Creating Blockchain with Python #5 - Validating Proof

Creating Blockchain with Python #5
Validating Proof

in this tutorial we will learn how to validate the proof, so we can add a new transaction in the blockchain.
we will use two functions to do validation: valid_proof() function and pow() function.

steps:
1. watch previous video
Creating Blockchain with Python #1 - Create a Chain with List
https://youtu.be/3QRwQ4VLdvw

Creating Blockchain with Python #2 - Adding New Transaction
https://youtu.be/cwPaN2N6nYo

Creating Blockchain with Python #3 - Genesis Block
https://youtu.be/IbnO2QLouY8

Creating Blockchain with Python #4 - Hash Function
https://youtu.be/78M86NFy-2s

2. download the code here
https://github.com/cryptocodecg/blockchain-cg/blob/master/blockchain-5.py

3. let’s take a look at the code
4. run the code

valid_proof() function has three arguments:
* Transactions: the transactions inside the block
* Last hash: the hash of the last block
* Nonce

pow() function:
* extracting the last block from the blockchain and putting it into last_block
* hashing the last_block and putting them into the last_hash
* while loops keeps running until the valid_proof function returns TRUE. (The not convert will convert the TRUE into FALSE and hence break out of the loop)
* The nonce is then returned

we are specifically looking for a hash which started with “00”. This is why, the computer ran through multiple hashes by changing the nonce until it finally stumbled upon a hash which fulfilled the given difficulty criteria.

now let’s test the code

look that we only have the genesis block
and LOTS of hashing trials until we get what we are looking for
001f946e8c2172affa830ef27761270aab2de515ffac8ae90e5de95b48dc366c (the hash with 00 in the beginning)
and the nonce we get is 93 (also means that the code tries 93 times to finally get the expected hash)

we can use different way to validate proof, for example adding difficulties by searching or hash with ‘00000’ in the beginning :) the point is that once the hash is found, then it is valid to add a new block :)

ok this is it for now, until the next tutorial, we will learning about mining ;)

please click subscribe and like and share and don’t forget to leave some comments ;)

thanks for watching :)