A Secure ID-Based Explicit Authenticated Key Agreement Protocol without Key Escrow

Key agreement protocols are essential for secure communications in open and distributed environments. Identity-based cryptography has become extremely fashionable in the last few years for its special advantages. In this paper, we point out some flaw in the scheme proposed by Wang et al., then we present a two-party identity-based explicit authenticated key agreement protocol with key confirmation, which was inspired on a new identity-based encryption scheme first proposed by Gentry and can be used properly in the escrowless mode. The scheme captures the attributes of known-key secrecy, key-compromise impersonation resilience, unknown key-share resilience, perfect forward secrecy, and no-key control. Especially, the scheme captures the PKG forward secrecy property. The PKG still could not recover all the userspsila past session keys even he knows the long-term private keys of all users.