Homework on Blockchain and Mining Visually - Questions

Blockchain and Bitcoin 101
#3015
  1. Because changing one block in the past would change its hash and therefore change also the hash of the next. If this were not the case, a bad actor could make a copy of the blockchain with modified transactions in the past and nobody would notice the change
  2. Timestamp, nonce, hash of the previous block, transactions and the new hash of the block
1 Like
#3016

That’s a great question, Ales. Thank you.

Each block contains a cryptographic hash of the previous block, a timestamp, and transaction data.

Wikipedia rocks!

1 Like
#3017
  1. Why is it important that the blocks are cryptographically linked together?

So that transactions in previous blocks can’t be changed without breaking the links in the following blocks.

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

The hash of a block is based on the previous blocks hash, the transactions within the block and a nonce (random number).

1 Like
#3018

  1. Blocks are linked cryptographically as to insure immutable. Any changes to a mined block will result in a block’s link to blockchain severed.

  2. A block has a list of transactions, the previous block’s hash, utxos, nounces, and target

1 Like
#3019
  1. Why is it important that the blocks are cryptographically linked together?
  • linking is essential to protect the integrity of the blockchain because if one link is broken though trying to manipulate the blockchain, all subsequent links will become invalid.
  1. What does the block structure look like in bitcoin?
  • block structure consists of (1) the hash of the previous block (2) the TX data and (3) the nonce, a random number
    These suggest the crypotgraphic answers to ‘puzzle’
1 Like
#3020
  1. Why is it important that the blocks are cryptographically linked together?

This secures the blockchain by making previous changes exponentially more difficult to remine.

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

The block consists of the transaction data, the previous hast and the nounce.

1 Like
#3021

1.) the blocks are linked together to ensure that all of them only confirm the chain while the previous hash is correct. that secures the network because no one can go back in time to change a transaction, double spent or take money back.

2.) a block consists of the previous hash, the current to confirm transactions and the nonce. all of that needs to get hashed, creating a new hash, confirming the block and it will be linked with the next block once it is hashed as well.

1 Like
#3022

Bitcoin Basics

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

This ensures that the individual blocks in the chain are fundamentally and consistently linked together, increasing the difficulty to make changes in the previously mined blocks / UTXO’s

What does the block structure look like in bitcoin?

The block contains 1 the nounce, 2 the tx (transactions UTXO input and output), and 3 the hash of the previous block. These components get SHA 265 hashed in a new fingerprint, which is first measured against the target, and if the nounce was guessed right by the miner, the block will then propagate and the miner gets a reward.

1 Like
#3023

  1. When it is linked together it will ensure integrity and security of the network.

  2. The block structure consists of the hash of the current block ,previous block hash, transaction list, and the nonce.

1 Like
#3024

  1. Why is it important that the blocks are cryptographically linked together?
    This increase the security of the data by ensuring that previous transactions cannot be altered and remain in the valid blockchain. It also disincentives cheating by requiring the re-mining of all subsequent blocks without the assistance of the network.

  2. What does the block structure look like in bitcoin?
    The previous block hash, transactions to be included, and a nonce value are hashed and that value competes to be below a target value.

1 Like
#3025
  1. Why is it important that the blocks are cryptographically linked together?

It increases the difficulty to change previously appended blocks.

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

It is a hash of the previous block’s hash and the transactions of the current block.

1 Like
#3026
  1. To maintain integrity and make it extremely difficult and a waste of money for anyone trying to compromise the chain.

2.A header (hash), transaction data, previous block hash, a nonce

1 Like
#3027

Homework on Blockchain and Mining Visually - Questions

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

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

  3. To prevent cheating in the system, as double spending. In that way no transactions can be changed in previous blocks as that will break the link to the next block and the block after and so on.The link between them is a mathematical puzzle that links all the previous blocks together.
    2- In the block we have previous hash, nonce, transaction data (UTXOs). Then the current block hash is calculated from all three.

1 Like
#3028

  1. Why is it important that the blocks are cryptographically linked together?
    This ensures that the data in the whole chain is valid and can’t be modified afterwards.

  2. What does the block structure look like in bitcoin?
    Block hash consisting of:
    TX data
    hash of previous block
    nonce

2 Likes
#3029
  1. Why is it important that the blocks are cryptographically linked together?
    So that if one block is modified all following blocks have to be modified too, making it impossible.
  2. What does the block structure look like in bitcoin?
    The hash of the blockj is made by the previous hash + the tx list + the nonce (randomly guessed number)
2 Likes
#3030
  1. Why is it important that the blocks are cryptographically linked together?
    If you modify something in block, you will suppose to generate new blocks, because hash was changed
  2. What does the block structure look like in bitcoin?
    Nounce, TX , prev hash
1 Like
#3031
  1. Why is it important that the blocks are cryptographically linked together?

It’s a way to make sure that previous block hasn’t been changed. It makes sure that previous transactions are not reversed or changed.
Block hash is determined by the block transactions and with previous block hash and with nounce.

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

Imputs from the wallet will generate UTXO. Miners integrate transactions UTXO into blocks. A block is given a hash depending on transactions, previous block hash and guessed nounce that is below target.

1 Like
#3032
  1. By linking blocks together cryptographically the network is considered secure as you are not able to go back and make a change without breaking the hash that validates each link.
  2. The structure of a block in bitcoin looks like this -

{Block Header -
Version
Previous Block Hash
Merkle Root
Timestamp
Difficulty Target
Nonce

All transactions within the block}

1 Like
#3033
  1. to give more security and stability as every block is linked to previous and ne ones.
  2. transactions, previous hash and the nonce
1 Like
#3034

  1. It makes it impossible for anyone to alter the previous blocks since they’re cryptographically linked together in a way that altering a previous block will change the data in the following blocks. This means attackers need to re-mine all the following blocks by the time the Blockchain mines the next block. Arguably impossible

  2. The blocks are linked based on the previous hash, TX list, and nonce, which creates the new hash. The next block will need the prev hash, tx list, and nonce to create new hash.

1 Like