Homework on Blockchain and Mining Visually - Questions

Blockchain and Bitcoin 101
#3175

  1. Why is it important that the blocks are cryptographically linked together?
    A) Keeps the network secure because if one block is corrupted it will cause the whole chain of blocks after to be broken.

  2. What does the block structure look like in bitcoin?
    A) Blocks consist of transactions, nonce, and hash of previous block to then create the hash of the current block to be added to the blockchain.

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#3176

Mining Visually - Questions

  1. Why is it important that the blocks are cryptographically linked together?
  2. they are liked together because they all use the previous hash from th block and the previous to the previous block. if the hash is not created from all previous blocks the new block will not work.
  3. What does the block structure look like in bitcoin?
  4. it looks like a Chain links together . looks like a chain
#3177

For my understanding the previous hash was used to calculate the hash of the block.

For example int his block (https://www.blockchain.com/btc/block/000000000000000000090ef0d38c6a5a8b7bf9348dbcb3dc801a0289fcd9bd29) Iā€™m not able to see the previous hash.

So the previous hash is used to calculate the hash of the current block or the previous hash is also a part of the current block ? :slight_smile:

#3178

How do the links in the chain look like? :wink:

#3179

Previous hash is included in the block header. Technically the block doesnā€™t contain its hash because it can be recalculated on the fly.
Explorers abstract data so they are more user friendly this is why some donā€™t show this info. :slight_smile:

https://github.com/bitcoinbook/bitcoinbook/blob/develop/ch09.asciidoc#structure-of-a-block

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#3180
  1. if they are not linked together, the chain wonā€™t exist
    each block has a piece of previous block in it (except the first block of the total chain)

2.itā€™s hash plus previous hash and the nonce

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#3181

Thanks Maki for pointing out, just read other answers :slight_smile: I misunderstood the question.

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#3182

Is the correct answer is: previous hash + transaction list + nonce ? Thanks and by the way how are you doing so far ?

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#3183

  1. Its important because of the security and privacy but also for miners to have a difficult time figuring out right nonce for adding new block to the chain.

  2. The block structure looks like random hashed numbers taken from UTXOs involved in newly added transactions that are now UTXO

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#3184

  1. Keeping the blocks cryptographically linked together ensures immutability, security and integrity of the entire Blockchain.

  2. Hash of the previous block, transactions and the nonce.

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#3185

Because this prevents changing any information at any point in the chain. Doing so would invalidate everything that came after the change.

There are the block transactions, the previous block hash, and a nonce. All of this produces the hash for the current block.

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#3186

  1. Why is it important that the blocks are cryptographically linked together?
    It makes the network more secure and almost impossible to hack.

  2. What does the block structure look like in bitcoin?
    Every block is connected with the previous and following blocks. Each block consists of a the blockā€™s transaction data, current hash number and the previous blockā€™s hash number.

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#3187

  1. The links contain the current transactions and contents of previous blocks thus to change one block would invalidate every other link from that point forward. The importance of this is to keep the integrity and security of the network so people canā€™t cheat.

  2. The block looks like current transaction plus previous hash and a nonce that needs to be guessed to calculate a new hash number thatā€™s below the target.

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#3188
  1. Why is it important that the blocks are cryptographically linked together?

it is important because it means that if you were to go back into an old block and change something then all the blocks after it wont be linked anymore making you lose money and electricity to reattach them.

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

The blocks are made out of:
Transactions in the current block,
The hash of the previous block
& an appropriate nonce.

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#3189

Thank you very much @Alko89 !

#3190

  1. Only by being linked together we get a stable, secure data structure which cannot be changed after creation.

  2. Previous Hash, Tx of current block and a nonce.

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#3191

  1. Why is it important that the blocks are cryptographically linked together?
    It is important that blocks are cryptographically linked together because this will make it impossible for a bad actor to change a previous block.

  2. What does the block structure look like in bitcoin?
    Block structure takes previous hash, transaction(data), Nonce to generate a new hash that will be used for following block.

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#3192
  1. Why is it important that the blocks are cryptographically linked together? Because if there was no dependency, a block could be changed without this impacting the subsequent blocks. With each block hash containing the hash of the previous block, if the hash of the current block changes, every block along the chain needs to be re-hashed which can never catch up with the process of the other miners adding more blocks to the blockchain.
  2. What does the block structure look like in bitcoin? A block contains a list of all the transactions that are included, the hash of the previous block and the nonce --> this information is put through the hash 256 algorithm and results in an output which is the hash of the current block which subsequently flows as an input to the hash of the block to follow.
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#3193

1- to prevent data alteration and maintain immutability.
2- Table 1. The structure of a block

Size Field Description
4 bytes Block Size The size of the block, in bytes, following this field
80 bytes Block Header Several fields form the block header
1ā€“9 bytes (VarInt) Transaction Counter How many transactions follow
Variable Transactions The transactions recorded in this block
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#3194
  1. The blocks need to be cryptographically linked together so that it would be difficult to go back and change a previous block without having to change its corresponding/following blocks.
  2. The block structure includes transactions, current block hash, the previous block hash, and the nonce.
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