This book is the proceedings of CRYPTO 86, one in a series of annual conferences devoted to cryptologic research. They have all been held at the University of California at Santa Barbara. The first conference in this series, CRYPTO 81, organized by A. Gersho, did not have a formal proceedings. The proceedings of the following four conferences in this series have been published as: Advances in Cryptology: Proceedings of Crypto 82, D. Chaum, R. L. Rivest, and A. T. Sherman, eds., Plenum, 1983. Advances in Cryptology: Proceedings of Crypto 83, D. Chaum, ed., Plenum, 1984. Advances in Cryptology: Proceedings of CRYPTO 84, G. R. Blakley and D. Chaum, eds., Lecture Notes in Computer Science #196, Springer, 1985. Advances in Cryptology - CRYPTO '85 Proceedings, H. C. Williams, ed., Lecture Notes in Computer Science #218, Springer, 1986. A parallel series of conferences is held annually in Europe. The first of these had its proceedings published as Cryptography: Proceedings, Burg Feuerstein 1982, T. Beth, ed., Lecture Notes in Computer Science #149, Springer, 1983.