Homework on Blockchain and Mining Visually - Questions

Blockchain and Bitcoin 101
#3095
  1. Why is it important that the blocks are cryptographically linked together?
    So that it is impossible to cheat. To change anything in any single block affects all other blocks that come after it so it is impossible to change all of the blocks plus the blocks that are appended in real-time.
  2. What does the block structure look like in bitcoin?
    Blocks are linked together. Blocks contain the previous block´s digital signature, transactions, and their own digital signature ( hash of transactions, previous block´s hash, and nonce)
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#3096
  1. To ensure the chain remains unidirectional.
  2. Block 1 hash provenance = Block 1 Tx list + Block 0 hash + nonce
    Block 2 hash provenance = Block 2 Tx list + BLock 1 hash + nonce… .and so on
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#3097
  • Why is it important that the blocks are cryptographically linked together?

It helps stop the date being altered and permenent

  • What does the block structure look like in bitcoin?

Each block is cryptographically linked together (like a chain) and contains the transaction, inputs and outputs.

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#3098

  1. If blocks are cryptographically linked together it stops people from having the ability to change information in previous blocks as it would invalidate all other blocks that follow.

  2. Previous Hash
    Transactions list
    Nonce

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#3099

1 the blocks must be linked so that the last block can be permanently connected to the chain using a hash
2 block structure includes transactions and the former block hash

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#3100
  1. The blocks are cryptographically linked to prevent modification of the blockchain. No one can double spend etc.
  2. Block structure is nonce, transactions and hash of the previous coin. The hash of the current block would be produced from these inputs.
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#3101

  1. It is important to cryptographically link blocks together as this provides immutability and integrity to the information stored on the blockchain due to the high degree of difficulty involved in changing the information stored on the blockchain.

  2. The structure of a block in Bitcoin contains transaction data, a hash of the previous block’s structure and a nonce number.

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#3102
  1. To preserve the integrity of the chain and security of the data.
  2. Hash of previous block + current list of transactions + nonce + current block hash.
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#3103
  1. It is important because the links between blocks are what denies anyone from editing a previous block.
  2. The block structure looks like a chain. :stuck_out_tongue_winking_eye:
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#3104

What do the blocks in that chain contain? :stuck_out_tongue:

#3105
  1. Makes it so you can’t go into previous blocks and change something without having to re-mine all that followed, each new block takes previous hash and by changing this you break the link.
  2. previous hash
    list of transactions
    nonce
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#3106

Homework - Mining Part 2
Bitcoin Basics

  1. Why is it important that the blocks are cryptographically linked together?
    • It is important that the blocks are cryptographically linked together because this is what helps define the faith in math and physics. If one transaction is changed the whole blockchain will be broken. This ensures the honesty in the system that all of the data is true to itself and no foul play will ever be involved.
  2. What does the block structure look like in bitcoin?
    • Each block will contain the hash from the previous block, the new hash of the current block, a list of transactions and fees, and the nonce.
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#3107
  1. The link is based on the solved puzzle which is based on the data and hash of the prevous block. if the data or hash of the previous blocks is modified it breaks the puzzle and therefore the link and the network looks for the longest chain.
  2. the hash of each block is calculated by hashing the: previous blocks hash, data in current block, plus the nonce. so there are 3 items in the structure of a bitcoin block.
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#3108
  1. Without a cryptographic connection between blocks in the chain, it would be impossible to ensure that no malpractice within the datasets could occur. By containing hash data from the previous block and thus data from every preceding block, the consensus network can quickly establish any alteration and deny the addition to the blockchain.
  2. The Bitcoin blockchain essentially looks like a linear dataset comprised of blocks containing transactional data and a block header which contains other vital information about the block including hash data and timestamps.
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#3109
  1. So that a change in the data of one block will ‘alert’ the network that something is wrong with that particular copy of the blockchain.
  2. Blocks are composed of:
    The hash of the previous block +
    The list of transactions for that block +
    the nonce
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#3110
  1. To create an immutable and incorruptible chain
  2. It has a header with metadata, like hash of previous block, nonce, height (which refers to the number of block in the chain), number of transactions,… Followed by a list of transactions.
    Together it makes up the hash of the block.
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#3111
  1. Why is it important that the blocks are cryptographically linked together?

When all blocks are chained together, it makes it harder to alter. It’s an immutable record of transactions. This system makes the data in each block immutable.
As mentioned on my previous homework assignment:

Every ten minutes a new block gets created and added to the blockchain, that has all transactions from the previous ten minutes. That block is linked to the previous block and all previous blocks, to create a chain of blocks. All blocks are time-stamped.
If a miner would want to hack a block or to alter a block, the miner would have to hack all
previous blocks across millions of computers at the same time, while new blocks are being added to the blockchain. Impossible. IF the signatures or the data doesn’t match, the block will no longer be chained to each other. That will indicate to other users of the blockchain that some data in the block was changed/altered. And since the blockchain is immutable, the system rejects a false change by shifting back to the previous record of the blockchain.

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

The hash of each block is based on the hash from the previous block + data + nounce.
As soon as a transaction or data is changed, the hash changes.
The hashes from the blocks are connected.

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#3112

  1. Why is it important that the blocks are cryptographically linked together?
    So the blocks can not be altered. You need the previous hash to create new hash on the next block.

  2. What does the block structure look like in bitcoin?
    Nonce(Random number)
    Data(Transactions on current block)
    Previous hash (All the previous data)
    =New hash (To create next block)

The target of the nonce depends on the hash power of the network. Lower the target, higher the difficulty.

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#3113

  1. This prevents the changing of data and ensures the security of the network.

  2. It includes a hash which is made up of transaction data, the hash of the previous block and the nonce.

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#3114

  1. Blocks must be cryptographically linked because of consensus there should be only one truth and also through linking the blocks cryptographically the is high security and integrity .

  2. The hash of current block is based on the hash of transaction list and the hash of the Previous block and the nonce , next block is a result of a puzzle consisting of bits from the previous blocks

I guess this answers the question of what came first the egg or the chicken :smile:

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