Encrypting a Column

A few years ago, I gave a session on Oracle’s Data Vault. An attendee from that session and I happened to be seated at the same table for lunch last Thursday when I presented at Utah Oracle User Group Fall Symposium. He asked if I’d ever found a way to encrypt a column from the prying eyes of the SYS user. I said yes, and he asked how. It was a bit more than could be explained at lunch and promised to put it on the blog.