msr90/luhn_algo.py

42 lines
1.1 KiB
Python

#!/usr/bin/env python
# Luhn Algorithm Example - Developed by acidvegas in Python (https://git.acid.vegas/msr90)
def modulus10(card_number: str) -> str:
'''
Validate a card number using the Luhn Algorithm
:param card_number: The card number to validate
'''
digits = [int(d) for d in card_number]
total_sum = 0
reversed_digits = digits[::-1]
for i in range(len(reversed_digits)):
digit = reversed_digits[i]
if i % 2 != 0:
digit = digit * 2
if digit > 9:
digit -= 9
total_sum += digit
check_digit = (10 - (total_sum % 10)) % 10
full_card_number = card_number + str(check_digit)
if (total_sum + check_digit) % 10 != 0:
raise ValueError('failed luhn check (non-divisible by 10)')
return full_card_number
if __name__ == '__main__':
card_number = input('Enter your card number without the last digit:')
if not card_number.isdigit():
raise ValueError('invalid card number')
print(f'Full card number: {modulus10(card_number)}')