This paper presents a message authentication scheme built on top of an original construct that combines a simple form of identity based cryptography with an iterated version of RSA. Our scheme blends the features of identity based cryptography and stream authentication while at the same time o®ering security comparable to that of the
basic RSA cryptosystem. As opposed to other authentication schemes
available in the literature, our solution does not rely on any public key infrastructure and, like any identity based cryptosystems, it does not require public key certi¯cates. A basic security analysis, performance evaluation and storage requirements of our scheme are also provided in the
paper. Furthermore, we explore a challenging application of our scheme: a scalable and lightweight key distribution service that o®ers authentication services to an infrastructure-less ad hoc network and that can be coupled with existing secure routing solutions.