# Richard Schroeppel

Richard C. Schroeppel ( * 1948 near Chicago, Illinois ) is an American computer scientist and mathematician who deals with algorithmic number theory and cryptography.

Schroeppel studied at MIT, where in 1968 he earned his bachelor 's degree. 1966 and 1967 he was there Putnam Fellow. 1991 to 1998 he conducted research on computer security issues at the University of Arizona. He is currently working at Sandia National Laboratories.

Schroeppel was with Michael Beeler and Ralph William (Bill) Gosper co-author of the famous "Artificial Intelligence Memos " HAKMEM (AIM -239, MIT ) from 29 February 1972. Later he discovered the subexponentielle runtime by some factorization algorithms such as the continued fraction method, he then was able to improve (method of the linear sieve ). After Carl Pomerance played his ideas, which he did not often publicized, a role in the development of the factorization of the quadratic sieve of Pomerance itself and also in the number field sieve.

In the 1970s he worked with Whitfield Diffie and Martin Hellman at Stanford in the analysis of the security of DES.

1998/99 he developed the Hasty Pudding cipher as a candidate in the competition for the cryptography standard AES.

He also dealt with recreational mathematics and certain, for example, the number of magic squares of side length 5