Cryptology ePrint Archive: Report 2003/164

Identity-Based Threshold Decryption

Joonsang Baek and Yuliang Zheng

Abstract: In this paper, we examine issues related to the construction of identity-based threshold decryption schemes and argue that it is important in practice to design an identity-based threshold decryption scheme in which a private key associated with an identity is shared. A major contribution of this paper is to construct the first identity-based threshold decryption scheme secure against chosen ciphertext attack. A formal proof of security of the scheme is provided in the random oracle model, assuming the Bilinear Diffie-Hellman problem is computationally hard. Another contribution of this paper is, by extending the proposed identity-based threshold decryption scheme, to construct a mediated identity-based encryption scheme secure against more powerful attacks than those considered previously.

Category / Keywords: cryptographic protocols /

Publication Info: A short version of this paper is to appear in the proceedings of PKC 2004.

Date: received 10 Aug 2003, last revised 23 Dec 2003

Contact author: joonsang baek at infotech monash edu au

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Note: This is a full version.

Version: 20031224:031929 (All versions of this report)

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