Homework on Blockchain and Mining Visually - Questions

Blockchain and Bitcoin 101
#2170

  1. Why is it important that the blocks are cryptographically linked together?
    Because each block links to its predecessor, data in the blockchain is immutable. The hashing function means that a change in any transaction will produce an entirely different hash, which will alter the hashes of all subsequent blocks. This is of great importance because there is no governance over the network and it is a built in measure to assure the users work for the good of the network. (Ultimate security of the network)

  2. What does the block structure look like in bitcoin?
    The block chain appears as a Merkle Tree Root. It shows the previous transactions, the date/timestamp, block number, a nonce, current block information.

A block is a container data structure . In the Bitcoin world, a block contains more than 500 transactions on average. The average size of a block seems to be 1MB (source). In Bitcoin Cash ( a hard fork from the Bitcoin blockchain ), the size of a block can go up to 8MB.

image

(Dev.to & medium.com)

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#2171

A merkle tree is a tree of hashes and its leaves are made of transaction hashes (txid), the tree root is then used together with previous block hash in the block hash calculation. The block chain itself has a linked list like data structure. :slight_smile:

#2172
  1. To prevent any changes, to make them truly immutable.
  2. Blocks filled with a list of transactions, a block number and a nounce, linked together by a unique hash which depends on the previous hash, the transactions in the block and the nounce.
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#2173

  1. By linking the data one block to the next it keeps the system honest and true or gives it data integrity you could say. by each block carrying information from the last block down the chain, it makes it impossible to alter the data in one block without changing the entire chain.

  2. A block consists of :

    • previous block hash
    • the list of transactions the miner put into the block
    • a nonce

I had difficulty with 2 if I am misisng anything please feel free to add

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#2174

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

Because that is what guarantees the integrity of the data

What does the block structure look like in bitcoin?

Like a bunch of numbers that do not make any sense!

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#2175
  1. it is important that the blocks are linked because it keeps the whole blockchain together amd no transactions can be changed and the links are special, also if they break it would mess up the blockchain.
  2. Data structure, previous block and nonce.
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#2176

Why is it important that the blocks are cryptographically linked together?
To prevent a malicious JPMorgan banker going back in time to change a transaction to suit themselves, with blockchain the banks can’t cheat they have to be truthful…

What does the block structure look like in bitcoin?
Block number
Transactions
Hash of previous block
Hash of current block
Hash of all the above plus the nonce to cryptographically link it all together

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#2177
  1. Without a link between the blocks it would be nothing to change a transaction in a previous block. Without a cryptographic link between the blocks it would be easy to change a transaction and recreate the links.
    2.in a block there is the hash of the preceeding block, the transactions in the current block and the nounce and then the hash of the current block (all data in the block)
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#2178

1 It ensures the data is immutable changing anything in the chain changes the whole chain.
2.The hash of the previous block all the tranactions and the nonce of this block once it is solved the resulting hash will then be used as part of the next block and so on and so on.

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#2179

While that is true on a really low level (basically how its stored on a hd) the data still has meaning on a higher level. That is what we would like to know :wink:

#2180

hahahaha I’ll have to go back and read! forgot.

#2181

Ok, biting from Investopedia:
It is an 80-byte long string, and it is comprised of the 4-byte long Bitcoin version number, 32-byte previous block hash, 32-byte long Merkle root, 4-byte long timestamp of the block , 4-byte long difficulty target for the block , and the 4-byte long nonce used by miners

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#2182

1)It secures and protects the network from being tampered with and if someone does to to, all blocks after that will need to be changed to cover it up.

  1. A Blocks items are: Magic number, block size, block header, transaction counter & transactions .
    A Block Header has: Version, previous block hash, merle root hash, time stamp, difficulty target & nonce.
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#2183
  1. Why is it important that the blocks are cryptographically linked together?
    It prohibits bad actors from attempting to alter the history of the chain.
  2. What does the block structure look like in bitcoin?
    The block structure is made up of the hash of the previous block, the transactions in the current block and the nonce (a random number), which then produces the hash of the current block.
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#2184

  1. It’s important that blocks are cryptographically linked together because it contributes to the immutability of the network. If someone were to hack/change the nature of a previous block, all links following that block are broken and must be re-mined in order to catch up to the running block chain. The longer the chain, the more P.o.W. and the more desirable it is to continue to add onto.

  2. The block structure in bitcoin is: a header - aka the Hash of the new block, the hash of the previous block, Transaction list, Nonce, block size, and current target

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#2185
  1. For the security of the blockchain. If something changes in previous blocks it would break links between all the block which are in blockchain
  2. Block number, previous hash, data, nonce, current hash
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#2186

1)Because each block varifies the previous block
2)Each block is linked to the previous block and the next block

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#2187

1 security even 1 character changed create a totally different hash(data security)
2 previous hash,current hash, tx list, nonce(random number)

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#2188

  1. It is important that the blocks are cryptographically linked together because this ensures the security and immutability of the blockchain

  2. The block structure in bitcoin is determinated by:

  • Txs list

  • hash from previous block

  • nonce

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#2189
  1. That’s where the security & longest chain principle comes from.
  2. Block nr (height)
    Nonce
    Transactions
    Prev Hash
    Hash
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