Homework on Blockchain and Mining Visually - Questions

Blockchain and Bitcoin 101
#3878
  1. So a block cannot be changed after it is included in the block chain. It would break all the links after that block.
  2. The accepted hash of the previous block, transactions and nonce.
1 Like
#3879

  1. Its important so that no one can go back and change a TX in a previous block/ double spend.

  2. Previous hash, TX list, and Nonce.

1 Like
#3880

1.So nothing in prev. blocks can be changed.
2. All blocks linked to prev. block with hash. Included in new block has the following: prev block hash, new block tx/rx and new blocks info hash combined into a new hash

3 Likes
#3881

1)Why is it important that the blocks are cryptographically linked together?

It is crucial to help keep the blockchain inmutable, if you change any information in the chain the chain will be broken which will ensure it is rejected by other nodes.

2)What does the block structure look like in bitcoin?

Previous Hash
Transaction List
Nounce

2 Likes
#3882

  1. Blocks on the blockchain are linked together to ensure that a bad actor can’t go back to a previous block and manipulate the data. If they were to do this, it would change the hash of that block and all blocks proceeding it. This means they would have to mine that block and all blocks following it for there to be a successful hack of the blockchain network. As doing this is unfeasible, given a significant size and hashing power of the bitcoin network, this is how the double spend problem has been solved.

  2. The block structure of a bitcoin block contains a block number, a nonce, block data, and a hash. The current block’s hash is based on the previous blocks hash, the current block’s data and the current blocks nonce.

2 Likes
#3883
  1. Why is it important that the blocks are cryptographically linked together?

To ensure that future block also include previous blocks in the hash (algorithm) and to make future blocks dependent on previous block (puzzle solves) so that it disincentivezes hackers to break the code, as the whole block depends on block integrity

  1. What does the block structure look like in bitcoin?
    Transaction hash’s linked to some of the previous hash including a nonce (solved puzzle) in a series of blocks.
3 Likes
#3884

  1. Because it creates a dependency between all blocks in the chain, making it increasingly more difficult to hack the blockchain as far as you move back from the current block.

  2. Each block contains a cryptographic hash of the previous block, as well as timestamp and transaction data. As blocks contain information from the previous they form a chain.

3 Likes
#3885

  1. Blocks that are cryptographically linked together provide a more secure structure. This security comes from the difficulty of a person going back to a previous block and making any changes. If a change has been made then all the proceeding blocks are “unlinked” as their hash values have also changed (hash is determined by previous hash x data x nonce). This means that all blocks must be re-mined which for one computer may take countless amounts of time.

  2. The block structure is essentially the current hash that is calculated by the previous hash with the transaction data and the nonce. The use of the previous block hash is the reason why the “chain” structure exists.

1 Like
#3886

1. Why is it important that the blocks are cryptographically linked together?
Because the cryptographic puzzle is based on previous blocks. It assures that the previous blocks cannot be changed, at least practically. After solving the puzzle a link is being added to the blockchain. If someone changes the contents of one block all the links after the block will be broken, making it practically impossible to redo the broken links and blocks. Furthermore, the cryptographically linked blocks assure that work needs to be done in order for the new link to be created because it is based on Proof of Work.

2. What does the block structure look like in bitcoin?
A block has transactions data and a block header that contains a timestamp, version, Merkle root, nonce, difficulty target and previous hash.

2 Likes
#3887

1.) It prevents the data from being changed. If a previous block were altered it would be very obvious to everyone in the network.

2.) In the block there is the hash of the previous block, nonce, and transactions, which are then used to compute the current blocks hash.

2 Likes
#3888
  1. Why is it important that the blocks are cryptographically linked together?
    So that it insures the integrity of the data.
  2. What does the block structure look like in bitcoin?
    The blocks are made out of data, previous block has and NONCEuntil the hash of the block is lower than a specific target.
1 Like
#3889
  1. Links between blocks are a mathematical puzzle, which connects all previous blocks all together.
  2. block is made out of data now + previous block hash + nounce, which is used to calculate a hash number below a certain (difficulty).
2 Likes
#3890

  1. Why is it important that the blocks are cryptographically linked together?
    –> this ensures that every change in the blockchain breaks the validity of the entire blockchain if modified

  2. What does the block structure look like in bitcoin?
    tx’s, previous block hash and nonce to be found, relative to target size

2 Likes
#3891

  1. Why is it important that the blocks are cryptographically linked together?
    The chain reinforces immutability. When a block is linked to a new block, the data is copied onto the new block. This process repeats indefinitely until the hard cap has been reached. Each new block holds a copy of the previous blocks, so alteration of data w/in each block will be significantly difficult.

  2. What does the block structure look like in bitcoin?
    Each block is composed of a hash, the previous block’s hash, transaction info, and nonce.

1 Like
#3892

So nobody can tamper with them. (no adjustments, no double spent,…)

Each block contains its own hash, the hash from the previous block, the nonce

1 Like
#3893

  1. Why is it important that the blocks are cryptographically linked together?
    So that it’s only a one way function and people cannot tamper with it.

  2. What does the block structure look like in bitcoin?
    First you have the nonce, then the txn details of the current block, the hash of the previous block and the current target

1 Like
#3894
  1. Why is it important that the blocks are cryptographically linked together?
    ans-to discourage anyone to make any altercations to previous blocks which makes it very secured.
  2. What does the block structure look like in bitcoin?
    *ans-it will need to have transaction lists, previous hash rate and nounce before being added as a new block with its own hash.
1 Like
#3895

  1. It is important that the blocks are cryptographically linked together together to maintain the integrity of the blockchain and ensure previous transactions cannot be altered and prevent things like double spend.

  2. The block structure is formed of the nonce, list of transactions, and the previous hash.

1 Like
#3896

  1. Why is it important that the blocks are cryptographically linked together?
    Because it prevents the data to be altered, as it would invalidate the blockchain

  2. What does the block structure look like in bitcoin?

Previous block hash
Transactions
Nonce

1 Like
#3897

  1. Why is it important that the blocks are cryptographically linked together?
    In order to detect any changes to previous blocks. Also the nonce of a new block is calculated using the link.

  2. What does the block structure look like in bitcoin?

Previous Hash
Nonce
Transactions
Hash

1 Like