Daniel Verite wrote: > That's a permutation, as used in symmetric ciphering. A proven way to > build one is to use a Feistel network:
Thanks. That looks to be pretty much what I'm after. > Here is a plpgqsl implementation: Wow. I really appreciate that. I'll have to test it out and chuck it on the wiki (if that's OK with you) for future use, alongside whatever I end up using for my check digit generator and verifier. Come to think of it, check digits are almost unnecessary; after all, in a large numeric space the chances of any misheard, typo'd, etc value happening to be another valid value is pretty minimal. A simple mod-10-of-sum-of-digits would probably be quite sufficient just to help the UI differentiate between "Whoops, that number was incorrectly entered or misheard" and "Customer not found". -- Craig Ringer -- Sent via pgsql-general mailing list (pgsql-general@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-general
