Homework on Blockchain and Mining Visually - Questions

Blockchain and Bitcoin 101
#1007

Don’t forget about the previous hash. Its important for making the links in the blockchain. A nonce is also one of the parts I would mention. There is more but these are the most important. :slight_smile:

#1008

No problem. If you need any help feel free to DM me. I am here to help. :smiley:

#1009

The links protect from any sort of block tampering. Changing just a single digit or letter will invalidate the block and all the blocks behind it. :slight_smile:

#1010

The new block is consisted of the blocks previous hash and not the whole previous block.

1 Like
#1011

Because changing any txs in a block will change its hash which is used in hashing the next block so all blocks need to be remined.

Block no.
Nounce
Data that contains txs
Previous hash
And they are all hashed into one hash

2 Likes
#1012

  1. Yes changing the block will invalidate all other blocks behind it.

  2. Previous hash* :slight_smile:

1 Like
#1013

Not all. Only the blocks that come after the block that has been tampered with. Older blocks are more secure than the newer ones. :smiley:

#1014

Yes, previous hash secures the blockchain. We link them to make sure the blockchain is immutable. :slight_smile:

#1015

Exactly. Changing a block would invalidate the blocks after it. Meaning an attacker would need to remine all the blocks they broke. (Without block rewards) :slight_smile:

#1016

  1. Its important that the blocks are cryptographically linked together in order to increase the difficulty required to alter the past blocks, and if altered one would have to hash consecutive blocks to create a link between them. This is nearly impossible as the energy and equipment cost required outweigh the returns.

  2. Bitcoin Blockchain structure designed listed below:

  • Version * Previous block hash * Merkle root hash * Timestamp * Difficulty target * Nonce * Block size * Block header * Transaction counter * Transaction
1 Like
#1017

1: it ensures the integrity of the blockchain if one block is modified it affects all blocks that follow

2: TX in block previous hash nonce

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#1018

1 It prevents someone to change it, ensure data integrity and the immutability of the network.
2. It has the transactions, the previous block hash , the nonce a random number.

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#1019

Why is it important that the blocks are cryptographically linked together?
To create security through immutuability possible in decentralised network. This is actually the major and game changing difference to standard centralised databases.

What does the block structure look like in bitcoin?
Eevery block has a header followed by block data. The Header contains the previous hash, the top level data hash and the nonce (and additional information, timestamp, difficulty level, etc.). The data segment contains all transactions and the first transaction is always the coinbase transaction containing the block reward for the miner.

1 Like
#1020

  1. Why is it important that the blocks are cryptographically linked together?
    it ensure the integrity of the block and that transactions cannot be altered.

  2. What does the block structure look like in bitcoin?
    It has:
    block#
    previous block
    nonce
    txn data

#1021
  1. Because blocks need to be linked, so the whole chain :link: can detect if someone is tempering with transactions.
  2. Transactions, nounce, target, hash from previous block, whole block hash
1 Like
#1022

  1. This is to ensure that the transactions are secure as any attempts to change the blocks will break the chain linking the blocks together.

  2. It contains the nonce, data, hash of the previous block and hash of the current block.

1 Like
#1023

  1. So that the security of the blockchain can be ensured by preventing tampering with transactions.

  2. Previous hash, nonce, transactions, current hash.

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#1024

  1. Why is it important that the blocks are cryptographically linked together?
    A: By linking all blocks together it ensures every transaction remains immutable (unchanged). This secures the blockchain by making it expensive to attack the blockchain by re-writing block(s).

  2. What does the block structure look like in bitcoin?
    A: Each block’s hash is calculated based on the previous block’s hash, the current block’s transaction list, and the nonce.

1 Like
#1025

Hi there! Just a minor correction, as its the previous block hash. The hash is like a summary of the previous block, and as the previous block contains the hash of the block before it, the current block will have the summary of all blocks in history since 2009!!!

Felipe.

#1026

  1. Blocks that are linked cryptographically are important for the security of the network. This link prevents the modification of data in the current and previous blocks; otherwise known as immutability.

  2. The block structure in bitcoin essentially comprises of the block hash, previous hash, nonce (variable target solution), and the TXs (transactions).

1 Like