Improve proof of work algorithm

[cosme12]

The current proof of work algorithm is really simple to solve. This make it easy for an attacker to destroy the actual blockchain.

[adanielpincab]

What time more or less do you want the proof of work to be solved? I've made one which prove is solved in an average time of 4.395 seconds, but I don´t know if it´s enough, or too much.

[adanielpincab]

Well, nevermind. I'll make a pull request adding a module with the proof of work, so it can be implemented later.

[adanielpincab]

Done! I've implemented my algorythm to the miner.py file. I think it works good, now the computational effort is harder. It's in my pull request, take a look to it 😄

[cosme12]

I will close this for now. Changing the proof of work algorithm will add unnecessary complexity to the code destroying its purpose.

[HourGlss]

def proof_of_work(last_proof, blockchain):
    def random_str():
        # Generate a random size string from 3 - 27 characters long
        rand_str = ''
        for i in range(0, 3 + secrets.randbelow(25)):
            rand_str += string.ascii_lowercase[secrets.randbelow(26)]  # each char is a random downcase letter [a-z]
        return rand_str

    def genhash():
        #Generate random string
        r = random_str()
        #Create hash object
        m = hashlib.sha3_256()
        #update that hash object with the string
        m.update(r.encode("utf-8"))

        #return the string format of the hash
        return m.hexdigest()
    pow_hash = genhash()

    start_time = time.time()

    #check to see if the first <work> characters of the string are 0
    work = 6
    while not (pow_hash[0:work] == ("0"*work)):

        # Check if any node found the solution every 60 seconds
        if int((time.time()-start_time) % 60) == 0:
            # If any other node got the proof, stop searching
            new_blockchain = consensus(blockchain)
            if new_blockchain:
                # (False: another node got proof first, new blockchain)
                return False, new_blockchain
        # generate new hash for next time
        pow_hash = genhash()
    # Once that hash is found, we can return it as a proof of our work
    return pow_hash, blockchain

Wouldn't this be better?