Homework on Blockchain and Mining Visually - Questions

Blockchain and Bitcoin 101
#2673

Cryptographically linking blocks together provides security for network and preserves its integrity. Changing data in a previous block would break the link with the following blocks (by changing the hash). So it secures the integrity of the blockchain. In theory, it might be possible to relink them but in practice, it cannot be done. Anyone editing a previous block would have to re-mine all the blocks thereafter, and also keep pace with the mining of new blocks.

    • A hash of the previous block (the digital fingerprint of the previous block).
    • The transactions list (new data being added to the blockchain).
    • Nonce, a random number. The miner will cycle through nonce values at random until the hash of all the block contents combined is less than the difficulty target.
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#2674
  1. So that it is impossible to change a transaction and therefore block(hash) from the past.
    Security and trustles.
  • TX (from mempool)
  • Prev hash
  • Nonce (needs to be guessed -> mining)
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#2675
  1. Why is it important that the blocks are cryptographically linked together?
  2. What does the block structure look like in bitcoin?

A1: This ensures that an attacker can’t go back and edit any transactions without re-hashing all of the intervening blocks.
A2: It’s the hash of the previous block, plus new transactions and the unique nonce that needs to be randomly guessed to generate a new hash that is below the target.

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#2676

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

If one block is tampered with, all blocks mined forward in time would become invalid and would have to be mined again.

What does the block structure look like in bitcoin?

Block are essentially data structures consisting of hashes, UTOX, previous hashes and the nonce that has to be figured out.

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#2677

  1. Because this cryptographic puzzle ensure with PoW, through math and physic laws, the data immutability in the blockcahin.

  2. The Block structure are made by block header, difficulty target, the nounce, all data structures of the transactions involved, previous block hash, current block hash.
    I guess surelly not in this order!

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#2678

Homework 1/20/21 Blockchain and Mining Visually

  1. Why is it important that the blocks are cryptographically linked together?
    To promote the integrity of the chain, immutability, makes the blocks manipulation-proof.

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

Data transactions, hash functions (previous hash functions), nounce, new hash output.
Block header, block size, data transactions/transaction counter, nonce, prev block hash.

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#2679
  1. they are all interlinked, if a previous block would be incorrect/altered it would affect all blocks down the chain.
  2. a block includes information, (tx) previous hash, nonce and current hash
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#2680
  1. To ensure previous blocks are not manipulated for malicious attempts and to detect if anyone is trying to modify it
  2. What does the block structure look like in bitcoin?
    Contain info like block size, nounce, gas, hash
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#2681

  1. It secures the system by not allowing transactions to be removed without breaking the chain.

  2. A chain of blocks. Each block contains the previous blocks has, the current transactions, and the nonce.

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#2682

  1. It protects the network from changes that are made afterwards.

  2. The Block is structured by a “target hash” which is made out of the Hash from the previous block + all the transactions that go into this new generated block + the random number called “Nonce”

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#2683

  1. So that the blockchain is virtually impossible to tamper

  2. Block hash
    Transactions
    Previous block hash
    Nonce

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#2684
  1. It give integrity as one block connects to the next with a link based on the previous blocks hash.
  2. It kinda looks like a doubly linked list.
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#2685

1 Because allow the Ledger to be immutable.
2 A chain.

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#2686

Homework on Blockchain and Mining Visually

  1. Why is it important that the blocks are cryptographically linked together?
    It is important that blocks are cryptographically linked together in order to secure the network and do not allow double spending and especially to make difficult, or better to say, impossible to going back in time.

  2. What does the block structure look like in bitcoin?
    The block is made of the transactions from the mempool that miners decide to include (usually firstly those with high payed fees) and the first transaction that is the inflationary reward, the hash of the previous block and the nonce that is a random number that miners need to guess in order that the hash of the current block is equal or less of a target.

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#2687
  1. It prevents the removal and changing of parts of the blockchain.
  2. SHA-256(DATA)*Previous hash *Guessed nonce=Hash, This is then checked against the target.
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#2688
  1. This secures the blockchain from fraud and tampering. If they weren’t linked someone could go back on the chain to change previous data with no consequences.
  2. A block consists of the previous block hash, transaction list, and nonce to create its own fingerprint/hash.
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#2689

Homework on Blockchain and Mining Visually - Questions

  1. Why is it important that the blocks are cryptographically linked together? It makes it difficult for cheaters or hackers who are nodes to go back and edit data on the blockchain.

  2. What does the block structure look like in bitcoin? A block structure has a nounce, data input and the previous blocks hash value.

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#2690

How do the nodes/blocks in the list/chain look like? :wink:

#2691

  1. it is important so that every following block has information of all the previous blocks. If a previous block changes, the hash of that block also changes, which will change all following blocks.

  2. Block #XY SHA256(Hash from previous block + transactions within the block XY + nonce)

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#2693

  1. Linking the blocks into a blockchain guarantees the integrity of all the previous blocks.

  2. Block structure = Previous Block Hash + Current TX + Nonce

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