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International Multi-Symposiums on Computer and Computational Sciences

An Improvement of an Identity-Based Key Issuing Protocol

Feng Cao, Zhenfu Cao, Licheng Wang

Published Jun 1, 2006• 6 citations
Publisher

Abstract

At TCP ADS 2005, Sui et al. proposed a novel separable and anonymous ID-based key issuing scheme without secure channel, and claimed the key-escrow problem has been solved. In this paper, we present a security analysis on their schemes and point out that their two protocols are not secure and they do not solve the key-escrow problem. Further, we present an improved key issuing protocol which is proved to be secure against adaptive chosen message attack without the random oracle model under the q - SDH assumption

DOI
10.1109/imsccs.2006.185

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Two improved identity-based key issuing protocols

Pla Information

The attack methods of two identity-based key issuing protocols are presented,and the conclusion that key generator center can compute secret key of any users is introduced.Two improved schemes are proposed in which the secret key of user is produced by the secret parameters of user and key generator center,and the reality of messages are varified in every step of the potocols,thereby,key generator center cannot get the secret key of users and the problem of secret key escrow is solved.The safety and computational complexity of improved schemes are analyzed.

•Jan 1, 2008•0 citations
At TCP ADS 2005, Sui et al. proposed a novel separable and anonymous ID-based key issuing scheme without secure channel, and claimed the key-escrow problem has been solved. In this paper, we present a security analysis on their schemes and point out that their two protocols are not secure and they do not solve the key-escrow problem. Further, we present an improved key issuing protocol which is proved to be secure against adaptive chosen message attack without the random oracle model under the q - SDH assumption
In this paper we analyze an ID-based key issuing protocol due to Gangishetti et al., designed for eliminating the need of secure channel between PKG and users and avoiding the key escrow problem. Their protocol consists of five sub-protocols, namely system setup, system public key setup, key issuing, key securing and key retrieving. We show that both the key issuing and the key securing sub-protocols suffer from impersonation attacks. Further, we present an improved key issuing protocol which is proved to be secure against adaptive chosen message attack in the random oracle model under the CDH assumption
Key issuing protocols deal with overcoming the two inherent problems: key escrow and secure channel requirement of the identity based cryptosystems. An efficient and secure key issuing protocol enables the identity-based cryptosystems to be applicable in the real world. We analyze an threshold key issuing protocol due to Gangishetti et al. and show that the protocol suffers from the attacks of the malicious KGC and the users can deny that they have never received the key. Furthermore, we present an improved protocol, which is undeniable and secure against KGC's attacks.
Key issuing protocols deal with overcoming the two inherent problems: key escrow and secure channel requirement of the identity based cryptosystems. An efficient and secure key issuing protocol enables the identity-based cryptosystems to be applicable in the real world. We analyze an threshold key issuing protocol due to Gangishetti et al. and show that the protocol suffers from the attacks of the malicious KGC and the users can deny that they have never received the key. Furthermore, we present an improved protocol, which is undeniable and secure against KGC's attacks.
The attack methods of two identity-based key issuing protocols are presented,and the conclusion that key generator center can compute secret key of any users is introduced.Two improved schemes are proposed in which the secret key of user is produced by the secret parameters of user and key generator center,and the reality of messages are varified in every step of the potocols,thereby,key generator center cannot get the secret key of users and the problem of secret key escrow is solved.The safety and computational complexity of improved schemes are analyzed.