend money in the form of electricity. Spending that money incentivizes them to mine and make that money back plus a profit.

  2. Because changing a transaction in a previous block would change its hash and therefore change the hash of all the following blocks and break all the following links between blocks. The miner would then have to rebuild the following blocks and catch up with all of the new blocks that have been created by other miners because the network will always choose the longest blockchain. This would require at least 51% of the global hash rate.

  3. The more miners there are, the lower the target. The lower the target, the greater the difficulty. This is because guessing the nonce that (along with the transaction list and hash of the previous block) produces a hash lower than the target becomes less probable and requires more guesses. This uses more electricity and costs more money.

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#4182

it is important so that miners lose money is they’re dishonest
a change to that block would change the next blocks in the chain
the more people that are mining the greater the difficulty, and the less people mining the easier the difficulty

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#4183

  1. It is important for Miners to spend a lot of money while mining because without suffcient electricity you will not be able to mine the Cryptographic puzzle to then add your hash to the new block.

  2. For someone to change a previous added block they would then have to validate all the block after that altered block. Doing that would cost you not only money but time as the farther you go back in the chain the exponentionally harder and longer it becomes to re-mine and re-hash all those block.

  3. The network regulates the mining difficulty by making it harder to hash new block to the chain. The more miners there are the more difficult it is to hash a function into the chain. This sysytem gets harder as time go on and the halving cuts the target in half making the target needed to hash a new function harder.

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#4184

  1. Why is it important to make sure that miners spend money (on electricity) while mining? 4. If your block is breaking rules it will be dropped and electricity costs will be your loss. Other nodes verify you are wrong and you will lose money as a result.

  2. Why would it be very difficult for someone to go back change a previously added block? When contents of a link on the blockchain have been altered both the has from the new block and the previous block are changed. The next link is broken and all links after due to each new link being created through solving a cryptography puzzle based on the blocks before it.
    Would take 1000s of years to try to remine and then catch up to new miners blocks. Network will always choose the longest chain PoW

  3. How does the network regulate mining difficulty? When many people are mining the puzzle is more difficult. The more miners the lower the target therefore harder to guess the nonce. Less Miners less difficulty to guess nonce.

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#4185
  1. Why is it important to make sure that miners spend money (on electricity) while mining?

To keep the POW integrity honest and accountable.

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

Any changes in hash functions changes the hash in previous blocks and in the current block. The miner would have to go back and fix the previous and current blocks which would put the miner behind and impossible for the miner to catch up.

  1. How does the network regulate mining difficulty?

Hash is based on previous hash, transactions in the current block and a random number aka nonce. Our hash, as a miner, must create a number that is less than a target the number. Target numbers depends on the difficulty of the Bitcoin network. The more miners the lower the target number will be.

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#4186

  1. Miners spend money means they are invested in the mining process. This will then incentivise the miners to follow the rules.

  2. The block and all subsequent blocks would need to be remined as all the hashes would have changed in addition to the current live blocks that have not been upended to the blockchain yet.

  3. It regulates mining difficulty through a random target. The hash has to be lower than the target. THe more miners there are the lower the target hence making it more difficult to mine the block.

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#4187

  1. Why is it important to make sure that miners spend money (on electricity) while mining?
    The first miner that solves the puzzle fastest gets the number 1 block reward, which is , inflation and transaction fees. the more computing power a miner consumes the more rewards they can possibly win. It also acts as an incentive to produce excellent POW results.

  2. Why would it be difficult for someone to go back and change a previously added block.
    You should never alter a confirmed block, only add new. The contents changed in a confirmed block will break the links between all blocks, damaging and breaking the puzzles the miner is trying to solve. The nodes will see the block is now invalid and you will need to resolve all the previous blocks which is practically impossible and enormously costly.

  3. How does the network regulate mining difficulty?
    Increased network difficulty it becomes easier for the miners and decreased network difficulty makes it harder for the miners. The Bitcoin protocol allows for 10 minute blocks so constantly is adjusting.

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#4188
  1. Why is it important to make sure that miners spend money (on electricity) while mining?

So that they have incentive to be honest about the transactions. If they break rules/aren’t honest, they will lose money, because their block will not be accepted by the network.

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

Yes, because it would invalidate the blocks coming after it as well, one would have to solve the cryptographic puzzle on their own for each block coming after the changed block. This would take thousands of years for 1 entity and even if this person succeeds after all that time, the network will be a lot of blocks ahead. Since the network will always choose for the longest chain, this chain would continue to fall behind further and further the more time passes.

  1. How does the network regulate mining difficulty?

By setting a hash target, this target has to be higher than the hash result with the inputs: previous hash, transaction list and nonce. The nonce is a number which miners use to try to produce a hash result that is lower than the target, if this fails, the miner has to try again. The lower the target is, the harder it is to find a nonce that produces a hash result lower than the target.

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#4189

[quote=“ivan, post:1, topic:8439, full:true”]
Homework on Mining and Proof of Work - Questions

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

it will create POW so that they feel obligated to create blocks so that transactions will happen

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

it will change the whole network from block to last block meaning that they will need to find the new Nounces to find the the correct hash.

  1. How does the network regulate mining difficulty?

With more miners they will make the difficulty high meaning that the hashrate number will be lower.

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#4190

  1. To incentivize miners to play by the rules and mine honestly. They will want to re-coup their money spent on electricity by minting a new block and getting the block reward and transactions fees.

  2. If you change a previous block you will invalidate that block and all the blocks that follow after it. This means you will have to re-mine all the affected blocks (which would take a lot of time); meanwhile, other miners will have minted new blocks to the network - and since the network looks for the longest chain, you will always be behind other miners with no practical way to catch back up.

  3. The more miners there are on the network the lower the target number will become, making it more difficult

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#4191
  1. Why is it important to make sure that miners spend money (on electricity) while mining?
    The money they have spent on electricity incentivises miners to mine so that they can recover their spent money and make profit from transaction fees and block rewards.
  2. Why would it be very difficult for someone to go back change a previously added block?
    A hash is based on a block’s transactions as well as the previous block’s hash and a nonce. Therefore, if a transaction in a previous block is changed, then its hash is changed and the links and hashes of all blocks following it in the blockchain are changed. All the nodes are able to see that the blocks have been invalidated. The only way to validate them again is to re-mine all the blocks which is practically impossible.
  3. How does the network regulate mining difficulty?
    To append a block to the blockchain, its hash has to be below a target number. To increase the difficulty, the target is lowered while to decrease the difficulty the target number is made higher.
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#4192

  1. This is the principle of PoW. By spending money to keep the network running they are de-incentivized to cheat on the network as if the network fails all their energy spent is wasted.

  2. Because in order to do that they would need to re-mine not only that block but also all the following ones too.

  3. Mining difficulty increases with more computational power being injected in the network.

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#4193
  1. Why is it important to make sure that miners spend money (on electricity) while mining?
    This is what proof of work is about. Miners need to put in the work (computational power) in order to solve the cryptographic puzzles to have their new blocks added to the blockchain.
  2. Why would it be very difficult for someone to go back change a previously added block?
    If you change a block in the past all the links are broken and all hashes of each of the blocks change. You would have to solve all puzzles of all blocks and then catch up with other miners which would take too long.
  3. How does the network regulate mining difficulty?
    The more miners the lower the target. The lower the target, the more difficult it is to find the correct input of previous hash, tx list and nonce.
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#4194

  1. To incentive playing by the rules. Miners need to recover their loses and not have their block rejected by the network

  2. Because each hash in a block is constructed by the hash of the previous block - by changing previously added blocks you change each connection between each block and need to re-mine it all

  3. Regulates difficulty by decreasing or increasing the target depending on how many miners on the network. More miners, more difficulty

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#4195
  1. It is important to make sure miners spend money/electricity while mining to continuously incentivize them to mine honestly and within the rules of the code so that they can earn block rewards + transactions to cover the cost of mining as well as produce additional income.
  2. It would be almost impossible to go back and change previously confirmed transactions on the blockchain since you would need to re-mine all of the blocks after that on the chain as well as catch up to miners that are still mining and creating new blocks on the subsequent chain during that time. Due to the hash rate target/difficulty on the network there is not enough computing power to do that fast enough for the malicious chain to become consensus.
  3. The network regulates mining difficulty by lowering the threshold target for the nonce. This in turn raises the difficulty of the cryptographic puzzle that miners must solve to append a new block. The more miners on the network the more difficult the hash becomes and vice versa.
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#4196

  1. It is important to make sure that miners spend money ( on electricity) while mining because to keep everyone playing by the rules, cheaters will get punished and honest miners will get block reward.

  2. It would be very difficult for someone to go back change a previously added block because it would break the chain of hashes and also the connect link to the blockchain.

  3. The network regulate mining difficulty by make it more difficult to mine and when the difficulty is higher, the target is lower.

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#4197

  1. Miners nee dto have skin in the game to incentivise them to be honest

  2. They would have to re-mine that whole block of data and ensuing blocks which is very time prohibitive

3.if there are many miners the level of difficulty finding the nonce is increased.

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#4198

  1. If a miner is dishonest and his block is rejected by other nodes he will lose money by still having to pay his electricity bill, hence incentives for miners to be honest

  2. If something is changed in a previous block the link will be broken from the changed blocks and any other block added after

  3. Target is low when difficulty is high

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