Cryptology ePrint Archive: Report 2012/483

An Efficient Signcryption Scheme from q-Diffie-Hellman Problems

Jayaprakash Kar

Abstract: Confidentiality and authenticity are two fundamental security requirement of Public key Cryptography. These are achieved by encryption scheme and digital signatures respectively. Here we present a provably secure signcryption scheme in random oracle model by modifying Libert et al's scheme [2]. Our scheme is more e±cient and secure than Libert et al's scheme. Tan [1] proved that this scheme is not secure against non-adaptive chosen cipher text attacks. It has been also proved that the semantically secure symmetric encryption scheme proposed in the Libert et al's scheme is not su±cient to guarantee to be secure against adaptive chosen ciphertext attacks. Here we proposed a modified version of Libert et al's scheme. The security of which is proven using two as- sumptions, namely the Strong Diffie-Hellman (SDH) and Diffie-Hellman Inversion (DHI) in the random oracle model.

Category / Keywords: cryptographic protocols / Isomorphism, Bilinear Pairing, provably secure, DHP, SDH.

Date: received 21 Aug 2012

Contact author: jayaprakashkar at yahoo com

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Version: 20120821:230519 (All versions of this report)

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