| A mobile agent is a multi-threaded autonomous program that can be distributed over a heterogeneous network to perform some predefined task for its human creator (user). The independence, flexibility and autonomy offered by the mobile agent paradigm hold many promises for the future of distributed computing [18]. However, for an agent to be autonomous, it must carry its code, states and results from host to host. Since an agent executes on remote potentially hostile environments, hiding information from hosts has proven to be a tough challenge.; This thesis introduces two novel ideas that can be used in the mobile agent paradigm. First, is the use of Shamir's [33] (t, n)-threshold secret sharing scheme for the distribution of the private key of a public/private key pair amongst n agents. Thus giving an agent the ability to use cryptographic primitives for protection of intermediate results obtained from previously visited hosts. An agent can use the public key for encryption while the private key is safely shared between the agent and its siblings. Second, a "cookie" will be introduced as an tool for avoiding agent collisions. Analogous to cookies used by web browsers for tracking of visitors to a site, it will be used as a tool for marking previously visited hosts. The goal of marking previously visited hosts is to resolve the problem of agent collisions. Agent collisions occurs when a group of agents from the same originator with the same purpose visits a particular host more than once. |
