Homework on Blockchain and Mining Visually - Questions

Blockchain and Bitcoin 101
#1047
  1. Why is it important that the blocks are cryptographically linked together?
    When blocks are cryptographically linked together, it is virtually impossible to make changes to previous blocks as they are interdependent; when a change is made to a block it affects the next block and the block after that which ensures immutability.
  2. What does the block structure look like in bitcoin?
    The hash of the block is based on the transactions in the block, the previous hash and the nonce that was used when the target requirements were met.
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#1048

  1. Why is it important that the blocks are cryptographically linked together? Further secures the network and prevents nefarious actors from changing the transactions once they’ve been confirmed.

  2. What does the block structure look like in bitcoin? A block consists of the previous hash, list of transactions, nonce, and the block hash is derived from those three things.

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#1049

1. Why is it important that the blocks are cryptographically linked together?
For the security of the network. No transaction can be changed on previous blocks.

2. What does the block structure look like in bitcoin?
The hash has to do whit the hash of previous blocks and the nonce to be guessed.

#1050
  1. The cryptographic link is important because it makes the hash for the new block based on the previous one so that to change it would take too much time and resources for it to be possible.
  2. In Bitcoin blocks are created every ten minutes, the difficulty adjusts every 2016 blocks, & the block reward is reduced by 50% every 210,000 blocks.The new blocks are created from the transactions plus the fees then the miner that guesses the nonce gets to validate the block & receive the block reward.
#1051

  1. Why is it important that the blocks are cryptographically linked together?
    That ensures data integrity. Thanks to hashing, even the smallest change in a block will result in a very different block hash.

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

  • previous block hash
  • nonce
  • transaction list
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#1052
  • Why is it important that the blocks are cryptographically linked together?
    So that network security is maintained by immediately identifying any changes in the previous block transaction as this will lead to the requirement to change the hash functions of the blocks ahead.
  • What does the block structure look like in bitcoin?
    Block structure includes : Transaction, Nounce and hash of the previous block.
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#1053

Why is it important that the blocks are cryptographically linked together?
Blocks that are cryptographically linked together are practically impossible to change after being
mined to the blockchain. It would take miners more money and time to go back and try to change a block rather
than not changing the block. The network makes it beneficial for miners to play by the rules.

What does the block structure look like in bitcoin?

Each connected Block has a Hash, a digital fingerprint based on all transactions in that block.
Each block is based on the hash of the previous block. Also each block has a secret number (nonce)
that miners must find to publish that block to the blockchain. After that miners must compare the hash
to the target (number based on difficulty of the Bitcoin network.

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#1054

QNS 1. Why is it important that the blocks are cryptographically linked together?
It is important for blocks to be cryptographically linked together as transactions will be tamper proof and any changes made to the existing chain of previously mined blocks will be classified as invalid across the whole blockchain.

QNS 2. What does the block structure look like in bitcoin?
The block structure in bitcoin consisted of a hash, transaction list and the previous hash of the previously block. It also has a nonce which miners must guess to publish the next block to the network.

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#1055
  1. Cryptographic linkage of blocks is what makes the blockchain immutable. It is the basis for the integrity of the whole system.
  2. a double linked data structure containing the previous hash, transaction data, and the nonce.
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#1056

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

By having blocks cryptographically linked together it makes it practically impossible for any changes to the blockchain to be made, thereby ensuring provenance and immutability.

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

Each block consists of the previous block’s hash, the block transactions, and the nonce. The hash of these three things is then placed in the next block.

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#1057
  1. Why is it important that the blocks are cryptographically linked together?
  2. What does the block structure look like in bitcoin?

A1. It is important for blocks to be cryptographically linked together to ensure integrity of the network. A new block depends on the accuracy of the previous block (PoW.)

A2. The bitcoin block structure is made of a box of data, a hash value from the previous block, a nonce value (target) and a newly created hash value.

#1058
  1. Why is it important that the blocks are cryptographically linked together?
    So that you cant modify one without affecting the all the others in the chain. You would have to re-mine the changes on and all the others going forward till the current which is impossible
  2. What does the block structure look like in bitcoin?
    Magic no
    Blocksize
    Blockheader: Version, hashPrevBlock, hashMerkleRoot, Time, Bits (Current Target), Nonce
    transactions
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#1059

It’s important that the blocks are cryptographically linked together because:

  • The links are based on the information in the previous block
  • So if the information was subsequently changed in the previous block, it would break the link
  • This means that any changes to information in previous will the blockchain, which is a big disincentive to tamper with the information in previous blocks

The block structure in Bitcoin looks like the following:
Block:

  • Nonce number
  • Transactions
  • Previous Hash
  • Current Hash

The Hash of the current block is based on the transactions data in the current block and the Hash of the previous block along with the nonce which is guessed by the miner.

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#1060
  1. To insure that data in blocks cant be doctored for fraudulent purposes. As such the integrity of the system is kept intact.
  2. It contains (a) previous blocks hash (b).transactions © nonce . = hash that less than target for present block…
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#1061
  1. It is important that blocks are cyptographically linked together as this provides network security. Nodes look for the longest chain and take that as the truth as it has the most proof of work. To change a prior block results in the rest of the chain changing. This forces a bad actor to remine the old block and everyone that follows it until it is longer than the real chain, this takes too much effort to be practical. So the linking adds security, making it to costly to alter previous blocks. This feature also adds censorship resistance.
    2.The basic structure begins with the hash of the previous block. To this you add the transactions of the block you are building and the nonce. You hash the previous hash/transactions/nonce and create a new hash. Your block is valid if the nonce you picked results in a hash that is less than the target.
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#1062

Hi there!! This is correct for the the blockchain, but what data can we find in each block?

#1063

We can also find the transactions included in this block :slightly_smiling_face:

#1064

Hi there! You are right here, although the question was focused on the structure of the block, so, what data can we find in each block?

#1065

Hi there! What do you mean by accuracy?

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#1066

Hi there!! did you miss some words here? :laughing: