signing is a more expensive operation by like factor of 4 or more than deriving a decryption secret and making a cipher block stream

not wanting to see messages that have been encrypted to you is quite retarded, i mean, i don't even know how to express how retarded it is to not want to spend the cheapest amount of crypto compute on seeing what people send you

signing stuff, that's a different issue because implicitly you are also sending that out, there should be a clear delineation between actions that are secret and actions that become public or at least move to private across the connection

i admonish you guys to do some more study on cryptography and signals intelligence, please 

 look, put it this way, if someone has already breached your system, they can see all yoru encrypted messages and you are whining because the signer asks you to derive a shared secret???? 

 sorry but this is beyond retarded

performing an action that has zero effect outside your computer should not need any permission