If a standard encryption scheme involves a nonce, as most do, can the nonce be used to hide another small message?
That is, the nonce (rather than being randomly generated) is a hidden message XORed with another secret key. As long as this other secret key is hashed/random and unique for each message, this is equivalent to random, right?
In an extended nonce setup (such as Xsalsa) 192 bits could be sent as a hidden/deniable message. I realise this is still tiny, but it seems truly deniable since you are using a standard encryption scheme, therefore overcoming the issue detailed in the answer here.
Aside from the obvious problem/hassle of exchanging a 2nd secret key and sending small messages as a series of larger ones, is this a viable idea?