Homework on Mining and Proof of Work - Questions

[Kelly-B]

Why is it important to make sure that miners spend money (on electricity) while mining?
It’s important that miners spend money on electricity in order so that they are more inclined to want to play by the rules. In order to compensate for the time and energy that they have used, they will strive and work hard to receive the incentives. This in essence could be seen as the fruits of their labour.

Why would it be very difficult for someone to go back change a previously added block?
It would be difficult to go back and change a previous block because it would alter all of the other blocks thereafter, making the rest of the blockchain invalid.

How does the network regulate mining difficulty?
The network regulates mining by increasing and decreasing the difficulty level based on how many people are mining at any on time. This ensures that the blocks are kept to an approximate time-frame of 1 block every 10 mins.

[Gene03]

1 . Since the miners already spent money on electricity, they are incentivized to follow the rules to get the reward. Otherwise, they run the risk of their transaction being rejected and wasting money on electricity without any rewards.

2 . Because each block is creating by hashing its own transaction data and a nonce together with the hash of the previous block. This means that any change in an old block would require re-mining all of its following blocks. Therefore while a miner would try to change an old block and re-mine all the following blocks, all the other miners would be during this time adding new blocks the blockchain and would in practice outpacing him which would make it infeasible for him to get his new blockchain accepted by the network.

3 . 1. Target difficulty depends on the number of miners in the network. The more miners in the network, the lower is the difficulty target. The lower the difficulty targer, the harder it is to guess the nonce to be hashed with the transaction list and the hash function of the previous block.

[H_P]

1. It is important to make sure that miners spend money in the form of expending electricity because it would prove that the mining devices have performed work of solving numerous cryptographic puzzles in order to get a valid block hash. hence miners are motivated to play by the rules, if not they incure losses for the amount of energy expended without being rewarded.

2. It would be very difficult for someone to go back and change a previously added block because that would then change the previous block hash, which in turn would change all the subsequent block hashes resulting in invalid blocks.

3. The difficulty is proportional to the hash rate of the network. As more and more miners join the network the Target becomes lower. The lower the Target, the higher is the difficulty.

[Mike_Russo]

1. Because mining uses a substantial amount of energy and miners are incentivized to to play by the rules it is in their best interest.

2. It would be difficult because a block is made of a hash that is based of three distinct features, one being the hash of the pervious block. If miners try to remine a block the hash would change, the miners would have to remine the blocks that were mined after it, while trying to catch up to the blocks continuously being mined after that block.

3. The target of the hash will be lower when difficulty is high incentivizing the miners by competing with other miners to validate the block to mine honestly.

[Mathewvizc7]

1. It can be used as PoW, which means that miners are investing a significant amount of energy to complete the puzzle to get the incentives (transaction fees and block reward) for mining the blockchain.

2. A previous hash is interconnected with the current hash, the TX list, and the nonce, and if you change data on previous blocks, hashing becomes harder because all the parameters would change and ruin the sequence in the existing header’s block. Also, miners may be risking losing all the efforts made to build the previous block, losing money by trying to break the algorithm, and having a hard time rebuilding and reaching the newly created sequence of blocks in the network.

3. By setting the hash target in a lower position, the difficulty of mining increases. It happens when there’s a large number of miners trying to solve the cryptographic puzzle. When the hash target is lower, it makes things harder for miners because the condition to include a new block hash in the blockchain is met when this new block hash is below the target.

[Wyse_Sousa]

1- Its important to make miners spend electricity to make sure that they follow the rules to receive the payement
2- changing a old block means breaking the chain. A new chain have to be created and validated by the miners.
3- mining dificulty is regulated by increasing or decresing the target… Lower the target is higher is the dificlty of mining

[AlfredHodiah]

1. Why is it important to make sure that miners spend money (on electricity) while mining?
   Answer:
   Its and investment with potential block reward, and making such a huge investment will motivate the miners to play along with the rule knowing that they stand the chance of losing their investment if they cheat.

2. Why would it be very difficult for someone to go back change a previously added block?
   Answer:
   Changing an already added block which was known by all the network participant is practically a waste of time because that modification will affect the rest of the following blocks, rendering them invalid from the chain, as such the miner must remine it as well as the once that follows and that will take more than the lifespan of that person to get such done, whereas others following the rule will get multiple reward ahead of him. For this it will practically be difficult for someone who is in for the incentives to try such.

3. How does the network regulate mining difficulty?
   Answer:
   It does that in such a way that the more the miners the higher the difficulties involve in guessing the nonce, It’s further done by halvenings, which reduce the mining reward by halve at approximately every four years, thereby increasing the mining difficulties and reducing inflation in the protocol.

[Shadowstep2003]

1. This process is what incentivizes the miners to follow the rules. By making sure there is some cost to the miner to obtain a reward it also serves as a catalyst for improvement since miners are incentivized to perform as much work as possible in the most efficient way

2. In order to go back and change a previous block they would then need to re-mine all the subsequent blocks (which would take an exponential amount of time).

3. The miners that come on makes the process of calculating the nonce more difficult. Essentially the target gets lower.

[Jules]

1. It is the “work” aspect of proof of work and is what incentivizes them. They spend electricity and get back BTC.
2. Because the hash of all the subsequent blocks would change and they would need to be re-mined. The power necessary to do this is incalculable.
3. More miners = more difficult.

[Schofieldj256]

1. So that they can get rewarded and have a reason to mine, they will not have a successful outcome if the don’t mine properly which then creates a more verified chain.
2. Because it would take to much time to go back and remine and it would be hard for them to make something off it in the end.
3. By having a specific target which get lower from each person that mines.

[sapiensphinx]

1. Requiring miners to spend electrical energy in order to mine incentivizes them to remain honest and not to try to deceive the network with an inaccurate or malicious block data. The incentive comes from the fact that if they do try and deceive the network their block, that they just spent an enormous amount of energy to mine, will be rejected and they will have lost the money it took to mine that block.
2. It is difficult to go back and change a block b/c one block’s nonce, transaction hash and the previous block’s transaction hash are tied together sequentially so much so that changing one single digit in a previous block will change the hashes of all subsequent blocks on up the chain. If one digit anywhere in the chain is changed, all other hashes after that block will also be changed…essentially changing the entire networks data. An enormous amount of energy would be required to do this and it is essentially impossible.
3. The bitcoin difficulty adjustment is such that as more miners, or hash power, enter the network the harder the nonce is to solve for. The difficulty goes up as more miners start mining.

[muhammad]

1. cos programmer set it like this its important to spend money so there will be a compitation to mine and find correct hash so they can be rewarded those they can recover there money
2. because when some one change a bit on the previose block all blocks goes red because there is an error that someone has change thinks. to correct it back they will be mine again
3. if there is more miner the network regulate more difficult to guess

[Menyawga]

1. Financial expenditure gives miners stake in the game while also increasing security against other miners who might want to cheat.

2. Changing a previous tx invalidates all blocks from that point onward, forcing a miner who changes anything to redo the proof of work on that block forward. This won’t work though, unless that miner can harness AND MAINTAIN enough hash power to create a blockchain that outpaces the combined hash of all other miners. This removes the financial incentive for any bad actors in the space (although there would still be incentive for someone who didn’t care about earning BTC but instead wanted to destroy the BTC network).

3. Every 2 weeks the mining algorithm target difficulty is readjusted to ensure new blocks are mined every 10 minutes on average.

[EduardoDaSilva]

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

   This will make them to pay an upfront cost to mine which will make them want the block reward and the fees to compensate the electricity cost. Preventing miners from cheating.

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

   It’s difficult because one node takes too much effort to mine a block. Given that the node trying to rewrite history will have to mine the block alone, and all the future blocks already mined by the other miners. The longest chain will win.

3. How does the network regulate mining difficulty?

   The hashrate of the blockchain determines how difficult the target number will be. The higher the hashrate the harder to find the nounce it’ll be

[theosebagh]

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 ensure that a blockchain network is as secure as possible, it needs its chain to be as long as possible, which implies having as many blocks as possible being appended to it (the longer a blockchain’s main chain is, the less likely its integrity is at risk of being compromised/altered).

To do so, miners are required to verify blocks’ transaction lists by correctly guessing a block’s nonce, which satisfies the target level to be met (the nonce value being dependent upon a block’s transaction list as well as the previous block’s hash value).

The processing of guessing the correct nonce to subsequently derive a block’s hash (in the hopes of having it fall below a specified target, depending on a network’s difficulty level) requires a significant amount of computational power to have computers continuously iterate over various nonce values (before randomly hitting the right one).

Doing so carries substantial electricity costs that incentivize miners to keep honestly playing by the rules (as it would be far more costly to try and modify a previous block whose new hash value would consequently be picked up by every block following it in the chain  all following “previous hash” values would be altered and no longer meet their respective block’s target).

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

As mentioned above, doing so would entail a huge amount of computational resources (i.e significant electricity costs) to accomplish this feat.

Not only would all ensuing blocks’ hash values would have to be recalculated/re-mined to achieve their required target requirements, but hackers/fraudsters would also have to play catch up with the blocks that are continuously being mined as they attempt this lengthy process in the first place (exponentially increasing the complexity of the task here).

No single individual or small group of hackers could reasonably attempt this as it would involve a huge amount of money to be deployed, in the infinitesimal hope of being successful (very low chance of success while it would cost them probably billions at first).

Additionally, should one or more hackers ever succeed in taking control of a blockchain (or simply modifying one past transaction to their benefit), the value of the coins would become worthless as the rest of the network would have been alerted to its integrity being compromised, thus leading to all other participants to massively sell off their assets as quickly as possible (leaving hackers with worthless coins after having spent an exorbitant amount to obtain them).

3. How does the network regulate mining difficulty?

A blockchain’s mining difficulty is directly related to the number of miners available to proof the blocks that need to be appended to its network.

The more miners there are, the greater the difficulty level as new block targets become increasingly lower in value. The target level falls in value because the network needs to ensure the blockchain’s security/integrity by increasing the complexity of guessing correct nonce values (since more miners become available, it potentially raises the risk of a 51% attack if enough of them band together)

[Ruben99]

1. By spending money to mine blocks, we make the network stronger because in order to make changes you need to spend resources, which makes it very expensive to act fraudulently. Also, the more people mining, the greater energy needed, so there’s a correlation between network security, price and energy usage.

2. It’s difficult because blocks are linked through previous hashes (merkle tree), and so any change in a previous block, will invalidate next one, making it necessary to expend a lot of computional power to mine it again.

3. The protocol is desgined to make every block about 10 minutes, so it can autoadjust de difficulty of this puzzle, to always match this criteria, wether there are lots of miners, or a few of them.

[Pippo83]

1. By spending money on electricity, the miners have incentives to follow.
2. Every block is linked with the previous block, in order to change this the miner would have to change all previous blocks as well which is not sustainable and nearly impossible to do for the miner.
3. more miners, the lower the target gets which makes it more difficult to guess the nonce.

[blockhead59]

1. Why is it important to make sure that miners spend money (on electricity) while mining?
   The money spent mining keeps miners honest and the blockchain secure. It a miner is dishonest they would lose money.
2. Why would it be very difficult for someone to go back change a previously added block?
   By going back and changing a block would require you to mine all blocks after the changed block again as their link is now broken.
3. How does the network regulate mining difficulty?
   It regulates mining difficulty by adjusting Target range for the nonce. The lower the target the more difficult it is to mine, the higher the target the target the easier it is.

[WillRead]

1.Because it incentivizes them to play by the rules , otherwise if they try and break any rules during the mining process the will be left with a very expensive electrical bill as the blocks will be disregarded and not be upended.
2.Because if you did it would invalidate all subsequent blocks after it in the chain and you would have to go back and remine all the blocks as well as new blocks currently being made ,which would be virtually impossible with one computer as it would be equivalent to the network hash rate.
3.Fewer miners means a higher target and less difficulty , more miner means a lower target which has a higher difficulty of your hash getting below the target .

[Berumen_910]

-This way you incentivize them to play by the blockchain rules and mine the Block in an ethical way.
-In order to create a new Block you need the hash from all the previous Blocks. One of the characteristics of hashing is that the most minimum change alters drastically the hash. So if alter an already existing block all the hash will change and the connection between the blocks will break. In order to mine all the blocks again, you will need a lot of time and computational power.
-Based on the amounts of miners on the network. By adjusting the target of the nonce.