Cayley–Purser algorithm: Difference between revisions

Revision as of 22:01, 10 November 2011

Revision as of 16:05, 19 March 2012

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Before this placement, Flannery had attended the 1998 [[Young Scientist and Technology Exhibition|ESAT Young Scientist and Technology Exhibition]] with a project describing already existing crytographic techniques from [[Caesar cipher]] to [[RSA (algorithm)|RSA]]. This had won her the Intel Student Award which included the opportunity to compete in the 1998 [[Intel International Science and Engineering Fair]] in the United States. Feeling that she needed some original work to add to her exhibition project, Flannery asked Michael Purser for permission to include work based on his cryptographic scheme.

On advice from her mathematician father, Flannery decided to use [[Matrix (mathematics)|matrices]] to implement Purser's scheme as [[matrix multiplication]] has the necessary property of being non-commutative. As the resulting algorithm would depend on multiplication it would be a great deal faster than the [[RSA (algorithm)|RSA]] algorithm which uses an [[exponent]]ial step. For her Intel Science Fair project Flannery prepared a demonstration where the same plaintext was enciphered using both RSA and her new Cayley-PurserCayley–Purser algorithm and it did indeed show a significant time improvement.

Returning to the ESAT Young Scientist and Technology Exhibition in 1999, Flannery formalised Cayley-Purser's runtime and analyzed a variety of known attacks, none of which were determined to be effective.

Flannery did not make any claims that the Cayley-PurserCayley–Purser algorithm would replace RSA, knowing that any new cryptographic system would need to stand the test of time before it could be acknowledged as a secure system. The media were not so circumspect however and when she received first prize at the ESAT exhibition, newspapers around the world reported the story that a young girl genius had revolutionised cryptography.

In fact an attack on the algorithm was discovered shortly afterwards but she analyzed it and included it as an appendix in later competitions, including a Europe-wide competition in which she won a major award.

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* Sarah Flannery and David Flannery. ''In Code: A Mathematical Journey''. ISBN 0-7611-2384-9

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[[Category:Asymmetric-key cryptosystems]]