IACR News item: 30 April 2014
Yu Chen, Qiong Huang, Zongyang Zhang
ePrint ReportIn this work, we intensively revisit the SOK IB-NIKE scheme, and present a series of possible and impossible results in the random oracle model and the standard model. In the random oracle model, we first improve previous security analysis for the SOK IB-NIKE scheme by giving a tighter reduction. We then use meta-reduction technique to show that the SOK scheme is unlikely proven to be secure based on the computational bilinear Diffie-Hellman (CBDH) assumption without programming the random oracle. In the standard model, we show how to instantiate the random oracle in the SOK scheme with a concrete hash function from admissible hash functions (AHFs) and indistinguishability obfuscation.
The resulting scheme is fully adaptive-secure based on the decisional bilinear Diffie-Hellman inversion (DBDHI) assumption. To the best of our knowledge, this is first fully adaptive-secure IB-NIKE scheme in the standard model that does not explicitly require multilinear maps. Previous schemes in the standard model either have merely selective security or use multilinear maps as a key ingredient. Of particular interest, we generalize the definition of AHFs, and propose a generic construction which enables AHFs with previously unachieved parameters.
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