Homework on Blockchain and Mining Visually - Questions

Blockchain and Bitcoin 101
#2613

The nodes on the singly linked list represent the blocks of the blockchain and they are linked in a way that the hash of the later block depends on the hash of the previous block.

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#2614
  1. As to ensure the integrity of the mining (double spend, reversing a previously made transaction).
  2. a hash, nonce, and transactions. the hash is based off the previous hash.
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#2615

  1. Block are linked together such that past and present and upcoming transaction can be verifiable by its unique hash output, to ensure that the network is highly immutable. Any attempt to alter any data in the previous block will brake link to next block.

  2. The block structure is a combination of block header, containing metadata such as: list of transaction, timestamp, target difficulty, block size, previous block hash and merkle root hash.

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#2616
  1. To keep the blockchain secure
  2. Previous block hash plus transactions and nonce makes a new hash.
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#2617

1.) blocks are cryptographically linked together in order to ensure that blocks remain immutable and cannot be altered.

2.) the block will contain the hash of the previous block, transactions within the block, and the nonce in order to find the hash of the next block.

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#2618

  1. Why is it important that the blocks are cryptographically linked together?
    Because the rules of the consensus mechanism have to ensure that the miners play by the rules and are not able to change transactions easily.
    Instead of one giant effort to manipulate the blockchain it would be a lot easier to manipulate a single block.

  2. What does the block structure look like in bitcoin?
    Each block includes the nonce, the hash of the previous block, transactions and the hash of the current block

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#2619
  1. Why is it important that the blocks are cryptographically linked together?

This makes it so that if you go back and try to change an old block, you would have to mine out blocks to catch up. This takes too many resources since they are linked together cryptographically. So, this feature secures the blockchain.

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

It is a nonce + transactions in the period + previous hash

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#2620
  1. Once they are confirmed, and hashed, no one needs to go back and verify any previous block as the chain is intact. As each block has its own hash, if any transaction is changed in the bloc, its hash would change and the would break. Without a break, we therefore know anything in the past is confirmed and can unaltered.
  2. Each block has the hash of the previous block, the nonce, the transactions (uxto’s) of that block and hash of the current block.
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#2621

Answers:

  1. It is important that blocks are cryptographically linked together so that prior blocks can not be tampered with or changes without affecting all future blocks. Once a prior link is broken this version of the blockchain is not valid since it is no longer the longest blockchain. This means an unscrupulous miner would need to hash the changed block and all subsequent blocks and would need to catch-up and surpass the most current (longest blockchain) that would have continued to be carried on by other miners. This effort would take enormous amounts of electricity and time and is practically impossible unless this control 51% of the hash power of the entire network.
  2. Includes the following items:
    Block number, nonce (random #), all the transactions, prior block hash and current block hash
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#2622
  1. Why is it important that the blocks are cryptographically linked together

The blocks are linked together for increased security, everytime a block is added a cryptographic link is created between the blocks. When the new block’s hash is created and when the new hash uses the previous hash to create the new one. If a single transaction is changed on a previous block it breaks all the links to the connected blocks and the ones that follow.

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

The block will have the previous hash, the transactions list and the nonce, the hash that is created for the current block will contain all of these factors.

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#2623
  1. To keep the integrity and security of the Chain
  2. You have Block Header which consists of Previous blocks Headers Hash,Timestamp, Nonce, Merkel tree root, Hash of the current blocks header andTransaction list.
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#2624
  1. To Secure the network
  2. The block has a previous hash, nonce and all the transactions that creates hash for the current block
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#2625
  • Why is it important that the blocks are cryptographically linked together?

It is important that blocks are cryptographically linked together because of security of blockchain. Change in previous block automatically changes next block and breaks their link.

  • What does the block structure look like in bitcoin?

Block structure consists of previous hash, TX list, nounce, hash of current block

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#2626

  1. Why is it important that the blocks are cryptographically linked together?
    It makes it almost impossible to change data on a block, because it would break the links with other blocks in the chain.

  2. What does the block structure look like in bitcoin?
    The current hash would include the hash of the previous block + transaction data of current block + nonce

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#2627
Bitcoin Basics

  1. Why is it important that the blocks are cryptographically linked together? It is important that the blocks are cryptographically linked together for the security of the block chain. If somebody was able to change a previous transaction it would break the whole chain.

  2. What does the block structure look like in bitcoin? The structure consists of the previous hash, nonse, transactions that are in the block.

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#2628
  1. For the security of the blockchain. That way the transactions cannot be changed in previous blocks because it would break the link to the next block.
  2. The block contains the previous hash, transactions and nonce.
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#2629
  1. Because any change of a previous block will cause the hash changed in all subsequent blocks, this ensures that the blockchain become safe against fraud
  2. Hash from previous block, transactions and nonce (puzzle)
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#2630
  1. So they cant be changed afterwards. If you change one, you break the chain.
  2. Previous block hash, plus new transactions, plus nonce.
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#2631
  1. Why is it important that the blocks are cryptographically linked together? Well, firstly it wouldnt be called a blockchain anymore but because even empty data represents a hex number or hash I suppose.
  2. What does the block structure look like in bitcoin? It has a hash, pervious hash, tx’s in an immutable chain.
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#2632

Answers Mining Visually

1. Why is it important that the blocks are cryptographically linked together?
That makes the blockchain immutable. A change in one block would invalidate all subsequent blocks which then would have to be mined again.

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

  • Data: Contains the list of transactions in that block
  • Previous Hash: The hash value of the previous block
  • Nonce: The guessed number to meet the target
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