Flexible Internet Secure Transactions Based on Collaborative Domains

Abstract. The absence of manageable global key distribution schemes is seriously hindering the deployment of basic security services in the In-ternet. The emergence of cryptosystems based on public key technology has represented a signicant improvement in this direction by removing the need of a mutual agreement on the encryption key. However, the certi cate structures that bind a user to his public key are dicult to deploy especially in inter-domain environments. As a consequence, al-though the need for security services like encryption or authentication is becoming crucial, most Internet transactions currently take place with-out the use of any of these services. This paper proposes a novel approach for simplifying key manageability relying on the notion of security do-mains. The fundamental idea relies on the fact that key management and thus security services are easier to achieve inside a well conned domain. Consequently, large scale security might be seen as a combination of intra-domain security and a secure framework for transactions between domains. In other words, user keys are managed internally and only do-main keys need to be handled globally. We present the cryptographic schemes needed to achieve condentiality and authentication based on the collaboration of security domains.