Homework on Blockchain and Mining Visually - Questions

Blockchain and Bitcoin 101
#262

  1. It ensures that it is extremely difficult to make changes to any of the blocks after they have been added to the chain.

  2. Each block has a hash pointer to the previous block in the chain as well as a hash of all the transactions, the previous hash and the nonce.

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#264

Answer:

  1. Any change of the data inside any block leads to a change of the hash. That hash is used in subsequent blocks. Any such change is easily noticed and rejected by the network. It ensures the immutability of the ledger. You can be confident that no data has been compromised inside that ledger. You trust the math.
  2. Bitcoin Block contains a block number, nonce, coinbase transaction ( subsidy ), data about all the confirmed transactions on the network, hash of the previous block.
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#265
  1. Why is it important that the blocks are cryptographically linked together?
  • It is important that the blocks are cryptographically linked together because it ensures that each transaction is appropriate to amend to the blockchain; thus, it ensures the network is secure
  1. What does the block structure look like in bitcoin?
  • The block structure in bitcoin includes the block, nonce, data, previous hash(unless it’s the first block), and the address of the new hash.
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#266

  1. Because if any prior block is modified, it will change all the blocks that came after it.

  2. a singe block consists of: prior block hash, data and nonce.

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#267

  1. It is important that the blocks are cryptographically linked together because that means if you try to change a block in the link, all of the links to the future blocks break and you would have to re mine from that point and catch up to the blockchain which is practically impossible.

  2. The block structure has a block number, a nonce, the data or transactions, the previous hash and the current block hash.

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#268
  1. Because in this way nobody can change anything in the past blocks.
  2. In a block there are the individual transactions, then the hash of the previous block and the nonce.
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#269

It is important because block can’t be changed what means immutability and security of the network.
2.The block structure in bitcoin have inside(transactions data of the block + hash of the previous block +nonce ) that gives together hash of this block --and next blocks are all linked same.

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#270

  1. Linking all of the blocks together is the backbone of the blockchains security. Changing one block would require you to change the entire chain in real time which is impossible

  2. In a block you have the data, the previous hash, the hash of the block that’s being created, block number, the transactions being put through, and a signature from the sender

#271

Signatures of the senders are inside the transactions. A Miner doesn’t sign a block when a new block is added to the chain.

#272
  1. Linking is what prevents data from being changed and thus ensures integrity. Any data being changed in previous blocks would break all block links from that point onward.
  2. nonce + current tx data + previous block hash
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#273

Ahh man I did mess that up, thank you sir I’m gonna go back and re-watch that lecture now

#274
  1. It is important that the blocks are cryptographically linked together to create the security of the blockchain. You can’t go back and alter a block without changing the previous and all following blocks.
  2. The bitcoin block structure includes previous hash, transaction list, and nonce.
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#275

Don’t worry, you seem to get most of it!
Just miners don’t sign blocks. Digital signatures is to validate transactions to spend and move UTXO’s (in transactions)
Miners are just trying to find a nonce to have their block reward. By adding transactions + random number into a block. Keep guessing the nonce, hash again, check if hash is low enough, repeat until they have a blockhash lower than target

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#276

1.It is important that blocks are cryptographically linked together for the security of the blockchain. That way no transactions can be changed in previous blocks because it would break the link to the next block and all that follow.
2.The hash of the block is based on the transactions in the block plus the previous hash and the nonce that needs to be guessed.

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#277
  1. It is important that the blocks are cryptographically linked together, because by maintaining an interconnected blockstructure, changing one bit changes the whole blockchain. Therefore changes which are accepted by the network, will either take into account a lot of effort (hashrate), or are to hard to reconstruct and at the same time keep up with the speed of the developement of the blockchain. Therefore security is very high.
  2. The block structure in bitcoin looks like a row row of blocks, connected in series by links, and consist in itself of the previous hash + Tx’s being put on the blockchain + nonce.
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#278
  1. since they are linked together, it is hard to change any block because you need to change all that follows.
  2. the block contains the transactions of that block, the hash of the previous block and a number nonce which through sha 265 gives the hash of the block
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#279
  1. It’s important because by that difficulty increases, by that we have more secure network
  2. We have: previous hash, current transactions and nonce that needs to be guessed, that all is calculated in new hash
#280

  1. For security purposes. That way, no one can alter one block because it will mess up the whole network

  2. The block is made out of data, previous hash of a block and a nonce.

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#281

  1. By cryptographically linking the blocks, the security of the network is ensured, as no changes can be made to already verified blocks without corrupting the rest of the network.

  2. Each block contains a hash comprised of:

  • The hash of the previous block
  • The list of transactions in the current block
  • The nonce of the current block
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#282

1. Why is it important that the blocks are cryptographically linked together?
It is important to link the blocks together because it makes it difficult to change or manipulate the block data as the block is dependent on the hash of the block and the hash of the previous block. When one block is changed, you have to change all the blocks and hashed relationships between each blocks. The link between each block is the bond of trust.

2. What does the block structure look like in bitcoin?
Version > Last Block > Merkle Root > Time > Target > Nonce

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