Secure group communication is significant for wireless and mobile computing. Overheads can be reduced efficiently when a sender sends multiple messages to multiple recipients using multi-recipient signcryption schemes. In this paper, we proposed the formal definition and security model of multirecipient signcryption, presented the definition of reproducible signcryption and proposed security th...

Signcryption is a cryptographic primitive which performs encryption and signature in a single logical step. In conventional signcryption only receiver of the signcrypted text can verify the authenticity of the origin i.e. signature of the sender on the message after decrypting the cipher text. In public verifiable signcryption scheme anyone can verify the authenticity of the origin who can acce...

In ATC 2007, an identity based signcryption scheme for multiple receivers was proposed by Yu et al. In this paper, we first show that Yu et al.’s signcryption scheme is insecure by demonstrating an universal forgeability attack anyone can generate a valid signcryption on any message on behalf of any legal user for any set of legal receivers without knowing the secret keys of the legal users. Al...

Since Al-Riyami and Paterson presented certificateless cryptography, many certificateless schemes have been proposed for different purposes. In this paper, we present a certificateless group oriented signature scheme based on bilinear pairing. In our scheme, only the members in the same group with the signer can independently verify the signature. We prove the signature scheme is existential un...

To avoid the inherent key escrow problem in ID-based public key cryptosystem, Al-Riyami and Paterson introduced a new approach called certificateless public key cryptography. Recently, several short certificateless signature schemes are presented to improve the performance. In this paper, we propose an efficient short certificateless signature scheme which is secure against the super adversary....

The aim of this paper is to provide an overview for the research that has been done so far in signcryption area. The paper also presents the extensions for the signcryption scheme and discusses the security in signcryption and the practical application of signcryption in real life. Because the elliptic curve cryptography became the newest and most efficient method for public key cryptography, i...

Certificateless cryptosystem is a hybrid scheme of traditional PKI and ID-based scheme and has positive aspects of both of PKI and ID-based cryptosystem, i.e. solving key escrow problem and certificate management problem simultaneously. Cryptographic schemes constructed in such a hybrid setting, generally called certificateless setting, retain these positive aspects and have been extensively st...

Petersen and Michels showed that Zheng’s signcryption schemes lose confidentiality to gain nonrepudiation. They also proposed another signcryption scheme modified from a signature scheme giving message recovery. The authors show that the Petersen-Michels scheme still violates the unforgeability property, and propose an improvement that overcomes the security leak inherent in the scheme. The imp...