Certificateless public key cryptography simplifies the complex certificate
management in the traditional public key cryptography and resolves the key
escrow problem in identity-based cryptography. Many certificateless
authenticated key agreement protocols using bilinear pairings have been
proposed. But the relative computation cost of the pairing is approximately
twenty times higher than that of the scalar multiplication over elliptic curve
group. Recently, several certificateless authenticated key agreement protocols
without pairings were proposed to improve the performance. In this paper, we
propose a new certificateless authenticated key agreement protocol without
pairing. The user in our just needs to compute five scale multiplication to
finish the key agreement. We also show the proposed protocol is secure in the
random oracle model
