Homework on Blockchain and Mining Visually - Questions

Blockchain and Bitcoin 101
#1889

  • because it’s the basic of the blockchain. every blocks needs to have a one single fingerprint and new blocks depends on the previous one. if even a single letter or number get changed in previous block, the entire blockchain after will be corrupted.

  • you see previous block hash, transactions, the number of the block and the nonce number

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#1890

Because, if the blocks weren’t linked, you would be able to change one without making the network crush. As we learned in the previous task, since blocks are linked, if small changes are made to one block, all subsequent blocks are crushed.

Block number
Nonce
Data
Previous hash
Actual Hash

Actual Hash = Previous Hash + Data (TX data) + Nonce

Actual hash is made considering the previous block hash, data from the UTXOs waiting for approval plus the NONCE. This way, all the blocks are linked with the previous one.

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#1891

  1. As previously mentioned - this makes changing any data in already mined blocks practically impossible or at least not worth spending resources on => providing security.

  2. We have a list of transactions (inputs / outputs), the hash-code of previous block, which the current one is linked to, nonce which needs to be guessed and is then used in hash calculation (along with the data mentioned above), timestamp.

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#1892

1.If they weren’t encrypted it would be easier to alter the transactions affecting the targeted block.
2. Hash, Prev Hash, Nonce, Tx(Data)

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#1893
  1. This helps to ensure that existing blocks cannot be changed.
  2. Includes a merkle tree of the transaction hash(s), the hash from the previous block, the block header, block size Nounce.
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#1894

this creates the block chain which ensures a safe network, no double spending.

the block number followed by the nonce, then the data. The data is then mined giving the hash and nonce then in the new block it has the previous hash.

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#1895

Homework on Blockchain and Mining Visually - Questions

  1. Why is it important that the blocks are cryptographically linked together?
  • To guarantee immutability. Any change in a previous block will cause subsequent blocks to be invalid.
  • Having to change a series of blocks to steal funds/do a double spend becomes pretty much impossible.
  1. What does the block structure look like in bitcoin?
  • It’s a linked list where each linked block’s hash is made up of previous block’s hash + Tx list + nonce.
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#1896
  1. Because it helps secure the system, it ensures that there is no alteration of the blocks, as well as making sure that transactions aren’t duplicated.
  2. The block structure is based on the current transactions of the block as well as the previous hash.
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#1897
  1. Why is it important that the blocks are cryptographically linked together?
  • to prevent changing history
  1. What does the block structure look like in bitcoin?
  • transactions, hash of the previous block, nonce
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#1898
  1. Why is it important that the blocks are cryptographically linked together?
  • This is important as the structure is built ensuring that the hash of the next block includes hash of the last block and so on. This ensures no amendments can be made thus making the blockchain immutable.
  1. What does the block structure look like in bitcoin?
  • A series of unspent inputs or UTXO’s and outputs that is used to calculate the sum of Crypto governed by said wallets transactional data for that block and so on. All this data includes the previous block hash and nonce.
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#1899

This adds to the security of the network, it keeps data linked together in a way that you can’t change previous transaction because you’ll need to change all next blocks that are appended after that block which is practically imposible.

The block structure consists of: list of transactions, hash of the previous block, nonce

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#1900

To estabilish a dependency relation between the blocks. This results an exponential increase in difficulty of changing the contents of a block. It also provides evidence for the order of the blocks.

Block header.
Hash of previous block.
Transaction data.
Nounce.

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#1901

  1. It is important that the blocks are cryptographically linked together to prevent duplicates and fraud.

  2. A bitcoin block structure has the previous block hash and the current transaction block.

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#1902

1 blocks are linked together with every new block having the hash of the previous block in it. If you change the content of one of the blocks, all hashes will change and later blocks should be mine again.
2 blockstructure contains the hash of the previous block, header transactions info, nounce

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#1903

  1. So block can be changed which secures the network.

  2. In bitcoin each block structure have - transactions in the current block.
    - ash from the previous block.
    - nonce (random number miner have to guess).
    So the ash of the current block has to be under a target which is set depending of the difficulty of the bitcoin network.

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#1904
  1. This ensures the immutability of the data between each block.
  2. image
    image1314×1220 51.8 KB

    (source: https://luxsci.com/blog/understanding-blockchains-and-bitcoin-technology.html)
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#1905
  1. Why is it important that the blocks are cryptographically linked together?
    It is important for the blocks to be cryptographically linked together in order to keep the information in the network secure.
  2. What does the block structure look like in bitcoin?
    Each block has the previous blocks hash, the transaction list, and a nonce, which are hashed to create its own hash
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#1906

1.so the security is maintained in the block chain. So that no prior transactions can be changed in the block chain.
2.There is the Hash of the block. Within the hash there are transactions and the hash of the previous block. A nonce is then guessed.

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#1907
  1. Incase a block is changed it breaks all links. Immutability
  2. Hash, previous hash, transaction list, and nonce.
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#1908

Homework on Blockchain and Mining Visually - Questions

  1. Why is it important that the blocks are cryptographically linked together?
    To give them security and remove trust, replacing it with verification and authentication provided from the blocks being joined together by Hash keys of the contents, ensuring the contents cannot be tampered with.

  2. What does the block structure look like in bitcoin?
    A database of Tx as a linked chain of blocks, each linked to the block before by a Hash that represents both the Tx and the block Hash.

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