Homework on Blockchain and Mining Visually - Questions

Blockchain and Bitcoin 101
#142

  1. The link is needed for immutability of previous blocks/data. When changes are made, all the blocks till present will be rejected cause the links will break. Beside that, a cryptographically link is needed there people can’t guess the link so it is infeasible to restore it that way.

  2. Main block hash - created by hash previous block and tx hash from current block. (pointers??)

#143

  1. The link between the blocks will provide the threat detection needed for the security in the blockchain. Cryptography is binary numeral which is sensitive to the slightest changes in the links between the blocks.

  2. First of all, the blocks have their number, each block will get a number, the genesis block has number “0”. The blocks each include “Data” that consist of the transactions from the mempool. The nonce is the number that the miners had to guess in order to be the one confirming/mine the block, this is also included in the block structure. Furthermore there are hashes for every block, the cryptographic links (hashes) between the blocks are generated thru the SHA-256 Secure Hashing Algorithm. Those are the main components of the blockchain structure in Bitcoin.

#144

  1. It allows verification and therefor security within the system, and you can’t double spend without the system rejecting you. All this without a central authority, like an institution or a bank.

  2. Sha256(The previous blocks hash + data in current block + nonce)

#145
  1. Any change on any block changes all the blocks after it. This is important because of security.
  2. Input, Output, and nonce are all part of the block structure.
#146

1 By cryptographically linking the blocks together you make the block permanent, can’t be altered.
2 Previous hash + data + nonce to make another hash.

#147
  1. Why is it important that the blocks are cryptographically linked together?

It maintains integrity and security of the blockchain. If you change something in a block, all links and content in subsequent blocks will be broken, and the blockchain would be invalidated.

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

A series of blocks linked together. When a block is hashed, the hash is derived from the data in the block AND the hash of the previous block, AND a random number the miner has to find (the nonce). The links also contain a hash of the nonce.

#148

helps to secure incentivize miners are spending electricity
prev hash transactions nonce hash function into next block

#149

Blockchain and Mining Visually - Questions

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

The data and hash of a block affects the next block’s hash. This adds to the security of the blockchain since if a block is tampered with, all following blocks in the chain will have their hashes altered, delegitimizing the chain at and following the point where data was tampered with.

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

Each block contains:
-The block’s index
-The nonce
-Reference to the previous block’s hash
-Current block’s hash
-Timestamp
-Merkle tree of the transaction data.

#150

Why is it important that the blocks are cryptographically linked together?
Immutability, each link increases the security of the network
What does the block structure look like in bitcoin?
A block contains a list of UTXO’s, block number, nonce, previous block and current block hash.

#151

  1. It is important to have the cryptographically linked together because this will help the data from being change in anyways possible.

  2. The block structure looks like in Bitcoin transaction, nonce, and previous hash.

#152
  • This helps prevent the data from being altered. Data immutability
  • TX hash
    Inputs
    Outputs
#153
  1. Because 1 block is altered it alters the rest of the blocks securing the blockchain.
  2. The hash of the block is the current nonce and transactions plus the previous hash
#154
  1. It secures the network by making sure the rules of the protocol are followed (proof of work).
  2. The block structure includes the previous hash, transactions list, nonce (has to be guessed, lower than the target).
#155

Question 1

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

The reason it is important blocks are cryptographically linked together is because it ensures the security and immutablily of the block making it impossible for anyone to alter a blockchain

Question 2

What does the block structure look like in bitcoin?

A block has the following structure

  1. Block header
  2. Hash of previous block
  3. Current target
  4. Transaction counter
  5. Transaction
  6. Blocksize
  7. Nuance
#156
  1. By doing so, it becomes impossible to manipulate the integrity of the previous transaction otherwise it will break the chain.
  2. Block #_____________________________
    nonce______________________________
    Transaction data______________________
    Previous hash________________________
    Hash_______________________________
#157
  1. Why is it important that the blocks are cryptographically linked together?
    to ensure that all parts of the block are immutable, becasue the change in one block would lead to change in all other follow-up blocks.
  2. What does the block structure look like in bitcoin?
    Header
    Nonce
    Hash of previous block
    Transactions
    Hash of current block
#158

Why is it important that the blocks are cryptographic-ally linked together?

Each Block is cleverly linked to the previous block via a Prev Block hash. This gives the Blockchain security. With this method it is impossible to change any Tx without breaking the link, once the link is broken the block is nullified. This is all done with a mathematical puzzle that link all previous blocks together.

What does the block structure look like in bitcoin?

Block Header

Block Size

Difficulty Target

Merkle Root Hash

Nonce ( number randomly guessed by Miners)

Transactions + Transaction Counter ( Timestamp)

previous Block Hash

#159
  1. This makes it impossible and to costly to chance a previous block. Because then you have to remine
    the next and new blocks.
  2. The hash of the previous block, transactions and the nonce.
#160
  1. By cryptographically linking blocks to their previous block, this ensures that the chain is hard to falsify. If a malicious participant was trying to change a particular block they’d have to then change every block thereacted (completing the POW for each block), which would be a very costly process.
  2. The block structure resembles a data structure known as a “linked list”, where every block contains the hash of the previous block linking them together.
#161
  1. Why is it important that the blocks are cryptographically linked together?
    if they are not it will be easy to make a change and security is not safeguarded
  2. What does the block structure look like in bitcoin?
    the previous block makes a hash,this data is linked to transaction and Nonce and makes a new hash to the next block