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SDSC's New Teraflops IBM SP Supercomputer Climbs to Top Ranks of RC5-64 Code Breaking Challengers

Published 01/05/2000

David Hart, SDSC,, 858-534-8314

UC San Diego - During the acceptance testing of the world's tenth fastest computer, a 1,152-processor IBM SP at the San Diego Supercomputer Center (SDSC), the machine demonstrated its computing power by climbing to the top ranks of participants in's RC5-64 code breaking challenge ( The IBM SP held the top position in this monumental computing task for several days during the December holidays.

"We decided to give the processors a workout," said Jeff Makey, a computer scientist at SDSC, a research unit of the University of California, San Diego, and the leading-edge site for the National Partnership for Advanced Computational Infrastructure (NPACI). "While we were running diagnostics and benchmark programs on the teraflops machine, many of the individual processors weren't being used. The RC5-64 Challenge software lets us test the rest of the system's processors at the same time."

From December 20, when it entered the contest in force, until December 27, when the full machine was needed for acceptance testing, the IBM SP consistently placed among the top five participants in the number of potential keys examined ( Ironically, on the machine's best day, December 24, it only placed fifth. Four other participants chose that day to submit results they had been accumulating for weeks or months.

Highly ranked participants are typically teams that represent the combined efforts of many individual computer systems. Other participants reach the top of the daily list by submitting the results of weeks or months of computation. The teraflops IBM SP is one of few single computers among the high-ranking participants.

The RC5-64 challenge involves testing the 2^64 possible encryption keys -- more than 18 billion billion possible combinations -- to find the one that properly deciphers the encoded message. Testing every possible 64-bit key requires an enormous amount of computing power. Tens of thousands of participants have been working on the problem since March 1997, donating the spare CPU cycles from computers ranging from mainframes to personal computers.

Each of the 1,152 Power3 processors in the teraflops IBM SP peaks at 736,000 RC5 keys per second, which gives an overall peak rate of 848 million keys per second. If the teraflops system could run at this speed for 24 hours it could test more than 73 trillion keys per day. On its best day to date, December 24, the machine tested nearly 60 trillion keys.

NPACI's IBM SP teraflops system at SDSC is the nation's most powerful computer system dedicated to unclassified research by qualified academic, government, and industry scientists and engineers. Allocations of time on the new IBM SP system will be made through national peer review, with preference given to problems that take advantage of the machine's unique capability. See for more information.

The San Diego Supercomputer Center ( is a research unit of the University of California, San Diego, and the leading-edge site of the National Partnership for Advanced Computational Infrastructure ( SDSC is funded by the National Science Foundation through NPACI and by other federal agencies, the State and University of California, and private organizations. For additional information about SDSC, NPACI, and the IBM SP teraflops system, see or contact David Hart,, 858-534-8314.