Homework on Blockchain and Mining Visually - Questions

Blockchain and Bitcoin 101
#1027

thanks for the clarification! your feedback is greatly appreciated! :+1:

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#1028

1.) It is important to keep the blocks cryptographically linked to secure the network. with all blocks being tied together keeps the double spending problem at bay along with other secure attributes.
2.) The current block of data along with the hash of the previous block and the guessing of the nonce creates the next block.

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#1029
  1. Why is it important that the blocks are cryptographically linked together?

To ensure the immutability of the blockchain. Once block depends on and incorporates the transactions of all prior blocks.
2. What does the block structure look like in bitcoin? Transactions, hash of prior block, nonce = hash for that block.

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#1030
  1. Because this ensures all blocks & their links are interdependent, binding them all together. A single chain anywhere along the chain will corrupt the chain.
  2. Block structure comprises a block ID, TX data, Nonce, previous block hash & current block hash
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#1031

Homework on Blockchain and Mining Visually - Questions

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

  • this way every change done in 1 of the blocks breaks the chain and becomes invalid => cheating becomes nearly inpossible

What does the block structure look like in bitcoin?
blockstructure contains :

  • previous hash
  • current list of Tx-transactions
  • NONCE (to be found by the miner) which must be lower that the target
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#1032
  1. for security reason data can not be changed and it ensure of integrity of the blockchain
    2.Transaction , previous block hash and nonce and new block hash
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#1033

  1. It is important that the blocks are cryptographically linked together because the SHA-256 hash of the contents of each block ensure the integrity of the data of each block - any change to the data will change the hash - and by cryptographically linking to the previous block the integrity of the blockchain itself is maintained

  2. The block structure consists of the transaction ledger, a hash of the ledger, the previous block’s hash, and the nonce

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#1034

  1. Why is it important that the blocks are cryptographically linked together?
    Because this makes it impossible to alter anything in one block alone. This would invalidate the entire chain!

  2. What does the block structure look like in bitcoin?
    A block consist of previous blocks Hash, TX and Nonce.

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#1035

1 - It creates security. Being cryptographically linked together means that a change in one transaction invalidates all the next blocks, because it will alter the hash of the block where it belongs, and this altered hash is part of the data that generates the hash of the next block, which will therefore also be altered, and so on and on. Any change will brake the whole chain os blocks. By default the longest chain is always used, so to be able to spend the transaction that was wrongly created the whole chain would need to be re-mined.

2 - Each block is composed by its transactions list, the previous block’s hash and the nonce. These 3 components together are the data that is hashed to generate this block’s hash. Mining is guessing the nonce that, concatenated with the 2 other components, generates a hash lower then the target, thus allowing this block to be attached to the chain.

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#1036
  1. Why is it important that the blocks are cryptographically linked together?

The links create a chain.
An unbroken chain is both proof of work, creates integrity and prevents the corruption of individual blocks. It’s also incentivizes being honest.
Longer chains are prioritised by the network. Changing data breaks the chain and remining individual blocks again is almost impossible.
2. What does the block structure look like in bitcoin? Each block contains transactions in a list, also the block has a random nonce, the hash of the previous block and a unique and low hash based on the three aforementioned.

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#1037
  1. so that a malicious change will invalidate the entire chain. Cryptographic hashes are nice because they can be applied to data of any size and still result in a 256 byte hash
  2. Block is made of previous block hash, nonce, trxs and timestamp
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#1038
  • It is important because any slight change to any transaction in a block will nullify the whole block and any appended blocks by altering the cryptographic hash of that block.
  • A block structure is made up of previous block hash, transaction hash and the nonce hash guess.
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#1039

  1. This is important for the security and integrity of the blockchain to maintain the consensus of the blockchain.

  2. Block structure includes
    The block’s hash
    Previous block’s hash
    Transaction list
    Current target/nonce

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#1040

  1. Why is it important that the blocks are cryptographically linked together?
    Because this insures the integrity of the chain. Whatever data is changed in any block outputs a unique hash which would differ invalidating the whole chain back to the block where the edited data is resident.

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

-Previous block hash
-Hash of the block containing the transactions (it could contain any number of transactions up to the full availability of the block)
-Nonce

Visually it looks like one of those trains used in mines where the head of the train has a previous hash=0 as there is no block or carriage before:-)

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#1041

Why is it important that the blocks are cryptographically linked together?
A cryptographical link makes sure that nothing can be changed once it’s linked in the blockchain.
If something does change, it means someone has broken the rules and the network won’t accept that.

What does the block structure look like in bitcoin?
A block contains the hash from previous block, the list of transactions and a nonce. Then you hash that all together.

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#1042

1- This is very important because if info is changed in a block, this would invalidate it and invalidate its link and the links before it (creating broken links). It keeps the integrity in the system.

2-Vertically:
Block number
Nonce
Data (Tx (s))
Previous Hash
Hash (of the current block as figured out by solving the puzzle of the mysterious nonce!)

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#1043

  1. It makes the records immutable and the only allowed change would be by including a new block rather than changing history.

  2. So the block contains these things: Previous block hash, transactions and a randomly generated nonce. These combined all need to generate a hash that corresponds to the current target rule.

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#1044

Thanks got it. The older the bock the more secure it is

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#1045

  1. The linking is what makes the chain so hard to alter or tamper with. Since they are dependent on the history the hash is affected by it and so if one tampers with the data it will easily be recognized and the alteration will be rejected.

  2. data, previous block hash and a nounce. Hash of current block is dependent on all of those.

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#1046
  1. It provides inconvenience for anyone to tamper with it. It creates transparency and traceability.
  2. a linear structure of blocks appended to each with links to the previous block (chain structure)