Browsing by Author "Chung, Kai-Min"

Now showing 1 - 3 of 3

Interactive Leakage Chain Rule for Quantum Min-entropy
(2019-01-01)
Lai, Ching-Yi
;
Chung, Kai-Min
;
電信工程研究所
;
Institute of Communications Engineering
The leakage chain rule for quantum min-entropy quantifies the change of min-entropy when one party gets additional leakage about the information source. Herein we provide an interactive version that quantifies the change of min-entropy between two parties, who share an initial classical-quantum state and are allowed to run a two-party protocol. As an application, we prove new versions of lower bounds on the complexity of quantum communication of classical information.
ON STATISTICALLY-SECURE QUANTUM HOMOMORPHIC ENCRYPTION
(2018-08-01)
Lai, Ching-Yi
;
Chung, Kai-Min
;
電信工程研究所
;
Institute of Communications Engineering
Homomorphic encryption is an encryption scheme that allows computations to be evaluated on encrypted inputs without knowledge of their raw messages. Recently Ouyang et al. constructed a quantum homomorphic encryption (QHE) scheme for Clifford circuits with statistical security (or information-theoretic security (IT-security)). It is desired to see whether an information-theoretically-secure (ITS) quantum FHE exists. If not, what other nontrivial class of quantum circuits can be homomorphically evaluated with IT-security? We provide a limitation for the first question that an ITS quantum FHE necessarily incurs exponential overhead. As for the second one, we propose a QHE scheme for the instantaneous quantum polynomial-time (IQP) circuits. Our QHE scheme for IQP circuits follows from the one-time pad.
Quantum encryption and generalized Shannon impossibility
(2019-09-01)
La, Ching-Yi
;
Chung, Kai-Min
;
電信工程研究所
;
Institute of Communications Engineering
The famous Shannon impossibility result says that any encryption scheme with perfect secrecy requires a secret key at least as long as the message. In this paper we provide its quantum analogue with imperfect secrecy and imperfect correctness. We also give a systematic study of information-theoretically secure quantum encryption with two secrecy definitions. We show that the weaker one implies the stronger but with a security loss in d, where d is the dimension of the encrypted quantum system. This is good enough if the target secrecy error is of o(d(-1)).