"sys_auth()" function in PHPCMS and Discuz writed by Python

sys_auth.py

import time
import hashlib
import base64 as b64


def md5(string):
    return hashlib.md5(str(string)).hexdigest()


# "sys_auth()" function in PHPCMS and Discuz
def sys_auth_v1(string, operation='ENCODE', key='', expiry=0):
    key_length = 4
    key = md5(key)
    fixedkey = md5(key)
    egiskeys = md5(fixedkey[16: 16 + 16])
    runtokey = (md5(time.time())[-key_length:] if operation == 'ENCODE' else string[: key_length]) \
        if key_length else ''
    keys = md5(runtokey[: 16] + fixedkey[: 16] + runtokey[16:] + fixedkey[16:])

    string = (('%010d' % (expiry + int(time.time()) if expiry else 0)) + md5(string + egiskeys)[: 16] + string) \
        if operation == 'ENCODE' else b64.b64decode(string[key_length:])

    result = ''
    string_length = len(string)
    for i in range(string_length):
        result += chr(ord(string[i]) ^ ord(keys[i % 32]))

    if operation == 'ENCODE':
        return runtokey + b64.b64encode(result).rstrip('=')
    else:
        if int(result[: 10]) == 0 or int(result[: 10]) - int(time.time()) > 0 \
                or result[10: 26] == md5(result[26: ] + egiskeys)[: 16]:
            return result[26:]
        else:
            return ''


def sys_auth_v2(string, operation='ENCODE', key='', expiry=0):
    ckey_length = 4
    key = md5(key if key != '' else key)
    keya = md5(key[: 16])
    keyb = md5(key[16: 16 + 16])
    keyc = (string[: ckey_length]  if operation == 'DECODE' else md5(time.time())[-ckey_length:]) \
        if ckey_length else ''

    cryptkey = keya + md5(keya + keyc)
    key_length = len(cryptkey)

    string = b64.b64decode(string[4:].replace('-', '+').replace('_', '/')) \
        if operation == 'DECODE' else (('%010d' % (expiry + int(time.time()) if expiry else 0)) + md5(string + keyb)[: 16] + string)

    string_length = len(string)

    result = ''
    box = range(0, 256)

    rndkey = {}
    for i in range(256):
       rndkey[i] = ord(cryptkey[i % key_length])

    j = 0
    for i in range(256):
        j = (j + box[i] + rndkey[i]) % 256
        tmp = box[i]
        box[i] = box[j]
        box[j] = tmp

    a = 0
    j = 0
    for i in range(string_length):
        a = (a + 1) % 256
        j = (j + box[a]) % 256
        tmp = box[a]
        box[a] = box[j]
        box[j] = tmp
        result += chr(ord(string[i]) ^ (box[(box[a] + box[j]) % 256]))

    if operation == 'DECODE':
        if (int(result[: 10]) == 0 or (int(result[: 10]) - int(time.time())) > 0) and (result[10: 10 + 16] == md5(result[26:] + keyb)[: 16]):
            return result[26:]
        else:
            return ''
    else:
        return keyc + b64.b64encode(result).replace('+', '-').replace('/', '_').rstrip('=')