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Erschienen in:
2011 | OriginalPaper | Buchkapitel
The Twin Bilinear Diffie-Hellman Inversion Problem and Applications
verfasst von : Yu Chen, Liqun Chen
Erschienen in: Information Security and Cryptology - ICISC 2010
Verlag: Springer Berlin Heidelberg
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We propose a new computational problem and call it the
twin bilinear Diffie-Hellman inversion (BDHI) problem
. Inspired by the technique proposed by Cash, Kiltz and Shoup, we have developed a new trapdoor test which enables us to prove that the twin BDHI problem is at least as hard as the ordinary BDHI problem even in the presence of a decision oracle that recognizes a solution to the problem. The relation between the two problems implies that many of the cryptographic constructions based on ordinary BDHI problem can be improved with a tighter security reduction. As one such application, we present a new variant of Sakai-Kasahara Identity-Based Encryption (SK-IBE) with a simple and efficient security proof in the random oracle model, under the computational BDHI problem. We also present a new Identity-Based Key Encapsulation Mechanism (ID-KEM) based on SK-IBE, which has a better security analysis than previous results.