Homework on Blockchain and Mining Visually - Questions

Blockchain and Bitcoin 101
#4262

1.it is important that blocks are cryptographically linked together for the security of the blockchain. That way no transactions can be changed in previous blocks because it would break the link to the next block and all that follow.
2.The hash of the block is based on the transactions in the block plus the previous hash and the nonce that needs to be guessed.

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#4263
  1. It makes the blockchain more secure and prevents previous blocks from being altered.
  2. Itā€™s like a puzzle, blocks and chains/links fully integrated into a secure network. Also made up of transaction hashes, nounces, inputs and outputs.
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#4264
  1. Why is it important that the blocks are cryptographically linked together?

This helps ensure that the immutability of the blockchain is maintained.

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

The blockchain is similar to a linked list data structure.

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#4265

  1. It is important that blocks are cryptographically linked together to insure the integrity of information and provide protection against any bad actor who might want to alter or change blocks for personal gain.

  2. The Hash of the current block is derived from:

  • Previous Hash
  • Transaction list
  • Nonce (Value guessed by Miners)
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#4266

1.secutity of the chain

2.block,nonce,data,hash

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#4267

  1. Blocks being cryptographically linked together allows the blocks to be immutable, any change to one block consequently requires a change to every block that follows.

  2. The structure of a block in bitcoin contains the list of transactions, the nonce, and the hash of the previous block.

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#4268

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

  • establishes a sequence for transaction history
  • it shows relationship between the blocks. And creates built-in security such that tampering with past data becomes too difficult to do and still be profitable.

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

  • the hash hash data of the previous block
  • nonce number
  • transactions
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#4269

  1. Why is it important that the blocks are cryptographically linked together?
    So malicious actors cannot go back to change transactions from already confirmed blocks. Whenever a transaction is changed in previous block, it changes the hash of that block and all hashes for the corresponding blocks.

  2. What does the block structure look like in bitcoin?
    Hash from previous txns + Nonce (random number) + current txns.

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#4270
  1. So if someone try to modify 1 block, it would have repercutions on the whole blockchain. It is for security.
  2. the hash of the block = nonce + data + previous block hash
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#4271
  1. So nobody can make (fraudulent) changes in the previous created blocks.
  2. Nonce + data + previous hash
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#4272
  1. Why is it important that the blocks are cryptographically linked together?
    Ensures security of the the blockchain as nobody can go back and modify data in the previous blocks as this will be practically impossible.

2.What does the block structure look like in bitcoin?
Previous hash, Tx list, nonce

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#4273
  1. It is important that the blocks are linked cryptographically together for the security of the blockchain. There will be no way that transactions can be changed in a previous block because this will break the link to the previous block that will follow.
  2. The structure of a block is based on the hash, the hash of the block is based on the transactions in the block plus the previous hash and the nonce that needs to be guessed.
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#4274
  1. Secure the network, security of the blockchain, stop blocks from being changed.
  2. Previous hash, transactions, transaction fees, block reward, nonce and new hash for block. All mentioned above has all this information in each new block entered into the blockchain and this is what the block structure looks likeā€¦les goā€¦
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#4275
  1. this makes the ledger immutable because of the many layers of hashing.
  2. the block structure literally looks like a chain of blocks witchains within each block.
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#4276

1.) To preserve the integrity of the blockchain. And for the benefits of provenance, consensus, security, immutability, and finality.

2.) The hash output of the previous block, timestamp, tx root and nonce

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#4277 
1- Why is it important that the blocks are cryptographically linked together?

To make blocks unchangeable because the hash of a block is calculated with an input of the previous block hash plus transactions plus nonce. Ich you change a block in this chain you have to automaticalle remine all foloowing blocks in the chain which is nearly impossible  (time & money)

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

Each block contains a list of transactions and is signed with a hash which is produced by a hash function with the input: hash of the prevoius block + all transactions + nounce. Timestamp is available also.
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#4278
  1. Why is it important that the blocks are cryptographically linked together?

For the security of the network. If the blocks in the chain wouldnĀ“t be linked together via hash puzzle, one could simply alter/ change/ delete transactions in any previous block. However through the links the whole chain wouldnĀ“t make any sense after altering the tx list and it simply wouldnĀ“t get accepted by the network (consensus).

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

Each block has its own transaction list and its own hash (signature), based from all containig tx, the previous blockĀ“s hash and the nonce, which the miner has to guess.

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#4279

  1. To verify that everything is correct, immutable and avoid fraud in the network.

  2. In bitcoin the block has Inputs, hash value and outputs.

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#4280
  1. Why is it important that the blocks are cryptographically linked together?
    To secure the network. So that any change in a previous block would need an update to all the next ones.
  2. What does the block structure look like in bitcoin?
    Each block contains the current time, a record of some or all recent transactions, a reference to the block that came immediately before it and the nonce.
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#4281

  1. The cryptographic linking of blocks ensures that any alterations of data on once block will affect all succeeding blocks, resulting in a completely different set of data that contradicts the consensus model of the protocol. This makes it almost impossible for miners to cheat the system and ensures that the blockchain remains transparent, decentralized, trustless, and free from amendments.

  2. The hash of each new block is comprised of the inputs and outputs of the given block (transactions), the previous blockā€™s hash, and the nonce, which is a randomly generated 256 digit number.

PS - is the 256 digit thing correct? I believe I read this somewhere on the intro courseā€¦

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