Homework on Blockchain and Mining Visually - Questions

Blockchain and Bitcoin 101
#1427
  1. Why is it important that the blocks are cryptographically linked together?
    • This keeps the ledger immutable
  2. What does the block structure look like in bitcoin?
    • header || nonce || data || previous block hash || current block hash
1 Like
#1428

  1. Because if you change just one caracter in one block, it will change the whole sequence of the blockchain and willnbe indentified as corrupted.

  2. The hashing of one Bitcoin block includes the hashing of the previous block, the transactions written in the block and the number of the nonce.

1 Like
#1429

  1. Why is it important that the blocks are cryptographically linked together?
    The links between blocks secure the network and make it practically impossible to double spend the UTXOs or changing the previous blocks. This links between blocks also make miners play by the rules.

  2. What does the block structure look like in bitcoin?
    Each block contains the hash of the previous block, a nonce (a random number) and the list of UTXOs and TXs. The hash of each block is created by hashing: the hash of the previous block, the UTXOs and TXs, the nonce; using SHA256 function.

1 Like
#1430

I just remembered that I forgot to ask exactly how do we send a txn to multiple addresses at the same time?

#1431
  1. Blocks are cryptographically linked together to make it difficult to impossible to make changes to previous blocks / transactions.
  2. Transaction data + previous block hash + nonce = current hash
1 Like
#1432

Most HD wallets do this for you in the background already. They have separate part reserved for change addresses there the change is sent back to you also is you have noticed on your Ledger for example every time you want to receive funds a new address is created for you.

Where you have to do this by hand is when you are creating raw transactions by yourself, which you can learn how to do in the Bitcoin programing course :slight_smile:

2 Likes
#1433

Awesome thank you for the explanation.
Cheers :beers:

Carl E. Gilliard / Cecil
Researcher

Brooklyn College
Undergraduate Earth & Environmental Science

#1434

1- It is important because if someone change anything in a block transaction the link will change and all the links coming after will change in this way the network is secured.
2- Transactions of the current block and the hash of the previous block and the nonce create the current hash block that has to be less then the target…

1 Like
#1435

[quote=“ivan, post:1, topic:8433, full:true”]
Homework on Blockchain and Mining Visually - Questions

  1. Why is it important that the blocks are cryptographically linked together?
    So data on the blockchain can not be tampered with,any change will break the links therefore the tampered block and every block after will be rejected
  2. What does the block structure look like in bitcoin?
    A block is a container data structure.It is composed of a header that contains 3 sets of metadata.
    1.the previous block hash
    2.Mining competition:it needs a valid hash containing time stamp,the nonce and the difficulty.
  3. merkle tree root:a data structure to summarize the transactions in the block
1 Like
#1436
  1. It is important because a secure blockchain is built upon math and physics instead of arbitrary decisions. This creates a more fair and long term stable environment for value exchange.
  2. Block Header- hash of previous block header(hash pointer) - Merkle Root - Tx data - New hash.
1 Like
#1437
  1. For more security. If it wasn’t like that, it would be easier to hack.
  2. Hash, confirmations, miner, block transactions, weight, size, nonce, reward…
1 Like
#1438

How is the difficulty TARGET calculated?

#1439
  1. if someone change the data in one block it will automatically corrupt all data in all blocks witch goes after that block. By using that concept we assure a security for the whole system
  2. bitcoin block made of [hash > previous block hash > transactions list > nonce #]
1 Like
#1440

The difficulty target is calculated based on the network hashrate so that a block gets mined approximately every 10 minutes.

3 Likes
#1441

  1. Why is it important that the blocks are cryptographically linked together?
    It is important that blocks are cyptographically linked together because this ensures that no tampering has been done to any historic block in the blockchain. Any change to any transaction in a prior block would result in the cyptographic links of all subsequent blocks being broken. The only way to restore the links would be to re-mine all the blocks, but all the “honest” nodes in the network would then reject that new blockchain.

  2. What does the block structure look like in bitcoin?
    The bitcoin block structure consists of a Nonce value, a set of transactions, the hash value of the prior block block, and lastly the hash value for the entire current block structure.

1 Like
#1442

1.Why is it important that the blocks are cryptographically linked together?
A. Because through cryptographic hashing any changes in data in any block
will break the link or chain, altering the chain altogether.

  1. What does the block structure look like in bitcoin?
    A. Hash of current block, which contains the hash of previous block, current
    transactions and a nonce.
1 Like
#1443
  1. Why is it important that the blocks are cryptographically linked together?

Is important because this make all this chain secure , unbreakable , and more convenient to build and not modify

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

The block structure in bitcoin is composed by :
-HASH OF PREVIOUS BLOCK
-TRANSACTION LIST OF CURRENT BLOCK
-NONCE
HASHING THIS INFORMATION RECIVE THE CURRENT BLOCK HASH AND COMPARE WITH TARGET NUMBER

1 Like
#1444

  • Why is it important that the blocks are cryptographically linked together?
    This keeps the blockchain secure as it keeps it from being alterered

  • What does the block structure look like in bitcoin?
    a block in bitcoin includes;
    block number
    nonce
    time stamp
    data (transactions)
    previous block’s hash
    current block’s hash

1 Like
#1445

  1. Mining ensures integrity of data.

  2. It creates links between blocks and is based on information from the previous block. The current hash is based on the transaction the previous hash plus transaction list plus nonce. The miner will have to guess and find a number less than the target.

2 Likes
#1446

1- to secure the network and for incentives

2- previous hash

  • transactions list
  • nonce
2 Likes