Brute Force Postgres Role Password Checker

cracker.py

import md5
import string
import time

'''
 # Brute force solves a md5 hash (for a postgres user role)
 # Assumes that password is only [a-zA-Z]
'''

def getNextCharacter(string,pos,characters):
    if pos == -1:
        return string;
    
    if string == characters[-1]*len(string):
        string = characters[0]*(len(string)+1)
    elif string[pos] == characters[-1]:
        string = getNextCharacter(string,pos-1,characters)
        string = list(string)
        string[pos] = characters[0]
        string = ''.join(string)
    else:
        string = list(string)
        string[pos] = characters[characters.index(string[pos])+1]
        string = ''.join(string)
    return string

user = raw_input("Enter Postgres Role Username ==> ")
md5hash = raw_input("Enter md5 hash of password ==> ")

start = time.time()
characters = list(string.ascii_uppercase)+list(string.ascii_lowercase)

string = characters[0];
m = md5.new()
m.update(string)
genhash = m.hexdigest();
count = 0

while genhash != md5hash and len(string) < 20:
    string = getNextCharacter(string,len(string)-1,characters)
    m = md5.new()
    m.update(string+user)
    genhash = m.hexdigest()
    count += 1

print count
print string
print genhash

print "Time Taken:",(time.time()-start)