Homework on Blockchain and Mining Visually - Questions

Blockchain and Bitcoin 101
#1467

Mining Homework 2

The links between the blocks are the Mortar that hold the chain together and ensure its integrity. The cryptographic nature of this link is directly related to the mathematical puzzle that must be solved to create the next block. This link must be formed cryptographically so as to protect the chain from being altered by a malicious party.

The structure of the blocks represents a chain with links that connect each block to the previous block. One might visualize this in the manner in which a railroad car engine has many railcars behind it, each attached to its former and previous railcars to create the entire length of the train.

1 Like
#1468

  1. It is important for blocks to be cryptographically linked to ensure security in the network. Each block is built based on the previous block making it infeasible to change transaction history.

  2. Previous block hash, current block transaction and nonce.

1 Like
#1469
  1. The fact the the blocks are linked together by the previous hash increases the difficulty to modify any previously validated blocks and increases security.
  2. The block structure of the block is Tx+Nonce- previous hash.
1 Like
#1470

  1. Why is it important that the blocks are cryptographically linked together?
    Because of data immutablity. The link is the mathematical puzzle that the miners have to
    solve, which is based on the content of the previous block, i.e. hash of the previous block.

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

    • Hash of the previous block
    • All the transacions of the current block
    • the nonce (random number), this is actually the mining itself, calculating the nonce over and
      over again until the hash of the nonce, the hash of the previous block and the tx of the current
      block is below a certain target.
1 Like
#1471

[quote=“ivan, post:1, topic:8433”]

  • Why is it important that the blocks are cryptographically linked together?
    the reason being that the transaction outputs remain immutable therefore the linking of the blocks depends on the accuracy and you cannot manipulate or change or undo the chain.
  • What does the block structure look like in bitcoin?
    hash, current block, hash of previous block, transactions , block header, current target and nuance
1 Like
#1472
  1. In order to keep the network security and integrity and make it difficult/practically impossible to change the contents of a previous block.
  2. Block number, hash of the block, transaction data, and hash of the previous block.
1 Like
#1473
  1. To secure the whole chain, not just the latest block.
  2. Current hash
    TXs
    Prev Hash
    Nonce
1 Like
#1474

Homework on Blockchain and Mining Visually - Questions

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

Answer: Makes it astronomically/geometrically more difficult to solve for a reward if you try to change thdata.

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

Answer: Data, previous hash (SHA-256), current hash, Nonce

1 Like
#1475

  1. Because it prevents block data to be changed.

  2. So, a block contains a list of transactions of the current block, the hash of previous block and a nonce value.

1 Like
#1476

Linking blocks in a blockchain is important for two reasons. First is that system will always pick longest chain for which all blocks must be linked, and secondly it prevents changes to any previous blocks, since any changes will sever links between the blocks which will trash that chain.

BTC block consists of three entries. Hash of previous block, transaction list of current block and Nonce.

1 Like
#1477
  1. maintains the integrity of the blockchain - if they werent then you alter transactions in blocks without penalty (double spend, send utxos back to originating wallet, etc…)
  2. Each block is hash of: its list of transactions, the hash of the previous block, nonce such that the block hash is less than target was when current block was mined.
1 Like
#1478
  1. The cryptographic link ensures the integrity of the blockchain making it impossible to change any data from previous blocks.
  2. the hash is calculated from the hash of the previous block, the data inside the block and from the “nonce”.
1 Like
#1479

  1. So it is difficult to break.

  2. Block number, nonce, transaction data, previous hash, current hash

1 Like
#1480

  1. Because that’s what makes the blockchain, blocks rely on previous blocks.

  2. A block has a hash, transactions and nonce . You activate the mining that activates/guesses the nonce that gives you a unique signature/hash.

1 Like
#1481
  1. so no one can alter data, if something changes in a block then there are changes happening in the previous block and so on. Any change would break the link between the current block and the previous one.

2.Current hash is based on previous block’s hash, transactions of this current block and discovering the nonce (random number). If the new hash is lower than the target (difficulty level) then the new block gets added to the chain.

1 Like
#1482

  1. It is important to cryptographically link blocks together to increase the security of the blockchain, that is it will take a lot of computing power to not only alter a single block, but also the links between each block.

  2. The block contains:
    a) TX hash
    b) inputs
    c) outputs
    d) nonce
    e) target

1 Like
#1483

  1. Why is it important that the blocks are cryptographically linked together?
    In order to append the block to the blockchain we got to solve the cryptographic puzzle (nonce) and once we find it we can create the link, these links between blocks are expensive, they are very special, they are based over the informations at the other blocks.

  2. What does the block structure look like in bitcoin?
    Block number
    Nonce
    Data (Transactions)
    Previous hash
    hash

1 Like
#1484

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

It is important that the blocks are cryptographically linked together to secure the network through the collective hash rate of miners. When blocks are cryptographically linked together transactions will be resistant to censorhip, UTSO’s cannot be double spent and you cannot remove old transactions. Proof of Work or consensus algorithm ensures agreement is validated with only one version of truth over which transactions occurred. With Proof of Work you do not need to trust any central authority for integrity of data but math and physics.

2 What does the block structure look like in bitcoin?

The block structure in Bitcoin interlinks previous blocks cryptographically in a secure manner on the network using a hash function called sha-256. The transactions constructed by a wallet is broadcast through the network by nodes and placed in a mempool. The nonce together with the previous hash and current transaction list selected from the mempool is picked up by miners to create a hash that is less than the target number. The new block is then confirmed and appended into the blockchain with only one miner securing a block reward currently 12.5 and transaction fees. A transaction can be added but its history remains unchanged.

1 Like
#1485
  1. Why is it important that the blocks are cryptographically linked together?
    hash function like hash256 can make unique digital signature so we can ensure all of the blocks are securely link in chronological order and avoid fraudulent transactions like double spending.
  2. What does the block structure look like in bitcoin?
    Each block has a hash output that is hashed with its nonce, data, and previous block hash output
1 Like
#1486

  1. This is an important part of the blockchain technology, it is important because every information you put in, changes the hash, and then it will linked to every singel block, you can never erase but you can always put more information. its ensures security and immutability. if you change something, you have to link every block again and you pay for the electricity again.

  2. Simplified, Blocknumber, Nonce, A list of transactions/ Data, Hash of previous block, Hash of current block.

1 Like