Homework on Blockchain and Mining Visually - Questions

Blockchain and Bitcoin 101
#2572

  1. Why is it important that the blocks are cryptographically linked together?
    prevents anyone from going back to previous TX and altering data.

  2. What does the block structure look like in bitcoin?
    Nonce, TX, previous hash

2 Likes
#2573

  1. It creates proof of work by consensus. No one can change an individual block (for some shenanigans) without totally screwing up their ability to earn money through the mining protocols.

  2. block number
    nonce
    data
    hash of previous block
    hash of block

2 Likes
#2575

Homework on Blockchain and Mining Visually - Questions

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

It adds integrity & security. You can not alter the blockchain because when you change one block it changes the hash value which makes every forthcoming linked block invalid.

What does the block structure look like in bitcoin?

Previous block hash
PLUS
Transaction list of current block
PLUS
Nonce
EQUALS
Hash of new block which must be lower than Target.

2 Likes
#2576

Answer to Homework on Blockchain and Mining Visually.

  1. Why is it important that the blocks are cryptographically linked together?
    It will make it very hard for someone to change a Block Data after it has been attached to the Blockchain.
    The Block will be unlinked from other Blocks that comes after, and it will need to be re-mined again, including all the next Blocks, faster than Network Mining speed to be approved.
    It makes it impossible and also unprofitable for the scammer.

  2. What does the block structure look like in bitcoin?
  • Structure of New Block Hash Number
    • Previous Block Hash Number
    • Current Block Number
    • Current Block Data (TXs)
    • Nonce Number, that Miners need to solve.

3 Likes
#2577
  1. it links their hashes together in such a way that changing a block would invalidate the rest of the blockchain
  2. previous hash > current block > nonce
1 Like
#2578

  1. This link it more difficult to change a block. Changing a block would require a change of all previous blocks and to create new hashes between all the blocks as well. This makes it virtually impossible to change a block. Furthermore, insures data immutability.

  2. The block structure in bitcoin consist of previous hash, transaction, and nonce.

1 Like
#2579

  1. It ensures the integrity of the historical transactions. Makes sure that the data is immutable.

  2. Block number + Nonce + Transaction list + Hash of previous block + Hash of current block

2 Likes
#2580
  1. Why is it important that the blocks are cryptographically linked together?
    Integrity of system.
  2. What does the block structure look like in bitcoin?
    Previous hash, transactions & nonce
1 Like
#2581

Blocks are linked together by has function because if data is change the hash changes & more electricity will need to be spent to fix it. Making the security of the network high because miners want to keep up and play by the rules so they can win the puzzle and make the money inflation + fees.

Blocks are the current transactions + all the hashes of the prior blocks.

1 Like
#2582

Plus the nonce in the current block - thanks to the contributors above my answer :grin:

#2583

1. Why is it important that the blocks are cryptographically linked together?
a. For security reasons, the links between blocks is a cryptographic puzzle that ensures
immutability and integrity of the network.

2. What does the block structure look like in bitcoin?
a. It consists of data transactions, previous hash function, nounce and a new hash output.

3 Likes
#2584

1.Why is it important that the blocks are cryptographically linked together?
To make sure that there is no malicious things are not included in the block like double spends.
2.What does the block structure look like in bitcoin?
A block structure in bitcoin is blocks linked together with their own unique hush and each blocks containing current transactions,the previous blocks hush and the nonce to be guessed.

1 Like
#2585

Blocks are linked together so no data in a block can be changed without unlinking the other blocks

1 Like
#2586
  1. Why is it important that the blocks are cryptographically linked together?
  2. What does the block structure look like in bitcoin?

  1. Blocks are cryptographically linked in order to secure the blockchain. Transactions can not be altered because this would require a change to the blockchain severing the chance of a connection to future blocks.

  2. The block is comprised of key elements such as data, the previous block hash and a nonce which is used to calculate the hash number.

when mining takes place the nonce is repeatedly generated until the algorithm determining proof of work returns a value lower than the difficulty target.
This hash value then becomes the definitive hash value for the block that has been mined.

1 Like
#2587 
  1. Why is it important that the blocks are cryptographically linked together?
        - That ensures the blocks cannot be altered.   As the hash of the previous block
          is in the next block and so on.. 
        - It sets up a dependency through what is like a singly linked list and requires
          each block to be 're-mined' and make it infeasable to do in time for the next blocks.
          And the longest chain wins. 

   2. What does the block structure look like in bitcoin?
         Magic Number - 4 bytes
         Blocksize  - Number of bytes following up to the end of the blok - 4 bytes
         Blockheader - with 6 items - 80 bytes 
              - Version - 4 bytes
              - hash of Previous block - 32 bytes
              - hash of merkle root - based on all transactions in the block - 32 bytes
              - Time - current block timestamp as epoch time - 4 bytes
              - Bits - current target number - diffulty adjustment -  4bytes
              - Nonce - 32 bit number - bytes 4
         Transaction counter - 1-9 bytes
         transactions - non-empty list of transactions - actual transactions (# of them equal to the transaction counter)
1 Like
#2588

1 & 2. It is important, so that if you try to change a previous tx, you would have to remine all the subsequent blocks (because each hash is dependent (besides nonce) on the hash of the previous block and the tx list. If you change a tx in a block, the hash of that block would change, meaning the hash of the next block would change etc., making it impossible to mutate previous blocks.

1 Like
#2589
  1. Why is it important that the blocks are cryptographically linked together?

so there can be no manipulation and have complete trust.

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

Hash
Nones
Previous Hash
TX records

1 Like
#2590
  1. To maintain integrity of the blockchain and to secure the chain from being manipulated.
  2. Hash of the previous block and the current block, data and the nonce
2 Likes
#2591

1 - It ensures that the blockchain is highly secured, as changes to 1 block will break the links connecting the blocks that come after it.
2 - Nonce - Timestamp - Transactions - Previous Hash = New Hash

2 Likes
#2592
  1. If previous block data is changed then it changes the hash of the newer blocks that are accepted to the blockchain, so you cant change data in previous block without creating new sring that needs to be accepted(51% attack).
    2.Block,nounce,block data,hash of previous block,hash of the current block
1 Like