A team at the German Federal Agency for Information Technology Security
(BIS) has announced the factorization of the 200-digit number known as
RSA-200. The team responsible for this factorization is the same
one that previously factored the 174-digit number known as RSA-576
(MathWorld headline news, December 5, 2003). While RSA-200 is a much
smaller number than the 7,816,230-digit monster Mersenne prime known
as M42 (the largest prime number known), its factorization is
significant because the RSA-numbers serve as benchmarks for users of the
RSA public-key cryptography algorithm in choosing suitable
key lengths that provide an appropriate level of security for data
encryption.