Homework on Blockchain and Mining Visually - Questions

Blockchain and Bitcoin 101
#2552
  1. In the blockchain, the hashing algorithm keeps the blocks linked to the previous blocks, making the transaction data immutable.
  2. The block structure consists of a block header, and the hashes of the latest transactions collected from the mempool (including a coinbase transaction at the top for the block reward). The block header contains the following information in this order:
  • Version (Block version used for voting the block)
  • PrevBlock (Hash of the previous block)
  • Merkleroot (Summary of all the hashes of transactions stored on the block in a hash)
  • Timestamp (Unix Time format)
  • Bits (Compact version of the target value- first 6 significant characters after the leading zeros)
  • Nonce (An incremental value starting at 0 increased by one until the target value has been reached)
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#2553
  1. So that a forking can’t be easily repaired, this securing the original blockchain.
  2. Like a train of carriages???
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#2554

What do the carriages contain? :stuck_out_tongue:

#2555

  1. Why is it important that the blocks are cryptographically linked together?
    This makes it theoretically impossible to change data in the blockchain. Because by changing a transaction in a confirmed block, the hash of that block will change. Since the hash of each block is used to calculate the hash of the next blocks, the blockchain connections will break if you change a transaction.

  2. What does the block structure look like in bitcoin?
    The blockchain consists of blocks linked together, 1 block after the other. Each block has a unique fingerprint (hash) which is determined by the list of transactions inside that block, the hash of the previous block in the blockchain and a nonce (=random number).

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#2556

For security of the blockchain. Any transaction that is changed would cause a break in the chain of previous blocks bc the cryptographic puzzle is based on previous blocks

Hash of previous block
Nounce
Hash of current block
previous blocks

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#2557

Homework on Blockchain and Mining Visually - Questions

  1. Why is it important that the blocks are cryptographically linked together?
    *This makes it extremely improbable that a 51% attack would take place. The reason is because of this complexity, if someone wanted to change a previous block to double spend, for example, they would have to also change every block that comes after it in order for the network to validate the change(s). To do this would take an amount of computing power that would cost so much money in electricity that it would not make sense to do such an attack. You would be better off using that power to mine properly and claim all the rewards and transaction fees.

This is not to say that it is not impossible though. If some nefarious group was ideologically opposed to the idea of Bitcoin, they may very well attempt this at great expense. It would be a fool’s errand though.*

  1. What does the block structure look like in bitcoin?
    *The block is made up of the block size, block header, tx counter, tx list *
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#2558

1) Why is it important that the blocks are cryptographically linked together?
A block needs information from the previous block. If information is changed in the previous block then that block becomes invalid and the current block becomes invalid and the link is broken. This makes changes to previous transactions virtually impossible.

2) What does the block structure look like in bitcoin?
The block is made of a header, containing metadata, followed by a long list of transactions that make up the bulk of its size. The block header is 80 bytes, whereas the average transaction is at least 250 bytes and the average block contains more than 500 transactions.
Source: https://www.oreilly.com/library/view/mastering-bitcoin/

2 Likes
#2559

The block header also contains the previous block hash which is important to link the blocks in a chain, though you did mention the information from the previous block in your first answer. :slight_smile:

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#2560
  1. Security, since they are cryptographically linked together it makes it practically impossible to alter a part of a block, re-mine everything, and catch up.
  2. Previous Hash, Transaction list, Nonce.
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#2561

  1. To make information unalterable and secure. If someone changes the information of one of the blocks, the whole chain becomes invalid because all blocks are cryptographically linked.

  2. TX information of current block
    Previous block
    Nonce

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#2562
  1. Why is it important that the blocks are cryptographically linked together?

-This makes it so you cannot alter or remove previous transactions. Every new block is based on the contents of every previous block.

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

-Inputs/Outputs
-Transaction hash
-transaction list
-nonce

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#2563
  1. It is important that blocks are cryptographically linked together in order to secure the network. Someone would have to change every subsequent block just to change one transaction. It would be much less secure if the blocks were isolated cryptographic puzzles that could be altered individually.
  2. Each block contains the previous hash, a list of transaction data, nonce, and hash of current block.
2 Likes
#2564

Homework on Blockchain and Mining Visually - Questions

  1. It’s a prevention to avoid the alteration of transactions
  2. What does the block structure look like in bitcoin?
    3.Header, data, previous hash
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#2565
  1. It is important that blocks are cryptographically linked together for the security of the blockchain. That way no transactions can be changed in previous blocks because it would break the link to the next block and all that follow.This makes it virtually impossible to hack.
    2.The hash of the block is based on the transactions in the block plus the previous hash and the nonce that needs to be guessed.
2 Likes
#2566
  1. it is important that blocks are cryptographically linked together as it provides another layer of security in the blockchain. just as we discussed in the conversation about hash functions, if any block in the chain is compromised, it invalidates the following blocks in the chain. this protects the integrity of the data, helps miners maintain full transparency, and allows the network to function in a trustless manner as intended.
  2. the hash of the most recent appended block is comprised of the transaction data within that block, plus the hash (and transaction data) of the preceding block, and the nonce accurately guessed to validate.
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#2567

  1. It is important that the blocks are cryptographically linked together to prevent anyone from breaking the rules and changing transactions in prior blocks, since they are all linked together based on the previous block the bitcoin system essentially fail.

  2. The blockchain structure in bitcoin is constructed of the previous hash, transactions list, and the nonce.

2 Likes
#2568

  1. The blocks must be linked together so that they are secure, if one changes they all have to change. This prevents fraud and foul play, such as a miner changing a particular transaction in a particular block.

  2. The block will have the hash of the previous block, the list of transactions within this particular block and the nonce that got the block mined.

3 Likes
#2569
  1. Why is it important that the blocks are cryptographically linked together?
    If this wouldn t be so, then it would be easy to change the data so for example we can not afford double spending…so the network has integrity and structure that noone can change
  2. What does the block structure look like in bitcoin?
    It looks like combinations of hashes that are dependent one on another, so it has the hash of the previous block, hash of your block and nonce the number which is cryptografic puzzle and miners need to guess it.
2 Likes
#2570

  1. Because it ensures the validity of all the blocks before and after it. Its a seamless way for nodes to verify that everything is “true”.

  2. Each BLOCK has a PREVIOUS HASH, NONCE & TRANSACTION LIST

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#2571
  1. Why is it important that the blocks are cryptographically linked together?

Because the the current block is based on the previous block data and if you don’t have a link it will be impossible to determine the value of the previous block.

  1. What does the block structure look like in bitcoin?
    Transaction
    Previous Block
    Nonce and a time stamp.
2 Likes