[LINK] A Tool to Verify Digital Records

stephen at melbpc.org.au stephen at melbpc.org.au
Wed Jan 28 04:00:36 AEDT 2009

A Tool to Verify Digital Records, Even as Technology Shifts 

By JOHN MARKOFF  Published: January 26, 2009 

On Tuesday a group of researchers at the University of Washington are 
releasing the initial component of a public system to provide 
authentication for an archive of video interviews with the prosecutors  
for the Rwandan genocide. The group will also release the first portion 
of the Rwandan archive.

This system is intended to be available for future use in digitally 
preserving and authenticating first-hand accounts of war crimes, 
atrocities and genocide. 

Such tools are of vital importance because it has become possible to 
alter digital text, video and audio in ways that are virtually 
undetectable to the unaided human eye and ear.

The researchers said history was filled with incidents of doctoring, 
deleting or denying written records. 

Now, they say, the authenticity of digital documents like videos, 
transcripts of personal accounts and court records can be indisputably 
proved for the first time.

Designing digital systems that can preserve information for many 
generations is one of the most vexing engineering challenges. 

The researchers’ solution is to create a publicly available digital 
fingerprint, known as a cryptographic hash mark, that will make it 
possible for anyone to determine that the documents are authentic and 
have not been tampered with. 

The concept of a digital hash was pioneered at I.B.M. by Hans Peter Luhn 
in the early 1950s. 

The University of Washington researchers are the first to try to simplify 
the application for nontechnical users and to try to offer a complete 
system that would preserve information across generations.

Both because of the rapid pace of innovation and the tendency of 
computers to wear out in months or years, the likelihood that digital 
files will be readable over long periods of time is far less certain even 
than the survival of paper documents. 

Computer processors are quickly replaced by incompatible models, software 
programs are developed with new data formats, and digital storage media, 
whether digital tape, magnetic disk or solid state memory chips, are all 
too ephemeral.

Several technologists are already grappling with the evanescent nature of 
digital records. 

Danny Hillis, a computer scientist, helped found the Long Now project in 
1996, warning about the possibility of a “digital dark age.” 

Mr. Hillis has argued that before the rise of digital information people 
valued paper documents and cared for them. Since then, there has been 
progressively less attention paid to the preservation of information. Now 
information is routinely stored on media that may last for only several 

To that end, another computer scientist, Brewster Kahle, founded the 
Internet Archive in 1996 in an effort to preserve a complete record of 
the World Wide Web and other digital documents. 

Similarly, in 2000 librarians at Stanford University created LOCKSS, or 
Lots of Copies Keep Stuff Safe, to preserve journals in the digital age, 
by spreading digital copies of documents through an international 
community of libraries via the Internet.

However, Ms. Friedman distinguishes her design work from those who have 
focused on the simple preservation of digitized materials. 

Instead, she said she was trying to design complete digital systems that 
would play a role in strengthening social institutions over time by 
creating a digital historical record that offered continuity across 
multiple life spans.

“Building a clock is iconic,” she said. “What is really different is that 
we are trying to solve socially significant, real-world problems.” 

Because problems like genocide, H.I.V. and AIDS, famine, deforestation 
and global warming will not be solved in a single human lifetime, she 
argues that information systems designed to ensure continuity across many 
generations are a necessity.

To ground the group’s research in a real-world situation, the researchers 
began by building an archive of video interviews with the judges, 
prosecutors and other members of the International Criminal Tribunal for 

The goal was to design a system that would ensure that the information 
was secure for more than a century.

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

After capturing five gigabytes of video in 49 interviews, the group began 
to work on a system that would make it possible for viewers to prove for 
themselves that the videos had not been tampered with or altered even if 
they did not have access to powerful computing equipment or a high-speed 
Internet connection.

Despite the fact that there are commercial applications that make it 
possible to prove the time at which a document was created and verify 
that it has not been altered, the researchers wanted to develop a system 
that was freely available and would stand a chance of surviving repeated 
technology shifts. 

At the heart of the system is an algorithm that is used to compute a 128-
character number known as a cryptographic hash from the digital 
information in a particular document. Even the smallest change in the 
original document will result in a new hash value. 

In recent years researchers have begun to find weaknesses in current hash 
algorithms, and so last November the National Institute of Standards and 
Technology began a competition to create stronger hashing technologies. 

The University of Washington researchers now use a modern hash algorithm 
called SHA-2, but they have designed the system so that it can be easily 
replaced with a more advanced algorithm. 

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

The problem is complex, said Michael Lesk, a professor in the department 
of library and information science at Rutgers University, because not 
only must you be able to prove that the information has not changed in 
its original format, but you must also be able to prove that once the 
format is altered, the original digital hash is still valid.

The Long Now Foundation is developing a software tool to easily convert 
documents between digital formats, said Stewart Brand, a co-founder of 
the project. “The idea is to be able to change anything into anything 
else,” he said.

A version of this article appeared in print on January 27, 2009

However there appear some doubters 'Canonical Hashes over video? Be 
skeptical' http://financialcryptography.com/mt/archives/001143.html 

Cheers people
Stephen Loosley
Victoria, Australia

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