Encrypt Information In Images Without Distortion 236
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."
Encryption? (Score:5, Informative)
Is it really encryption? (Score:5, Informative)
Re:Signed Hash (Score:4, Informative)
A signed hash can be separated from an image, while this type of watermarking cannot.
Re:Encryption? (Score:4, Informative)
This is called digital watermarking.
Re:I don't get it... (Score:2, Informative)
Or you could embed a ton of secret messages in a simple server-to-server mirroring operation, and still wind up with a 1:1 mirror - never tipping anyone off that anything but the visible content was transferred.
That way when the bad guys find it they see no distortions, can find no trace that the image was ever altered, and just think you're looking at porn.
Covert Channels (Score:3, Informative)
Re:My bullshit detector is on yellow alert (Score:5, Informative)
from here [vividlight.com]:
"Finally with a nod toward law enforcement the EOS-1Ds is the first digital camera that offers the ability to verify that images are unaltered originals using the Data Verification Kit DVK-E1, consisting of a dedicated IC card and card reader, together with software for Windows 2000/XP. This package is available to verify that EOS-1Ds image files are absolutely unaltered. "
It DOES distort the image!!! (Score:4, Informative)
Re:Holy Cow!! This Is Awesome! (Score:4, Informative)
These watermarks vs. Digimarc watermarks (Score:4, Informative)
This is called digital watermarking.
But unlike Digimarc watermarks, this kind of watermark isn't designed to survive being sent through the analog hole.
Some more information I googled (Score:4, Informative)
The abstract of the paper (Reversible Data Hiding) is: "We present a novel reversible (lossless) data hiding (embedding) technique, which enables the exact recovery of the original host signal upon extraction of the embedded information. A generalization of the well-known LSB (least significant bit) modification is proposed as the data embedding method, which introduces additional operating points on the capacity-distortion curve. Lossless recovery of the original is achieved by compressing portions of the signal that are susceptible to embedding distortion, and transmitting these compressed descriptions as a part of the embedded payload. A prediction-based conditional entropy coder which utilizes static portions of the host as side-information improves the compression efficiency, and thus the lossless data embedding capacity"
In case anyone is interested.
Re:Amazing, nobody here understands the point (Score:2, Informative)
You don't have to carry around two images when you digitally sign one. You just need the image and it's signature (~160 chars or so), and can make both as public as you want.
Re:Encryption? (Score:5, Informative)
Type I simply embeds the data into the spectrum of the image and uses modulo addition as necessary to prevent overflow. Unfortunately, this causes "salt-and-pepper artifacts" because this sometimes affects the most significant bits in a pixel's representation.
Type II uses the traditional method of overwriting the least significant bits or high-frequency coefficients in the image (depending on image encoding).
What this paper does is describe a method that employs Type II encoding and saves the overwritten bits by compressing them and inserting into the embedded data stream. Unlike simple Type II encodings such as always using the lowest two bits, this paper varies the number of bits which are used in each byte. This value is determined according to their compressibility and other parameters in the image. By doing this, the paper obtains a more efficient tradeoff between storage and distortion.
The journal article is "Reversible data hiding" in IEEE Internation Conference on Image Processing, 2002, volume 2, pages 157-160 http://ieeexplore.ieee.org/servlet/opac?punumber=
Re:Holy Cow!! This Is Awesome! (Score:3, Informative)
Re:If Hollywood says it's true... ;-) (Score:1, Informative)