Insider-secure Hybrid Signcryption SchemeWithout Random Oracles

Abstract

Confidentiality and authenticity are two important security requirements in most secure systems. To efficiently provide data privacy (confidentiality) and (data/user) authenticity simultaneously, the notion of signcryption scheme was first introduced by Zheng in 1997. The security model for signcryption scheme was proposed by Baek et al. and An et al. in 2002 independently. Since then, many signcryption schemes were proposed; they are either a public-key signcryption or a hybrid signcryption. But, only few proposed signcryption schemes were supposed to be in the insider security, for example, Libert-Quisquater's signcryption schemes at PKC'2004 and SCN'2004 respectively and Yang-Wong-Deng's signcryption scheme at ISC'2005. Although all the above mentioned signcryption schemes were proved insider-secure against adaptive chosen ciphertext attack in the random oracle models, Tan showed that all the above mentioned signcryption schemes were not insidersecure against adaptive chosen ciphertext attack in 2005 and 2006 respectively. Up to our knowledge, it seems that none of insider-secure hybrid signcryption scheme is constructed without random oracles. In this paper, we proposed a hybrid signcryption scheme and showed that the proposed scheme is insider-secure without random oracles.2 It is noted that Dent's signcryption scheme is not "fully" insider-Second International Conference on Availability, Reliability and Security (ARES'07) 0-7695-2775-2/07 $20.00 © 2007 Pr[ Hk(y) = Hk(x) and y = x : given x ∈ {0, 1}l, choosek ∈K; y ← A(Hk) ] ≥ tcr . Definition 3 (Key Derivation Function). Let KDF : K → K 1 × K 2 be a key derivation function from a key space K to key spaces K 1 ×K 2 . We say that a key derivative function is ( kdf , t)-secure if no t-polynomial time algorithm A, which Second International Conference on Availability, Reliability and Security (ARES'07) 0-7695-2775-2/07 $20.00

Efficient signcryption in the standard model

“…In 2007, Tan proposed a hybrid signcryption scheme in the standard model using a key derivation function, a one‐time message authentication code, a one‐time symmetric key encryption scheme, and a strongly unforgeable signature scheme in the standard model . This signcryption scheme is a hybrid construction.…”

“…Compared with Tan's schemes, , Li et al 's corresponding schemes have 20 % faster speed in the key encapsulation, 33 % faster speed in the key decapsulation, 33 % shorter public key, 60 % shorter private key, and | p | bits shorter ciphertext. All of these schemes are hybrid construction. In 2008, Tan proposed a signcryption scheme based on the Boneh and Boyen's identity‐based encryption scheme and the Boneh and Boyen's short signature scheme .…”

Implementation of Schnorr Signcryption Algorithm on DSP

“…Even if the receiver's private key is discovered, the attacker will not be able to know the real message from the ciphertext. The other type of security which is the outsider security, it means to keep protecting from the third party's attacks, as the attacker knows the public keys of the sender and receiver of the message [18].…”