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Ochanomizu University

Academic institutionasia · jp
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Research library4linked papers
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Selected work

Representative Papers

PRA-TLS: Attestation of a Client Application for TEE

Oct 05, 2026

This study addresses the risk of tampering by untrusted applications at Trusted Execution Environment (TEE) interaction boundaries by proposing the PRA-TLS protocol. For the first time, this work extends remote attestation to the client application layer, employing a customized Attester Daemon to perform runtime measurements of both host and application states. This approach establishes an end-to-end chain of trust, ensuring that only legitimate environments can invoke enclaves. A prototype implementation is developed using Intel SGX, accompanied by comprehensive performance evaluations. Furthermore, the protocol’s security properties are formally verified using the Tamarin Prover. The results demonstrate that the proposed scheme achieves rigorous security guarantees and effectively defends against input and output tampering attacks.

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Stabilizing Private LASSO under Heterogeneous Covariates via Anisotropic Objective Perturbation

May 02, 2026

This work addresses the instability of objective perturbation in high-dimensional LASSO under differential privacy, which arises from heterogeneity in covariate scales and compromises both estimation accuracy and privacy guarantees. The authors propose an anisotropic objective perturbation method based on the Gram matrix, employing a “pre-distortion” strategy to counteract perturbation distortions induced by covariate structure and thereby restore isotropy in the estimation process. Notably, this approach directly incorporates structural information of the covariates into the perturbation mechanism, eliminating the need for privacy-budget-consuming data preprocessing. By integrating the algorithm within an approximate message passing (AMP) framework and leveraging state evolution analysis, the method achieves significantly improved convergence stability, statistical efficiency, and privacy performance while maintaining rigorous differential privacy guarantees.

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Meta Theorem for Hardness on FCP-Problem

Apr 16, 2025

This paper addresses the computational complexity of the Fewest Clues Problem (FCP) variant for NP-complete problems, specifically asking whether the FCP variant of every NP-complete problem is Σ₂^p-complete—a long-standing open question, previously resolved only for isolated cases. Method: We introduce the first general metatheorem that characterizes sufficient structural conditions for Σ₂^p-completeness of FCP variants, integrating polynomial-time reductions, second-order Boolean logic modeling, and constructive Σ₂^p-completeness techniques. Contribution/Results: We rigorously establish Σ₂^p-completeness for the FCP variants of canonical NP-complete problems—including SAT and Vertex Cover—and derive a reusable hardness certification framework. This resolves the open problem in full generality, providing both a foundational theoretical basis and practical tools for future analysis of FCP variants.

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Recent publications

Latest Papers

PRA-TLS: Attestation of a Client Application for TEE

Oct 05, 2026

This study addresses the risk of tampering by untrusted applications at Trusted Execution Environment (TEE) interaction boundaries by proposing the PRA-TLS protocol. For the first time, this work extends remote attestation to the client application layer, employing a customized Attester Daemon to perform runtime measurements of both host and application states. This approach establishes an end-to-end chain of trust, ensuring that only legitimate environments can invoke enclaves. A prototype implementation is developed using Intel SGX, accompanied by comprehensive performance evaluations. Furthermore, the protocol’s security properties are formally verified using the Tamarin Prover. The results demonstrate that the proposed scheme achieves rigorous security guarantees and effectively defends against input and output tampering attacks.

0 citationsRead paper

Stabilizing Private LASSO under Heterogeneous Covariates via Anisotropic Objective Perturbation

May 02, 2026

This work addresses the instability of objective perturbation in high-dimensional LASSO under differential privacy, which arises from heterogeneity in covariate scales and compromises both estimation accuracy and privacy guarantees. The authors propose an anisotropic objective perturbation method based on the Gram matrix, employing a “pre-distortion” strategy to counteract perturbation distortions induced by covariate structure and thereby restore isotropy in the estimation process. Notably, this approach directly incorporates structural information of the covariates into the perturbation mechanism, eliminating the need for privacy-budget-consuming data preprocessing. By integrating the algorithm within an approximate message passing (AMP) framework and leveraging state evolution analysis, the method achieves significantly improved convergence stability, statistical efficiency, and privacy performance while maintaining rigorous differential privacy guarantees.

0 citationsRead paper

Meta Theorem for Hardness on FCP-Problem

Apr 16, 2025

This paper addresses the computational complexity of the Fewest Clues Problem (FCP) variant for NP-complete problems, specifically asking whether the FCP variant of every NP-complete problem is Σ₂^p-complete—a long-standing open question, previously resolved only for isolated cases. Method: We introduce the first general metatheorem that characterizes sufficient structural conditions for Σ₂^p-completeness of FCP variants, integrating polynomial-time reductions, second-order Boolean logic modeling, and constructive Σ₂^p-completeness techniques. Contribution/Results: We rigorously establish Σ₂^p-completeness for the FCP variants of canonical NP-complete problems—including SAT and Vertex Cover—and derive a reusable hardness certification framework. This resolves the open problem in full generality, providing both a foundational theoretical basis and practical tools for future analysis of FCP variants.

0 citationsRead paper