CDR: VASCO gizmos

Hi! Anybody knows anything about the VASCO Data Security gizmos' algorithm? [You enter your pin, and it generates a 7-digit number, which is synchronized with the number on the server you're authenticating to; the number is valid for 30 secs or 1 minute, I'm not sure.] We just got some at our company, and they're open to at least a replay attack, but I'm curious what algorithm do they use for generating those numbers. Mark --- All inventions or works of authorship original to me, herein and past, are placed irrevocably in the public domain, and may be used or modified for any purpose, without permission, attribution, or notification.