Crypto - Proof of Work sample code in Python

proof_of_work.py

from hashlib import sha1
import sys


def pow(challenge = "Bitcoin", numZeros = 2):
    """
        Calculating the token that matches the proof of work. 
        Sample values by default: "Bitcoin" and 2 consecutive zeroes.
    """

    # Building the sequence of zeroes
    strZeros = '0' * numZeros
    index = 0

    while True:
        value = sha1( challenge + str(index) ).hexdigest()
        print value
        if value[:numZeros] == strZeros:
                print
                print "Match found: " + challenge + str(index)
                print "\tChallenge --> " + challenge
                print "\tToken     --> " + challenge + str(index)
                print "\tHash      --> " + value
                break
        else:
                index+=1

def show_usage():
    print("Usage: hashcash_sample.py <CHALLENGE> <NUMBER_ZEROS>")


if __name__ == "__main__":
    if len(sys.argv) == 3:
        pow(sys.argv[1], int(sys.argv[2]))
    else:
        print("Hey! Two parameters are required.")
        show_usage()