base10digest.py

"""
Use for anonymizing strings not for cryptographic purposes

Makes use of the following identities::

    ord('1') % 48 == ord('a') % 48 == 1
    ord('2') % 48 == ord('b') % 48 == 2
    ...
    ord('6') % 48 == ord('f') % 48 == 6

There are 6 orders of magnitude less possible 32-character digests in base 10 than base 16.

"""

from hashlib import md5
from random import random

def base10digest(text, length=32, chunk=None, sep='-', salt=None, force=False):
    if not force and text.isdigit():
        # if it is numeric already just return same text
        return text
    salt = salt or str(random())
    chars = ''.join(
        str(ord(x) % 48) for x in md5(text + salt).hexdigest()[:length]
    )
    if chunk:
        chars = sep.join(chars[i:i+chunk] for i in range(0, length, chunk))
    return chars

if __name__ == '__main__':

    print(base10digest(''))
    print(base10digest('', length=20))
    print(base10digest('', length=20, chunk=4))
    print(base10digest('', length=21, chunk=3, sep='#'))
    print(base10digest('', length=22, chunk=3, sep='#', salt='asdf'))
    print(base10digest('12345789273637'))