Homework on Blockchain and Mining Visually - Questions

Blockchain and Bitcoin 101
#484

  1. Because this ensures that if anything in one of the previous blocks is changed, then the links to the future blocks will be broken thus the network will reject. If they weren’t linked, it would be possible to change a previous block and the network would not know it.

  2. Block structure is:
    header
    hash of previous block
    timestamp
    difficulty target
    merkle root of transactions
    nonce

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#485

  1. To ensure that a miner can not double spend or change previous transaction.
    If the miner would do that, his/her block wouldn’t fit any more in the link of the blockchain.

  2. The block structure consist of the previous has + transaction list + the nonce.

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#486
  1. It is imortant that the blocks are cryptographically linked together because in such a way data cannot be altered. Changing data in a specific block will break the link with all the subsequent blocks. This cryptographic links assure that this does not happen.
  2. The block structure in bitcoin consists of the list of data (transactions), the hash of the previous block and the nonce.
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#487
  1. Why is it important that the blocks are cryptographically linked together?

So that each subsequent block’s validity is dependent on the full integrity of all prior blocks.

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

Uh- like a chain of blocks :sunglasses:. Each block includes the previous block hash, a block of transactions specific to this block (merle root), and a nonce (found by a miner, which is below the difficulty target required at the time of block generation). Finally, a hash of the new block is generated by hashing all of these items contained within the new block, and the resultant hash is the ‘previous block hash’ for the subsequent block.

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#488
  1. Blocks being cryptographically linked together secures the network making it virtually impossible to change the transaction data .
  2. The block structure consists of previous hash , transaction data from current block and the nonce.
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#489

1.) they need to be link together for security of the network its the beauty of it. you cant change a block without changing the rest of blocks till the most recent one.with is almost imposible to achieve.
2.) looks like a chain. Each block is connected, and the block is hashed using the previous hash linking the chain and with the transactions the nonce and data

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#490

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

It is important to have blocks cryptographically linked so that provenance and authenticity can be determined. If each block was unlinked chronologically, the linear events of transactions would be disrupted. Allowing vulnerability to information adjustments and hash functions not communicating.

What does the block structure look like in bitcoin?

Version
Amount of Inputs

  • Hash Key
  • Index Number
  • Script Length
  • Response Script
  • Input Sequence Number

Amount of Outputs

  • BTC Value
  • Script Length
  • Public Key Script
#491
  1. To mantain immutablility. By all of the block being cryptographically linked, if anyone tries to change any previous block, then the link is broken.
  2. Block in bitcoin structure has the hash of the previous block, data(transactions) and nonce.
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#492
  1. security of the chain.
  2. previous hash, tx list and nonce
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#493
  1. It is important that blocks contain the hash of the previous blocks’s data to ensure the integrity of the data on the blockchain. It forces congruence of all the blocks in the chain.

±-------------------------------------+
| PREV BLOCK DATA HASH
| NONCE
±-------------------------------------+
| tx 1 a -> b
| tx 2 c -> d
| tx 3 e -> f
±-------------------------------------+

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#494
  1. In order to prevent future fraud or changes in previous blocks.
    2)Previous Transaction Hash -> nonce -> current transactions
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#495

  1. Blocks need to be cryptographically linked to verify the integrity of the blockchain. If they weren’t cryptographically linked then stuff could get changed, without people knowing about it. The latest block’s hash is a fingerprint of the entire blockchain up to that point.

  2. The block structure of the current Bitcoin block has a hash of the transactions, with the nonce, and the previous block hash.

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#496 
  1.  Why is it important that the blocks are cryptographically linked together?

To ensure integrity of transactions and to prevent illegitimate activity

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

Block number, Nonce, Data, Previous Hash, and Current Hash

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#497

  1. A blockchain is a cryptografically decentralized, distributed, digital ledger that is used to record transactions across many computers so that any involved record cannot be altered retroactively, without the alteration of all subsequent blocks.

  2. A block is a container data structure. Each block contains a cryptographic hash of the previous block a timestamp, and transaction data (generally represented as a Merkle tree).

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#498
  1. The blocks need to be cryptographically link together as it ensures the precision of information in each block.
  2. The block has a Block number, A Nonce number, the Transactions or Data, the previous Hash and the new Hash number.
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#499
  1. Why is it important that the blocks are cryptographically linked together?
    It makes it very hard to change a block because if only a single bit is changed the block and blocks afterwards have to be re-mined for them to be valid again.
  2. What does the block structure look like in bitcoin?
    Nonce
    Transactions
    Hash of previous block
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#501

This is more details of transactions.

The bitcoin block structure:
Magic nr.
Blocksize
Blockheader

  • version
  • hashPrevBlock
  • hashMerkleRoot
  • Time
  • Target
  • nonce

Transaction counter
transactions

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#502

  1. Why is it important that the blocks are cryptographically linked together?
    The blocks are cryptographically linked together because it makes the network more secured. This makes it where no transaction in a previous block can be changed, but will not be accepted by other blocks, so it will be dropped.

  2. What does the block structure look like in bitcoin?
    The hash of the block is created by the previous hashes, this hash is used to come up with the nonce. The lower the nonce, the harder the difficulty is.

#503

  1. The blocks should be linked together to prevent a double spend by ensuring that it is near impossible to go back and change all the blocks instead of just one

  2. The block structure consists of previous block hash as well as all the hashes of the tx in that block, this forms the structure of the current block and the reward is paid according to the Block reward plus the transaction fees

#504
  1. To ensure security and data immutability
  2. Hash of the previous block + transactions + nonce. The hash of the current block is based on all three.
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