Avoiding Key Off-Set attack in a Pairing-Free Certificateless Key Agreement Protocol based on ECC

A key establishment protocol allows entities to establish a common secret key to ensure secure communications over an insecure public network.This paper proposes two new twoparty key agreement protocols.Both protocols do not involve bilinear pairings.The first protocol is a certificate-based key agreement protocol that is more efficient than [1] due to its dependence on the elliptic curve discrete logarithm problem and the second is an extension to a certificateless key agreement protocol.Both protocols depend on the use of an authentication message to check that the shared session key is equal for both entities before using it.This authentication message prevents the key off-set attack that is valid for the Haiyan-Sun protocol [2].The security analysis of the second protocol is discussed.The proposed certificateless key agreement protocol is compared with other protocols in literature [2,3,4] and it requires minimal computational cost.Moreover, this protocol is implemented using the Mathematica (7) program.