Homework on Blockchain and Mining Visually - Questions

Blockchain and Bitcoin 101
#1547

  1. It is important because this is what makes Bitcoin a very secure network. As time goes on and more blocks are added, the more difficult it is to cheat the network and change anything long back in time.

a) The Bitcoin ID number = 0xD9B4BEF9
b) Block Size
c) The Block Header
d) Transaction Counter
e) Transaction list

Inside the block header:

a) Version
b) timestamp
c) difficulty target
d) hash of the previous block
d) nonce
e) hash of the merkle root

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#1548

Why is it important that the blocks are cryptographically linked together?
Blocks need to be cryptographically linked together for the security of the blockchain. No transactions can be changed in previous blocks as it would break the link to the next block and all that follow.

What does the block structure look like in bitcoin?
The block structure of the block is based on the, transactions in the block, plus the previous hash and the nonce (that needs to be guessed)= the hash.

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#1549
  1. Why is it important that the blocks are cryptographically linked together?
    This increases the security of the network. It is very important that the nodes immediately see when data has been altered. The nodes can give a quick response by rejecting a block.
  2. What does the block structure look like in bitcoin?
    A block contains: a number of the block (1), a nonce (2), data (transactions) (3) and the hash of the previous block (4). Than you have a hash of the block itself which is the result of hashing the nonce, data and previous hash.
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#1550

1 this is the basis of bitcoin and why the system works.you can verify all previous transactions.
2.In the block there is own hash, previous hash ,current transaction and nonce.the own hash has all the details included like a fingerprint

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#1551

Block does not only consist of transactions :slight_smile: there are some more important parts of it. Can you figure them out? :wink:

2 Likes
#1552

Ok my bad. I guess I misunderstood the question.

  1. Wallet with private key sends transactions
  2. mempool with nodes collects transactions while they wait to be added to a block
  3. miners hash blocks to get the block reward of transactions
  4. then concensus
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#1553

Homework on Blockchain and Mining Visually - Questions

  1. Why is it important that the blocks are cryptographically linked together?
    Blocks are cryptographically linked with the same digital hash fingerprint of the previous block. The block being constructed has to have the same input information as the previous block. If there is any change in the data, the chain of the blocks loses integrity and validity of the Bitcoin blockchain. This ensures the same UTXO cannot be spent more than once, changed or be removed from the transaction.

  2. What does the block structure look like in bitcoin?
    The PoW structure is a sequence of blocks linked together by math and physics. Block structure in Bitcoin carries data from one block to the next using Hash function SHA-256 = (data) = hash = new block mined and confirmed. This is repeated as new transactions are added to the mempool of the network nodes. New blocks are mined and added to the blockchain.

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#1554

  1. For people not to attempt cheating (changing previously mined blocks)

  2. Current transaction Hash + previous Hash + nonce.

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#1555
  1. Why is it important that the blocks are cryptographically linked together?
    So, all data are public, and any change happen with any block would be prevented.
  2. What does the block structure look like in bitcoin?
    Inside a block is made from hash function of all transactions from the previous block and the upcoming transactions and a nounce.
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#1556

it is important that the blocks are cryptographically linked together because trying to change a transaction on a block will effect the rest of blocks after that, which means the miner will have to change all blocks after that one using massive amounts of energy (money). making it not worth it for the miner to change the transaction.

a bitcoin block structure will have transactions that have been confirmed in the network it will also have the previous hash and nounce.

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#1557
  1. It will prevent to change the former blocks and increase the security.
  2. The block contains previous hash, transactions and nonce.
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#1558

This ensures validity and immutability of the chain. Any transaction change anywhere in the blockchain will render the block and subsequent blocks invalid.

A block consists of

  • the hash of the previous block
  • The hash of the current block
  • Transaction data of the current block
  • Nonce
  • Block number
2 Likes
#1559

  1. So that the difficulty of modifying or going back and changing a block is greatly increased. Security purposes.

  2. Because its based on the transactions of the blockchain and the inputs and outputs that are created from it.

2 Likes
#1560
  1. Itā€™s why we can trust the blockchain. If any data is changed in previous blocks, the hash changes, the links would be broken and would need to be re-mined which is mathematically impossible.
  2. hash of the previous block + transactions + correctly guessed nounce
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#1561
  1. It is important that the blocks are cryptographically linked together because if they werenā€™t then the blocks would be more vulnerable to previous blocks being changed, which would then cause each preceding block to have to be remined and the entire process would take too much time and destroy the link throughout the blockchain between each block. And as each new block is added, without the proper cryptographic link, transactions will be more susceptible to being doubled, meaning transactions would be verified when they shouldnā€™t be. So the cryptographic link is important because it maintains the integrity of the blockchain as a whole.
  2. The block structure of bitcoin is comprised of a hash output, which is determined by the hash input of the previous block in the blockchain, as well as the data that consists of all the transactions that make up the block, as well as a random number known as the nonce. These three aspects together make up the block structure that creates an output which then becomes the input of the next block which then has its own transaction data and nonce, which then creates another output, and so on.
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#1562

1. Cryptographically linking all the blocks ensures the integrity and security of the blockchain.
2. A bitcoin block has a list of transactions, the hash of the previous block, and the nonce which needs to be smaller than the target number.

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#1563

1 - It secures them, and ensures that the history is immutable and cannot be changed. This way, the integrity of the blockchain is assured mathematically.
2- A block is made up of a transaction list, the hash of the previous block and a Nonce.

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#1564

Hi Ivan and All!

It important that the blocks are cryptographically linked together because this is what makes them immutable and secure.

The block structure in bitcoin is a container data structure which contains the: previous blockā€™s hash, transaction list, nonce, transaction counter, block size, block header, timestamp, and the target.

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#1565

1 - So as to raise the difficulty of mining blocks and if one of the blocks are changed it will affect the whole blockchain making it invalid/unrewarded for that particular miner.

2 - Previous hash + Transactions + Nonce = HASH

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#1566

  1. To ensure the integrity and security of the data. The link connects one block hash to the prior blockā€™s hash.

  2. Block Number
    Nonce
    Data
    Prev:
    Hash

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