Encryption method getting the picture
Eugen Leitl
eugen at leitl.org
Thu Oct 24 03:19:04 PDT 2002
http://news.com.com/2100-1001-963054.html?tag=dd.ne.dtx.nl-sty.0
Encryption method getting the picture
By Sandeep Junnarkar
Staff Writer, CNET News.com
October 23, 2002, 9:06 AM PT
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.
Its uses could range from sensitive military and medical diagnostic images
to legal documents and photographs of crime scenes. The technique could
also be used to encode information within the image itself for cataloging
and retrieving from databases.
Concerns about the authenticity of Web-based tickets, receipts and signed
contracts have hampered the development of some e-commerce applications.
While digital watermarking offers protection against tampering in most
situations, it can also irreversibly change the quality of an image.
Current data-embedding techniques insert additional watermarking
information, which inevitably distorts an image. While the distortion is
small, it is usually irreversible. 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, the researchers said.
Although the technique is software-based, it could be implemented in
hardware or in devices in which tightly controlling the image is critical,
according the researchers.
For instance, a digital camera that carries the new algorithms could be
used to gather forensic evidence for use later in a courtroom. Any
subsequent manipulations of the pictures could be detected, and the area
where they occurred could be pinpointed.
The technique was recently described in a research paper presented at the
IEEE 2002 International Conference on Image Processing in Rochester, N.Y.
It was co-developed by Mehmet U. Celik and A. Murat Tekalp of the
University of Rochester and Gaurav Sharma and Eli Saber of Xerox.
The University of Rochester filed a patent application on the methods
developed for reversible data hiding and plans to share the rights of the
invention with Xerox.
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