Script to check a plaintext password against an OpenNMS password digest

opennms_check_password.py

#!/usr/bin/env python

import sys
from hashlib import sha256

def checkPassword(encrypted, plaintext, iterations=100000, verbose=False):
    hexstring = encrypted.decode('base64').encode('hex') # i hate working with bytes
    salt = hexstring[:32]
    correct = hexstring[32:]
    if verbose:
        print "[+] plaintext: {}".format(plaintext)
        print "[+] salt: {}".format(salt)
        print "[+] target hash: {}".format(correct)
    testinput = salt.decode('hex')+plaintext
    
    for i in range(1,iterations+1):
        s = sha256(testinput)
        h = s.hexdigest()
        if h == correct:
            if verbose:
                print "{} iterations".format(i)
            return True
        else:
            testinput = s.digest()
    return False

def run():
    if len(sys.argv) < 3:
        print "Usage: {} base64value plaintext".format(sys.argv[0])
        sys.exit(1)
    
    if checkPassword(sys.argv[1], sys.argv[2], verbose=True):
        print "Correct!"
    else:
        print "Nope"

if __name__=='__main__':
    run()