Steganography tools

[mbalensiefer]

Hi.

 Is anyone here "protecting" their online images with a stego tool? I have my images watermarked...but of course watermarks are not permanent.
 Adobe PS has their "default" program..but it costs a bit and what really annoys me about their tool is that it artifacts my images.

 Any other programs used? Names and whys appreciated.

~Michael

[Jonathan Wienke]

One of my other hobbies is cryptography and steganography. My understanding is that if the embedded stego watermark is not prominent enough to visibly artifact the image, then a simple resize or even re-compressing a JPEG with the same pixel dimensions can destroy the watermark. I recently took a digital forensics course that covered steganography (one of the less savory uses of steganography is hiding kiddie porn images in innocuous video, audio, or image files). It is particularly difficult for an invisible stego watermark to survive resizing of the image.

The same problem applies to hashing and any other "digital fingerprinting" technology--even fairly minor alterations can destroy the the fingerprint. IMO it's not worth the bother. If you can't identify an image as being yours by looking at it and you haven't registered for copyright, then stego watermarking is a waste of time that is more likely to piss off your customers than offer you any real protection.

[Panopeeper]

Is anyone here "protecting" their online images with a stego tool? I have my images watermarked...but of course watermarks are not permanent

Steganography and watermarking are principally different. Using steganography for marking property is nonsensical.

The basic differences are:

- the data embedded by steganography is not supposed to be recognizable by anyone without the authorization; not even the fact, that something is embedded, is supposed to be recognizable,

- steganography is typically sensitive to changes in the base data, because it has to retrieve the embedded data with 100% accuracy; for example editing, resizing, etc. the base image most probably destroys the hidden data,

- watermarking may or may not be visible for the outsider (or one can use one visible and one invisible version),

- watermarking does not have to preserve the information with 100% accuracy, but it has to be recognizable even after robust changing of the base.

[Jonathan Wienke]

Steganography and watermarking are principally different. Using steganography for marking property is nonsensical.

True, but that hasn't stopped people from offering stego-based "invisible watermarking" tools...