Cryptology ePrint Archive: Report 2012/392

ID Based Signcryption Scheme in Standard Model

S. Sharmila Deva Selvi and S. Sree Vivek and Dhinakaran Vinayagamurthy and C. Pandu Rangan

Abstract: Designing an ID based signcryption scheme in the standard model is among the most interesting and important problems in cryptography. However, all the existing systems in the ID based setting, in the standard model, do not have either the unforgeability property or the indistinguishability property or both of them. In this paper, we present the first provably secure ID based signcryption scheme in the standard model with both these properties. The unforgeability property of this scheme is based on the hardness of Computational Diffie-Hellman problem and the indistinguishability property of this scheme is based on the hardness of Decisional Bilinear Diffie-Hellman problem. Our scheme is strongly unforgeable in the strong attack mode called insider security. Moreover, our scheme possess an interesting property called public verifiability of the ciphertext. Our scheme integrates cleverly, a modified version of Waters' IBE and a suitably modified version of the ID based signature scheme in the standard model proposed by Paterson et al. However, our security reductions are more efficient. Specifically, while the security reductions for indistinguishability is similar to the bounds of Waters' scheme, the unforgeability reductions are way better than the bounds for Paterson et al.'s scheme.

Category / Keywords: public-key cryptography / Provable Security, ID based signcryption, Strong Unforgeability, Standard Model, Public Ciphertext Verifiability, Insider Security

Publication Info: Full version of a paper appearing in ProvSec 2012

Date: received 16 Jul 2012

Contact author: dhinakaran2705 at gmail com

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Version: 20120720:211101 (All versions of this report)

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