Protecting Functions From View It

Hello,
I wrote some complicated functions (and stored procedures) in database
at my work. System administrator (and every db user) can view codes
(in Enterprise Manager for eg.). My employer needs periodic modifying
of code and so I'm required to do it. But I can loose my job :)
because users are able to modify code (althout they ware too lazy to
create it by themselves).

Is this possible to protect functions from view it?

[please, don't mind my english]