app/django/utils/checksums.py
author Sverre Rabbelier <srabbelier@gmail.com>
Thu, 16 Oct 2008 23:23:16 +0000
changeset 363 d35ffa6ca643
parent 54 03e267d67478
permissions -rw-r--r--
Add a framework for generic views This commit does not enable the new code, as such there should be no change in functionality. In order to use the new code the maps.py file should be updated to point at the new views/models/sponsor.py module. Patch by: Sverre Rabbelier Reviewed 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