Homework on Blockchain and Mining Visually - Questions

Blockchain and Bitcoin 101
#1507

  • Why is it important that the blocks are cryptographically linked together?
    The linking of blocks cryptographic ally is what gives blockchain technology credibility. It ensures security, immutability and trust.

  • What does the block structure look like in bitcoin?
    It is made up of data from a previous hash, a list of transactions and a nonce which are all used to give the block its own hash.

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#1508

  1. Because that is what makes it un-hackable and so secure.

  2. Prev block Hash, Tx list and nonce

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#1509
  1. Why is it important that the blocks are cryptographically linked together?
    This secures the network. You cannot alter anything in a block, it would break the chain/link and all the other links to blocks that followed. This process is impossible to do. The network retains its immutability
  2. What does the block structure look like in bitcoin?
    A block is build by the time, a list of TX, hash from pre-block, the nonce number and the difficulty target
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#1510

  1. It is important for the blocks to be cryptographically linked for the security of the network and for the immutability of the blocks.

  2. A block in bitcoin is identified by a unique hash. This hash is the output of hashing the hash from the previous block, together with the transactions in that particular block, and the nonce.

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#1511
  1. The blocks are cryptographically linked together to preserve the immutability of the block chains. A small change would affect the linked blocks which would cause the succeeding blocks that are linked to it to fail.
  2. The block structure in a bitcoin has the previous hash + transaction + nonce. all of these combined are hashed together to form a unique hash, which could in turn will be used to the succeeding block that will link to it and so on.
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#1512
  • Because this way itā€™s ensured the immutability of the blockchain, the links get invalidated if a modification occurs in previously mined blocks. Basically the chain is cut and therefore is not longest chain anymore.
  • Block number, nonce, transactions, hash of the previous block and hash of the current block.
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#1513

  1. It is important that the blocks are cryptographically linked together so it ensures security in the way that it is extremely difficult to change future blocks after changing a previous one. (The hash if tampered with will have to be reevaluated and changes in future blocks.)

  2. A block in bitcoin has a transactions list, a hash (of it and precious block), and a nonce, and inputed and outputted data.

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#1514

Why is it important that the blocks are cryptographically linked together?
Answer: Itā€™s important for security so that it is not easy for someone to go back and change a previously mined block. By changing one block from the past, you break the entire chain in front of it.

What does the block structure look like in bitcoin?
Answer: The block structure includes a linked list with the hash from the previous block, a timestamp, the nonce, and the list of current transactions.

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#1515
  1. Why is it important that the blocks are cryptographically linked together?

The link between the blocks is a mathematical puzzle that links all previous blocks together. Therefore ItĀ“s important that blocks are cryptographically linked together for the security of the blockchain and also ensures immutability.

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

The hash of the block is based on the transaction list in the block plus the previous hash and the nonce (number randomly guessed by Miners).

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#1516
  1. to insure that previously mined blocks are not changed.
  2. Blocks contain a hash of the previous block, as well as the current block and the nonce which proves the authenticity.
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#1517
  1. It is important for blocks to be cryptographically linked together for immutability, security, and data integrity. It ensures that the blockchain will never be tampered with. If someone tries to change data of a single block, all the linked blocks become invalidated.
  2. The block structure of btc contains four main properties. 1. The hash of the current block, which is made up by 2.the hash of the previous block, 3.the transaction data, and 4.a nonce.
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#1518
  1. Why is it important that the blocks are cryptographically linked together?

The truthfulness or immutability of the network depends on a cryptographical puzzle, otherwise entities would alter the history of transactions (including unspent transaction outputs) in their favor. The current cryptographic puzzle is called SHA-2 or more specifically, SHA-256.

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

The block structure is hashed with the appending block and includes the following elements (credit to ā€œGoosieā€):
Version
Previous Block hash
Merkle root hash
Timestamp
Difficulty target
Nonce
Block Size
Block header
Transaction counter
Transactions

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#1519
  1. The link between blocks is what makes the blockchain immutable. With sufficient network size, it is practically unfeasible to go back and change data in a block because you would then need to change every subsequent block in the chain.
  2. Bitcoins blocks include the hash of the previous block in the chain, the transactions that the miner obtained from the network of mempools, and the nonce. All of which must have a hash value under the target difficulty based on the networkā€™s current hashrate.
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#1520

  1. Why is it important that the blocks are cryptographically linked together?
    To ensure integrity of the network. Without this feature, anybody could change any block and thus send bitcoin to themselves.

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

  • Block Number
  • Nonce
  • Tx List
  • Previous block hash
  • Hash of current block
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#1521

Why is it important that the blocks are cryptographically linked together?
The importance of Bockcahain use matematical crytographic tool (like hash function, elliptic curve) is to provide immutability, security, privacy, transparency (anyone can see all transactions).
All in all, the importance of blocks are cryptographically linked together, is to fully provide a trustless system to store value

What does the block structure look like in bitcoin?
Among other things:
Block head

  • version
  • Prev. Block
    -Merkle root
  • Nonce
  • Time
  • Block hash

List of transactions

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#1522

Only the hash function is used for linking blocks. The elliptic curve is used to derive public key from the private key :slight_smile:

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#1523
  1. This ensures security and data immutability in the blockchain.
  2. structer is the previous hash, and nonce joined together
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#1524

  1. Because in this way hacks in previous blocks (e.g. double spending) could be prevented. Any modification in the previous blocks will modify the upcoming blocks hash. The modified blocks are not solving the cryptographic puzzles, thus will be rejected. So, these links guarantee the blockchainā€™s immutability.

  2. The block contains the hash of transactions and the previous blockā€™s hash (this is the connection between the previous and the current block). A block has also a version number and time stamp. For every completed block a nonce is also required (a nonce is an arbitrary string, a random number, which is concatenated with the blockā€™s hash) and of course the target difficulty number is also part of the block.

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#1525

Hello Alko89.
Thanks for the clarification. :wink:

#1526

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

Blocks being cryptographically linked together makes the blockchain immutable which prevents data added to it from being altered.

What does the block structure look like in bitcoin?

The structure of the block contains the list of transactions added by the miner, the hash of the previous mined block and the nonce which is a hash that the miner must use electricity to guess/solve.

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