Homework on Blockchain and Mining Visually - Questions

Blockchain and Bitcoin 101
#825

  1. The hash function is the key to the immutability of the chain.

  2. What an interesting question…
    My answer is more of what is in the block. Is it square though? Or block a label. A pneumonic device? Anyway…

Block number
Height
Nonce
Transaction Data
Hash of Previous Block Hash
Current block Hash

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#826

  1. Why is it important that the blocks are cryptographically linked together?
    This make it difficult to manipulate/ change a block that has been previously mined which help to secure valid transactions.

  2. What does the block structure look like in bitcoin?
    it will be a block with the previous hash, time stamp the Transaction root and nonce.

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#827
  1. Why is it important that the blocks are cryptographically linked together?
    Answer: To make it practically impossible to change the history of the resulting “ledger” - achieving immutabability, trustlessness, etc.
  2. What does the block structure look like in bitcoin?
    Answer: A block in bitcoin has transactions, hash, previous block hash, and nonce.
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#828

1.this ensures network security, prevents double spending, makes the chain practically impossible to break,each block is an integral part of the next one
2.Previous Block Hash,Merkle Root,Timestamp,Difficulty Target,Nonce

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#829

Thanks so much. Very clear.

2 Likes
#830

To improve security and assurance of no double spending or changes in the older blocks.

  • Previous hash
  • Transactions and fees
  • Nonce
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#831
  1. By linking the blocks cryptographically together, the blockchain becomes immutable. A change in a previous block will break the chain.
  2. A block consists of the previous hash, the list of confirmed transactions and a randomly generated number (nonce). All of them together generate the hash of the current block.
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#832
  1. it makes the network secured so there is no manipulation or double spend.
  2. Data(hash), prev. hash, TX list, random value(nonce)
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#833

  1. It is important that the blocks are cryptographically linked together because anything that is changed in or added one block will change the rest of the blocks that are appended to the block. As shown in the video, all three blocks in the blockchain were green at first. When anything was added or changed (i.e. the nonce or the data in the block) all three blocks turned red. When Block #1 was re-mined, all of the blocks were green again and were considered accepted.

  2. In bitcoin, the block structure looks like a set of blocks linked together. Each block contains a nonce, a list or description of the data, the hash of the previous block, and the hash of the current block.

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#834
  1. To make the chain tamperproof / immutable (by making its aggregate state dependent on the state of every single block of the chain. That way any block that is hacked will trigger the links between the blocks to break and the chain becoming invalid from the manipulated block going forward)
  2. Block header, Hash, previous hash, list of transactions, timestamp, nonce
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#835
  1. It is important for the following reason: if a block is fraudulently altered in the blockchain, it is the linking of the blocks that necessitates the complete PoW re-determination of the nonces, beginning in the block that was altered and ending in the last block added to the chain (see my previous post for a detailed explanation). In other words, the blockchain is so difficult to corrupt, first and foremost because the linking of the blocks causes the computational effort needed for corrupting it to be enormous.
  2. Each block consists of a header and a body of transactions. The transactions form the leaves of a corresponding Merkle tree, and the root hash (or Merkle root) of that tree effectively encodes all of the block’s transactions in a single hash. This single hash, representing all transactions in a block, is placed in the block’s header together with the hash of the previous block’s header, a time stamp, and a nonce. The nonce is a number, the determination of which is made by means of the PoW computational labor. More precisely, the nonce must be determined—or computationally guessed—in such a way that the hash of the entire block header (including the nonce itself) is smaller than a certain target value that in turn defines the current PoW level of difficulty for the entire bitcoin network.
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#836

  1. It proves the current block is valid as it proves its could only have been derived from the previous valid. The same logic would apply to that previous block and the one before and the one before and on.

  2. A block structure will contain a nonce, the transactions the miner would have confirmed and the previous block’s hash.

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#837

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

    It is done so that the network can be secure so no one can go back and change blocks without changing every block after that.

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

    It includes the hash of the previous block, the transactions and hash of the current block, the nonce, fees and times stamps.
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#838

  1. this makes the blockchain immutable and secure. Changing a single thing in one block would break the link to all following blocks unless you mine all following blocks over again , which would cost a fortune (due to electricity costs)

  2. A block consists of the transaction data, the hash of the previous block and the nonce. These 2 things create the hash of the block (=digital fingerprint of this block) which is also used in the following block.

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#839
  1. to create a secure network where transactions cannot be changed or altered in any way
  2. each block is of a determined size (bytes), comprised of transactions that can vary in size, the previous block’s hash and a random nonce… to create it’s own unique hash that is less than the predetermined target value.
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#840

hello,
1) It is important that the blocks are cryptographically linked together to preserve the integrity of the network. A broken blockchain would indicate invalid blocks.
2) the block structure for bitcoin is:
Block number
Nonce
Data
Hash to the previous block
Hash to the new block

1 Like
#841

  1. It is to keep the network secure and much harder to alter.

  2. Block number
    Nonce
    Data
    Hash from previous block
    Hash from current block

1 Like
#842

  • Why is it important that the blocks are cryptographically linked together?
    By cryptographically linking the blocks together, it is virtually impossible to make changes to previous blocks as they are interdependent; As soon as one change is made it affects the next block and the block after that. This would break all the links.

  • What does the block structure look like in bitcoin?
    It is made up of the previous block’s hash, the transactions within the block, and the nonce

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#843
  1. So that a change to one will affect the others.
  2. Streams of data linked by hashes which are composed from the preceding blocks.
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#844

  1. Because the hash of the current block is partly affected by the hash and its related transactions from the previous block, and therefore you can see the audit trail of a transaction from start to finish. It maintains integrity and security of blockchain

  2. It looks like a square block, and beneath it you can see the previous hash and the current hash. The mining button enables the computer node to guess the nonce, and when it does the box turns green

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