January 27, 2009

New System Authenticates Digital Records For Generations

A team of University of Washington researchers released on Tuesday the first part of a public system that will authenticate video archives of interviews with prosecutors and other participants of the International Crime Tribunal for the Rwandan genocide.  Initial portions of the Rwandan archive will also be unveiled, according to a report in the New York Times.

The system, whose digital technology will make it more difficult to misrepresent historical events in the future, seeks to digitally authenticate and preserve first-hand accounts of war crimes, genocide and other atrocities.

Such tools are of critical importance since it is now possible to digitally alter video, text, audio and other material in ways that are undetectable without the aid of technology.

Indeed, history is filled with cases of altering, deleting or denying written records, the researchers said. But now, for the first time, the authenticity of digital documents such as videos, court records and transcripts of personal accounts can be unquestionably verified.

"The closest analogy are the revisionist histories of the Holocaust, where there are assertions that people weren't put in camps and put in ovens,"  Batya Friedman, a computer science professor at the University of Washington told the New York Times.

"It doesn't take a rocket scientist to say that in a period of time some people will say there really weren't 800,000 people who were massacred with machetes."

Designing systems to preserve information for years to come is one of the most troublesome engineering challenges.  The University of Washington researchers decided to create a publicly available cryptographic hash mark, a type of digital fingerprint, which will allow anyone to verify that documents are authentic and unaltered.

Hans Peter Luhn at IBM pioneered the digital has concept in the early 1950s. The University of Washington team is the first to simplify the application for non-technical users, and to comprehensive system that would preserve information for generations to come.

The quick pace of innovation, combined with the propensity of computers to wear out in months or years, has reduced the likelihood that digital files will be readable over long periods of time. 

Indeed, processors are often replaced by incompatible models, new software applications are developed with different data formats and digital storage media such as magnetic disk, digital tape or solid-state memory chips are often short-lived.

The problem has caused scientists to look for new ways to address the fleeting nature of digital records.

In 1996, computer scientist Danny Hillis helped found the Long Now project, which warned of the possibility of a "digital dark age."   The group is now creating a clock that will "tick" each year and have a 10,000-year life span.  The group hopes the clock will serve as a counterpoint to the "faster/cheaper" culture of today's increasingly computerized world.

Prior to the rise of digital information, people valued paper documents and cared for them, Mr. Hillis has said.  However, since then people have paid progressively less attention to the preservation of information, which is now typically stored on media that may only last several years.

Brewster Kahle, another computer scientist, founded the Internet Archive in 1996.  The group seeks to preserve a complete record of the World Wide Web and other digital documents.  

Similarly, a group of Stanford University librarians created LOCKSS, short for Lots of Copies Keep Stuff Safe, in 2000.  The organization seeks to preserve journals by distributing digital documents through an international community of libraries via the Internet.

However, Ms. Friedman distinguishes her work from those who simply preserve digital content.  LOCKSS, she said, is instead attempting to design comprehensive systems that would strengthen social institutions over time by creating digital historical records that provide continuity across multiple generations.

"Building a clock is iconic," she told the New York Times.

"What is really different is that we are trying to solve socially significant, real-world problems."

Since problems like genocide, AIDS, global warming and famine will not be solved in a single generation, Friedman says that multi-generational information systems are required.

To keep the work grounded in real world events, the researchers began by creating an archive of video interviews with prosecutors, judges and other members of the International Criminal Tribunal for Rwanda, with the goal of designing a system that would secure the information for more than 100 years.

Ms. Friedman traveled with a group of cinematographers and legal experts to Kigali, Rwanda and Arusha, Tanzania, where the tribunal is based, to conduct video interviews last fall.

After 49 interviews that gave researchers more than five gigabytes of video, the group began devising a system that would allow viewers to verify that the videos had not been altered, even if users were without powerful computing equipment or an Internet connection.

Despite the availability of commercial applications that verify when a document was created and whether it was altered, the researchers sought to develop a system that was readily available and would survive repeated changes in technology.

The system is based on an algorithm that is used to compute a 128-character number, known as a cryptographic hash, from the digital information contained in the document.  Even the tiniest change in the original document will change the hash value.

However, researchers have identified some weaknesses in current hash algorithms in recent years.   Hoping to address the issue, the National Institute of Standards and Technology began a competition last November to create stronger hashing technologies.  

The University of Washington team now use a modern hash algorithm known as SHA-2, but designed the system such that it can be easily replaced with a more sophisticated algorithm.

Their system will be distributed as part of "live CD," making it possible to compute or verify the hash by merely inserting the disk in a computer.   The disk will also include components that will allow users to view documents and videos that may not be accessible by future software applications.

Michael Lesk, a professor in the department of library and information science at Rutgers University, said it's a difficult problem.   The system must not only prove that information has not changed from its original format, but also verify that once the format is altered, the original digital hash is still valid.

Stewart Brand, a co-founder of The Long Now Foundation, said the group is developing a new software tool to easily convert documents between digital formats.

"The idea is to be able to change anything into anything else," he told the New York Times.


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