|Abstract: Okamoto and I presented a fully secure functional encryption (FE) scheme for a wide class of relations, that are specified by non-monotone access structures combined with inner-product relations in CRYPTO 2010. The security is proven under a standard assumption, the decisional linear (DLIN) assumption, in the standard model. We developed a new technique to prove the security based on the DLIN assumption in a hierarchical manner. This provides a new methodology of employing a simple assumption defined on primitive groups to prove the security of a complicated scheme that is designed on a higher level concept, dual pairing vector spaces. Based on the methodology, we also presented a fully secure (adaptive-predicate unforgeable and private) attribute-based signature
(ABS) scheme in the standard model in PKC 2011. I will talk about the new methodology for FE and ABS.