NTT Basic Research Laboratories, NTT Corporation, 3-1 Morinosato-Wakamiya, Atsugi, Kanagawa, 243-0198, Japan.
Department of Physics, Graduate School of Science, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-0033, Japan.
Nat Commun. 2018 Apr 13;9(1):1450. doi: 10.1038/s41467-018-03729-4.
Cryptographic protocols are the backbone of our information society. This includes two-party protocols which offer protection against distrustful players. Such protocols can be built from a basic primitive called oblivious transfer. We present and experimentally demonstrate here a quantum protocol for oblivious transfer for optical continuous-variable systems, and prove its security in the noisy-storage model. This model allows us to establish security by sending more quantum signals than an attacker can reliably store during the protocol. The security proof is based on uncertainty relations which we derive for continuous-variable systems, that differ from the ones used in quantum key distribution. We experimentally demonstrate in a proof-of-principle experiment the proposed oblivious transfer protocol for various channel losses by using entangled two-mode squeezed states measured with balanced homodyne detection. Our work enables the implementation of arbitrary two-party quantum cryptographic protocols with continuous-variable communication systems.
加密协议是我们信息社会的支柱。这包括两方协议，可以为不信任的参与者提供保护。这种协议可以由一个叫做不经意传输的基本原语构建。我们在这里提出并实验证明了一种用于光学连续变量系统的不经意传输的量子协议，并在噪声存储模型中证明了其安全性。该模型允许我们通过发送比攻击者在协议期间可靠存储的更多量子信号来建立安全性。安全证明基于我们为连续变量系统推导出的不确定性关系，这些关系与量子密钥分发中使用的关系不同。我们通过使用平衡零差探测测量的纠缠双模压缩态，在各种信道损耗的原理验证实验中实验证明了所提出的不经意传输协议。我们的工作使得使用连续变量通信系统实现任意两方量子密码协议成为可能。
