Denny Cherry explains why encrypting stored procedures is a fool’s errand:
To this I point out, that if you’ve encrypted your code so that I won’t look at it by accident, you are actually getting the exact opposite result. Because you are encrypting code that means that I can’t see if. That means that I want to make sure that you aren’t hiding any stupid practices from me. That means that as soon as I see your encrypted procedures I’m decrypting them to see what is going on with this code.
Along with this, because you’ve bothered to encrypt the stored procedures that means that I can’t get an execution plan, and query store can’t be used for the queries within the stored procedure. And since I’m guessing that I can performance tune your database better then your developers can, I’m going to be decrypting the procedures so that I can tune the system.
They’re trivial to decrypt and Denny points out a few reasons why it’s just a bad idea.