RSA's RC5-64 Secret Key Challenge has been solved.

[Trei, Peter]

First, the official PR release:
---------------------------------------------------

Distributed Team Collaborates to Solve Secret-Key Challenge

Contest designed to keep the cryptographic community updated
on new achievements and help organizations maintain highest
levels of security

Bedford, MA, Thursday, September 26, 2002 - RSA Laboratories,
the research center of RSA Security Inc. (Nasdaq: RSAS), the
most trusted name in e-security(r), today announced that a
coordinated team of computer programmers and enthusiasts,
known as distributed.net, has solved the RC5-64 Secret-Key
Challenge. The distributed.net team solved the challenge in
approximately four years, using 331,252 volunteers and their
machines. Distributed.net receives a cash prize of $10,000 for
solving the challenge.

Established in 1997, RSA Laboratories' Secret-Key Challenge is
offered to quantify the strength of symmetric encryption
algorithms such as DES and the RC5(r) algorithm with various
key sizes. By sponsoring an actual contest, RSA Laboratories
helps the industry confirm theoretical estimates, and through
this constant evaluation, vendors are motivated to continue to
improve their security solutions. The distributed.net
consortium utilized the idle time of computers throughout the
world to search through the list of all possible 64-bit keys
for RSA Security's RC5 algorithm to find the one secret key
selected at random by RSA Laboratories that decrypts a given
message correctly.

RSA Laboratories sponsors a series of cryptographic challenges
that allow individuals or groups to attempt to solve various
encryption "puzzles" for cash prizes. The RC5-64 Challenge is
one of a series of contests held to determine the difficulty
of finding a symmetric encryption key by exhaustive search
(trial-and-error). Previous contests include the DES
Challenge, the RC5-40 Challenge and the RC5-56 Challenge.

"We're very appreciative of all the volunteers who offered
their time and computer's idle processing time to help solve
this challenge," said David McNett, distributed.net co-founder
and president. "We have once again shown how collective
computing power can be applied to security technology with
ordinary PCs. We look forward to future RSA
Laboratories-sponsored challenges that will assist in helping
the cryptographic community gauge the strength of an algorithm
or application against exhaustive key search."

"RSA Security congratulates the distributed.net team in
solving the RC5-64 Secret-Key Challenge," said Burt Kaliski,
chief scientist at RSA Laboratories. "We appreciate the
persistence of distributed.net and the many individuals
involved in completing the search for this one key. Their work
helps the industry confirm how much work is involved to search
exhaustively for a key - and how a huge volume of computing
time can be harnessed. The various challenges we sponsor are
very useful for tracking the state of cryptographic
achievements and helping ensure that organizations are
maintaining the highest levels of security to protect their
most critical data assets."

----

About RSA Security Inc.  

RSA Security Inc., the most trusted name in e-security, helps
organizations build trusted e-business processes through its
RSA SecurID(r) two-factor authentication, RSA ClearTrust(r)
Web access management, RSA BSAFE(r) encryption and RSA Keon(r)
digital certificate management product families. With
approximately one billion RSA BSAFE-enabled applications in
use worldwide, more than 12 million RSA SecurID authentication
users and almost 20 years of industry experience, RSA Security
has the proven leadership and innovative technology to address
the changing security needs of e-business and bring trust to
the online economy.  RSA Security can be reached at
www.rsasecurity.com.

RSA, RC5, BSAFE, ClearTrust, Keon, SecurID and The Most
Trusted Name in e-Security are registered trademarks or
trademarks of RSA Security Inc. in the United States and/or
other countries. All other products and services mentioned are
trademarks of their respective companies.

---------------------------------

A personal note:

In case people are wondering, the key turned out to be
63 DE 7D C1 54 F4 D0 39
and the encrypted message was
> "The unknown message is: Some things are better left unread."
> 
I'm really happy with this - I wrote to Jim Bidzos proposing
the contests way back in the fall of 1996, long before I came
to work at RSA. 

At the time, I was aimed at killing DES, and creating 
pressure to ease the export limits on key size (they had just 
been raised from a ludicrous 40 up to 56. I didn't think 
this was good enough). I feel that I entirely suceeded.

So I was in at the start of the contests, and at the end of
this one (I was one of the two people at RSA who 
independently confirmed the decryption).

I expect that this will be the last one attacked for 
a while - the next keylength is 72 bits, and at d.net's 
current rate, that would take them several centuries.

Peter Trei


 

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