The RSA Factoring Challenge is a challenge put forward by RSA Laboratories on March 18 1991 to encourage research into computational number theory and the practical difficulty of factoring large integers. They published a list of semiprimes known as the RSA numbers with a cash prize for the successful factorization of some of them. The smallest of them, a 100 decimal digit number called RSA-100 was factored in a few days, but many of the bigger numbers have still not been factored and are expected to remain so for quite some time.

This challenge is interesting not only from the number theory point of view, but also in a very practical sense — as a solution is more or less the same thing as breaking a RSA public key. The RSA public key algorithm is a keystone of many cryptographic protocols — including some used by the financial system. Progress in this challenge should give an insight into which key sizes are still safe and for how long. As RSA Laboratories is a provider of RSA-based products, the challenge is used by them as an incentive for the academic community to attack the core of their solutions — in order to prove its strength.

See also

• The Magic Words are Squeamish Ossifrage, the solution found in 1993 to another RSA challenge posed in 1977
• RSA Factoring Challenge numbers list

External links

• The original challenge announcement on sci.crypt
• The RSA Factoring Challenge FAQ