app/django/utils/checksums.py
author Pawel Solyga <Pawel.Solyga@gmail.com>
Thu, 09 Oct 2008 15:10:51 +0000
changeset 290 2a92b866ed40
parent 54 03e267d67478
permissions -rw-r--r--
Create a submit_buttons block in group edit profile template so that submit buttons can be customized. Replace submit_message usage with new notice block (still work in progress in Lookup User views). Add customized edit profile template for Sponsor with delete button (not used yet, upcoming commit). Add delete Sponsor request handler. Patch by: Pawel Solyga Review by: to-be-reviewed

"""
Common checksum routines (used in multiple localflavor/ cases, for example).
"""

__all__ = ['luhn',]

LUHN_ODD_LOOKUP = (0, 2, 4, 6, 8, 1, 3, 5, 7, 9) # sum_of_digits(index * 2)

def luhn(candidate):
    """
    Checks a candidate number for validity according to the Luhn
    algorithm (used in validation of, for example, credit cards).
    Both numeric and string candidates are accepted.
    """
    if not isinstance(candidate, basestring):
        candidate = str(candidate)
    try:
        evens = sum([int(c) for c in candidate[-1::-2]])
        odds = sum([LUHN_ODD_LOOKUP[int(c)] for c in candidate[-2::-2]])
        return ((evens + odds) % 10 == 0)
    except ValueError:  # Raised if an int conversion fails
        return False