Homework on Blockchain and Mining Visually - Questions

[saintsMike]

• Why is it important that the blocks are cryptographically linked together?
  A: To prevent changing a transactions, The encryped linking prevents history of transaction from changing, since the hash fingerprint of the link of the previous block is also part of the hash fingerprint of the current block
• What does the block structure look like in bitcoin?
  A: The block has the following fields: 1) Block number, 2) Nonce, 3) list of transactions, 4) Hash fingerprint of the previous block, 5) Hash fingerprint of the current block

[infinitegrowth]

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

It is important because each block creates a hash function with a unique finger print from the transaction that each block is given. So it creates a link from previous blocks from those unique fingerprint to the next block in line. If those transaction was changed then the connection to each block will break because it will create new hash with a different unique fingerprint and create a new link base on the new ones. This is how the block prevents the network to be tampered with, If that happens it will be impossible to catch up and fix.

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

It has the block number, the nonce, the data and previous hash. The block then creates its own unique hash from the; nonce, previous hash and data for the next block to be linked with.

[jsilver]

1. it is important that blocks are cryptograhically linked as this is what makes sure that the distributed ledger is an append (not amend) only ledger.

2. A block includes the has from the previous block, new transactions, a nonce, and the block hash.

[M_Alex]

1. Why is it important that the blocks are cryptographically linked together?
   A: Because this increases the security of the network. the links between blocks are expensive and special - they are based on the information in the previous blocks, If someone changes a transaction in a block, then the link between the block and the subsequent block is broken, and the only way to make the blockchain to make sense again is to solve the new puzzle (to re-mine).
2. What does the block structure look like in bitcoin?

Block number
Nonce
Data/List of transactions
Hash of the previous block
Hash of the current block

[Rodolfogzr]

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

This ensures that the chain is almost impossible to alter.

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

It contains:

The block number,

The Nonce

Data / List of transaction (UTXO’s) in the block

The hash from the previous block

The hash from the block.

[Bg8r]

1. It’s important for blocks to be linked together so as to avoid the potential of altering previous transactions. Any alteration of previous block completely invalidates the subsequent blocks in that chain.

2. The block structure is the previous hash, the new hash, a list of transactions and a nonce.

[bboothe]

1. It’s important for security reasons, the links between blocks is a cryptographic puzzle that ensures
   immutability and integrity of the network.

2. It consists of data transactions, previous hash function, nonce and a new hash output.

[Assassin167]

1. It is important that the blocks are cryptographically linked together to protect its integrity so that no data can be changed without disrupting the chain.

2. Previous hash-Transactions- Nonce

[DavidZimbric]

1. So that the block chain is secure, and has very good integrity, so that there cannot be any double transactions that are not legit.

2. Hash, previous hash, and the nonce and a target.

[Bensen]

1. Why is it important that the blocks are cryptographically linked together?
   To ensure integrity,
2. What does the block structure look like in bitcoin?
   previous hash, last Hash, current transactions, nonce, transactionsize, mining difficulty, timestamp, blocknumber,

[Keljaze]

1. Cryptographically linking the blocks together adds an additional layer of security to the blockchain as each block is dependent upon the hash or the previous blocks in addition to the data contained in the current block and the nonce.
2. The block structure is made up of the following in bitcoin:

• The previous block’s hash
• Data or the transaction list of the current block
• The nonce
• The hash of the current block

[gambit6049]

1. It is important that the blocks are cryptographically linked together to prevent alteration of data in the blockchain which keeps the blockchain immutable.

2. Bitcoin block structure consist of block header, previous hash, nonce, block hash and list of transactions.

[Davelopa]

@ivan

Homework on Blockchain and Mining Visually - Questions

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

@Davelopa

Hashing function in proof-of-work consensus mechanism makes tampering with previous blocks basically impossible.

The math problem miners are solving is partly based of on the content of previous blocks. As block are linked using hashing even a slightest change on previous block would mean that all block after that would need to be re-solved and re-hashed.

@ivan

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

List of transactions, previous hash and nonce are needed in producing the current hash for a block.

A block contains a list of transactions that makes up the block data. Nonce is the “target” for miners and determines the difficulty of the hashing calculation. Hash is the output of the hashing function and is produced out of transactions data, previous hash, nonce and current hash.

[Lennon_Borrel]

1. The cryptographic links between blocks secures the blockchain.
2. The block structure contains list of transactions (mempools), previous blocks and nonce.

[Flamboezel]

1. else you could go and change blocks from each other.

2. previous hash, TX, Nonce

[Ma1402]

1- To insure date immutability.

2- Version number,Previous Blc hash, nonce, difficulty target, etc.

[FaronLee]

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

• Because blocks are cryptographically linked together, it is practically impossible to go back and fraudulently change what has already been accepted onto the blockchain. To do so would throw the whole chain into disarray, and it would be obvious that someone had tried to do it. (We need to apply blockchain technology to our history books)

2. What does the block structure look like in bitcoin?
   It contains the hash of the previous block; then another part of it is encryption from its own data. Then a “nonce” is created, which is a random number which distinguishes this block from all others, a unique fingerprint of its own.

[FaronLee]

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

• This keeps those that are confirmed from being altered afterwards.
  If someone attempts to do so, it will confound the entire blockchain from that point, making the fraud obvious.

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

• It contains the hash of the previous block (which will be changed if someone messes with that block, and set off alarms),
  a new hash from the present block, which is dependent on the previous hash and the contents of the present block, and a random number called a nonce.
  The nonce is what must be guessed by the miners.

[Captain]

1- the importance of have the blocks cryptographically linked together insure that any data within the block cannot be changed without subsequently affecting the following blocks. Thus guaranteeing security and immutability.
2- Block structure in Bitcoin consists of previous hash, transaction list and nonce.

[Lucas_Galvez]

1.- Because when they are linked, any single change anywhere in the chain will affect the subsequent group of blocks. So linking is the key to inmutability.
2.- Like a chain.