Homework on Blockchain and Mining Visually - Questions

Blockchain and Bitcoin 101
#343

  1. Why is it important that the blocks are cryptographically linked together?
    It is important that the blocks are cryptographically linked together to ensure the data integrity. If a change is made in a block that is already accepted and added into the blochchain, then this block and all the following ones will have to be recalculated.

  2. What does the block structure look like in bitcoin?
    A block structure contains the hash of the previous block, the transactions list of the current block and the nonce which is a random number to guess and that has to be less than the target.

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#344
  1. That prevents someone to change a block entry.
  2. A header including: version, previous hash, merkleroot hash, timestamps, bits, nonce and all the transactions
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#345

Homework on Blockchain and Mining Visually - Questions

  1. Why is it important that the blocks are cryptographically linked together?
    By linking the blocks together by maths, you ensure the network’s IMMUTABILITY.

Because once you want to change something in a previous block, the hash of each following block is changed, and therefore also the outcome of every crypto graphic puzzle outcome.

  1. What does the block structure look like in bitcoin?
  • transaction hash
  • hash of the previous block hash
  • the hash of the nonce

=> hash = all must be lower than the target.

#346
  1. So that it is quite impossible to alter successfully the previous blocks since every block has a hash value based on the previous ones.
  2. A bitcoin block is composed of three elements : a list of transactions, a nonce (random number) and the hash value of the previous block. The first block has a succession of zeros as a previous block hash value since there are obviously no previous blocks. Every block has its unique hash value based on the three elements described above.
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#347

1. Why is it important that the blocks are cryptographically linked together?
Because it will make sure the security of the blockchain. If someone wants to change the content of the block, the link will also be changed and the relation between each block will be broken.

2. What does the block structure look like in bitcoin?
It made of three-part: the previous hash, the content of the current block, and nonce. What the miners do is hashing these three things and get the hashing number of current block.

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#348
  1. To assure that no one can change transaction on the previous blocks.
  2. you have tx list, the hash of the previous block and nonce.
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#349

  1. that’s the whole point isn’t it. them being linked prevents UTXO’s from being spent twice.

  2. a block consists of – hash of previous block – transactions (TX) – nonce – current hash ( I think )

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#350
  • Why is it important that the blocks are cryptographically linked together?

When blocks are linked through hash functions then it doesn’t matter how big or small of a change is that is made on an old transaction, because every hash moving forward will completely change and break the link.

  • What does the block structure look like in bitcoin?

A block is structured with 4 things;
a hash of the previous block
a timestamp
a list of new transactions
a randomly guessed number ‘Nonce’

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#351

  1. to prevent tampering of any and all blocks

  2. the previous block hash, the nonce, data, and that blocks hash

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#352
  1. So that the integrity and security of the blockchain is maintained. This makes it mathematically impossible for anyone to cheat the system by changing a previously written block in the chain. The whole system becomes trust less with no central control and censorship is not possible.
  2. The first block is created when a new coin is minted, this becomes the input data for the next block, its unique hash number. The miners create the next block using this hash number to calculate a new hash number by guessing the nonce of the new block along with the data contained in the new block. The outcome of this equation creates a new hash number.
#353

1] Immutability - Prevents the mined blocks from being altered

2] Hash = Hash of the transactions in block + Previous Hash + a random number (nonce)

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#354

1] Mining expends electricity to solve the cryptographic puzzle (proof of Work). In so doing they are rewarded by incentives (Block Reward and mining fees)

2] To do so would require re-mining that and all subsequent blocks

3] The more miners the lower the value of the target, and the lower the target the higher the difficulty. This may serve as a disincentive for least efficient miners forcing them to stop mining and thus reducing the hashrate.

#355
  1. To assure that transactions in the blocks are secured and not changeable.
  2. Bitcoin block structure:
    a. Hash of previous block
    b. Transactions list
    c. Nonce (random number)
    d. Hash of current block
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#356
  1. This assures that the network has not been changed and or tampered with. This maintains the integrity of the blockchain.
  2. Each block contains a hash from the previous block, a nonce number, transactions, and a hash the current block.
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#357
  1. So that any change in a prior block will invalidate following blocks and force them to be mined again at a significant cost.
  2. Prior hash, Transactions, Nonce, Hash of current block.
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#358
  1. For security of the blockchain. To make sure transactions can not/do not get altered.
  2. Includes Previous hash, transactions list and nonce.
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#359

  1. This creates a link between blocks which functions as a kind of tamper seal. If anyone attempts to alter the blockchain history, these links will be broken.

  2. Blocks consist of a header hash, which is a hash of the previous hash, the incorporated txns, and a nonce.

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#360

  1. Why is it important that the blocks are cryptographically linked together?
    This provides proof that the blocks and network are secure and have not been altered.

  2. What does the block structure look like in bitcoin?
    Block Header, Timestamp, Size, Transactions+Counter, Nonce, Previous Block Hash, Block Size, Difficulty Target, Version, Hash of Merkle Root (not in order)

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#361

Homework on Blockchain and Mining Visually - Questions

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

Ans: Because the blocks are permanent and each block has a connection to the next so if anything were to change, it would change everything and this keeps the incentives for miners to play by the rules. If they didn’t, they would lose money and eventually have to stop mining.

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

Ans: The block structure the previous hash, a list of the transactions, and the nonce which has been guessed and will passed to the next block.

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#362

  1. The longest chain of hashes = the greatest immutability.

  2. The Block Header includes metadata containing the previous hash + time stamped nonce + tx list in the form of a merkle tree.

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