Homework on Blockchain and Mining Visually - Questions

Blockchain and Bitcoin 101
#1627

To ensure integrity of the blockchain.

block = Hash + Previous Hash + Transactions

1 Like
#1628
  1. With this it is not possible to go back and double spend or manipulate.
    1. The blocks connected together by the hashes. If I change a block the hash of the block changes and with this the connection of the next block is breaking as well as the connection to the privious block.
1 Like
#1629
  1. Why is it important that the blocks are cryptographically linked together?

Having the blocks cryptographically linked together helps maintain the integrity and security of the entire blockchain since changing one iota of data in one block changes the hash of that block plus previous blocks. It makes the blockchain extremely robust and infeasible to change considering the current state of our technology and abilities.

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

It’s linked in a linear way and each block is connected to the previous block through a hash of it along with a hash of the nonce and the transactions in the current block. Each block also has a timestamp, a version number, a block header and a list of all the current transactions.

1 Like
#1630

  1. The reason why it is important that blocks are cryptographically linked together: is because that is the foundation of the framework that ensures it is (almost) not possible to change the data in any one block (i.e. censorship resistant), because a change to any one block will break the link between the block and the following block it is linked to, and on and on until the last block, so that any miner that wants to change the data in one block will need to change the information of every following block (re-mine each link), for which too much hash power is necessary (in theory).

  2. Each block contains:

  • Blocksize;

  • Transaction Counter;

  • Transactions;

  • Blockheader: which consists of - i) Hash of previous block; ii) Hash merkle root (based on transactions in the block); iii)Timestamp; iv)Target; and v) Nonce.

1 Like
#1631

1.Why is it important that the blocks are cryptographically linked together?
it ensures the immutability meaning that changing each block would change all the following blocks and will cut the link
2.What does the block structure look like in bitcoin?
block is represented with by a hash that is made of the previous block hash and the tx data in the block and the random number(nonce).

1 Like
#1632
  • Why is it important that the blocks are cryptographically linked together?
    ITs important becasue you want to make it extreemly difficult to change anything in a previous block. By linking them you make tampering very difficult because all the following block after the one you tampered with will cascade fail.
  • What does the block structure look like in bitcoin?
    you have the transactions the hash of the previous block, time stamp, block id and the nonce. These are all hashed together to give us the hash of the current block.
1 Like
#1633

  1. To ensure any tampering or double spending would change the hashes or any blocks after, requiring remining, and wasting electricity to catch up.

  2. It looks like a current hash, previous block hash, current transactions, and a random nonce to solve.

1 Like
#1634

  1. Why is it important that the blocks are cryptographically linked together?
    So that they can’t be changed. Too hard to Hash previous and future blocks if date is changed.

  2. What does the block structure look like in bitcoin?
    Previous Hash, Transactions, Nonce, And Hash of current block.

#1635

It’s not really a problem about the date, but if you change information in 1 block, the link between the the blocks are broken. Because you need a special kind of hash with enough leading zero’s. So you basically need to remine that block + all blocks that follow. Because each block has the hash of the previous block init. The further you go in time, the more blocks you need to re-mine. And you need to accomplish it all before other miners find the next block (approx 10minutes)

3 Likes
#1636

  1. To avoid suspicious actions such as removing and editing transactions. It also adds more security so that it wont need someone to supervise it.

  2. The hash of the block is based from the previous hash and it also has the previous hash plus the nonce that is needed to be guessed.

1 Like
#1637

  1. This is done to prevent tampering with the tx of any block in the blockchain. Because blocks are cryptographically linked by a puzzle that is based on the contents of the previous block. This adds more security against tampering.

  2. previous hash, transactions, nonce and hash of the current block.

1 Like
#1638

  1. It assures the immutability of the blockchain - every transaction is connected to the last block, so any changes made to the previous blocks will be rejected by the network.

  2. A hash of previous block, merkle tree of all transactions and a nonce.

1 Like
#1639

1- that what make blockchain is solid. if you change one all will be changes - that make the integrity and security of blockchain network.
2- blocks of data all connected with mathematical structures using hash.

#1640

Thank you for the input.
Greatly appreciate it!

(it was a key stroke error. I was on my iPhone, it should be data, not date)

1 Like
#1641
  1. It keeps the entire blockchain immutable, without having to actually go back and check the whole chain. The true chain is constantly preserved through the hashes which are based on previous hashes. Change any of it, and the false information is immediately traced, spotted, and rejected.
  2. A straight line, intertwined by unbreakable hashes.
1 Like
#1642
  1. It’s important because the blockchain keeps a record of all transactions on the network in a sequential order which prevents a user from making a double spend. Additionally it prevents unauthorised changes being made to the blockchain.
  2. The current time, some or all recent transactions, previous block hash, block size, the current target and the nonce.
1 Like
#1643

  1. Any change in data to any given block will cause a change in the hash that is produced which will break all following links, all blocks would have to be re-mined.

  2. H(k|x) = y K=nonce X=hash of the block Y= the difficulty target

1 Like
#1644
  1. So that they are secure, no one can alter them and avoid double spend.
  2. Current Hash, previous hash from previous block, List of transactions and nonce.
1 Like
#1645
  1. this is safe and trustworthy, reduce cost and raise efficiency.
  2. a block consists hash, previous block hash, transactions and nonce.
1 Like
#1646

By linking the blocks together cryptographically, the integrity of transactions is assured. A transaction cannot be altered without altering the entire blockchain after that transaction’s block.

The block contains a set of transaction data, the hash of the previous block and the “nonce” which produces the correct hash value for the block. The block also has a block number which identifies it.

1 Like