The role of cryptography as a central component in the design, analysis and implementation of secure systems and communications is clear today. The wide applicability of cryptography raises issues ranging from the creation of pure mathematical objects to the detailed engineering specification of complex cryptographic systems. Theoretical analysis and mathematical proof play an essential role in backing the security of cryptographic systems. In contrast to many other engineering areas, applied cryptography cannot use simulations or other empirical methods to ``prove'' that a given cryptographic construct meets its alleged security properties. It requires a mathematical proof based on a careful modeling of the security objectives of the construct and of the attacker capabilities. This situation gives rise to a challenging role for crypto theory: to provide models and constructions that represent in a satisfactory way the needs of actual cryptographic practice. In particular, the need to come up with relatively simple and efficient constructions while not giving up in the essential role of sound mathematical analysis. As a result of this close relationship between theory and practice in the cryptography and security areas, we have seen in recent years an increased in.uence of the crypto community in the development of standards and other widely used security systems. This workshop is intended to highlight, expose and encourage work that has a signi.cant theoretical analysis component and, at the same time, has meaningful implications and relevance to practical cryptographic and security schemes. Work that highlights the cryptographic requirements of security systems will be solicited as well. It is expected that the interaction among cryptographic and security experts will increase the awareness of the need of sound cryptography at the basis of actual security systems and will contribute to a better understanding by the crypto community of the actual needs of practical security systems.