insecure-hash.py

#!/usr/bin/env python3

# eytlus in Freenode/#python wrote this.
# I decided to keep my own copies of it around.

# I've edited this. See the revision history for diffs and originals.

from __future__ import print_function, division

def eytlus_hash(text, a=0, b=0):
    CHARS = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789`~!@#$%^&*($"
    for char in text:
        try:
            char_index = CHARS.index(char)
        except ValueError:
            char_index = len(CHARS)
        for __ in range(16):
            a = a * -4 + b + 0x7494 - char_index
            b = b // 5 + a + 0x85A8 - char_index
    return a, b

if __name__ == '__main__':
    import argparse
    import sys

    argument_parser = argparse.ArgumentParser()
    argument_parser.add_argument('-s', '--string', action='append', dest='strings', help="Print the hash of the given string")
    argument_parser.add_argument('--block-size', default=512, type=int, help="Read this many bytes from each file at a time")
    argument_parser.add_argument('files', nargs='*', type=argparse.FileType(mode='rb'))
    args = argument_parser.parse_args()

    if (not args.files) and (not args.strings):
        args.files = [sys.stdin]

    for file in args.files:
        a, b = 0, 0
        if file == sys.stdin:
            file = sys.stdin.buffer
        while True:
            block = file.read(args.block_size)
            if not block:
                break
            block = ''.join(chr(byte) for byte in block)
            a, b = eytlus_hash(block, a, b)
        print("Eytlus(file({filename!r})) == ({a:#08x}, {b:#08x})".format(filename=file.name, a=a, b=b))

    for string in args.strings:
        a, b = eytlus_hash(string)
        print("Eytlus({string!r}) == ({a:#08x}, {b:#08x})".format(string=string, a=a, b=b))