Homework on Blockchain and Mining Visually - Questions

Blockchain and Bitcoin 101
#242
  1. To maintain the blockchain structure
  2. Previous hash, transactions, nonce
#243
  1. To secure the blockchain
  2. Previous hash, transaction data, nonce, block number, has of current block
#244
  1. Why is it important that the blocks are cryptographically linked together?
    It is important that block are cryptographically linked together to secure the network and ensure that the blocks cannot be changed or the chain will be broken.
  2. What does the block structure look like in bitcoin?
    previous block hash, input transaction, nonce, difficulty setting, output transaction.
#245

The newly mined block contains the hash of the previous block. It would be impossible to know wich hash the next block is. (you probably switched by mistake, because in the second question you wrote it right.

#246

It includes the hash of the previous block (not transaction) . in 1 block there are lots of transactions.

1 Like
#247

By linking the blocks together cryptographically, it makes it makes the blockchain immutable. Their prevents double spending because it is inordinately complex to cheat and change a transaction because the transactions are part of the input for the block output hash so any change in the transaction changes that hash. As that hash is an input hash to the next block (a linked list) any change invalidates any subsequent blocks.

A block contains the has of the previous block, transactions and the nonce required to produce a qualifying output hash.

#248

That’s right, thank you!

1 Like
#249

  1. Because of the security of the blockchain. If we woud change a transaction on a existing block all the block that follow must be mind again (that would take infinity, because the new block will be mind and you would need to catch up). If we wand to hash a new block we need the hash of the previous block, and if we changed something (Transaction) in the block we get a new hash.

  2. Struckture of block in Bitcoin:
    a) List of Transactions
    b) the Hash of the previous Block
    c) Nonce (random number)

1 Like
#250

  1. To secure the blockchain. If a single block in the blockchain is altered it becomes apparent in all the subsequent blocks and the change is therefore invalidated.

  2. The simplified bitcoin data structure consists of a nonce, transaction data, hash of the previous block and hash of current block.

#251
  1. Why is it important that the blocks are cryptographically linked together?
    To secure the network
  2. What does the block structure look like in bitcoin?
    The structure are all transactions, which is data.
#252

Why is it important that the blocks are cryptographically linked together?
This is to ensure that previous blocks cannot be altered without invalidating the following blocks and in essence breaking the chain.

What does the block structure look like in bitcoin?
Prev Hash
list of transactons including coinbase reward
nonce
new hash (below target)

1 Like
#253

The cryptographically linked blocks create a chain of the history of transactions for the network. If someone tries to alter this history it will be detected. Changing anything in a block will invalidate the hash of that block and all subsequent blocks.

Each block contains a list of transactions, the hash of the previous block in the chain, a random value nonce, the block number and a time stamp.

1 Like
#254

  1. If the blocks are linked together, it creates better security because the entire network must agree on every transaction in every block. This incentivizes all miners to use the same identical blockchain, without changing everything.

  2. Each bitcoin block has a hash and lists all the transactions made inside the block.

#255

To secure the blockchain. trying to make a change in a block will change the hash and therefore all blocks after will also be invalid when checking the consensus with other copies of the blockchain and will be rejected by the network.

hash previous block, hash current block, Nonce and tx’s(data)

1 Like
#256
  1. So they are imposible to modify.
  2. A block with its transactions, linked to the next block.
#257

  1. All transactions within the blockchain to stay immutable.

  2. Input (the previuos block outputed hash), new transactions, nonce and an hashed output.

#258

  1. Ensure the integrity of the chain allowing you to see if anything has been altered.

  2. Theblock structure in bitcoin is a cryptographic linked list.

#259

  1. This is for the security and integrity of the network. If someone altered a part of the chain it would affect all blocks after it.

  2. Version - Last Block - Transactions - Time - Target

#260
  • Why is it important that the blocks are cryptographically linked together?
    to setup a blockchain of integrity, to secure the network to ensure no double spend
  • What does the block structure look like in bitcoin?
    linked list with hash of each block and hash of previous block in the blockchain. In bitcoin it will have UTXO and a current block reward of approx 12.5 BTC plus any transactions rewarded.
#261

  1. it is important for the security of the network. No changes can be made to the transactions of the previous blocks because it breaks the chain of all subsequent blocks.

  2. A block structure in bitcoin is made up of transactions, the hash of the previous block, and the nonce to guess. Then you create a new hash to build the next block