The patent for the RSA algorithm (U.S. Patent 4,405,829) was issued on September 20, 1983, exclusively licensed to RSA Security Inc. by the Massachusetts Institute of Technology, with an expiration date of September 20, 2000. RSA Security maintained a standard, royalty-based licensing policy that could be modified for special circumstances. In the U.S., a license has been needed to make, use or sell products that included the RSA algorithm. However, RSA Security has long allowed free non-commercial use of the RSA algorithm, with written permission, for academic or university research purposes.
On September 6, 2000, RSA Security made the RSA algorithm publicly available and waived its rights to enforce the RSA patent for any development activities that include the algorithm occurring after September 6, 2000. From this date forward, companies are able to develop products that incorporate their own implementation of the RSA algorithm and sell these products in the U.S.
(Question updated 9/13/2000)