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lib/Algorithm/CouponCode.pm  view on Meta::CPAN

=head1 DESCRIPTION

A 'Coupon Code' is made up of letters and numbers grouped into 4 character
'parts'.  For example, a 3-part code might look like this:

  1K7Q-CTFM-LMTC

Coupon Codes are random codes which are easy for the recipient to type
accurately into a web form.  An example application might be to print a code on
a letter to a customer who would then enter the code as part of the
registration process for web access to their account.

Features of the codes that make them well suited to manual transcription:

=over 4

=item *

The codes are not case sensitive.

=item *

lib/Algorithm/CouponCode.pm  view on Meta::CPAN

=head2 Randomness and Uniqueness

The code returned by C<cc_generate()> is random, but not necessarily unique.
If your application requires unique codes, it is your responsibility to
avoid duplicates (for example by using a unique index on your database column).

The codes are generated using a SHA1 cryptographic hash of a plaintext.  If you
do not supply a plaintext, one will be generated for you (using /dev/urandom if
available or Perl's C<rand()> function otherwise).  In the event that an
'inappropriate' code is created, the generated hash will be used as a
plaintext input for generating a new hash and the process will be repeated.

Each 4-character part encodes 15 bits of random data, so a 3-part code will
incorporate 45 bits making a total of 2^45 (approximately 35 trillion) unique
codes.


=head1 EXPORTS

The following functions can be exported from the C<Algorithm::CouponCode>
module. No functions are exported by default.