Homework on Blockchain and Mining Visually - Questions

Blockchain and Bitcoin 101
#3838

My Answers:

  1. To create immutability and a secure system.

  2. A block contains:
    a) a list of transactions, decided by the miner and usually based on the highest transaction fees.
    b) Hash, a unique fingerprint for that block. Created using the data in the block, the hash of the previous block and the nonce.

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#3839

  1. Each block has a hash, a digital fingerprint. It is based on all the transactions within that block. Each hash and block are based on the calculations of the previous hash and block. If anything is changed in transactions within any of the blocks, all of the other blocks will change. Having blocks cryptographically linked together ensures the integrity of all blocks.

  2. The blocks have a version such as SHA256, a time stamp, a nonce number, a data field with transactions, a field with a hash based on the previous block and a field with a unique hash based on all of the above, an implied difficulty target and possibly a transaction counter.

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#3840
  1. Blocks need to be linked together because they host each other’s previous links. This shows the validity of the chain, creating transparency and a trustless network.
  2. A Block consists of 'the previous harsh, the transaction data, the nonce and the current harsh.
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#3841

  1. To create a chain. If one block changes, every block after that block changes too. When the hashes of those blocks change, they all need to be remined, which is a lot of work. This is the aspect that ensures the safety of blockchain. For example, ecause of this, it is very very difficult to double spend.

  2. A block consists of the following:

  • A list of transactions

  • The hash of the previous block

  • A nonce

  • The blocknumber

    All this information is then hashed into the hash of the new block if the guessed nonce was correct.

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#3842
  1. Why is it important that the blocks are cryptographically linked together?
    It’s important because it ensures the security and integrity of the network: if a block is changed all the following must be re-mined and that’s pretty much impossible.
  2. What does the block structure look like in bitcoin?
  • Previous hash
  • Transactions
  • Nonce
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#3843
  1. Why is it important that the blocks are cryptographically linked together?
    To maintain data integrity and build a solid chain between blocks that makes it exponentially hard to tamper with.
  2. What does the block structure look like in bitcoin?
    Like a chain of blocks? Linkedlist? a block consists of (1) tx list (2) previous hash (3) nonce
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#3844
  1. Its keeps the network safe by preventing data from being altered also referred to as immutable.
  2. It’s a hash of a block based on the transaction plus the the previous hash and the nonce that needs to be guessed.
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#3845
  1. Blocks should be linked cryptographically together in order to increase security of the network and make sure no one double spends.
  2. The block structure looks like blocks connected to each other with chains in a straight line. The block’s hash is comprised of the previous block’s hash, the transaction list, and the ‘nonce’.
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#3846

to fight manipulation of the blockchain network. there is a safety procedure when tx are erased/double spend etc which means that links are broken.

the hash=digital fingerprint including previous hash and the tx

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#3847
  1. Why is it important that the blocks are cryptographically linked together?

So that changing a previous block will change the hash of all proceeding blocks, which will cause the need to remine all of the proceeding blocks, thereby, making it practically impossible to catch up to the legit blockchain.

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

Current Transactions + Previous Block Hash + Target Nonce = New Block Hash

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#3848
  1. The goal is to keep blocks immutable and to make it impossible to alter a single block. A alteration triggers all blocks linked to break if any malicious action is taken within a single block. Making it not possible to game the system.
  2. Previous Hash, Data and Nounce make up the current block
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#3849
  • Why is it important that the blocks are cryptographically linked together?

prevents the ability to change previous blocks

  • What does the block structure look like in bitcoin?

previous block’s hash
nonce
transactions
target
hash of all of the above

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#3850

  1. Any change in any block will corrupt the next blocks and so forth. It make it impossible to corrupt.

  2. Prev hash, nonce, tx list.

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#3851
  • to secure the network since if someone chages transactions of previous blocks all hashes will be changed
  • hash, transactions and nonce. all blocks are linked
#3852

In order for al blocks being cryptographically linked, each block needs also the hash of the previous block.

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#3853
  1. Helps create a trustless system. Security, reliability, dependability
  2. Version
    Previous Block hash
    Merkle root hash
    Timestamp
    Difficulty target
    Nonce
    Block Size
    Block header
    Transaction counter
    Transactions
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#3854
  1. Why is it important that the blocks are cryptographically linked together?

The link between the blocks is a mathematical puzzle that links all the previous blocks together.

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

The block is made of a header, containing metadata, followed by a long list of transactions that make up the bulk of its size. The block header is 80 bytes, whereas the average transaction is at least 250 bytes and the average block contains more than 500 transactions.

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#3855

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

#3856

1.In this way it is assured the integrity of the blockchain, if any block is modified, it will break the whole chain
2. It conformed by the hash from previous block + current transactions + the nonce.

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#3857
  1. To ensure that if you make a change to a previous block, all future blocks will fail as all the hashes will change.
  2. Hash of the previous block / List of transactions / Nonce.
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