Re: Q: Stegoanalysis

On Sep 30, 12:28 pm, Mok-Kong Shen <mok-kong.s...@xxxxxxxxxxx> wrote:
Spinner wrote:
if somebody has the original photo, a single bit change is detectable

No problem with that, I surmise. The original photo one took could be
deleted. It's the key that determines the positions of the stego bits
that has to be secret.

The question at hand was not about keeping the message secret. It
was about keeping the existence of the message secret. (No surprise
that Mok forgot his own question).

Keeping the stego key secret may actually increase the risk of
having a message's existence detected if the draconian measures
taken to guarantee the key's secrecy get noticed. This may
reduce the worst case estimate of available covert capacity from
1 bit with 50% probability of detection to 0 bits with 100%
of detection.

But I digress. Mok has already publicly plonked me.