Homework on Blockchain and Mining Visually - Questions

Blockchain and Bitcoin 101
#545

1.) That way no tx can be changed in the previous block, because it would break the link to the next and following blocks

2.) The block is made of txs, previous block hash, difficulty target, nonce, hashnumber below treshhold

1 Like
#546

It is important that the blocks are cryptographically linked together to keep anyone from changing any one block data. The block structure in bitcoin is base off previous blocks.

#547

  1. To provide security and immutability.

  2. The Nonce, Block header, hash of previous block, current target, block size, transactions and tx counter.

1 Like
#548

  1. Why is it important that the blocks are cryptographically linked together?
    Security and immutability…

  2. What does the block structure look like in bitcoin
    Hash of (Nonce, hash of previous block, transactions )

1 Like
#549
  1. Because being connected to each other if someone tries to change one, they will invalidate all those who come later and they should be mined again, which is impossible.
  2. The block structure of Bitcoin is composed of transactions, previous hash and nonce, with which a new hash is created. Then everything is repeated.
#550

  • Why is it important that the blocks are cryptographically linked together?
    Because they influeze each other to increase the security. Igf an older block gets altered all next blocks are invalidated. Thus increasing the difficulty to mess with the blocks astronomically.

  • What does the block structure look like in bitcoin?
    previous hash + nonce + transactions -> hash that has to be lower then the target. Each blocks are linked. All hashes change when something changes.

#551

It is important, why?
because this creates a robust chain of data that cannot be altered/modified, this is called immutability.

A block structure contains the hash of the block and the hash of the previous block.

#552
  1. Why is it important that the blocks are cryptographically linked together?
    This ensures immutability.
  2. What does the block structure look like in bitcoin?
    Each block in the chain has its own hash and the hash of the previous block.
1 Like
#553
  1. Why is it important that the blocks are cryptographically linked together?
    The tight linking of cryptographic links keep the network secure and immutable, and importantly easily verifiable.
  2. What does the block structure look like in bitcoin?
    At a high level, the blockchain is a linked list of blocks. Each unconfirmed block has a list of transactions, a difficulty level and a hash of that data. Once included in the chain, there is additionally a reference to the hash of the previous block, and a further hash of the block with all this information.
#554
  1. Prevent double spending or change to prev transaction
  2. transaction, prev hash, nonce, data
#555

  1. It ensures that no one changes or erases the information that constitutes the blockchain. If an attacker tries to do so, subsequent blocks in the chain would be altered as well and the protocol would render them invalid. It’s like duplicating cells, if one cell show up with a different DNA than expected, it is destroyed and not allowed to live in the organism.

  2. Each block is made up of the hash from the previous block, a transaction list, and a nonce lower than a target # calculated by adjusting the difficulty rate.

#556

  1. It keeps everyone honest and secured the network

  2. One block connected to the next block by a hash so that the slightest change shows a bad actor in the environment

#557

  1. So that a slight change in any block affects all of the following ones. This makes it practically impossible to cheat. With the sha256 its impossible to guess what nonce must be added so that the hash is lower than the difficulty target.

  2. A block consists of the transactions, the previous hash and the nonce (a random number) all of these are variables that will be taken into account by the sha 256. Then every Block is numbered, but that number does not get hashed.

#558
  1. In order to secure the network, keep it immutable and impossible to censor as well as to make sure the people play by the rules and don’t double spend or withdraw previous transactions for example
  2. A linked list of blocks which are interconnected with each block comprising of Tx hashes with details about inputs and outputs (UTXOs).
#559

1/ It is important to link them together so that modification of past block is infeasible and costly
2/ The block is composed of some transactions, hash of previous block, and a nonce.

#560
  1. This prevents tampering with historic transactions.
  2. Data consisting of many components such as previous hashes, timestamps, a nounce, UTXOs, and many other things I don’t understand just yet.
#561
  • Why is it important that the blocks are cryptographically linked together? >> because in this case every block confirmed the block before with the generated hash based on the previous hash
  • What does the block structure look like in bitcoin? Previous hash+Transactions+Nonce
#562
  1. It’s important so that the block isn’t changed because that would result in all hash changing and so the edited block would get rejected.
  2. Hash of the block is combined from TRANSACTIONS, PREVIOUS HASH, and the correct NONCE.
#563
  1. because the link between the block depends on the previous block which makes the system more secure
    2 prev hash. Nounce. new hash
#564
  1. To prevent anyone from changing a past record on the database without alerting the whole network.
  2. A block is made of Previous block hash, TXs of the block and a NONCE. The nonce is guessed by brute-force and a successful guess reward the miner with BTCs and Fees