A Security Architecture for the Internet Protocol

In this paper we present the design, rationale, and implementation of a security architecture for protecting the secrecy and integrity of Internet traffic at the Internet Protocol (IP) layer. The design includes three components: (1) a security policy for determining when, where, and how security measures are to be applied; (2) a modular key management protocol, called MKMP, for establishing shared secrets between communicating parties and meta-information prescribed by the security policy; and (3) the IP Security Protocol, as it is being standardized by the Internet Engineering Task Force, for applying security measures using information provided through the key management protocol. Effectively, these three components together allow for the establishment of a secure channel between any two communicating systems over the Internet. This technology is a component of IBM's firewall product and is now being ported to other ISM computer platforms. A s the Internet evolves from an academic and research network into a commercial network, more and more organizations and individuals are connecting their internal networks and computers to it. The secrecy and integrity of the data transmitted over the Internet have become a primary concern , and cryptographic data encryption and authen-tication constitute the tools to address this concern. We subscribe to the view that the Internet Protocol (IP) layer' is a good place to secure the data being communicated. Reasons include: (1) The IP layer is at the choke point of Internet communication; it can capture all packets sent from the higher-layer protocols and applications and all packets received by the lower-layer network protocols. (2) By the very definition of IP, security provided at this layer is independent of lower-layer protocols. (3) Security provided at this layer can be made transparent to the higher-layer protocols and applications. Many application environments can benefit from security provided at the IP layer. Figure 1 depicts some of them, including mobile-to-base communication, telecommuting, and site-to-site or system-to-system communication. Three components are needed in order to provide IP layer security through cryptographic means: 1. A security policy to define the characteristics of the desired security. Such a policy specifies how the packets between two communicating systems must be protected. 2. A key managementprotocol to establish and maintain the necessary information as prescribed by the security policy. Such information usually includes cryptographic algorithms, secret keys, and other parameters shared between two communicating systems. 3. Aprotocol for security at the IP layer to protect …