Homework on Blockchain and Mining Visually - Questions

Blockchain and Bitcoin 101
#625
  1. It ensures the integrity and security of the blockchain. alteration of one block affects all the others
  2. It consists of
    a) The hash of the previous block
    b) A Nonce value
    c) The hash of the transaction data in it (i.e. the Merkel Tree Hash)
    d) A time stamp
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#626

  1. Because then the blocks can “communicate” with the following. Each change would affect following blocks. The blockchain thus become immutable.

  2. Nonce
    Timestamp
    Data (transactions)
    Previous hash
    Hash of current block

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#627

  1. It is very important because the blockchain is a decentralized, public and digital ledger that is used to record all transactions across many computers. That means any record cannot be altered, without the alteration of all subsequent blocks. The cryptography make the blocks more secure and anonymous is well.

  2. You have a hash of the block and also you have a previous block hash plus all TX transaction and the nonce which need to be guessed to add this block to blockchain by miner…to solve the puzzle

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#628

  1. It is important so data from previous block cannot be altered.

  2. it consist of 1. previous hash 2. transactions 3. nonces and this creates a new hash for this block

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#629

  1. Why is it important that the blocks are cryptographically linked together?
    This is what makes it of value because the final blockchain cannot be altered and contains the ledger.

  2. What does the block structure look like in bitcoin?
    Block number > Nonce > Transaction Data > Hash of the Previous Block > Hash of current block continuous until completed with target

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#630

  1. Why is it important that the blocks are cryptographically linked together?
    It is important because the links between the blocks guarantee security by making the network secure. If a link would break, the hash value of the next block would change and be invalid.

  2. What does the block structure look like in bitcoin?
    The block structure in bitcoin has the list of transactions, previous block hash and the nonce.

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#631

  1. It is important that blocks are cryptographically linked together because the link ensures security of the blockchain. That way no transactions can be changed in previous blocks because any change made will break the link between the blocks and make it invalid.

  2. The block structure of bitcoin includes:
    Block header
    Version
    Block size
    Previous Block hash
    Merkle root hash
    Timestamp
    Difficulty
    Nonce
    Transaction counter
    Transactions

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#632
  1. So that changing a transaction in a previous block will break every chain from that point onward. It makes the blockchain secure.
  2. It looks like a block with transactions inside. It is linked to the previous block by the hash of that previous block. Now this hash is hashed again alongside all data in the new block and a nonce. If the result is below difficulty level then you’ve got a full block with a link to the next one. The hash of the block acts as a link between its own block and the next. The first block has only zeroes in its previous hash.
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#633

  1. for security and immutability purposes.

  2. it looks like a chain, hence the word blockchain

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#634

Q1: This helps keep the structural integrity of the blockchain network intact by making it close to virtually impossible for miners to corrupt the chain for their own benefits.

Q2: The structure is as follows : hash of the previous block
TX list for that block
NONCE needed for block rewards

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#635

  1. It is important that the blocks are cryptographically linked together to ensure integrity of the blockchain. Links between blocks ensures the security of the networks and allows PoW for mining.

  2. Block structure in bitcoin is a network of blocks that have transactions + previous hash and a nonce

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#636
  1. Why is it important that the blocks are cryptographically linked together? It is important to keep the network secure from being altered. If the data in a block is altered, all the blocks will change and the nonce will have to be “guessed” again.
  2. What does the block structure look like in bitcoin? Previous block hash, current block transaction, nonce, and target of difficulty.
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#637
  1. It allows immutability and trustlessness
  2. Transactions, previous hash, and nonce
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#638

1:
The puzzle of new blocks is always based on earlier TXs
Puzzles are always unique

2:
Prev hash
TX list
Nonce

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#639

  1. This makes it difficult to change a block. If there is a change in the previous block everything will change. Sow hole the system has to work by the rules.

  2. We have the block number, nonce, transaction data, the hash of the previous block en the hash of the current block.

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#640
  1. Why is it important that the blocks are cryptographically linked together? security of the network against tampering and fraud.
  2. What does the block structure look like in bitcoin? Nonce, blocksize, blockheader (w/hash of prevous block), transaction counter, transactions.
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#641

For Blockchain integrity. As mentioned in previously Homwork, if you change something in a previously block everything “after it” (which means all the blocks that have been added since that particular block also will change). This is because all new blocks consist of “information” of the previous block, not just the transactions. (the link will break). Then if you go back in time and change a previously block, you need enough time/power to reproduce all the blocks that was later than the block you change, but also keep up with the new blocks added to the blockchane (which happens every 10 minutes). This all is basically impossible.

In the blocks in bitcoin the blocks consist of transactions (TX) and PREV TX (from last block in the chain) + nonce (random number, to keep the miners spending energy.

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#642

1: So it makes it extremely difficult to change any transaction in a previous block so it improves integrity of the chain.
2: Hash from previous chain, that blocks transactions and the nonce

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#643
  1. Its about security. Without the cryptographic link the security of the block-chain is not validated in any way - remember the trust lies in the validation.
  2. The hash from the previous block is related to the next block plus the nonce which the miners have to guess.
#644

  1. It is important because it is what makes blockhain immutable since when you make a change to a block, it invalidates all the following blocks. So it makes it almost impossible to make a change to a block since when you make a change to a block, you have to mine all the following blocks to make the chain valid.

  2. A block in blockchain is composed by:

  • Number of block
  • Nonce
  • Transactions
  • Hash of previous block
  • Hash of block