This book constitutes the refereed proceedings of the First International Workshop on Practice and Theory in Public Key Cryptography, PKC'98, held in Pacifico Yokohama, Japan, in February 1998.The volume presents four invited contributions together with 18 revised full papers selected from 30 submissions.

Distributed public key cryptosystems.- How (not) to design RSA signature schemes.- Overview of elliptic curve cryptography.- Lattices and cryptography: An overview.- A signcryption scheme with signature directly verifiable by public key.- Guaranteed correct sharing of integer factorization with off-line shareholders.- Lower bounds on term-based divisible cash systems.- Certifying trust.- On the security of server-aided RSA protocols.- On the security of ElGamal based encryption.- An authenticated Diffie-Hellman key agreement protocol secure against active attacks.- On the security of Girault's identification scheme.- A scheme for obtaining a message from the digital multisignature.- Secure hyperelliptic cryptosystems and their performance.- A practical implementation of elliptic curve cryptosystems over GF(p) on a 16-bit microcomputer.- Two efficient algorithms for arithmetic of elliptic curves using Frobenius map.- Public-key cryptosystems using the modular group.- A cellular automaton based fast one-way hash function suitable for hardware implementation.- A new hash function based on MDx-family and its application to MAC.- Security issues for contactless smart cards.- Parameters for secure elliptic curve cryptosystem -improvements on Schoof s algorithm.- A note on the complexity of breaking Okamoto-Tanaka ID-based key exchange scheme.