Cryptology ePrint Archive: Report 2004/164

ID-based Cryptography from Composite Degree Residuosity

Man Ho Au and Victor K. Wei

Abstract: We present identity-based identification (resp. encryption, signature, blind signature,ring signature) from composite degree residuosity (CDR). Constructions of identifications and signatures motivated by several existing CDR-based bandwidth-efficient encryption schemes are presented. Their securities are proven equivalent to famous hard problems, in the random oracle model. Motivated by Cocks,we construct an identity-based encryption from CDR. Its security is proven equivalent to a new problem, the JSR (Jacobi Symbol of Roots of two quadratic polynomials) Problem. We prove JSR is at least as hard as QRP (Quadratic Residuosity Problem). Furthermore, we present the first two-way equivalence reduction of the security of Cocks' IBE, to the JSR Problem.

Category / Keywords: ID-based Cryptography

Date: received 12 Jul 2004, last revised 12 Jul 2004

Contact author: mhau3 at ie cuhk edu hk

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Version: 20040714:190534 (All versions of this report)

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