/bangkokhotel/lib/python2.5/site-packages/django/utils/checksums.py
https://bitbucket.org/luisrodriguez/bangkokhotel · Python · 22 lines · 11 code · 3 blank · 8 comment · 5 complexity · 55675dafc05a3857ee55a42bbddf7654 MD5 · raw file
- """
- 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