Robust Cryptography in the Noisy-Quantum-Storage Model

Previously, we demonstrated that cryptographic primitives can be implemented based on the assumption that quantum storage of qubits is noisy [Phys.Rev.Lett. 100, 220502 (2008)]. In this work, we analyze a protocol for the universal task of oblivious transfer that can be implemented using quantum-key-distribution (QKD) hardware in the practical setting where honest participants are unable to perform noise-free operations. We derive greatly improved trade-offs between the amount of storage noise, the amount of noise in the operations performed by the honest participants and the security of oblivious transfer with individual-storage attacks. As an example, we show that for the case of depolarizing noise in storage we can obtain secure oblivious transfer as long as the quantum bit-error rate of the channel does not exceed 11% and the noise on the channel is strictly less than the quantum storage noise. Finally, we show that our analysis easily carries over to quantum protocols for secure identification.