UNIX and Apache compatible MD5 password encryption

md5crypt.py

#!/usr/bin/env python
# Based on FreeBSD src/lib/libcrypt/crypt.c 1.2
# http://www.freebsd.org/cgi/cvsweb.cgi/~checkout~/src/lib/libcrypt/crypt.c?rev=1.2&content-type=text/plain

# Original license:
# * "THE BEER-WARE LICENSE" (Revision 42):
# * <phk@login.dknet.dk> wrote this file.  As long as you retain this notice you
# * can do whatever you want with this stuff. If we meet some day, and you think
# * this stuff is worth it, you can buy me a beer in return.   Poul-Henning Kamp

# This port adds no further stipulations.  I forfeit any copyright interest.
from random import choice
import hashlib, string, sys, getopt, getpass

def md5crypt(password, salt, magic):
    # /* The password first, since that is what is most unknown */ /* Then our magic string */ /* Then the raw salt */
    m = hashlib.md5()
    m.update(password + magic + salt)

    # /* Then just as many characters of the MD5(pw,salt,pw) */
    mixin = hashlib.md5(password + salt + password).digest()
    for i in range(0, len(password)):
        m.update(mixin[i % 16])

    # /* Then something really weird... */
    i = len(password)
    while i:
        if i & 1:
            m.update('\x00')
        else:
            m.update(password[0])
        i >>= 1

    final = m.digest()

    # /* and now, just to make sure things don't run too fast */
    for i in range(1000):
        m2 = hashlib.md5()
        if i & 1:
            m2.update(password)
        else:
            m2.update(final)

        if i % 3:
            m2.update(salt)

        if i % 7:
            m2.update(password)

        if i & 1:
            m2.update(final)
        else:
            m2.update(password)

        final = m2.digest()

    # This is the bit that uses to64() in the original code.

    itoa64 = './0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz'

    rearranged = ''
    for a, b, c in ((0, 6, 12), (1, 7, 13), (2, 8, 14), (3, 9, 15), (4, 10, 5)):
        v = ord(final[a]) << 16 | ord(final[b]) << 8 | ord(final[c])
        for i in range(4):
            rearranged += itoa64[v & 0x3f]; v >>= 6

    v = ord(final[11])
    for i in range(2):
        rearranged += itoa64[v & 0x3f]; v >>= 6

    return magic + salt + '$' + rearranged

def genrandom8():
    return ''.join([choice(string.letters+string.digits) for i in range(1,8)])
    
def usage(exitcode=0):
	print "usage: md5crypt.py [-h] [-a] [-u]\n"
	print "UNIX and Apache compatible MD5 password encryption\n"
	print "optional arguments:"
	print "\t-h, --help\tshow this help message and exit"
	print "\t-a, --apache\tencrypt password like htpasswd"
	print "\t-u, --unix\tencrypt password like passwd (default)"
	sys.exit(exitcode)

def main():
    try:
        opts, args = getopt.getopt(sys.argv[1:], "hua", ["help", "unix", "apache"])
    except getopt.GetoptError, err:
        print >> sys.stderr, str(err) + '\n'
        usage(2)
    magic = '$1$'
    for o, a in opts:
        if o in ("-h", "--help"):
            usage()
        elif o in ("-a", "--apache"):
            magic = '$apr1$'
        elif o in ("-u","--unix"):
            pass
    print "=> %s" % md5crypt(getpass.getpass(),genrandom8(),magic)

if __name__ == '__main__':
    main()