Encrypt Information In Images Without Distortion

Nomikos writes "C|Net reports: Researchers have created a new way to encrypt information in a digital image and extract it later without any distortion or loss of information. A team of scientists from Xerox and the University of Rochester said that the technique, called reversible data hiding, could be used in situations that require proof that an image has not been altered."

Comments

Re:This has been done forever.

[Valar]

This isn't really feasible if you are trying to extract the data losslessly. The original image file will not match with the extracted file. There is loss in the printing (ink smudge, low resolution printer), loss in the photography (ambient light, noise on the film, thumb in front of lens) and loss in the scanning process. As a result, even if the scanned image is in the same format as the original, there is still loss.

I don't get it...

[RomikQ]

The new technique builds on previous methods but modifies the lowest levels of pixel values using data-embedding algorithms. It allows authorized viewers to extract the embedded authentication message while also removing any distortions created by the embedded information

So while the encrypted data is in the image, the picture is still distorted, it's only when you take the data out, then you get the original. What's the point of that??? I mean that was what it was like before, wasn't it?

By the way, adding plain text to the end of a jpeg file doesn't alter the image in any way, no matter how much you add. So you could encrypt the text you want and add it at the end and there you go, lossless data encryption in images :). Do I get a Nobel prize now?

Re:Holy Cow!! This Is Awesome!

[packeteer]

They are refering to water marks. This is not about "encryption" or even "stenography". The problem is proving a document is original. Normally you put and ugly water mark on the image. With this techinque you can put the water mark in but you also put in data "securly encrypted of course" about how to get the water mark out.

Sheesh i feel dirty now that i have summed up the whole article because people post before they read it.

"Optimal"

[fireboy1919]

Have you studied any image compression theory? Have you heard of the famed graduate student method for fractal compression?
Here it is
1) Lock a graduate student in a room with an image and a huge collection of mathematical knowledge about fractals
2) Tell him/her to compress the image by finding and modeling fractal patterns
3) Wait four days...
VOILA! 10000x compression is not unheard of with 1% or less degredation.

Ever image format that we use today is sub-optimal. We don't even have a mathematical formalism to perfectly identify the entropy (i.e. information) encoded within an image (though we can make rough estimates) to determine the maximum compression. Also, consider than even given the techniques we have today, jpeg isn't the best thing out there, though it is the standard. jpeg2000 is better, and there are some even more highly sophisticated and accurate wavelet based approaches. If we can ever get the kind of computing power available to the supercomputers of today we can do even better by modeling our images using more complex basis functions than sinusiods and wavelets.

Just one final note to sum up: finding optimal compression is definitely an NP-hard problem. Who knows what kind of stuff can be thrown in there without affecting much.