Homework on Blockchain and Mining Visually - Questions

Blockchain and Bitcoin 101
#2834
  1. Because that is what makes it secure. Each hash from a block is based on previous hashes.
  2. A block contains a hash from the previous block, a list of transactions, and a nonce.
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#2835

  1. It is important that the blocks are cryptographically linked together because it creates an immutable record system.

  2. Block 1 { SHA-256 (tx data + 0 + nounce) = Hash 1} ===> Block 2 { SHA-256 (tx data + hash1 + nounce) = Hash 2} ===> Block 3 { SHA-256 (tx data + Hash 2 + nounce) = Hash 3}

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#2836
  1. more security,
    a) so that you cannot double spend a UTXO
    b) so that you cannot alter history of a block
  2. hash of previous block
    transactions of current block
    nonce (random number)
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#2837

  1. If somebody tries to change a transaction the cryptographical link makes all the following blocks invalid they will be rejected by the network. That makes manipulation impossible.

  2. It has a hash value as an id, no nonce, the hash to the previous block a list of transactions.

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#2838

  1. It is important because it shows the integrity of the chain if they are linked together it means everything in the block is done correctly, so it is verification at the same time that everything is working, no cheating no errors.

  2. Previous hash + TX list + Nonce. From these we can hash the newblocks hash number which will have to be lower than target number in order for this new block to be accepted to the network.

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#2839
  1. as this provides the security of the blockchain. Makes it immutable. If a block is altered by amending a single TX this breaks the chain to all subsequent blocks.
  2. each block has a hash, transactions and fingerprint of the previous block and the nonce that has to be found via solving the mathematical puzzle
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#2840

  1. It is important the blocks are cryptographically linked together to increase security and make it difficult make false blocks.

  2. The block structure has the previous hash, verified transactions, and a nonce.

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#2841

:slightly_smiling_face:

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#2842

  1. Why is it important that the blocks are cryptographically linked together?
    It ensures integrity within the blockchain. If the chain is broken then everything would need to be recalculated. Its like a digital stone that cannot be manipulated.

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

There is a list of transactions, the previous hash and the new hash which is based from the previous hash, nonce.

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#2843
  1. Because that encryption ensures the integrity and immutability of the blockchain.
  2. A block structure basically contains:
  • block number
  • nonce
  • data (tx)
  • prev block hash
  • block hash
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#2844

Homework on Blockchain and Mining Visually - Questions

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

-1 immutability can be guaranteed this way

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

-Previous block hash, current block data and nonce.

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#2845
  1. Why is it important that the blocks are cryptographically linked together?

It is important for security so that people can’t alter a block that was previously added to the blockchain. Doing so would alter all of the blocks that follow it. A miner would never be able to compete with other miners because they would fall behind miners that have not altered blocks. If the blocks were not cryptographically linked, then someone could alter the data in a block and continue mining new blocks without any negative consequences.

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

A block contains the data of the hash from the previous block, the transaction list, and a nonce. This new hash must be lower than the target hash. If it is not lower than the target, miners continue to “guess” a new nonce until the resulting hash is lower than the target.

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#2846
  1. Why is it important that the blocks are cryptographically linked together?

To mathematically make sure a proper ledger of transactions is kept.

  1. What does the block structure look like in bitcoin?
    input (data), prev hash, hash (created by input), and a nonce.
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#2847

  1. That no one can cheat the protocol and try and change a block without breaking the
    rest this ensures that no double spending, censorship. Secures the network.

  2. A record of all transactions, a reference to the block that came before it, puzzle that is based of
    previous blocks, and a Nonce.

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#2848

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

This ensures security and if you now cryptography, you know the complexity behind it and that gives it integrity.

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

A block has a hash witch contains previous hash, tx data and a nonce.

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#2849

  1. Why is it important that the blocks are cryptographically linked together?
    This ensures that that transactions in the block are immutable, because any change would result in hashes from other block changing also. The cryptography also enhances privacy.

  2. What does the block structure look like in bitcoin?
    A block is a containment unit, comprising of a header, and a list of inputs and outputs. This is connected to a previous block via a cryptographic link. Each block has a hash function, this hash includes the transactions within the block and the hash of the previous block.

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#2850
  1. Why is it important that the blocks are cryptographically linked together?

This is what maintains an unalterable chain. If one block changes anywhere, all following blocks do and this means they can all be seen as invalid.

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

Block Size - 4 bytes
Block Header - 80 bytes
Transaction Counter - 1-9 byter (Variable Integer)
Transactions - Variable

Block size details the size of the total block in bytes.

Block header contains three sets of metadata:

  1. Previous block hash
  2. Difficulty, timestamp and nonce
  3. Merkle tree root, used to summatize all the transactions on the block.
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#2851

  1. It is important that the blocks are cryptographically linked together so that they form a true chain of dependency on eachother, such that a change in one would impact (break), the blocks after, assuring its integrity (or that a lack of integrity would be immediately noticed and flagged).

  2. The block structure in bitcoin consists of information about the block (in a block header), and a list of transactions.
    Block information includes: block number, version, time stamp, number of transactions, the merkle root (a type of hashing) of all the transactions in the block, block size (various types of sizes measured, including energy, bits, difficulty), the nonce for the block, the hash for the block block before), the fees and the rewards for the block.
    see: https://www.blockchain.com/btc/block/00000000000000000002ffe06c76b7d29c07d8a19ca26d4ffc6e7c0d01970232

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#2852

1. to make sure it is immutable
2.
a. The current block version number
b. the current time stamp
c. the current difficulty target
d. hash of the previous block
e. hash of Merkle root
f. Nonce

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#2853

Homework mining p2

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

What does the block structure look like in bitcoin?

1 This is because we don’t want the blockchain to be altered , so this makes it more difficult to change a block of the blockchain. So when you change one you have to change all of them which is not easy to do.

2 Previous hash of the block, current block transactions , and the nonce

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