mirror of
https://github.com/django/django.git
synced 2024-11-18 15:34:16 +00:00
35 lines
988 B
Python
35 lines
988 B
Python
"""
|
|
Common checksum routines.
|
|
"""
|
|
|
|
__all__ = ['luhn']
|
|
|
|
import warnings
|
|
|
|
from django.utils import six
|
|
from django.utils.deprecation import RemovedInDjango20Warning
|
|
|
|
warnings.warn(
|
|
"django.utils.checksums will be removed in Django 2.0. The "
|
|
"luhn() function is now included in django-localflavor 1.1+.",
|
|
RemovedInDjango20Warning
|
|
)
|
|
|
|
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, six.string_types):
|
|
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
|