Homework on Blockchain and Mining Visually - Questions

Blockchain and Bitcoin 101
#1307

Homework: Mining Visually Qs

  1. It’s a chronological data structure building integrity over time. The longest chain wins and continues stacking blocks. If it weren’t linked, miners could hypothetically change data / double spend, breaking the integrity of the data structure. However you can’t change one block without changing all post blocks due to the corresponding hashes. Then it’s a race to recreate the broken chain to be the longest chain, which isn’t really possible.
  2. Previous block hash, Data hash, and Nonce
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#1308
  1. Why is it important that the blocks are cryptographically linked together?
  • To secure the network through integrity. Ensure there is no double spending. Consensus
  1. What does the block structure look like in bitcoin?

UTXOs
Previous block hash
current block hash
Nonce

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#1309
  1. It’s important for blocks to be linked cryptographically so that any changes to a previous block will be picked up as the hash will change and therefore the block gets removed from the blockchain.
  2. A block contains 3 components to make a hash: the nonce (a target number the miner needs to guess), the transactions, the hash from the previous block. Combined together gives the block the hash to be used for the next block.
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#1310

  1. It ensures legitimity of the network. When one of the blocks is changed, thanks to the link, the other blocks change too and it results in invalidating the node which has that changed copy of the network.

  2. It contains transactions, previous hash, nonce and it is all hashed together to create the current hash.

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#1311

Homework on Blockchain and Mining Visually - Questions
1. Why is it important that the blocks are cryptographically linked together?
To make it almost impossible to change one block without get noticed, as the chain will be broken if one of the block is changed and it also happens to all those predating blocks. As the old nonce value dosent match the previous calculated hash vale in that particular block, also the next block hash value based on the previous therefore the hole chain is un-valid after the tampered block. To fix this corrupt chain each block is needs to be re-mined and re hashed before accepting the change done in the previous block, and that will almost be impossible with today’s computer/miners.
2. What does the block structure look like in bitcoin?
The structure is a list of blocks with transactions in it, and are sorted in particular order. The blocks are linked together with a hashed pointer that’s glue them together. So each block consist of a block header, hash of previous block header and the merkle root. So in that way the block can prove both the integrity and validity of all transactions in the blockchain

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#1312

All tx data (except the witness in Segwit), not just the UTXOs which is part of a tx structure :slight_smile:

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#1313

  1. Why is it important that the blocks are cryptographically linked together?
    R: It is important for security. In this case it is practically impossible to change anything in the chain.

  2. What does the block structure look like in bitcoin?
    R: Hash from the previous block/ Transaction/ Nonce/ Hash from the current block

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#1314
  • Why is it important that the blocks are cryptographically linked together?

It is important that blocks are linked together because it makes it pretty much impossible to make a change to the blockchain. If you change the contents of a block, it breaks the cryptographic chain. Miners would need +51% of the hash rate to re-mine the blocks and create a longer chain that would result in double spending. In theory, if there was no chain you could change the contents of the blocks independently without affecting other blocks.

  • What does the block structure look like in bitcoin?

Block number
Nonce (Changes to the nonce change the Block hash)
Transactions (in/out)
Hash of previous block
Block hash (Needs to be within Target)

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#1315

  1. so no hacker wouldnt profitibly hack in beacause they would have to mine each block agean and catch up with the new blocks so they would need 51% of the whole hash rate and it would take thousands of years to catch up and it would be much more profitible mining by the rules.

  2. theres the hash, the list of the TXs, and there is the nonce. (and the block number)

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#1316
  1. Because that way the block chain remains unbreakable or immutable.
  2. Something like, block number, block hash, previous block hash, nonce and list of TXs.
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#1317

Why is it important that the blocks are cryptographically linked together?
It makes the chain tamper proof.

What does the block structure look like in bitcoin?
Simplified:
Block number.
Nonce.
A list of transactions / Data
Hash of previous block.
Hash of current block.

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#1318

Why is it important that the blocks are cryptographically linked together?
So that immutability is guaranteed across the entire network, by causing a hashing error when a new block is appended to the chain, if any change of state happens in any transaction in any prior block in the chain.

What does the block structure look like in bitcoin?
Hash of current block
List of transactions of current block
Hash of prior block (via pointer)
Block identifier
Nonce

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#1319

That ensures the Network security of the Blockchain.

It is made from Data from the previous Block hash, Transactions and nonce to calculate the difficulty.

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#1320

  1. Since a block contains the hash of the previous block, when you change a block all later blocks need to be changed in order for the rules to be followed. When miners solve the puzzle, they really solve a puzzle specific to the entire chain including all preceeding blocks and the present block. Therefore the longer back you want to change something, the more expensive it will get to remine all blocks after that.

  2. [ transactions1, nonce1, previous hash1 ] ----- [ transactions2, nonce2, previous hash2 ] ----- …

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#1321

  1. Why is it important that the blocks are cryptographically linked together?
    the linked hashing throughout the blocks in the chain are what gives the blockchain its immutability and security

  2. What does the block structure look like in bitcoin?
    each block contains - the hash of the previous block, transactions, nonce

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#1322
  1. is it important that the blocks are cryptographically linked together for security purposes. If the any transactions are changed in the previous Block the next link is broken and all following links are broken.
  2. (Previous hash) and (Transactions) make up the (nonce). The hash of the current block are made up of these three. The nonce is the random number that is calculated and has be low than the target in order for the miners’s block to be appended to the blockchain.
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#1323

Why is it important that the blocks are cryptographically linked together?
to assure immutability and accuracy of the blockchain

What does the block structure look like in bitcoin?
previous block HASH + new transactions + nonce

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#1324

  1. To ensure security immutability, secures the network and prevents scams, whilst also incentivising miners to play by the rules and reap the rewards legitimately.

  2. Each block contains transactions (that have been confirmed from the mempool). Each block has its on hash number or block header AND the hash number of the previous block, as it uses the hash number of the previous block to generate its own hash. Each block has its own block size and its own unique nuance number, that was used to reach a hash below the target number at that time.

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#1325

  1. It protects the chain of utxo and links them all together making it nearly impossible to hack or change.

  2. Hash numbers or transactions, the previous block hash and a nounce

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#1326
  1. Linking blocks together keeps participants from changing previous blocks without consequences
  2. Bitcoins block structure is a blockchain. Its a chain of blocks linked together such that no one can change previous blocks without causing the whole chain to fall apart
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