Goichiro Hanaoka

Efficient key encapsulation mechanisms with tight security reductions to standard assumptions in the two security models

2016 · Security and Communication Networks

Abstract In this paper, we propose two new practical constructions of chosen ciphertext attack secure (CCA secure) key encapsulation mechanisms (KEM, which is the main building block for public key encryption in hybrid encryption), with …

A New Combiner for Key Encapsulation Mechanisms

2019 · IEICE Transactions on Fundamentals of Electronics Communications and Computer Sciences

Key encapsulation mechanism (KEM) combiners, recently formalized by Giacon, Heuer, and Poettering (PKC'18), enable hedging against insecure KEMs or weak parameter choices by combining ingredient KEMs into a single KEM that remains secure assuming just …

A privacy-enhanced access log management mechanism in SSO systems from nominative signatures

2017 · International Journal of Applied Cryptography

In online services, a service provider (SP) manages access logs containing customers' buying histories. Therefore, user's information is revealed from the exposed logs if each customer can be linked. In fact, such information exposure has …

On Key Substitution Attacks against Aggregate Signatures and Multi-Signatures

2025

When we use signature schemes in practice, we sometimes should consider security beyond unforgeability. This paper considers security against key substitution attacks of multi-signer signatures (i.e., aggregate signatures and multi-signatures). Intuitively, this security property ensures …