Searching by hash, where the hash is locally generated and then sent to the server, avoids this sort of surveillance issue. It doesn't stop the issue of forced

Searching by hash, where the hash is locally generated and then sent to the server, avoids this sort of surveillance issue. It doesn't stop the issue of forced changes to code that impair that local hashing, but it's detectable by the user. Server-side encryption/hashing isn't detectable by the user, and that's an important consideration in any secure system. Best of luck with your project.