On the Relations Between Diffie-Hellman and ID-Based Key Agreement from Pairings

This paper studies the relationships between the traditional Diffie-Hellman key agreement protocol and the identity-based (ID-based) key agreement protocol from pairings. For the Sakai-Ohgishi-Kasahara (SOK) ID-based key construction, we show that identical to the Diffie-Hellman protocol, the SOK key agreement protocol also has three variants, namely \emph{ephemeral}, \emph{semi-static} and \emph{static} versions. Upon this, we build solid relations between authenticated Diffie-Hellman (Auth-DH) protocols and ID-based authenticated key agreement (IB-AK) protocols, whereby we present two \emph{substitution rules} for this two types of protocols. The rules enable a conversion between the two types of protocols. In particular, we obtain the \emph{real} ID-based version of the well-known MQV (and HMQV) protocol. Similarly, for the Sakai-Kasahara (SK) key construction, we show that the key transport protocol underlining the SK ID-based encryption scheme (which we call the "SK protocol") has its non-ID counterpart, namely the Hughes protocol. Based on this observation, we establish relations between corresponding ID-based and non-ID-based protocols. In particular, we propose a highly enhanced version of the McCullagh-Barreto protocol

Cryptanalysis of an e_cient three-party password-based key exchange scheme

AbstractIn order to secure communications between two clients with a trusted server's help in public network environments, a three-party password-based authenticated key exchange (3PAKE) scheme is used to provide the transaction confidentiality and e_ciency. In 2010, Lou-Huang proposed a new simple three-party password-based authenticated key exchange (LH-3PAKE) scheme based on elliptic curve cryptography (ECC). By analysis, Lou-Huang claimed that the proposed LH- 3PAKE scheme is not only secure against various attacks, but also more e_cient than previously proposed 3PAKE schemes. However, this paper demonstrates LH-3PAKE scheme is vulnerable to o_-line password guessing attacks by an attacker