Homework on Blockchain and Mining Visually - Questions

Blockchain and Bitcoin 101
#1647

Nonce is in fact also a part of the hash (so H(k|x|y)) where X is the previous block hash :wink:

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#1648

Thanks for the clarification, although i do understand that nonce is a part of the hash it was more so the formula in which i wrote it that i didn’t fully understand.

#1649

  1. Blocks need to be cryptographically linked together to stop miners from trying to cheat and amend previous blocks without consequences.

  2. Bitcoin block structure looks like:
    -Hash (digital finger print)
    -Transaction list (of current block)
    -Hash of prev block
    -Nonce (random number to guess)
    The hash has to be less than the target and this target depends on the difficulty of the puzzle. The lower the target, the more difficult it is solve the puzzle.

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#1650

Homework on Blockchain and Mining Visually - Questions

  1. Why is it important that the blocks are cryptographically linked together?
    It prevents double spending and because of validation and because of hashing function

** 1 block comes from the previous block**

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

Previos block, hash, nonce, target, transactions, reward

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#1651
  1. Blocks need to be linked so that the previous block is part of the next block. This makes it so any changes to the previous block will also impact the next block. The dependency acts as a check that the previous block is still valid.
  2. The block starts with the hash from the previous block, adds the hash for the current transactions then hashes in the nonce to be able to get the number low enough to be an accepted block. That hash is then added to the next block.
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#1652
  1. To ensure that no double spending occurs and ensures that previous blocks can’t be changed.
  2. Input(s)—(Tx)—output(s).
#1653

you are describing how a transaction looks like.
The block structure has a header wich includes version, time, bits, nonce, HASH Previous Block!!, hash merkle root.
Then you have the list of all transactions.
This whole block is off course also hashed.

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#1654

  1. Why is it important that the blocks are cryptographically linked together? Data manipulation is prevented by having the blocks cryptographically linked together because changes in one block will force changes in the others.

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

  • block header-- hash of previous block, difficulty, timestamp, nonce, and merkle root which summarizes all transactions in the block
  • list of transactions
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#1655

  1. It is important that blocks are cryptographically linked together so that all the nodes are able to identify the longest chain.

  2. The structure of a block on the Bitcoin blockchain consists of:
    Version
    Last block hash ID
    Transactions
    Timestamp
    Target value

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#1656
  1. That’s the best way of enhancing the blockchain and keeping it immutable.
  2. The block is made of a header, containing metadata, transactions that make up the bulk of its size, and nonce.
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#1657

Its important to mention that the block header includes the hash of the previous block which is how the blocks are linked together :slight_smile:

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#1658

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

So that it creates an immutable chain that cant be changed, the link between the blocks is a mathematical puzzle that links all previous blocks together thus creating the blockchain.

What does the block structure look like in bitcoin?

The block is made out of data, previous block hash and a nounce, which is used to calculate a hash number below a threshold (difficulty aka the target).

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#1659

  • Why is it important that the blocks are cryptographically linked together?
    A change in the past effects all future blocks

  • What does the block structure look like in bitcoin?
    Last hash+TX+nonce ==> new block hash

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#1660

Why is it important that the blocks are cryptographically linked together?
It ensures the integrity of the blockchain and makes cheating economically and physically infeasible.
What does the block structure look like in bitcoin?
Each block contains the hash of the previous block, a list of transactions, the nonce guessed by the miner.

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#1661

  1. So that the integrity of the blockchain is maintained. If a like is broken, the miner would lose money.

  2. The block consists of the previous hash, transactions, and nonce.

1 Like
#1662

  1. The blocks being cryptographically linked together keeps the network secure and strengthens integrity.

  2. A block has a hash that is based on it’s transaction list, previous block’s hash, and the nonce.

1 Like
#1663

  1. Why is it important that the blocks are cryptographically linked together?
    So that if someone tries to change one in the past, they have to change all the other blocks as well

  2. What does the block structure look like in bitcoin?
    Block #
    Nonce
    Tx Data
    Previous Hash
    Current Hash

1 Like
#1664

  1. Because if you change something in a previous block, the link to the next block gets broken (because the hash of that block = the hash from the previous block + data from current block) and the next block and so on (chain reaction)

  2. Block structure in bitcoin:

  • hash of previous block
  • txs of current block
  • nounce number
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#1665

#1.- SECURITY , SECURITY . with much time spent one can de-code the
cryptography , but any changes one tries to implement cause a whole new set of problems.
#2.- Each block can have any number of transactions with 1 hash that corres-ponds to the previous block and fees from all transactions within that block
plus if the Miner does everything right with guess and nonce he can add his block on to chain and get a reward.

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#1666
  1. To maintain the integrity of the blockchain
  2. Previous hash, transaction list and nonce
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