Homework on Blockchain and Mining Visually - Questions

Blockchain and Bitcoin 101
#2049

  1. Why is it important that the blocks are cryptographically linked together?
    * Because it makes the blockchain unmodifiable so very secure

  2. What does the block structure look like in bitcoin?
    * It is based on a Nonce random number guessed by the miner , TXs and the hash from
    previous block. Those 3 componets builds the current block Hash

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#2050

  1. Why is it important that the blocks are cryptographically linked together?
    Blocks are cryptographically linked together to maintain the integrity of the data contained in them. The puzzle that is required to be solved in order to add a block to the chain is based on the contents of the previous block.

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

The most current block in a bitcoin blockchain will contain three major components, the hash of the previous block, the data/TXs being added, and the nonce required to solve the puzzle and initiate the confirmation of the block.

The blockchain structure is a linked list structure, a sequence of blocks each containing data linked to the next block via a hash pointer which creates a chain. Inside each block is a block header, the hash of the previous block header, and the merkle root. Inside the block header is the version (block number), difficulty target, previous hash, timestamp, hash of the tx root, and nonce. Inside the merkle root is the “hash trail” of all previous hashes contained in previous blocks pointing back to the original data blocks.

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#2051
  1. It is important that blocks are cryptographically linked together because if someone attempts to change a previous block, it forces them to change every block in front of it making it more difficult.
  2. The block structure on bitcoin contains the previous hash, current transaction list, and the nonce, which is all then hashed in the new block.
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#2052

  • Why is it important that the blocks are cryptographically linked together?
    it is a security measure so no one can change the content of blocks

  • What does the block structure look like in bitcoin?
    a block contains: hash of the current block (based also on a previous block), nonce, hash of the previous block, data (transactions)

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#2053
  1. This feature/rule ensures the integrity/trust in the data on the blockchain. Any change in one of the previously mined blocks will affect the resulting hashes in the next block and thus the chances are the resulting combination of the previously guessed nonce and the hash of the tampered block will not meed the difficulty target and thus be invalid.
  2. The block structure on the bitcoin blockchain contains the following elements:
    image
    image1181×730 278 KB

    Lee, W.-M. (2019). Beginning Ethereum Smart Contracts programming : with examples in Python, Solidity, and JavaScript . New York: Apress.,p. 18
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#2054

Merkle root is a tree of hashes of transactions contained in a block. :slight_smile:

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#2055
  1. cryptographically linking the blocks together prevents the previous records from being changed. the smallest change in any block results in a drastically different hash number.
  2. each block contains the previous block hash, the hash of the transaction list in the proposed block, and the nonce. a nonce is a random number that miners guess. the sums of these three components produce a block hash. if the block hash is lower than the target number then that block is propagated through the network for verification. if the network verifies the block the miner receives the block rewards and their block is added to the chain. if the block hash is higher than the target the miner rehashes with a new nonce over and over again until it finds a has lower than the target number.
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#2056

  1. To make sure people don’t double spend. They do this by making the block’s hash based on the last blocks hash, so since all the blocks are connected, if any were to change, all blocks after it would change.

  2. The block uses data from the last block, the data in it’s own block, and the nonce. That is all used to calculate it’s own hash.

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#2057

  1. This is important with hashing to ensure security on the blockchain. When one tx is changed all others change to alert the miners that there is an issue.

  2. It is based upon the nonce, data and the previous hash.

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#2058

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

    This ensure the security of the blockchain, as this prevents previous blocks and records in them to be changed.

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

    The block contains its own hash which is generated by including all transactions of that block, the hash of the previous block, and a nonce.

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#2059

  1. Why is it important that the blocks are cryptographically linked together?
    It adds security by preventing other from changing previous information in the blocks, it prevents the double spending problem as well.

  2. What does the block structure look like in bitcoin?
    Block structure- Previous Hash, transactions (tx), new hash, nounce, time stamp.

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#2060

(1) It is important so data can’t be changed.
(2) Transaction hash, inputs, outputs.

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#2062

Thanks I wasn’t sure how to phrase this I appreciate the reply :slight_smile:

#2063

  1. Why is it important that the blocks are cryptographically linked together?
    That the blocks are cryptographically linked together makes the security of the blockchain high. If you change anything in the current or previous block, the hash changes and it would break the link to the next block and all that follow.

  2. What does the block structure look like in bitcoin?
    The block structure in bitcoin includes the previous block hash, transaction list of the current block and the nonce (guessing of a random number).

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#2064
  1. To ensure security and integrity of the blockchain.
  2. The structure of the block is the hash of : prev block link hash, transaction list, nonce
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#2065

A block contains some other metadata as well. Most important the hash of the previous block that chains the blocks together. :slight_smile:

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#2066

to secure the network, not sensorship , not doyble spending
2. hash, previous hash, tx list, nonce

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#2067

  1. To prevent a change in an already mined block by causing a cascading effect of changes to the following blocks. To make the blockchain immutable.

  2. The block structure is a chain of blocks connected by links.

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#2068

Blocks are cryptographically linked so that a block cannot be changed without changing all blocks that follow it.

Bitcoin’s structure looks like a linked list with the hash of the previous block as part of the next block.

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#2069
  1. It’s important because that way each block contains copy of the previous block and the hash graph would change instantly giving a totally different output.
  2. Data of previous block, transaction and nonce.
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