Homework on Blockchain and Mining Visually - Questions

Blockchain and Bitcoin 101
#2130

  1. Why is it important that the blocks are cryptographically linked together?
    If someone is changing or hacking a block, all the next blocks will change as well. So its very important from safety prospective reasons

  2. What does the block structure look like in bitcoin?
    Nonce, Transactions, Prev. Hash

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#2131

  1. It is important that blocks are cryptographically linked together as it increases security, preserves data integrity and battles data manipulation effectively.

  2. In bitcoin blocks are chained together and each block has a unique hash output. This unique hash output per block is based on the previously mined blocks hash, a nonce number that is guessed by miners that has to be below a certain predefined secret target established by the network and based on mining difficulty, as well as transactions that are stored on the block and are picked from a mempool by the miner that chains the block successfully.

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#2132

Homework on Blockchain and Mining Visually - Questions

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

To increase security. If changes are made to one block then changes will have to be made to all other blocks made after. Would be too costly for miner to go through all that. Would be more profitable to just mine new blocks.

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

Hash of current block is made up of hash of previous block + transactions added to current block + nonce. This hash must be below target.

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#2133
  1. To ensure the security of the entire blockchain
  2. Transactions data, hash of previous block, nonce and hash of current block.
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#2134

Homework on Blockchain and Mining Visually - Questions

  1. Why is it important that the blocks are cryptographically linked together?
    To make sure the network is secure without double spend,no censorship

  2. What does the block structure look like in bitcoin?
    previous hash +data + Nonce

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#2135

  1. It is important because if they weren’t linked together, if someone went back and changed something they’d only need to fix that one block making it possible to cheat the system. But with how they are linked now changing one block changes all of the ones to follow it making it almost impossible to cheat because you’d need to fix all the blocks. On top of that more and more blocks are being accepted and you are falling behind trying to re hash all of the blocks.

  2. A block consists of the following. Transactions or data the miner selected, previous blocks hash number, a Nonce which is the number the miner must guess in order for the block to have a lower hash then the target goal. This numbers difficulty to guess comes with a certain difficulty level depending on amount of miners on the network. Finally a block has its own hash number which is what needs to be lower then the target number for it to become accepted as a block.

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#2136

  1. Why is it important that the blocks are cryptographically linked together?
    Integrity and so none are changed post Block Mining (immutably)

  2. What does the block structure look like in bitcoin?
    Previous block hash (as input)
    Timestamp
    TX data
    Nonce
    Block Size
    Block Hash

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#2137

  1. it is important for security, because if a previous link in the chain is broken, transactions in previous blocks can’t be changed. data immutability.

  2. Block number > Nonce > Transaction Data > Hash of the Previous Block > Hash of current block

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#2138

  1. The integrity of the blocks are cryptographically linked together to secure the network.

  2. The structure of these blocks are made up of input/output transaction data, previous block hash and a nonce value which is used to calculate the next hash value.

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#2139
  1. Ensures integrity of the chain.
  2. Current hash, previous hash, current block transactions, nonce.
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#2140

  1. So that previous blocks cannot be altered.

Previous Hash
Data
Nonce
Proof of Work (hash of this block)

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#2141

  1. The importance of the cryptograhically linked block is all in the security of the network. With each block containing the combined hash of it predecessors it makes it impossible to manipulate any of the previous blocks. this means that when a transaction is sent you know that, A) the person who sent it had enough value in their wallet to send it and B) they can’t take it back once it has been sent. This ability cryptographic security is at the heart of a trustless, decentralised currency.

  2. The block contains

A) all the transactions that are waiting to be validated
B) The merkle root ,which is the root hash of all the other previous blocks
C) The prevoius blocks hash
D) A nonce, or target number. Miners have to solve this puzzle before being allowed to confirm a new block.
E) A time stamp

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#2142

Blocks being cryptographically linked together keeps them more secure. These links give the entire blockchain a unique fingerprint all the way back to the first transaction. Anything that a miner would attempt to change from the past blockchain ledger will then alter every future transaction after it until the present. This is a security feature that keeps the unique integrity of the entire blockchain of transactions.

The structure of a Bitcoin blockchain contains all previous transactions. In a order of previous hashes, transactions, and a nonce.

2 Likes
#2143

1 It adds to the difficulty/ cost of successfully changing an old block. It is one of the most important tool for maintaining immutability.
2. block size, block header, transaction counter, transactions

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#2144

Changing a previous block invalidate that block and all subsequent blocks that have to be remined.

the hash of the nonce, the previous hash, and all transactions in the block

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#2145

Can you tell what is in the block header? :wink:

#2146

  1. One important reason is that if one of the computers crash, all the others still have your info. They also need to be linked because each block uses the previous hash to mine.

  2. (From how Ivan shows it) The block structure are thousands of square blocks all connected to each other through strings, and they all store your data

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#2147

That is how they are visualized :smiley: in reality they are just bits of data in memory. What chains these blocks together? :wink:

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#2148

1.It is important that the blocks are cryptographically linked together to make network secure and trustless.
2. It contains: block number, nonce, transaction data, hash of the previous block, hash of current block.

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#2149
  1. Security, and immutablility
  2. Transactions, hash, previous blocks hash, and nonce
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