Simmons was born in
West Virginia and was named after his grandfather, a
prohibition officer who was gunned down three years before Gustavus was born. He began his post-secondary education at
Deep Springs College, and received his
Ph.D. in mathematics from the
University of New Mexico, Albuquerque. Simmons has published over 170 papers, many of which are devoted to
asymmetric encryption techniques. His technical contributions include the development of
subliminal channels which make it possible to conceal covert communications in
digital signatures and the mathematical formulation of an authentication channel paralleling in many respects the secrecy channel formulated by
Claude Shannon in 1948. In the 1980s, he helped found the
International Association for Cryptologic Research (IACR). He is also the creator of the
Ramsey/
graph theory-based mathematical game
Sim. At Sandia, Simmons was primarily concerned with the command and control of
nuclear weapons, where the objective is to separate possession of a weapon from the ability to autonomously use it, something which should only be possible on receipt of an authenticated order from the National Command Authority, in using authentication to make possible the verification of compliance with various arms control treaties, and in the cryptographic aspects of verifying adherence to the
Comprehensive Test Ban Treaty for nuclear weapons. In a review of
Contemporary Cryptology (see publications),
Don Coppersmith summarized the problem: Is the host substituting a false signal to mask the fact that it is continuing tests? Is the monitor really using the device to transmit other information than that allowed by the treaty? Who supplies the hardware? Can that person cheat? ==Awards and recognition==