Homework on Blockchain and Mining Visually - Questions

Blockchain and Bitcoin 101
#323

  1. It is fore safety of malevare. If they would not be linked togeather it would be easy to go to some block in the cahin and change its transactions and make some random money appear. But since they are linked if you make a change in any block, the links breake and you would have to remine all the blocks and links witch is near to impossible and therefore the chain is safe and decentralized and trustless

  2. If I understand correctly the question. The block consists of transaction, a hash of previous block and a nounce. Then each block is connected to the next block with a link witch is partly a hash of previous block.

#324

Answers:

  1. Because of communication in the blocks one to another being correct to secure network.
  2. Nonce, tx, previous hash.
#325
  1. Because that makes it impossible to mess with previous data without changing the whole blockchain that is linked together.
  2. A block includes transactions, previous hash, the nuance and there is a target that this hashed information has to meet.
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#326

  1. It provides a one-way link into the blockchain, providing a very good defense to attacks, by invalidating block next to the one modified.

  2. It looks like a giant chain of blocks, all linked together by cryptography.

#327

  1. It is important so that if someone wants to change a previous block he would have to change all the links and mine every block again.

  2. A block is composed of -

Block number
Timestamp
Previous block hash
The nonce
Transactions
Current block hash

Am I missing something?

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#328

  1. Through the use of cryptographic hash functions it becomes easily detectable when even the smallest changes are made to the block chain. Also because the hashes of later blocks depend on previous ones, they automatically would become invalid, which breaks the links between all blocks starting with the one that was tampered with.

  2. A block in ₿ contains it’s own hash, a list of transactions, a nonce and the hash of the previous block.

#329

Answers

  1. It’s the fundamental of the secure system behind the blockchain. This is the perfect system to guarantee data immutability and to prevent double-spending.

  2. A block in bitcoin includes: list of transactions, previous hash, nonce and the current block hash.

#330
  1. It is important so that if we change a transaction in the past is very difficult (practically impossible) to catch up with the length of the current chain and overtake it.
  2. Block hash = previous block hash + TX list + nonce such that the block hash is below the current target.
#331
  1. Why is it important that the blocks are cryptographically linked together?
  • Fixed variable attributes linking the blocks is the best way to ensure immutability - no one can change a block as corresponding blocks will alter also. Being cryptographically linked ensures that no reverse engineering can be done.
  1. What does the block structure look like in bitcoin?
    Block Number
    Nonce
    Transactions
    Block Hash
    Previous Block Hash

The perfect structure.

#332

You can always check out a block in the block explorer :wink:

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#333
  1. To make it harder to tamper with existing transactions, since, if you change an old transaction, you don’t only have to re-mine that one block; you have to re-mine all descending blocks too, which, in practice, is impossible (and becomes exponentially harder the older your transaction is).
  2. A block consists of a list of transactions, a nonce (the puzzle), the hash of the parent block, the block height and finally the hash of the current block, which is calculated by the block data (txs, hash of parent block, nonce and block height).
#334

  • Why is it important that the blocks are cryptographically linked together?
    cryptographically link makes the blockchain secure and ensures the immutability of data

  • What does the block structure look like in bitcoin?
    prev. hash + tx list + nonce

#335

  1. Verifies information from the original source. Its important they are cryptographically linked to ensure authenticity and no original information or transaction has been altered.

  2. Transaction data, nonce , and hash.

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#336

  1. Why is it important that the blocks are cryptographically linked together?
    The blockchain maintains trust, integrity, and immutability by ensuring the blocks and cryptographically linked.

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

A block has the following components pieces;

HASH
PREVIOUS HASH
TRANSACTION DETAILS

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#337

  1. Why is it important that the blocks are cryptographically linked together?
    to make it secure and immutable

  2. What does the block structure look like in bitcoin?
    it looks like the mix of: - prev hash
    - tx list
    - nounce

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#338

  1. To secure the network, meaning no censorship, no double spend, no altering of previous data.

  2. Previous hash+ Tx list+ NONCE (random number > crypto puzzle to be solved)

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#339

  1. Why is it important that the blocks are cryptographically linked together?
    It ensures that there is integrity in the data so that it can’t be altered.

  2. What does the block structure look like in bitcoin?
    Hash of previous block, current transaction inputs and outputs and the target nonce.

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#340
  1. It is important that the blocks are cryptographically linked together because it makes the blockchain immutable.
  2. The block structure consists of
    a block header
    the data of the block (transactions)
    previous block hash
    nonce number
    timestamp
    present block hash (created from previous hash, present data, and nonse #)
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#341
  1. So that the security of the network can be maintained.
  2. Nonce
    data
    Prev. hash number
    New hash number
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#342

1- so it becomes impossible to make changes to the blocks and outsmart the consensus, because a tiny little change in one block could have a huge domino effect in the subsequent hashes and it is impossible to rehash the whole thing before the network rejects the cheating.

2- the hash of each block is based on the transactions, the hash of the previous block and the nonce.

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