Python string permutations to generate all possible password variations with given length and known characters

PasswordGenerator.py

from datetime import datetime

startTime = datetime.now()
password = "abba"
character_list = 'abcdefghijklmnopqrstuvwxyz'
a = []

for current in xrange(len(password)):
    a = [i for i in character_list]
    for y in xrange(current):
        a = [x+i for i in character_list for x in a]

print "We generated all possible passwords in", datetime.now() - startTime
print "Our password is", a.index(password), "in the list of all passwords"