Homework on Blockchain and Mining Visually - Questions

Blockchain and Bitcoin 101
#2814
  1. Why is it important that the blocks are cryptographically linked together?
    Having each blocks hash based on the previous block makes it impossible to go back and change previous data without it being noticed by the network
  2. What does the block structure look like in bitcoin?
    hash of the previous block + transaction data + nonce (random number)
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#2815
  1. Ensures the security of the blockchain. If a miner tries to apply changes to previous blocks the links between them will be broken and it will be practically impossible to re-mine them and catch up with the new upcoming blocks.
  2. Number of the block, transaction data, nonce, hash of the previous block, hash of the current block.
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#2816

  1. This system makes people trust the blockchain and makes it very secure. Because if the blocks were not linked together, it would not be this strong.

  2. The first block starts with no previous hash number as it’s the first one. On each block there is block number, nonce, data, previous hash number and the hash number.

The next block’s hash number is created by using the previous block’s hash, the transactions written on it.

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#2817
  1. Why is it important that the blocks are cryptographically linked together?
    So, you can`t corrupt the data’s. If you do change in one block it will affect whole block chain after that block.
  2. What does the block structure look like in bitcoin?
    Chain of blocks linked to each other.
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#2818

  1. Because it disallows for changes to information in the blocks without being noticed. All following blocks in a chain would need to be re-mined.

  2. Previous hash, block, nonce, and transactions.

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#2819
  1. It ensures that the block remains unchained over time(immutable).
  2. It includes the hash from the previous block, the transactions list and a nonce.
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#2820

  1. It is important that the blocks are cryptographically linked together to preserve the immutability of the blockchain as any alteration in one block will affect the previous and subsequent ones .

  2. The Bitcoin block structure contains the following: -Block header, transactions , hash of the previous block, block size, nonce, block size and transactions counter.

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#2821

  1. It makes it impossible to change a block. When you change one block, it means you must change the following blocks by catching up with other miners.

-Data transactions
-Previous hash block hash
-Nonce
-Block header
-Current header

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#2822
  1. Why is it important that the blocks are cryptographically linked together?
    Ensures immutability
  2. What does the block structure look like in bitcoin?
    Previous Hash
    Transactions of the new block
    Nonce
    and the new hash which is the result of combining the 3 previous elements
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#2823
  1. Why is it important that the blocks are cryptographically linked together?

Because the cryptographic puzzle (which needs to be solved in Pow in order for miners to create the new block and get rewarded with block reward and transactions fees) contains a hash of the previous block and all the previous hashes. Knowing the fact that the hash algorithm (SHA-256) used for hashing all this information is unidirectional, this means that the network is unbreakable, as changing one single piece of information in any of the previous blocks would result in the break of the system (such as double spending).

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

Block Number, Nonce, Data (transactions), Previous Hash, New hash (the hash of this block).

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#2824

  1. To insure the integrity of the blockchain so that if any changes are made the entire network is alerted.

  2. Previous hash–Current transactions–Nonce

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#2825
  1. They need to be cryptographically linked because otherwise every other block would fail if even the slightest thing is off. Which could lead to manipulation we need to maintain the security and integrity of the blockchain.
  2. The structure is The hash of the previous block, previous hash, the transaction list, and the nonce.
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#2826

  1. Why is it important that the blocks are cryptographically linked together? - Having the blocks cryptographically linked together keeps the system honest. You cannot change transactions other wise it breaks the links and that is not acceptable to the system. All prior things must stay as they were when added to the chain.

  2. What does the block structure look like in bitcoin? There are blocks and links in the structure of bitcoin. Blocks have the previous hash, the transactions added to the block and the nonce which results in a HASH that must be lower than the target created for them to meet on this block. The links are linked to the data in the prior block that they are linked to. If you were to change the data in one block the link connecting that block and all going forward would break.

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#2827

The cryptographic linking is the essence of fluidity in the Blockchain. As a block is added it contains the previous hash, transactions, and nonce. This is repeated with each new block added and creates a sequential trail that can be traced. It would be mathematically astronomical to go back in time and change a block and rehash all following blocks to get ahead of the miners producing correct blocks. This results in the integrity of the Blockchain encourages miner’s to stay honest.
2.) Each block contains previous block hash, transaction list, and nonce (random number). Each following block in the chain follows the exact pattern.

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#2828

Why is it important that the blocks are cryptographically linked together?
Because the blocks in the blockchain are cryptographically linked together it makes it difficult to change the blockchain. This ensures security of the network.
What does the block structure look like in bitcoin?
Bitcoin uses the proof of work block hashing algorithm called hashcash. The hashcash algorithm takes the following input that is with in the header:
-A. service string- encoded in the block header data structure and includes:
1. a version field- block version number
2. the 256-bit hash of the previous block
3. The root hash of the Merkle tree of all the transactions in the block.
4. Time- current block timestamp as seconds since 1970-01-01T00:00 UTC
5. Difficulty
-B. Nonce (Number Only used oNCE). Nonce is an arbitrary 32-bit number that is part of the hashcash algorithm (also part of other hashing algorithms). Nonces are generated using larger length random number generation to minimize collision attack.
Nonce is the number that blockchain miners are solving for.
The process of guessing the hash starts in the block header. It
contains the block version number, a timestamp, the hash used in the
previous block, the hash of the Merkle Root, the nonce, and the target hash
-C. counter- the counter parameter is small at 32-bits. So, each time it wraps the extra-nonce field, it must be incremented (or otherwise changed to avoid repeating work) .

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#2829

Why is it important that the blocks are cryptographically linked together?
If the clocks are not linked together there is no way to verify and confirm the current block of transactions against the existing or previous block of transactions
What does the block structure look like in bitcoin? Blocks linked together by the hash of the previous and current block

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#2830
  1. Why is it important that the blocks are cryptographically linked together?
    It ensures that the data in each block cannot be tampered with without compromising the whole chain.
  2. What does the block structure look like in bitcoin?
    The block contains data (transactions), a nonce, a unique hash, and the hash of the previous block.
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#2831

  1. It is important that the blocks are cryptographically linked together because it means that they are essentially tamper proof. This means that if someone was to edit a block in any capacity the rest of the network would know immediately as the blocks would no longer seamlessly fit together.

  2. The block structure consists or the hash of the previous transaction plus the nonce and all of the data of the new block that needs creating.

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#2832

  1. If they wouldn’t be cryptographically linked, miner wouldn’t have to solve mathematically equations. The whole PoW system wouldn’t exist.

  2. Previous hash + Tx list + Nonce = Hash

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#2833
  1. it is important to make sure that there are no mistakes and cheatings at all.
  2. hash of the previous block + list of transactions + nonce which is a random number
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