Homework on Blockchain and Mining Visually - Questions

Blockchain and Bitcoin 101
#3255

“A chain that links every block with next block” this the structure of the chain, the block structure in bitcoin contains the list of transactions, the hash of the previously mined block and the nonce and the hash of the block itself

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#3256
  1. it essentially stops people going back to alter data… meaning that the process is more secure
  2. hash is made via; prev hash, tx, nonce
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#3257

  1. Why is it important that the blocks are cryptographically linked together?
    To preserve the integrity of the chain.

  2. What does the block structure look like in bitcoin?
    Blocks of data, linked cryptographically together, with no reasonable way to alter the data in any way as each block and link is intimately related to and relies on the blocks and links before it.

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#3258

What links these blocks together? :wink:

#3259

Ah! Those special Hashes?! Each hash having been made up of some of the block before it and so on and so on - the hashes link and cannot be broken without breaking the entire chain after the initial break. :sweat_smile: :slight_smile:

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#3261
  1. Why is it important that the blocks are cryptographically linked together?
    Because it preserve the integrity of the blockchain since to go back and change one old block will force to mine again also all the other following blocks
  2. What does the block structure look like in bitcoin?
    It is composed by and hash (digital fingerprint of the block) and the TXs list. The hash is based on the previous block hash, the TXs list and the nonce.
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#3262

  1. It ensures the finality of data in the blockchain as the links become invalid if changes are made to a previous block, as the hashes of the blocks change then, which changes all hashes of the following blocks

  2. The block contains the list of tx, the hash of the previous block, a nonce. The current blocks hash then needs to be derived from those and fit in the target set through difficulty

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#3263

1. Why is it important that the blocks are cryptographically linked together?
This prevents transactions on a block from being changed, because it would break the links on the subsequent blocks and need to be re-mined and cost a tremendous amount of time and electricity.
2. What does the block structure look like in bitcoin?
transactions + hash of previous block + nonce = hash

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#3264
  1. For the sake of blockchain integrity, all blocks are linked and immutable.
  2. The block contains the nonce, transactions and previous block hash which is used to make create the new hash.
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#3265

So that it will take the miners computational power to confirm a transaction and keeps the network secure.

In the block is the previous hash, current hash, transaction, timestamp and nonce

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#3266

To ensure nobody changes previous blocks afterwards - meaning all the blocks are depending on each other. If one is „out-of-sync“ all the subsequent ones will also have an error. Hence in a way it‘s temper-proof:-)

The structure consists of previous hash, tx list of the current block and the nonce (random# that needs to be less than the target given).

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#3267

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

It is importanant to maintain the properties of blockchain, that all the info stored in the blocks cannot be changed

What does the block structure look like in bitcoin?
Each block has a hash generated by the miner. And it is generated from hash of the previous block, tx in the block and a random nonce.

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#3268

So that if a previous block is attempted to be altered – the rest of the hashs will change, invalidating all the blocks which throws out their blockchain.

A block is made up of the previous hash, the list of transactions in the block and the nonce.

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#3269

1_ To ensure a single alteration invalidates the entire thing,

2_ Hash {Hash of prev block, Txlist, Nonce}

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#3270
  1. It ensures the security of the blockchain as it is nearly impossible to modify transactions from previous blocks.
  2. Previous hash, transactions and nonce
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#3271

  1. To prevent any changes to the prior blocks

  2. A header containing the information about the block.
    The previous block hash - as every blocks inherits from the prior block
    Block identifier - timestamp, the nonce and the difficulty
    Merkle tree root - a data structure verifying the integrity of the data

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#3272

  1. Why is it important that the blocks are cryptographically linked together? One of the cornerstone of bitcoin protocol that guarantee history immutability.

  2. What does the block structure look like in bitcoin? Hash of previous block, nonce, list of all transaction including COINBASE transaction.

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#3273

  1. Fact that they are linked together makes it very very difficult (almost impossible) to change transactions, which makes blockchain secure and safe

  2. It’s build out of hash of previous block, transaction’s data, nonce, and hash of current block

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#3274

Building it that way prevents cheating. If they’re linked together and changing on block would require to change also previous one it would require resolving the puzzle again. By creating it this way it is unprofitable to cheat.
2.
Blocks are linked together, longest block are favourable>are chosen by blockchain.

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#3275

  1. It is important for the blocks to be cryptographically linked together because this is what ensures it is immutable. If something is changed on a previous block, it changes the rest of the blocks which is what ensures somebody can not go and change a transaction on the blockchain.

  2. The block is made from data from the previous hash, transactions in the block and the nonce. The nonce is calculated to create the hash. The hash has to be below a certain target which measures the difficulty of creating the block.

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