secret key for encryption - Mailing list pgsql-admin

This isn't exactly a Postgres question, but I hope someone in the community has solved it.

I want to encrypt some data in Postgres that arrives from Apache.  How do you store an encryption key in such a way
thatApache CGIs can get it, but a hacker or rogue employee who manages to access the machine can't find out the
encryptionkey? 

Thanks,
Craig