Hi everyone - I’m trying to implement a legacy hashing algorithm written in PHP into Python. But I’m having some trouble, and I think it’s when trying to find an equivalent of the
pack function from PHP.
The purpose of doing this is so that users of a website with passwords hashed with the old algorithm will be able to authenticate with the new, rewritten site (at which point their password will be hashed with something better). I’m relatively new to Python but not new to coding in general.
Here’s the PHP code. I will follow it up with the Python equivalent I’ve written. The password and seed are just sample data, but I expect it to always produce the same output every time.
$password = "password"; $seed = "dfa187ec"; $key = str_pad($seed, 64, chr(0)); $ipad = str_repeat(chr(0x36), 64); $opad = str_repeat(chr(0x5c), 64); echo md5(($key^$opad) . pack('H*', md5(($key^$ipad) . $password)));
This produces the output
e53ae584fb2ac17712785143b7bd1279 which is what I will expect when using the same data in Python.
Here’s my Python implementation (it’s a bit more verbose than the PHP algorithm for the sake of clarity):
from binascii import unhexlify import hashlib password = 'password' seed = 'dfa187ec' key = seed.ljust(64, chr(0)) ipad = chr(54) * 64 opad = chr(92) * 64 # Equivalent of PHP $key^ipad ipad_xor = "" for c in [ord(a) ^ ord(b) for a,b in zip(ipad, key)]: ipad_xor += chr(c) # Equivalent of PHP md5($input) hashed = hashlib.md5((ipad_xor + password).encode('utf-8')).hexdigest() # Equivalent of PHP pack('H*', $input) packed = "" for c in unhexlify(hashed): packed += chr(c) # Equivalent of PHP $key^opad opad_xor = "" for c in [ord(a) ^ ord(b) for a,b in zip(opad, key)]: opad_xor += chr(c) final_hash = hashlib.md5((opad_xor + packed).encode('utf-8')).hexdigest() print(final_hash)
This produces the output
ce7a3ced60ceb06e746665fd5d22a2a0 which is not the same as the PHP implementation’s
I should note that I’m running the PHP on an online PHP application, which might be a factor. I haven’t confirmed if running PHP on my local system will produce different results.
I think the problem is in the call to
unhexlify since everything before that point, when debugging, matches what I expect from the equivalent steps in the PHP algorithm. How do I ensure that my output of Python unhexlify matches the output of PHP pack? Here’s the comparison of the output in both cases (which may or may not be useful)
NE��@S�Gu�$ҕC (copied from browser)
NE¸¬@S´GuÔ$ÒC (copied from terminal output - note that this is 1 character longer than the PHP output)