I am intending to add new module to CPAN that calculates the Modulus
10 Double-Add-Double checksum. This is also called the LUHN
Formula. My current name is Algorithm::LUHN, since LUHN is way shorter
than its other name. This checksum is used to validate credit card
numbers. Also the Standard & Poor's company uses it to validate the
security identifiers they administer (CUSIP, ISIN, and CINS). This is
a precursor to Business::CUSIP and Business::CINS which I intend to
add in a couple days.
Does Algorithm::LUHN seem like a good name? Thanks!
Hope you have a very nice day, :-)
Tim Ayers ([EMAIL PROTECTED])
CPAN ID = TAYERS
--------------------------- pod ----------------------------------------
NAME
Algorithm::LUHN - Calculate the Modulus 10 Double Add Double checksum
SYNOPSIS
use Algorithm::LUHN qw/check_digit is_valid/;
$c = check_digit("43881234567");
print "It works\n" if is_valid("43881234567$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);
$c = check_digit("A2C4E6G8");
print "It worked again\n" if is_valid("A2C4E6G8$c");
DESCRIPTION
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 & Poor's security identifiers such as CUSIP's and
ISIN's.
You can find plenty of information about the algorithm by searching the
web for "modulus 10 double add double".
FUNCTION
is_valid CHECKSUMMED_NUM
This function returns true if the final character of CHECKSUMMED_NUM
is the correct checksum for the rest of the number. The final
character does not factor into the checksum calculation.
This function is equivalent to
substr $N,length($N)-1 eq check_digit(substr $N,0,length($N)-1)
check_digit NUM
This function returns the checksum of the given number.
valid_chars [LIST]
By default this module only recognizes 0..9 as valid characters, but
sometimes you want to consider other characters as valid, e.g.
Standard & Poor's identifers may contain 0..9, A..Z, @, #, *. This
function allows you to add additional characters to the accepted
list.
LIST is a mapping of c<character> => c<value>. For example, Standard
& Poor's maps A..Z to 10..35 so the LIST to add these valid
characters would be (A, 10, B, 11, C, 12, ...)
Please note that this *adds* or *re-maps* characters, so any
characters already considered valid but not in LIST will remain
valid.
If you do not provide LIST, this function returns the current valid
character map.
AUTHOR
This module was written by Tim Ayers
(http://search.cpan.org/search?mode=author&query=tayers).
COPYRIGHT
Copyright (c) 2001 Tim Ayers. All rights reserved
LICENSE
This program is free software; you can redistribute it and/or
modify it under the same terms as Perl itself.
