Homework on Blockchain and Mining Visually - Questions

Blockchain and Bitcoin 101
#303

1 , It is important so that previous blocks cannot be changed , immutable .
2 , Block 1 consists of Transactions , a nonce and a hash
. Block 2 consists of Previous hash (block 1) , transactions , nonce , and new hash .
Block 3 consists of Previous hash (block 2) , transactions ,nonce , and new hash
and so on and so on .
A nonce is used to determine a difficulty level for miners

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#304

  1. It is important because if a miner tries to change a block it also changes the subsequent blocks and every block from that one onwards will be broke. Therefore there is an incentive for the miners to play by the rules.

  2. In a block there is a hash, previous hash, transaction list/data and the nounce.

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#305
  • Why is it important that the blocks are cryptographically linked together?
  1. Being cryptographically linked together by a previous hash allows the network to know when any fragment of information has changed. Without SHA-256 encryption, the previous information stored in a current block might be altered in previous blocks with little to no signal of alteration.
  • What does the block structure look like in bitcoin?

(Block#/Nonce/Data/Prev.Hash/Hash)--------(Block#/Nonce/Data/Prev.Hash/Hash)---------(Block#…etc

Previous Hash is the umbilical cord that connects the blocks together.

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#306

  1. That makes the network secure since the hash makes all information secret and unguessable. In that way there are no incentives to try to brute force the system as it will be infeasable or almost impossible and extremely expensive.

  2. The block contains hash from the previous block, a nonce, tx data and the generated hash for the block.

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#307

1.so if one change is to occur in the transactions it will have a chain reaction( you see what i did there, chain reaction :wink: ) because that change in transactions changes the blocks hash code, which changes in the next block chain, which is hashed based on the block before and its content. Its just a mess man, forget it.

2.The block structure in bitcoin looks like a structure that would be used for bitcoin. This includes from what we learned the Block Number, Hash of Transaction Data, Previous Block Hash, nonce.

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#308

  1. Why is it important that the blocks are cryptographically linked together?
    Its about security and data integrity. It makes it very difficult to change a block, since if a block would have been altered, the ‘newer’ blocks would also needed to be changed due to the hashed relation (link) in between all the blocks.

  2. What does the block structure look like in bitcoin?
    Inputs
    Outputs
    Transactions
    Nonce
    Hash from the previous block
    Hash from the current block

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#309

  1. Changing an older block means re-mining every subsequent block because they are cryptographically linked together. Older blocks are virtually buried by newer blocks making it almost impossible to change blocks already added to the blockchain. The older the changed block is, the more blocks that would have to be re-mined.

  2. Each block includes a timestamp, the hash of the transaction merkle tree root, the hash of the previous block, the difficulty, the block version number, transaction counter, the transactions and the nonce used to achieve the target.

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#310

By cryptographically linking blocks together, security of the network becomes very strong. It’s infeasible to change anything in the previous blocks and not to break the already established connection between blocks.

A block contains the hash of the previous block, the transactions of the current block, the unknown piece of the puzzle, called nonce and the hash of the current block.

#311
  1. Why is it important that the blocks are cryptographically linked together? The importance of the blocks being cryptographically linked together is to ensure that prior blocks cannot be altered, as the link between a block contains the cryptographic hash from the prior block, which contains the hash from the prior block; changing one block changes the entire chain (of blocks).
  2. What does the block structure look like in bitcoin?
    Heading = HASH(Prior Block Hash, Nonce, Current TXs) – plus likely other info
    Transactions List
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#312

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

To avoid changes to be sent into the network. if data changes in a block the cryptography will change as well

What does the block structure look like in bitcoin?
Field:
Magic no.
Blocksize
Blockheader
Transaction counter
Transactions

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#313
  1. because it makes impossible to break the blockchain and easy to identify a discontinuity in the block.
  2. It is a list of transaction, time subsequential
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#314

Annotation 2020-03-31 160621

  1. (1) Keeps the network secure by having it constantly updated . (2) Provides security by making extremely difficult to make changes in previous blocks . (3) It carry previous difficulty of previous block so next one can be adjusted .

  2. To my understanding so far Block contains previous block hash, list of transactions, nonce,

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#315

  1. For security. You cannot change a transaction in a previous block without changing the hashes of that block and all of the linked blocks after it. So it becomes impossible to change the blockchain without spending a considerable amount of time and energy.

  2. Previous block hash + signed transactions + nonce

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#316

And most importantly, the blockhash of the previous block! +nonce, difficulty,…

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#317

  1. The importance of the blocks being cryptography linked together is the security of the Blockchain. The link as a result of the mathematical puzzle, is based on the contents of the previous block and on the previous link too.

  2. The block has a hash that is based on the previous hash, the transaction list and the nonce which is a random number.

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#318

1. Why is it important that the blocks are cryptographically linked together?
In order to Hash a Block you need the Hash Value of the Previous Block.
If someone manages to modify a value inside a Block, the Hash Value of that Block will be modified. This will result in the destruction of the Link between the Blocks, causing a Domino Effect which will lead to the collapse of the Blockchain, more or less.

2. What does the block structure look like in bitcoin?
Previous Block Hash + Transaction Hash + Nonce = HASH OF THE BTC BLOCK

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#319

  1. It is important that the blocks are cryptographically linked together because it provides security to the blockchain preventing any change to the data already in it. If data is changed, all links after the block changed would be broken.

  2. The block structure of BTC contains the previous hash+transaction list+nonce.

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#320

blocks are cryptographically linked to secure the network
2) What does the block structure look like. It consists of previous transactions -each block has a hash - nonce( a number that has to be guessed through mining)

#321

To secure the network no double spend
It is a series of transactions in the block that mathematically links all blocks together
The block is made up of transactions- hash and nonce

#322

  1. It is very secure to link the block cryptographically together. If there is a change in one block the following blocks will be not accepted from the network any more. This change is useless unless you mine all following blocks what is impossible if you dont have minimum 51% of the hash power.

  2. The blocks including the nonce (target) a random number, the new transactions which the miner like to write in the new block and the hash from the previous block.

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