Algorithm::LUHN 1.00

Algorithm::LUHN is a Perl module to calculate the modulus 10 double add double checksum.

SYNOPSIS

use Algorithm::LUHN qw/check_digit is_valid/;

$c = check_digit("43881234567");
print "It worksn" if is_valid("43881234567$c");

$c = check_digit("A2C4E6G8"); # this will cause an error

print "Valid LUHN characters are:n";
my %vc = Algorithm::LUHN::valid_chars();
for (sort keys %vc) {
print "$_ => $vc{$_}n";
}

Algorithm::LUHN::valid_chars(map {$_ => ord($_)-ord(A)+10} A..Z);
$c = check_digit("A2C4E6G8");
print "It worked againn" if is_valid("A2C4E6G8$c");

This module calculates the Modulus 10 Double Add Double checksum, also known as the LUHN Formula. This algorithm is used to verify credit card numbers and Standard & Poors security identifiers such as CUSIPs and CSINs.

You can find plenty of information about the algorithm by searching the web for "modulus 10 double add double".