Ronald L. Rivest is an American computer scientist and a professor at the Massachusetts Institute of Technology (MIT). He is best known for co-inventing the RSA encryption algorithm, which is widely used for secure data transmission. Rivest's work has significantly impacted the fields of cryptography and computer security. In addition to his contributions to cryptography, Rivest has authored numerous papers and books on algorithms and computer science. He is also a co-founder of VeriSign, a company that provides internet infrastructure services. Rivest's research continues to influence modern computing and security practices.