International Association
for Cryptologic Research

In this article we propose an identity based key agreement protocol based on elliptic curve cryptography (ECC) between users of different networks with independent private key generations (PKGs). Our protocol is based on Cao et al.\'s protocol ,proposed in 2010, in which instead of bilinear pairings, elliptic curves are used for constructing an ID-based key agreement protocol . Our protocol develops Cao et al\'s protocol for situations that two users of independent organizations or networks with separate servers (that in this article, are named PKGs, because their main duty is generating private keys for the users) want to share a secret key via an insecure link. We also prove the security of the protocol in the random oracle model.