Homework on Blockchain and Mining Visually - Questions

Blockchain and Bitcoin 101
#3356
  1. Why is it important that the blocks are cryptographically linked together?
  • To prevent anyone from tampering with previous blocks.
  1. What does the block structure look like in bitcoin?
  • hash of previous block, transactions in current block, guessed nonce and hash of current block
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#3357
  1. so that any change made to one block affects the rest of the chain as well.
  2. hash from previous block plus the transactions plus the nonce to hit target.
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#3358

1.This makes up the “chain” in the blockchain. It is for security of the blockchain. If somone try to change anything in the chain, all links after this will need to be changed as well. Which is impossible.
2. The hash in a block is base on the previous transaction hash, transaction on the block and the nonce that was guessed by the miner.

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#3359

  1. Why is it important that the blocks are cryptographically linked together? To ensure the integrity and security of transaction data that has already been accepted by the bitcoin network. This ensures a trustless network effect.

  2. What does the block structure look like in bitcoin?
    Previous block hash + transactions list in current block + nonce

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#3360

[quote=“ivan, post:1, topic:8433, full:true”]
Homework on Blockchain and Mining Visually - Questions

  1. Why is it important that the blocks are cryptographically linked together?
    this way no transactions can be changed.

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

The structure of a block in bitcoin contains the list of transactions, the hash of the previously mined block and the nonce, which is essentially a random number which is used to try and get the hash low enough to be accepted.

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#3361
  1. Blocks are cryptographically linked together to ensure data is immutable and cannot be changed. Also it ensures that new transactions are processed safely because new blocks can only be accepted and appended if the hash result is a product of previous hash data which ensures nothing is changed from the past transactions and blocks.
  2. The block structure in BTC contains the block header, transaction data, the hash of the previous block, the nonce and the target.
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#3362
  1. Why is it important that the blocks are cryptographically linked together?
  • it makes the network more secure because you cannot cheat unless you can change all of the linked blocks. If a fraud occurs in a block, it is invalidated because it lost the link to other blocks.
  1. It looks kind of like a long train.
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#3363

  1. Why is it important that the blocks are cryptographically linked together?
    Makes the system fraud proof / secures the network. If the smallest detail in a previous block is changed. All subsequent blocks need to be changed/remined. As a consequence malicious alteration of the blockchain are prevented and immutability of the network is guaranteed.

  2. What does the block structure look like in bitcoin?
    A block consists of the previous block hash, TX data, a merkle tree, a time stamp, the block size, a block header, a transaction counter and a nonce. Miners need to guess the latter in order to meet the target, meaning the hash needs to be below a certain threshold.

Is the TX data embedded in the merkle tree or are those different things?

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#3364

How do the carriages look like? :smiley:

#3365

The merkle tree is a tree of hashes, doesn’t contain any other data. Transactions are stored in the block data.

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#3366
  1. Why is it important that the blocks are cryptographically linked together?

It is important for the integrity of the blockchain. as they are linked it is very hard for anything to be changed the longer the chain is.

  1. What does the block structure look like in bitcoin?
    hash- previous hash- transcation list - nonce (jimmy saville :wink:
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#3367

Why is it important that the blocks are cryptographically linked together?
this makes it impossible for anyone to manipulate the blockchain.

What does the block structure look like in bitcoin?
Magic No,Block Size,Block Header,Transaction Counter,Transactions. The Block Header
This is very important part in Block structure and this has further 6 items Block header in Bitcoin has,version,previous block hash.merkle root hash,timestamp,difficulty
nonce.

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#3368
  1. It is important for the security of the blockchain. That way no transaction can be changed in privious blocks because it would break the link to the next block and all that follow.
  2. The hash of the current block is based on the previous hash + data + nounce.
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#3369

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

A: For security reasons. So, no one can manipulate the system to double spend, reverse transactions or change them.

Q: What does the block structure look like in bitcoin?

A: A block is made up of the transaction list (data), the previous hash and a nonce which is a random number. With these three the hash of the block is created and the structure of the block.

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#3370
  • Why is it important that the blocks are cryptographically linked together?
    This makes it more difficult to change a block. When you change one block, you have to change all the blocks and create new hashed relations between the blocks, something which is impossible.
  • What does the block structure look like in bitcoin?
    Version
    Previous Block hash
    Merkle root hash
    Timestamp
    Difficulty target
    Nonce
    Block Size
    Block header
    Transaction counter
    Transactions
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#3371
  1. It is important that the blocks are linked together because it makes the structure more efficient and less likely to be disrupted.
  2. The block structure looks like blocks made up of a nonce, data input, the previous hash, and the current hash. If the data input changes, you must remine so that the hash is below the nonce.
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#3372

  1. For the security and integrity of the blockchain. When blocks are linked together if someone hacks or tries to somehow cheat and go back in time to change a transaction, the blocks directly linked and affected by it will break the chain and relationship with it which would mean that the miner responsible for that would have to mine the broken blocks by himself while everyone else is moving on with hashing and mining other blocks and the perpetrator would have to catch up to them too which would require an impossibly powerful computer and TONS of electricity.

  2. A block contains its hashing ID as well as the hashing ID of the block previous to it. This helps in such a way that if a transaction is changed all hashing ID’s relating to the block whose transaction is changed change their hashing ID. In addition, the block contains the random nonce that is randomly guessed.

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#3373
  1. Why is it important that the blocks are cryptographically linked together?
    Its important to make the blockchain secure
  2. What does the block structure look like in bitcoin?
    Transactions
    Hash from previus block
    Hash from current block
    Nonce
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#3374

  1. Makes it improbable to change or alter a previous block since you’d need many powerful computers to recreate links between blocks as new ones are being added to the blockchain.

Nonce number
Data (TX List)
Prev. Hash
New Hash being created

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#3375

1. Why is it important that the blocks are cryptographically linked together?
A: To ensure the integrity of transactions as a change in any of the previous blocks would break the link

2. What does the block structure look like in bitcoin?
A: The block contains the hash from the previous, the validated transactions and a nonce whose hash has to fall below a threshold (a proxy for the difficulty) and acts as the proof of work

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