Homework on Blockchain and Mining Visually - Questions

Blockchain and Bitcoin 101
#1167

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

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

  3. Because if you try to alter data in the past it changes the hash from that block moving forward. This means you would have to remine that block and every block moving forward. Not only this but you must catch up to the network this is very impractical and difficult to do not to mention extremely expensive.

  4. Previous block hash, transactions, nonce, these are hashed to produce the block current block hash

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#1168
  1. Why is it important that the blocks are cryptograpcally linked together?
    To ensure the security of the network.
    What does the block structure look like in bitcoin?
  2. Maigc numbers - identify custmers and what software (2) Bitcoin block size - how long is the transaction (3) Block Header - consist of version, identify the format of block (4) Transaction counter - list of transaction. Hash of the previous block is the hash of the header, (5) Miners, Time, Target and Nonce
    Bitcoin uses the public blochain and the structure is decectralised open to anyone who wants to participate. It is decentralised system built on cryptographic tecnique and stores data which is inseparably linked to the previous block, create a chain called blockhain and nearly imposible to change records. The miners uses computing power to validate data of the new blocks and the miners receives the block rewards which is the newly genarated bitcoin. For security and transparency bitcoin uses the private key.
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#1169

  1. It is important that blocks are cryptographically linked together because it ensures the immutability of the blockchain. In this way, changes to one block would break the chain.

  2. In bitcoin the hash of each block is determined by hashing all transactions within the block, the previous blockā€™s hash, and the nonce (a random number.)

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#1170
  1. secures PoW and integritiy of the entire BC, only by using the datas of the previous block the next block can be created, creating an indestructable chain of interlinked blocks, one block depends on the other
  2. BTC hash-function SHA 256 defines ho the blocks are interlinked. Each block in order to be confirmed as successful mining has to consist of:
    a) data created by the hash-function based on the previous block
    b) the actual TXs
    c) NONCE - mathematical puzzle to be solved, lower than the set-up target
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#1171

  1. To secure the network and make it hard and expensive any attempt of hack.

  2. You have the nonce; the transactions and the hash of the previous block.

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#1172

Nonce is not the puzzle :slight_smile: Check the reply I gave you in Mining and Proof of Work homework :slight_smile:

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#1173

  1. It helps to increase safety of blockchain against any fraud. Anybody trying to cheat would have to change and re-mine not only all the following blocks, but also all links between the blocks, which are closely connected to the blocks.

  2. Version
    Previous Block hash
    Merkle root hash
    Timestamp
    Difficulty target
    Nonce
    Block Size
    Block header
    Transaction counter
    Transactions

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#1174
  1. You cannot make a change to one block without affecting all subsequent blocks which produces a strength in numbers effect due to having to re-mine the changed and all subsequent blocks. This helps secure the network.
  2. The block structure is made of up the previous hash, previously guessed nonce, and new transactions of that block
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#1175
  1. This prevents the data to be altered and provides the immutability of the blockchain. Previous and following hashes get changed.
  2. current transactions, nonce, previous hash and hash of all that informations
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#1176

1 one block after another so it is obvious where the change occurred more easily rectified also no short cuts must change each block sequentially equaling exorbitant cost of money and time
2 inputā€”initial block --output (merkel pool) ā€“ registered with minersā€“input -block output --merkel pool -registered with miners etcā€¦

#1177

I believe only the previous hash is important. :slight_smile:

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#1178

It is important that the blocks are cryptographically linked because that is the structure that holds the blocks together.

Block number, transaction + previous hash, new hash, nonce, and repeat.

#1179

What parameter in the block makes them linked together? Also, what will happen to the network without these links?

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#1180
  1. Why is it important that the blocks are cryptographically linked together?
    To preserve immutability of the blockchain.
  2. What does the block structure look like in bitcoin?
  • hash
  • previous hash
  • TXs list
  • nonse
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#1181
  1. That makes the blockchain secure. If you change one block your at the same time changing all the follwing blocks, since the blocks hashĀ“s are depending n each other.
  2. Hash of block + (TXs of block + hash of previous block + nonce)
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#1182
  1. It is important that blocks are cryptographically linked together because, then we can follow the note ā€œverify - donā€™t trustā€. Means that if some block is changed other blocks in front will change too. Which will break the connection and then the miner will be punished. Simply put ensures that blocks remain immutable.

2.Bitcoin block structure can be described as following. The hash rate of the block is based on the hash rate of the previous block plus on the nonce that needs to be guessed plus on the target that is set according to amount of miners

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#1183

1: It is important for all blocks to be cryptographically linked to ensure the integrity and security of the blockchain, no reversals or changes can be made without breaking the link.

2: Block structureā€¦

Previous Hash
Current block hash
Target (difficulty)
Nonce (magic number)
Block size
TX input/ outputs

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#1184

  1. Blocks are cryptographically linked in order to secure the blockchain and provide integrity to the blockchain. Transactions become immutable and any change to a transaction completely changes transactions that follow.

  2. Block structure in Bitcoin transactions consists of the block number, the nonce, data sets (transactions), previous hash and then final hash which becomes the previous hash for the following block.

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#1185

Actually changing the transaction in an already mined block changes the merkle tree root, and consequently the block hash :slight_smile: A specific transaction hash only depends on its own parameters (though in case of a false input that would also be true).

I think you are switching blocks and transactions. Blocks contain transactions and those blocks are linked together in a chain where the link is the previous block hash.

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#1186

Homework on Blockchain and Mining Visually - Questions

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

The cryptographic links between blocks makes blockchains, like bitcoin, immutable. Each block is built on all the previous blocks in the chain, and the network will always choose to continue building on the longest chain. PoW blockchains are in this way secured by the miners, by cryptographically linking blocks together. As a block gets ā€œburiedā€ deeper and deeper in the chain, itā€™s harder and harder to change or remove.

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

The block structure of bitcoin is made of a block hash and transactions (among other things). A block hash is constructed from hashing all the transactions, the previous block hash and a nonce together. The nonce is always just a random number. The transactions are collected from the mempool. The block reward (+ fees) will also be the first transaction in the block, and will have no inputs.

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