Store an encryption key in Keychain while application installation process

Question

I need my application to use client\'s phone-number to generate unique ID for my web-service. Of course a phone-number is unique, but it must be secured. So it can be implem

Answer 1

I don't think you're going to be able to do what you want securely with symmetric encryption. With asym you can send the public key without worrying about it too much (only threat is someone substituting your key with their own) and validate the encrypted unique id on your server with the private key.