Homework on Blockchain and Mining Visually - Questions

Blockchain and Bitcoin 101
#885

sorry no meeting the target, it’s to be below the target.

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#886
  1. Why is it important that the blocks are cryptographically linked together?
    It must be cryptographically linked together to prevent modification of any TX. If one TX is changed on the network, then all blocks on the network become invalid.
  2. What does the block structure look like in bitcoin?
    The block structure consist of the previous hash, TX, and nonce. A nonce is a random number that the miner has to guess less than the target.
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#887

  1. Why is it important that the blocks are cryptographically linked together?
    because in this way by modifying one all the next one would change, in other words it ensure the chain can not be modified

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

every block has an hash which is calculated from the previous block has + the bloc transactions + a random number

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#888

  1. This way, when you change a block, you simultaneously have to change all the blocks (basically remine them).

  2. A block consists of the hash of the previous block, the list of transactions and the nonce.

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#889

1. Why is it important that the blocks are cryptographically linked together?
a. By cryptographically linking blocks together, it is almost impossible to tamper with or manipulate the blockchain for malicious intent, without it being noticed by the network. This makes the blockchain very secure and warrants its immutable nature
2. What does the block structure look like in bitcoin?
a. Each block contains
aa. The list of transactions within the Merkle tree
ab. The block hash and a whole lot of additional meta-information, such as the
aba. nonce
abb. block size
abc. version
abd. merkle root hash
abe. block reward
abf. reward from fees
abg. difficulty
abh. number of transactions
etc. pp

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#890

  1. Because the links are based on the information in the previous block. If something is changed in the previous block the link will be broken because the puzzle was based on the content of that block and link.

  2. Block, nonce, data, prev hash, hash

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#891

  1. Because it ensures the integrity of the data in the blockchain since if you change any previous block in the chain will lead to all blocks broken.

  2. Its contains the list of transactions, the hash of the previously mined block and the nonce, which is a random number and is used to try and get the hash lower than the target.

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#892

Why is it important that the blocks are cryptographically linked together?
If the blocks are linked, it makes almost impossible to alter. When someone tries to change something in a block, the hash will change and the next block will change since one of the conditions are the hash of the previous block.

Furthermore, doing this makes possible to have a totally random number based on the nonce and the hash, and solve the puzzle is an action that makes miners spend a lot of electricity. In order to make profit and get a reward, they have to be honest and play by the rules, what guarantees the integrity of the network.

What does the block structure look like in bitcoin?

Block N-1:
- n-2 block hash
- n-1 block TX
- Nonce
Output: N-1 block hash

Block N:
- N-1 block hash
- N block TX
- Nonce
Output: N block hash

Block N+1:
- N block hash
- N+1 block TX
- Nonce
Output: N+1 block hash

…

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#893
  1. For security and integrity of the transaction, when a transaction in an previous block is changed all chain is modified, from there all chain will collapse.
  2. The block structure contain: cryptographic hash of the previous block, plus the all transaction on this block ,plus the nonce, which gives the cryptographic hash on the next block.
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#894

  1. It is important for the blocks in the blockchain to be cryptographically linked together, because this ensures that it is extremely difficult, in practice for bad actors to attempt to manipulate the network. This keeps the mining process secure, and in turn secures the network on all fronts.

  2. The block structure is set up linearly based on which block came first. The Genesis block starts the chain, and then each subsequent block is chained to the previous block, until you reach the most recent block.

As it pertains to individual blocks, the block structure contains the hash of the last block, the transaction list for the current block, and the nonce. All these elements combine to form the block’s overall hash, which then becomes a part of the next block as well.

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#895
  1. To ensure the integrity of the data in the network. If someone change any previous block in the chain every following block have to be re-link.
  2. Block structure consist of the list of transactions, the hash number of the previous block, nonce which is random number.
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#896

Blocks being connected prevents data from being altered.

Each new block includes the hash of the previous block linking the chain, hash, transactions and nonce

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#897
  1. It guarantees that it will be very difficult to change past inputs, because all later blocks will have to be remined. It becomes extremely expensive and difficult to change blocks and alter the blockchain.
  2. Every block hash consists of the information of the prior block. It contains previous hash, nonce and data (transactions)
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#898

It is important that the blocks are cryptographically linked together because this helps to secure the network and prevent someone from changing a past transaction. It sets the blockchain “in stone” and makes it very difficult to tamper with.

The block is made up of:

  • Block header
  • Previous Hash
  • Transactions
  • Nonce

I think there are many other things in a bitcoin block that haven’t been discussed like timestamps and Merkle roots.

Each block is linked to a previous block in a long chain, hence, blockchain. There is a 1:1 relationship between blocks.

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#899

To prevent data from being manipulated.

The block has a hash which is based on previous hash, transactions and nonce.

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#900
  1. This ensures immutability and security of the block.
  2. Each block contains transaction data + prev hash + nonce = current blocks’ hash (must be below target).
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#901

Homework on Blockchain and Mining Visually - Questions

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

This is needed to verify that blocks cannot be tampered with. When any value in a block that has been mined is changed, the hash changes. Since the hash of a block consist of the nonce, the hash of the previous block and the transactions of the current block a change to any of them will result in a change in the hash of all blocks.

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

It consists of a nonce, hash, the transactions and the hash of the previous block.

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#902

  1. It ensures the security of the network as once a block is recorded then it is immutable for all intents and purposes

  2. Txs Hash, inputs and outputs

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#903
  1. so that it is very difficult to go back and rewrite the history of the blockchain
  2. it depends on how close you look… if you look close enough it looks like 1’s and 0’s represented by other character’s to create a chain or information which relies on all the other links in the chain to maintain accuracy
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#904

  1. Why is it important that the blocks are cryptographically linked together?
    If someone wants to change a block in the past he has to remine a whole chain of blocks.

  2. What does the block structure look like in bitcoin?
    Block header
    nonce
    Transactions
    Previous Block hash

=> hash (less then target)

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