5 papers
Trapdoor Functions with Secure Key Leasing and Copy Protection
Fuyuki Kitagawa, Ryo Nishimaki, Yuki Shirakawa +1
Inspired by the no-cloning theorem in quantum theory, a variety of quantum cryptographic primitives with unclonable functionalities, such as secure key leasing and copy protection,…
Towards the Impossibility of Imperfectly Complete Key Agreement in the QROM
Fuyuki Kitagawa, Ryo Nishimaki, Agi Villanyi +1
We make progress towards the impossibility of imperfectly complete quantum-computation, classical-communication (QCCC) key agreement by constructing the first unconditional attacks…
Multi-Copy Security in Unclonable Cryptography
Alper Çakan, Vipul Goyal, Fuyuki Kitagawa +2
Unclonable cryptography leverages the quantum no-cloning principle to copy-protect cryptographic functionalities. While most existing works address the basic single-copy security,…
On the Cryptographic Futility of Non-Collapsing Measurements
Alper Cakan, Dakshita Khurana, Tomoyuki Morimae +3
We investigate quantum analogues of collision resistance and obtain separations between quantum ``one-way'' and ``collision-resistant'' primitives. 1. Our first result studies one-…
A Unified Approach to Quantum Key Leasing with a Classical Lessor
Fuyuki Kitagawa, Jiahui Liu, Shota Yamada +1
Secure key leasing allows a cryptographic key to be leased as a quantum state in such a way that the key can later be revoked in a verifiable manner. In this work, we propose a mod…