Homework on Blockchain and Mining Visually - Questions

[VBence99]

1.) Every block’s hash is basically based on every previous block’s hash. This secures the network because if anyone wants to change something, they’ll have to re-mine all the blocks that came after.

2.) A block consists of the hash of the previous block, a transaction list, and a nonce.

[runHikeClimb]

1. So it will create an unbreakable chain, making the recorded transaction true(set in “stone”)
2. Current hash contains, previous hash, nonce, transaction list/data

[eunice_salimao]

1. Why is it important that the blocks are cryptographically linked together?
   This is important to protect the integrity of the data as one of the main characteristics of the blockchain is immutability.
2. What does the block structure look like in bitcoin?
   A block structure in bitcoin contains the hash of previous block, transaction list, and nonce.

[tenbad]

1. The blocks are linked so that it is extremely difficult (or practically impossible) to change any of the existing data, since that would require changing all subsequent blocks.
2. The hash is based on the transactions in the block, the previous hash, and the nonce (guessed random value).

[SamEdwards]

1. Why is it important that the blocks are cryptographically linked together?
   It’s important because the cryptographic link creates a trustless system built on permanence. This structure prevents previous blocks from being changed. Any change to a previous block would break the link and all future blocks in the chain. That way, users can trust their transactions when it is etched into the blockchain.

2. What does the block structure look like in bitcoin?
   The block structure is a data structure that is forged with three ingredients: a list of transactions, the hash of the previous block, and the nonce. Cryptographically combined, this creates the new hash for the block.

[CryptoRavioli]

1. Why is it important that the blocks are cryptographically linked together?
   Having the blocks linked together cryptographically gives finality. A block can not be changed without invalidating all blocks which follow it.

2. What does the block structure look like in bitcoin?
   The transaction list, the hash of the previous block, and the nonce are hashed using SHA265 to give the block hash. Interfering with any data within the block will output a different hash there by invalidating the block and any block after it.

[Hallow]

1. Why is it important that the blocks are cryptographically linked together?
   The fact that block are linked is important because its makes altering the previous blocks impossible, making the network secure from that point of view.

2. What does the block structure look like in bitcoin?
   Nonce
   Transactions
   Previous hash
   Current hash

[Juan_araujo]

1. Why is it important that the blocks are cryptographically linked together?
Because, if any block is altered the rest of the network will be broken.
This is why the blockchain has immutability.

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

-Previous block H. functions

• Nonce
  -Tx list

Then, a new hash number to reach the target and later, approve the transaction.

[Zaqoy]

1. Why is it important that the blocks are cryptographically linked together?
   If data is changed in a block, the hash will be changed for every block thereafter.

2. What does the block structure look like in bitcoin?
   A block for the bitcoin blockchain includes the previous block hash, transaction data of the current block, and a nonce that needs to be guessed.

[Grdylineman]

1. Why is it important that the blocks are cryptographically linked together?
   It will make it more secure and make it harder to change any data within that block
2. What does the block structure look like in bitcoin?
   Version, Last block, merkle root, time, target, nonce, block size, block header, transaction counter

[Gutto13]

1. It improves security and immutability. Changes cannot be made to one block without changing all blocks thereafter. Changed blocks will be recognized by other nodes and be deleted from the blockchain. Since it takes time to re-mine all changed blocks, newer blocks would be added to the blockchain and prevent those changes from being accepted on the blockchain.
2. The structure of a block in bitcoin contains the link from the previous block, a list of transactions, and a specified target depending on the hash power of the network which ultimately determines the nonce needed to add the block to the blockchain.

[PapaCoins]

1. Why is it important that the blocks are cryptographically linked together?
   This prevents modification of the already generated blocks and provides integrity to the network.

2. What does the block structure look like in bitcoin?
   The block consists of the “previous hash + transactions in the block + nonce” to generate a new hash.

[stg3o]

1. To ensure the validity of the blocks added continually.

2. Each block contains the hash of the previous block, current block hash, UTXO’s, block header and nonce.

[M.K]

1. Why is it important that the blocks are cryptographically linked together?
   so that when any previous block is tampered, it breaks all other forward blocks. This will hamper the double spend effort in terms of more time needed to re create next fraudulent block. The attempt to re create a fraudulent block or blocks at a lesser block scenerio, in terms of time will lose to the other miners, This will create a protection against double spend attempts. Because network always choose the longer chain as the single truth version.

2. What does the block structure look like in bitcoin?
   nonce
   txn list
   previous hash

[Beverley]

1. Secures the network, no censorship, cannot double spend, cannot alter history.
2. A block is made of a header which contains metadata, followed by a long list of transactions that make up the bulk of its size.

[Alko89]

@Grdylineman

Version, Last block, merkle root, time, target, nonce, block size, block header, transaction counter

@Beverley

A block is made of a header

What is in the block header?

[Beverley]

The head of the block is divided into components:

• the version number of the software
• the hash of the previous block.
• the root hash of the Merkle tree.
• the goal of the current difficulty.
• the nonce.

[jayharden1]

1. Why is it important that the blocks are cryptographically linked together? This provides security and ensures that no one can make changes to blocks in the chain. No changes, no double spending, etc. Hence making transactions safer and trustable.
   2. What does the block structure look like in bitcoin? previous hash, nonce, transactions and all Hashed together give the Hash for the current block

[marius]

1. To ensure that no changes can be made in any of previous of blocks as that will break a blockchain and it will be invalid. Don’t matter how small or big change, different hash going to be produce accordingly. This prevents double spending of coins also doesn’t allow to make any changes of the past data.

2. Version - Previous Block Hash - Merkle Root - Timestamp - Difficulty Target - Nonce

[nunomgsilva]

1Why is it important that the blocks are cryptographically linked together?
Is important because it ensures the integraty of the data in the blockchain. If we change a single block in the block chain, subsequent blocks would be need to be re-mined.
2What does the block structure look like in bitcoin?
The hash of the block as the nounce (random number) wich as to be guessed by the miners + transactions + Previous block hash.