Homework on Blockchain and Mining Visually - Questions

Blockchain and Bitcoin 101
#2754

1.- to make it harder to modify. Because if you modify a block, you’d be modifying all the blocks that come next

2.- previous hash + current transaction hash + nonce

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#2755
  1. It is important to link the blocks together cryptographically because it helps to insure that there is no double-spending, altering block data, and keeping the blocks immutable. If a change is made to one block, this change can be realized and seen by viewing the data of the linked blocks *the hash will change and not match).
  2. The block consists of the previous block hash, the data from the transactions it holds, and a nounce. These items are what creates the hash for the block which is also used for the next block.
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#2756
  1. To ensure that previous transactions are immutable.
  • Hash of previous block
  • Transactions
  • Nonce
  • Hash of current block
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#2757
  1. Why is it important that the blocks are cryptographically linked together?

That secures the whole network, cause one block cannot be easily changed without compromising the whole blockchain.

  1. What does the block structure look like in bitcoin?
    It contains block number, previous hash, transactions, nonce, and current block hash
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#2758
  1. It is important that the blocks are cryptographically linked together to secure the network and make it impossible to change the data in a block.
  2. The block structure includes the previous hash, a nonce, and the transaction data. The block is hashed to create the digital thumbprint of this block, then the chain continues.
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#2759

1- It is important to be cryptographically linked, so that it makes it almost impossible to remove a block or change a transaction inside it which means in another word data immutablity.

2- a block in bitcoin is composed by the previous hash, tx list and a nonce. It create a unique hash that needs to be less than the target

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#2760
  1. it makes sure they are all in the correct order and unchaged or edited which secures the blockchain and network.
  2. it has a header which contains previous blocks hash, difficulty, nonce, this blocks hash timestamp and all the TX of the block a typical block contains 500 TX’s.
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#2761
  1. The linking of the blocks makes it necessary to mine all following blocks if an attempt to rehash a previous block is made. This design is the main reason WHY blockchain is secure.
  2. Previous Hash, transactions, nonce
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#2762

Homework on Blockchain and Mining Visually - Questions

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

Cryptographically linked blocks are effectively the “proof of work” which ensures the integrity of the data stored in the network so that the blockchain can truly function as a ledger in which only transactions may be added and not altered or erased. In other words, it is an extra security layer to the blockchain which makes it exponentially more difficult to alter the data stored in a given block because altering any information will break all previous and subsequent links, and a ton of hashpower would be required to guess the links of previous and subsequent blocks. The links are unique to the cryptographic puzzle solved by a miner in the construction of a block, and so the computational power required to guess the link would not be the most lucrative–to put it mildly.

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

The block structure for bitcoin consists of previous hash, hash based on transaction list, and nonce (randomly generated number), and all those elements combined will generate a unique hash for that block which will be linked–the link is generated by a cryptographic puzzle in the construction of a new block–to a subsequent block and IS linked to a previous block, thus establishing the “chain.”

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#2763

1.- For the security of the transactions, so the datas are not being altered
2.- Previous hash, transaction data, and nonce= current block hash.

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#2764
  1. It is important because if someone tries to change the information inside the block, the link that follow is broken and therefore all the links and blocks that follow must be mined again.
  2. Is like a database where transaction list of the block, previous block’s hash and a nonce create the new hash code for the new block
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#2765
  1. Why is it important that the blocks are cryptographically linked together?

This is to ensure the security of the blockchain and that no data in the chain can be altered.

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

The blockchain structure is made of the data in the block, the hash of the previous block and a nonce that falls within a specific range as set by the mining difficulty.

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#2766

  1. Why is it important that the blocks are cryptographically linked together?
    Blocks are cryptographically linked to keep the entire blockchain secure and prevent previous blocks from being changed.

  2. What does the block structure look like in bitcoin?
    A block is comprised of the hash of the previous block, a hash based on the transactions in the block and a randomly generated number called a nonce.

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#2767

  1. Why is it important that the blocks are cryptographically linked together?
    To ensure integrity of the blockchain and data immutability. Any change in one block would cause demage of this particular block and so the links between this one and all the next that follow after it.

  2. What does the block structure look like in bitcoin?
    Block hash that is based on transactions that it contains inside, previous block hash and nonce.

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#2768

  1. To increase security. In order to change a transaction from a previous block, you have to break the link between the blocks, meaning you`ll have to find a different hash number for that block and all subsequent blocks.

  2. A block comprises of a list of Tx, the hash rate of the previous block and a random nonce.

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#2769
  1. Why is it important that the blocks are cryptographically linked together?

The hash of the previous block in the next block ensures that transactions in previous blocks can’t be tampered with.

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

Like a linked list of hashes, where the link is the hash of the previous block included in the current block. Not user friendly at all, even if you know exactly what you’re looking at!

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#2770

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

They are not cryptographically linked to gather. Each individual hash is constructed using the hash of the previously block.

This means there is a bit dependency between block, which is implemented using cryptographic functions.

This dependency, in turn, is important because it means that is significantly the threshold for fraudulent actions in the network. Changing an older block means having to change all subsequent blocks AND maintaining the longest chain.

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

A block is constructed out of a block header and a body.
The header contains all relevant meta-data used by the protocol and the body contains all transactions.

The header consists of:

  1. the hash of the previous block
  2. time in seconds since 1970-1-1
  3. target of current difficulty
  4. the nonce
  5. root hash of the Merkle tree
  6. version number
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#2771

  1. Why is it important that the blocks are cryptographically linked together?
    Any change in one of the blocks invalidates the following blocks. Every block needs to have a previous block hash number and the new hash number depends on the value of the previous one.

  2. What does the block structure look like in bitcoin?
    There is a:
    Block number, Nonce, data, previous hash, hash

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#2772

  1. In doing so we get an immutable blockchain, where if any previous component within any previous block is altered, all future hashes change. Making it impossible for the current and true chain to be altered.

  2. Block hash - based on previous hash plus tx within current block plus the nonce
    The tx data within the block - inputs used and new UTXO’s

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#2773

1. Why is it important that the blocks are cryptographically linked together?
It secures the blocks from data manipulation, because the slightest change in data / transactions would change the complete hash structure.
2. What does the block structure look like in bitcoin?
SHA256(previous block hash | all transactions in the block | nonce) = new block hash*
*if result is below the target value

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