>Rick Smith wrote:
>> It sounds like there are a number of interesting design questions. For
>> example, the sender and recipient must obviously share a secret key.
At 10:18 PM 01/26/2000 +0000, Ben Laurie wrote:
>Why is that obvious? What's wrong with encoding with the recipient's
>public key?
It depends on what you're encoding.
I expect we end up with a three step process: first, encrypt the data,
second, stego it into the image or other file, and third, provide the
recipient with information for recovering the hidden data.
If we're talking about the first step, encryption of the raw data that's
being stego'ed (is there a more legitimate verb for that?), then I'd prefer
to use secret key encryption, since it introduces fewer uncertainties
regarding the safety of the ciphertext.
As to step 3, how this secret information is shared with potential
recipients, public key techniques are fine. If we're talking about Russ
Nelson's "forward stego" problem, then PK is overkill -- he just needs to
publish the secret information and voila, the previously hidden information
is uncovered.
As to Russ' problem of how to keep the information "available," I suggest
we look around our environments and take stock of what iconic images or
files we all have and for some reason can't part with. Perhaps there's some
really great crt wallpaper image that would do the job, or one could embed
it in a Craig Shergold make-a-wish chain letter. Those things NEVER die.
Rick.
[EMAIL PROTECTED]
