I want to use a stream cipher to encrypt a continuous bitstream. Additional to that, I want to generate an additional stream to guarantee the integrity of the ciphertext.
- stream a: ciphertext.
- stream b: integrity check on stream a.
I am aware of authenticated encryption where the MAC can be accumulated and sent. I want to avoid that.
Is it possible to do this by encrypting the same plaintext using a different algorithm, key or iv? Will that actually protect against say bit-flip attacks? Does it cause any vulnerabilities?
Is there a better (preferably cheaper) way to do this?
Note that this has to be done in hardware and I am extremely limited on energy so I can't add any sort of control logic.