Homework on Blockchain and Mining Visually - Questions

Blockchain and Bitcoin 101
#645

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

  • It’s important because it grants security and immutability to the system, a change in a block generates a change in its hash, so the following chain will not exist anymore, you should mine it again and the network will take the longest chain, that meanwhile will be built by other miners

What does the block structure look like in bitcoin?

  • It has in its inside the previous block’s hash, the nonce and the list of transactions
#646

To avoid any manipulation/alteration of the data/information inside the block.

A bitcoin block among other things (timestamp/others technical information) contain the list of transactions , the nonce , the hash of the previous and current block.

#647
  1. To ensure finality and immutability.
  2. Merkle tree.
#648

  1. Since the blocks are linked together via the previous hash in the chain, if someone goes and changes any bit of information from a previous block, the hashes after that point will have all been invalidated.

  2. The block is comprised of the Previous Hash of the block before it in the blockchain. It has the total list of transactions to be included in the new block. It also has the nonce. The nonce is randomly guessed thousands of times over and over until the hash that comes out of SHA 256 is less than the target.

#649
  1. If the blocks weren’t cryptographically linked together by the hashes, the date could be changed in a block and wouldn’t effect the following blocks. This would destroy the integrity of the network and remove the immutability characteristic.
  2. Block 1 contains transaction data and a nonce. This produces the hash of block 1
    Block 2 contains transaction data of block 2, the hash of block 1, and a new nonce. This
    produces the hash of block 2.
    This repeats.
#650

  1. Miners use links based on the previous blocks to solve the cryptographic puzzle/equation and earn rewards.

  2. Nounce, current transactions, previous hash = hash of new block.

#651

  1. It is important that the blocks are linked together cryptographically because it provides proof and confidence in the entire network. The miners provide the proof of work necessary so that participants need only to trust the math and not any single entity like a central bank, private company or government.

  2. The block structure of Bitcoin looks like hashes that are interwoven together through Hexadecimal Notation. Each block consists of a hash that was produced from a miner by solving a puzzle that involved the previous hash in the chain, the transactional data within their proposed block, and a nonce. If any data within a miner’s block is altered, the entire chain is invalidated by the network.

#652
  1. To ensure integrity of the block and prevent people from changing transactions on their blocks leading to things like double spending.

2.It is made up of the previous block hash, current transactions and the nonce

#653

1. Why is it important that the blocks are cryptographically linked together? To ensure blocks remain immutable.

2. What does the block structure look like in Bitcoin? The block contains the previous block hash, the nonce and the list of transactions.

#654
  1. Because if anything is changed in previous blocks, all the links between blocks would be broken(from the changed block to the newest one). That way, changing a transaction is pratically impossible because you would need to confirm all the following blocks all by yourself, all over again.
  2. It contains transactions, hash of the previous block, nonce, and all that creates a hash for the current block.
#655

  1. to secure the network and make it immutable and that no transactions can be changed.

  2. the current block with a hash, that’s based on previous hash and transactions in the current block and ALSO based on a random number that miners have to find called the nonce.

#656

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

To make the blockchain immutable.

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

Block
Block Header
- Version
- Last Block
- Merkle Root
- Time
- Target
- Nonce

Block Body
	= Coinbase Transaction
	- Transaction ( Input/Output )
#657

  1. It is important that the block are linked together because it makes the network more secure and harder to edit already validated transactions.

  2. The block structure is a hash of the previous hash, the nonse, and the transactions the miner has decided to add. This hash has to be lower then the target to be accepted into the network.

#658
  1. For make the database safe . If in one block you change something all the added blocks chain will broken . Its important for data immutability
  2. The block contains - previous block hash , list of transactions , and nonce / random number
#659

Linking is important to insure the immutability of the blockchain
The structure of the block requires the hash of the previous block,nonce and transactions to create the hash of the new block.

1 Like
#660
  1. The blocks are cryptographically linked together to ensure that any changes in the previous blocks are not carried forward and break the cryptographic link for the blocks associated with it.
  2. It consists of the following things
  • Version number
  • Previous block hash
  • Merkle root
  • Time stamp
  • Nonce
  • Transactions
#661

makes changing and re-mining previous blocks prohibitively costly and time-consuming
contains prev block’s hash, nonce and transactions

#662

  1. Because this allows for hashes of previous blocks to be included in the next mined block. It denotes the accuracy and integrity of the entire chain.

  2. A previous hash and the nonce and transactions of the entire block. The next block repeats the same structure and so on.

#663

  1. Why is it important that the blocks are cryptographically linked together?
    Because in that way sabotage becomes unfeasible.

  2. What does the block structure look like in bitcoin?
    It is built by the given previous hash, a nonce, a list of chosen transactions and the new hash that gets created out of all of them.

#664
  1. So transactions in any block cannot be changed, and if they were it would be very easily noticed due to all the following blocks hashes changing and would then be rejected by the network.

2.Data, hash of previous block, nounce which is all hashed and then that hash is used to make the next block