Homework on Blockchain and Mining Visually - Questions

Blockchain and Bitcoin 101
#2432

  1. because then 1 block can’t be changed without changing previous blocks, which takes waaaaaay to much time (practically impossible

  2. tx data
    previous hash
    nonce
    = new hash

which has to be smaller than the target

1 Like
#2433

1- is a puzzle.
2- Hash, transactions and nonce.

#2434

What hash? :slight_smile:

#2435

Homework on Blockchain and Mining Visually – Lesson 19 - Questions

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

So that miners cannot go back to a previous block to change transactions. The hashing links between the blocks serve as a permanent integrity check for the entire blockchain = PoW.

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

Each block on the blockchain consists of three parts:

  1. The hash of the previous block
  2. The register with the unconfirmed transactions
  3. The nonce
1 Like
#2436

Mining Visually Answers

  1. Its important blocks are cryptographically linked together to secure the network and to prevent changing any TX.

  2. The data, a hash from the previous block and current block, TX list of the current block, and the number of nonces.

1 Like
#2437

  1. To secure the network, make the mathematical puzzle for the next block.

  2. previous hash
    hash
    tx list
    nonce

3 Likes
#2438

1. Why is it important that the blocks are cryptographically linked together?
so nothing in the previous blocks can be changed since the person would have to change every single block after that and play catch up
2. What does the block structure look like in bitcoin?
Hash⬛ = (Prev hash, tx list, nonce)

2 Likes
#2439 
  1. Why is it important that the blocks are cryptographically linked together?

any change on any block would be immediately noticed by other blocks. Therefore a block that is trying to be appended to the blockchain will be rejected there is tampering with any previous block. And it’ll ensure immutability.

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

current block hash (fingerprint) = # tx 's , nonce (needed to be guessed), and previous block hash.

1 Like
#2440
  1. So everyone tries to alter a block should mine all the rest block to be valid, almost impossible you need 51% of the network to do that
  2. Its a hash based on the hash of the previous block, the transaction, and a nonce
1 Like
#2441
  1. It generates a tessellating checksum verifying all previous blocks’ data integrity on the blockchain, ensuring data integrity in an efficient manner.
  2. There is a ledger, the previous block’s hash, and a nonce (and the block’s hash).
1 Like
#2442
  1. Why is it important that the blocks are cryptographically linked together?

It ensures that every transactions is immutable and with that ensures the networks security.

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

Hash
list of transactions
previous hash
nonce

1 Like
#2443

  1. Ensures that the blockchain is immutable, is secure - unbreakable, ensures that it is trustless and that the PoW remains

  2. Inputs, outputs, numeric values, hashes, , information from previous data, transactions, nonce

1 Like
#2444
  1. Why is it important that the blocks are cryptographically linked together?

This insures and incentivizes security. It also makes more lucrative to be honest than dishonest.
2. What does the block structure look like in bitcoin?

It’s linked between hashes and blocks and nounces which are the transactions. It’s blocks and lines between each blocks.

1 Like
#2445
  1. because that way it is almost impossible to hack the blockchain as the blocks build ontop of each other and manipulating one block means having to re-mine the following blocks as they’re using the hashes of the previous block
  2. a block is made out of the previous block hash, the current block transaction data and a nonce, which is a random number that has to be guessed in order to create a hash that meets a certain target
1 Like
#2446

  1. Why is it important that the blocks are cryptographically linked together?
    So that the data (transactions) contained in the whole block chain cannot be modified.

  2. What does the block structure look like in bitcoin?
    Each block has a set of transactions and a block number. Then there is the hash of the previous block, a nonce and then the hash of the current block.

1 Like
#2447

1. Why is it important that the blocks are cryptographically linked together?
Having the blocks cryptographically linked ensures data immutibility. A bad actor must have at least 51% of the hashing power in the network in order to mine all of the blocks in their fake blockchain + mine the current block faster than all other miners.

2. What does the block structure look like in bitcoin?
The block structure of bitcoin consists of the previous block’s hash, the current tx list of the proposed block, and the nonce which the miner must guess.

1 Like
#2448
  1. Blocks need to be cryptographically linked together to ensure security of the chain. This ensures that no transactions can be changed in previous blocks since it would break the link to the coming block and others following. This prevents things such as double-spend.
  2. The hash of a block is based on the transactions, the nonce, and the hash of the previous block.
1 Like
#2449

Course: Blockchain and Bitcoin 101
Section: Bitcoin Basics

19 Homework: Blockchain and Mining Visually

Q1. Why is it important that the blocks are cryptographically linked together?
A1. The cryptographic linking of the blocks makes it nearly impossible to change, delete, or add to data in a block that is already part of the blockchain. This leads to data integrity and having a permanent ledger record of all the transactions.

Q2. What does the block structure look like in bitcoin?
A2. According to https://en.bitcoin.it/wiki/Block#Block_structure, a block has the following parts:

  • Magic no (value always 0xD9B4BEF9)
  • Blocksize (number of bytes following up to end of block)
  • Blockheader (consists of 6 items)
  • Transaction counter (positive interger)
  • Transactions ( the (non empty) list of transactions)
  • The data.

The 6 items in the Blockheader are as follows:

  • Version (Block version number)
  • hashPrevBlock (256-bit hash of the previous block header)
  • hashMerkleRoot (256-bit hash based on all of the
    transactions in the block)
  • Time (Current block timestamp as seconds since 1970-01-01T00:00 UTC)
  • Bits (Current target in compact format)
  • Nonce (32-bit number (starts at 0))
1 Like
#2450
  1. To prevent someone from double spending and changing the cryptography in the previous blocks.
  2. It is the hash of the previous hash, UTXO’s and the nonce
1 Like
#2451

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

  • It makes sure that no changes can be made in the past without breaking the linkage between the blocks. When a change is done in the past, all the future linkages need to be re-generated, which is almost impossible for a single entity to do - as the rest of the network is further continuing the work on the longest chain right now.

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

  • Blocks contains the transactions, connection to the previous block through the hash of that block, timestamp, and a nonce (random number). When all this information is hashed together, it will generate a hash of that block, which needs to satisfy some condition (being smaller than a specific target).
1 Like