Homework on Blockchain and Mining Visually - Questions

Blockchain and Bitcoin 101
#785
  1. Prevention of alterations and double spendings
  2. version -> Merkle Root -> pre-hash -> hash -> nonce -> difficulty -> Data
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#786

Because it increases security. If anyone would want to alter anything in previous blocks, hash of that block would be change and the link to other block and any other following would be change to.

It consist of all the transactions in current block, hash of the previous block and the nonce - a random number that needs to be guested by miners in order to append the block to the blockchain.

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#787
  1. Ensures immutability of blocks. Data and transaction can not be altered.
  2. Previous hash + Transaction list + Nonce.
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#788
  1. Why is it important that the blocks are cryptographically linked together?
  • provides trustless validation and resiliency to the network, one of the keystones that imo makes it able to be sound money compared to fiat garbage.
  1. What does the block structure look like in bitcoin?
    | header | = genesis hash | header 1 with genhash|
    | txo | ============>> | nonce | ======> " "
    | hash | | hash |
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#789
  1. Why is it important that the blocks are cryptographically linked together?

Because the content found in one block is based on the contents of the previous blocks. That being said, if a transaction was removed from a block then it would destroy the links of the blocks proceeding it.

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

A block is composed of the nonce, transactions, and previous hash.

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#790

With cryptographical link we mean that each block contains the hash of the previous block,
meaning that the smallest modification on a previous block breaks all following links.
You could also say that each block contains all previous blocks, not the readable content
but their fingerprints.
The cryptograhical link between blocks is important because it makes the whole block chain immutable.

Each block contains the following informations:

  • Version number
  • the Height (incremental block number)
  • the Hash of the previous block
  • the Merkle Root (a hash based on the transactions contained in the block)
  • a “Nonsense” Number (Nonce, a random number)
  • the Timestamp the block was created ()
  • the Target used for finding the correct nonce
  • all Transactions
  • the Creator (signature of the miner)
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#791

Blocks are linked so they can not be changed in any other way but only by mining.

tx .previus hash ,nonce .

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#792

1.For integrity and security. Also you cannot double spend because of the chain connecting all the blocks.
2. Block structure:
Block Hash, block number
previous block hash
TX(transactions, data)
nonce

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#793
  1. So that the data is secure and can’t be changed
  2. Nonce, data/transaction, previous hash
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#794

  1. It’s important because the cryptographic puzzle is based on the contents of the previous blocks, this ensures the network is secure and that nothing can be altered.

  2. There is a block has a hash number, a nonce, the previous hash number, and a transaction list. The link between the block is the cryptographic puzzle.

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#795

1.- It’s important to ensure nobody could change the data, and the only way of adding new blocks are mining using hash functions

2.-

  • Block Hash, block number
  • Previous block hash
  • DATA (transactions)
  • Nonce
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#796

  1. Why is it important that the blocks are cryptographically linked together?
    Thanks to math, it is harder now to change just one block. Thanks to the system, if someone would change something, all blocks will change and you would have to solve every puzzle to fing the correct links again.

  2. What does the block structure look like in bitcoin?
    hashed block+ all previously hashed blocks+ Nonce

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#797

  1. Bitcoins blocks are linked in a block chain the enables security and transparency of the transactions by a network consensus. Each block contains a chain structure that creates a dependency from the previous block (any information changed on the previous block affects the next block) and if this information is changed post registration, breaks the chain link, requiring a lot of energy and factor combination (including hashing) to restructure the chain based on the changed information.

  2. A block is similar to a stone data structure, that can contain around 1MB (if not considered SegWit) and around 3,500 transaction if any transaction occupies 570 bytes.

Each block contain no less than:

¡ Version: to identify software and protocol used

¡ Previous Block Hash

¡ Merkle Root: Hashing from all transaction in the block

¡ Time Stamp: Time when the new bock was created

¡ Bits: Block target. The hash must be less or equal this number to be validated

¡ Nounce: number combined with all others in the block will provide the Block Hash

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#798

Not all blocks be invalid. Only the blocks that are after the block we want to change.

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#799
  1. I would add a nonce and the current hash as well. These are the 4 most important ones in my mind.
#800

it is crucial that the difficulty increases because the more it increases the more secure the network is.

yes we have the prior hash current transactions and no one that needs to be guessed that all is calculated in new hash

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#801

Very good. Keep it up! :raised_hands:

#802

Yes. The other nodes won’t accept your change, because your chain will shorter. Longest chain always wins.

#803

Correct. I wouldn’t say rule myself, but work rather. Either way good answer.

#804

Correct answer. Here is some more info:

Taking the hash from a previous is not the only thing that enables us immutability. It is important that miners spend real life electricity when mining a new hash. Even though links would still be broken in a case without mining, they could be rebuild pretty fast. :smiley:

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