RE: [WM]: What is different bewteen watermarking and steganography

[JJTC.COM <jjtc.com@gmail.com>]

I thought I answered this before...

The main difference between steganography and watermarking is intent of use.  Yes, I know it sounds quite subjective...

Steganography: a message is concealed so it should not be detected.  The object of the communication channel is the hidden
message.  The carrier is simply an envelope to carry the hidden message.

Watermarking: The information embedded in a carrier can be considered as an attribute of the carrier.  The embedded information
conveys additional information about the carrier (copyright, tracking, ownership, tampering, etc.).  The object of the communication
channel is the carrier - the embedded information provides additional information.

Since crypto was mentioned below, I'll address it as well:

Some organizations identify steganography as a subset of cryptography.
 I provide some differences as follows:

Steganography: hides information by "camouflaging" it in some form of innocent-appearing carrier.  The intent is to reduce the
chance of discovering the embedded information (whether or not this information is encrypted).

Cryptography: scrambles information so it should not be understood.  Encrypted data may be observed in communication or in state.

--

Neil F. Johnson, Ph.D.



-----Original Message-----
From: watermarking-owner@watermarkingworld.org
[mailto:watermarking-owner@watermarkingworld.org] On Behalf Of Hans Georg Schaathun
Sent: Tuesday, April 04, 2006 5:41 AM
To: watermarking@watermarkingworld.org
Subject: Re: [WM]: What is different bewteen watermarking and steganography

On Fri, Feb 24, 2006 at 06:49:21PM -0800, huynh hoc wrote:
>   I am confusing about the terminology "watermarking" and
> "steganography". Could you help me to classify these terminology. What
> is different bewteen watermarking and steganography?

There is probably more than one answer to this, but this is mine.
Please be invited to criticise.

Steganography is used for the following scenario:
  Alice wants to send a secret message to Bob, without
  Eve's knowing that there is a secret message.
  (This is usually obtained by hiding the secret message
  in an innocent message, but this is not important for the
  concept of steganography.)

[Cryptography:
  Alice wants to send a secret message to Bob, without
  Eve's knowing what the secret message is.
  (She is allowed to know that there is secret communications
  though.)
]

Robust watermarking:
  Alice want to send a information message coupled with a host
  message, in such a way that Bob (or anyone else) is not able
  to retransmit a message similar to the host without also
  retransmitting the information.  (The information is not
  necessarily secret.)

Fragile watermarking:
  Alice wants to send an information message coupled with a host
  message, in such a way that Bob (or anyone else) is not able
  to retransmit a modified message similar to the host while
  retaining the information.

Obviously, watermarking is more than one thing; these to are not the only ones.  My own background is in security/cryptography,
where steganography is fairly well-defined for a couple of millenia.
Watermarking covers many different things, which are widely different from a security perspective.


--
:-- Hans Georg                             http://www.ii.uib.no/~georg/

`This Universe never did make sense; I suspect that it was built
on government contract.'                                     (Heinlein)



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