Many years ago people (including me [1]) started using the Skipjack cipher for the purpose of obfuscating sequential numbers when they needed to be externalized (e.g. putting auto-incremented ids in urls). Since it was originally designed to encrypt media in realtime on 90s era silicon it's quite low overhead. I've often wondered if/when a database vendor would get around to building similar functionality directly into their engine since that would make the approach much more practical to adopt.