Re: newbie Q: "Stacked" public key algorithm

I've also thought about something like a watermark, but the problem is that
the original message would be send only once to the company itself and then
distributed internally, so the sender himself can't neither add a personal
watermark nor use e.g. the public keys of the employees itself for
encryption, as he just don't know them at that moment.


But as more I'm thniking about, I feel there's really no other way as to set
up a central encryption authority in the company who does personal
encryption for the different employees with their personal keys...


Skybuck Flying wrote:

Won't work.

Alice can simply decrypt the company secret, and then give it to somebody
else.

Any company employee could have done that.

If you want to know who leaked information than normally some secret
information is added which uniquely identifies each copy that was given
out.

For example a watermark in a picture or so... each copy of the picture
will have a secret code in it... like a bar code ! ;)

Bye,
Skybuck.

.

Relevant Pages

  • Re: sf not worth stealing?
    ... In a digital image, for example, the watermark is buried in the last bits of some widely scattered pixels. ... And this method can't particularly be a secret, ... Finding out -which- watermark method was used, if any, will be the stumbling ... Jack Tingle ...
    (rec.arts.sf.written)
  • Re: Invisible watermarking
    ... watermark dependent upon a secret key. ... originals in this case might be paper computer-printed pages, ... embedded in whatever movie someone got caught downloading (with at ...
    (sci.crypt)
  • Re: sf not worth stealing?
    ... the watermark is buried in the last bits of some widely scattered pixels. ... which includes 'how to extract the information that tells you where ... And this method can't particularly be a secret, ... medium still quite usable will generally be trivial. ...
    (rec.arts.sf.written)
  • Re: Invisible watermarking
    ... watermark dependent upon a secret key. ... A common attack is simply using ... to test the robustness of your watermark embedding. ...
    (sci.crypt)
  • Re: newbie Q: "Stacked" public key algorithm
    ... the original message would be send only once to the company itself and ... watermark nor use e.g. the public keys of the employees itself for ... Employee sends encrypted message to company. ... Company makes a copy for everyone else and adds a watermark for each ...
    (sci.crypt)