More Efficient Adaptively Secure Lattice-based IBE with Equality Test in the Standard Model

Identity-based encryption with equality test (IBEET) is a variant of identity-based encryption (IBE), where any users who have trapdoors can check whether two ciphertexts are encryption of the same plaintext. Although several lattice-based IBEET schemes have been proposed, they have drawbacks in either security or efficiency. Specifically, most schemes satisfy only selective security, while adaptively secure schemes in the standard model suffer from large master public keys that consist of linear numbers of matrices. In other words, known lattice-based IBEET schemes perform poorly compared to the state-of-the-art lattice-based IBE schemes (without equality test). In this paper, we propose a semi-generic construction of CCA-secure lattice-based IBEET from a certain class of lattice-based IBE schemes. As a result, we obtain the first lattice-based IBEET schemes with adaptive security and CCA security in the standard model. Furthermore, our semi-generic construction can use several state-of-the-art lattice-based IBE schemes as underlying schemes. Then, we have adaptively secure lattice-based IBEET schemes whose public keys have only poly-log matrices

A Generic Construction of CCA-secure Attribute-based Encryption with Equality Test

Attribute-based encryption with equality test ($\mathsf{ABEET}$) is an extension of the ordinary attribute-based encryption ($\mathsf{ABE}$), where trapdoors enable us to check whether two ciphertexts are encryptions of the same message. Thus far, several CCA-secure $\mathsf{ABEET}$ schemes have been proposed for monotone span programs satisfying selective security under $q$-type assumptions. In this paper, we propose a generic construction of CCA-secure $\mathsf{ABEET}$ from delegatable $\mathsf{ABE}$. Specifically, our construction is an attribute-based extension of Lee et al.\u27s generic construction of identity-based encryption with equality test from hierarchical identity-based encryption. Even as far as we know, there are various delegatable $\mathsf{ABE}$ schemes. Therefore, we obtain various $\mathsf{ABEET}$ schemes with new properties that have not been achieved before such as various predicates, adaptive security, standard assumptions, compact ciphertexts/secret keys, and lattice-based constructions

A region of the sulfonylurea receptor critical for a modulation of ATP-sensitive K(+) channels by G-protein βγ-subunits

To determine the interaction site(s) of ATP-sensitive K(+) (K(ATP)) channels for G-proteins, sulfonylurea receptor (SUR2A or SUR1) and pore-forming (Kir6.2) subunits were reconstituted in the mammalian cell line, COS-7. Intracellular application of the G-protein βγ2-subunits (G(βγ2)) caused a reduction of ATP-induced inhibition of Kir6.2/SUR channel activities by lessening the ATP sensitivity of the channels. G(βγ2) bound in vitro to both intracellular (loop-NBD) and C-terminal segments of SUR2A, each containing a nucleotide-binding domain (NBD). Furthermore, a single amino acid substitution in the loop-NBD of SUR (Arg656Ala in SUR2A or Arg665Ala in SUR1) abolished the G(βγ2)-dependent alteration of the channel activities. These findings provide evidence that G(βγ) modulates K(ATP) channels through a direct interaction with the loop-NBD of SUR