No, I do mean random. Block ciphers, such as AES, model PRFs. One cannot get IND-CPA security by just passing the message into AES ala ECB mode. Instead, one has to use randomness, in the form of a nonce, as in CBC mode, to obtain IND-CPA security.<p>Sure, the resulting ciphertext is only computationally indistinguishable from random. But the point of IND-CPA security is that one can&#x27;t differentiate between two encryptions of different messages. Adding randomness gives you this.