stdnum.verhoeff

The Verhoeff algorithm.

The Verhoeff algorithm is a checksum algorithm that should catch most common (typing) errors in numbers. The algorithm uses two tables for permutations and multiplications and as a result is more complex than the Luhn algorithm.

More information:

• https://en.wikipedia.org/wiki/Verhoeff_algorithm
• https://en.wikibooks.org/wiki/Algorithm_Implementation/Checksums/Verhoeff_Algorithm

The module provides the checksum() function to calculate the Verhoeff checksum a calc_check_digit() function to generate a check digit that can be append to an existing number to result in a number with a valid checksum and validation functions.

>>> validate('1234')
Traceback (most recent call last):
    ...
InvalidChecksum: ...
>>> checksum('1234')
1
>>> calc_check_digit('1234')
'0'
>>> validate('12340')
'12340'

stdnum.verhoeff.calc_check_digit(number)

With the provided number, calculate the extra digit that should be appended to make it pass the Verhoeff checksum.

stdnum.verhoeff.checksum(number)

Calculate the Verhoeff checksum over the provided number. The checksum is returned as an int. Valid numbers should have a checksum of 0.

stdnum.verhoeff.is_valid(number)

Checks to see if the number provided passes the Verhoeff checksum.

stdnum.verhoeff.validate(number)

Checks to see if the number provided passes the Verhoeff checksum.