Homework on Blockchain and Mining Visually - Questions

Blockchain and Bitcoin 101
#2090
  1. so past blocks cannot be changed
  2. the structure is based on the last block’s hash, the current block’s transactions, and the nonce.
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#2091
  1. Why is it important that the blocks are cryptographically linked together?
    A: Because if you alter one it changes all of them.
  2. What does the block structure look like in bitcoin?
    A: previous hash+ tx list+ nonce, which needs to be guessed
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#2092

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

This ensures that the blockchain is functionally immutable. Any attempt to change data in a block will break the links from that point forward along the blockchain. Those links will have to be re-mined which is astronomically cost prohibitive.

What does the block structure look like in bitcoin?

Each block contains Block number, current timestamp, current difficulty target, hash of previous block, Nonce, and hash of merkle root of the data in this block.

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#2093
  1. Why is it important that the blocks are cryptographically linked together? To insure the immutable of the blocks.
  2. What does the block structure look like in bitcoin?

The previous block hash

The Merkle root hash

The Timestamp

The Difficulty target

The Nonce

The Block Size

The Block header

And the Transaction counter

Transactions

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#2094

  1. It is important because it makes it infeasible to alter any data on the blockchain.

  2. In each block there is the previous hash, this hash’s data, the guess of the nonce, and based on those 3 inputs, you get the hash output for this current blocki

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#2095
  1. That gives the chain security and ensures that block cannot be edited.
  2. Prev hash + transaction list + nonce
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#2096
  1. This validates the chain as any information changed in a particular block would void any blocks created after that. This mathematical verification ensures that the information is immutable and reliable.
  2. Each block structure includes a hash for the current block, a hash from the previous block, transactions contained within the current block and a random number which is called a nonce.
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#2097
  1. It assures the immutability of the network.
  2. Blocks of transactions linked historically to one another so that any change in a transaction in a previous block changes and invalidates all subsequent blocks.
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#2098

  1. It helps ensure the integrity of the network while not allowing any double spending to occur. Any change within a block will void any connections to the next or previous blocks.

  2. It will have previous info such as hash, timestamp, nonce, along with much more. As well as the current data for that block.

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#2099

1.it is important so no one can alter past transactions,and gives safety by the one way encryption for the entire blockchain.

2.It is a nonce plus current transactions and previous block hash.

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#2100
  • Why is it important that the blocks are cryptographically linked together?

to have integrity and security in the network…i.e. no double spends.

  • What does the block structure look like in bitcoin?

the block is made up of:
prior hash
txns
nonce

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#2101

  1. Insures blockchain security against many discrepancies such as double spending and transaction manipulation.

  2. It includes:

Previous Block Hash
Transaction data
Nonce
Current Block Hash
Difficulty Target
Block header

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#2102
  1. To provide the security the network needs to protect the interests and welfare of everyone involved.
  2. It includes the previous hash, the transaction list, the nonce (a random number that is guessed) When these three are combined and the number is less than the target, a new block is formed.
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#2103

  1. It is important that the blocks are cryptographically linked so that it is infeasible to alter a transaction from the past and to prevent double spending.

  2. Each hash of a block is made up of the hash from the previous block, the transactions contained in that block and a randomly chosen nonce which sets the difficulty for the miners.

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#2104

1)It makes it difficult to change a block.

2)It has the hash of the previous block, transactions and the nounce.

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#2105

Why is it important that the blocks are cryptographically linked together?
It is important that the blocks are cryptographically linked together because then for someone to mine/hash one previous block, they will also have to go and rehash the previously block connected to that one until they have rehashed all the blocks. Because the blocks are cryptographically linked together, this helps secure the network to prevent people from trying to double spend.

What does the block structure look like in bitcoin?
The block structure in bitcoin looks like this: A Block includes the previous hash, a transaction list and will be hashing to try to match the nonce with the target to have their block added into the network first to be paid from TX Fees and block rewards. The nonce must be less than the target to be guessed correctly. All Bitcoin nodes will then grab the winning block to add to the network and the block will eventually get to everyone’s local node copy as long as everyone verifies and agrees that the block is valid.

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#2106

  1. To Cryptographically link the blocks together insures that no one can go back and alter the history contained in the blockchain. If someone were to try and alter the history this would cause the chain to break and it would be recognized right away by the network. You might say it’s tamper proof.

  2. The block structure
    Version>previous block hash>Root hash>time>target>nounce>this blocks data & transaction data.

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#2107

2
Blocks in the chain are linked by a mathematical puzzle which is resolved with the correct hash identity of the previous block. And any hash is generated with the transactions so if one transaction changes, it changes the hash, which which break the mathematical puzzle between block…

1
• Hash of current block
• Hash of previous block
• Transaction
• Nounce
• block number

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#2108
  1. The blocks are cryptographically linked to each other so that upon a change in a block this will lead to a cascade of changes in hashes in the ensuing blocks. Linking newly mined nodes to a changed block will require a lot of computational resources and therefore makes the entire blockchain cryptographically secure.
  2. A block structure contains:
  • The hash of the current block (its digital fingerprint, dependent on the hash of the previous block)
  • Its transaction list
  • and a guess of a nonce
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#2109

The nonce is just a random number. It doesn’t need to be lower than the target.
The entire blockhash must be lower than the target to be accepted by the network.
Because hashes are not predictable, it is hard to get a hash that starts with a bunch of leading zero’s. So miners need to add a random number (nonce) to make the blockhash low enough. They basically keep guessing new nonces, hash it again and check if the blockhash is low enough.

Try this website out. Enter some information and try to guess the nonce so that the blockhash starts with 4 zero’s. This website can mine it by clicking on the button. Then it will check many nonces in the background until the blockhash is low enough.

There are more than 1 possible nonces that could result in a valid hash.

And the more leading zero’s it must have, the harder it is to find it. In this website, you only require 4 leading zero’s. Otherwise it would take to long to solve it

https://andersbrownworth.com/blockchain/blockchain

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