quantum cryptography based solely on bells theorem文档.pdf

Quantum Cryptography Based Solely on Bell’s Theorem Esther H¨anggi1 Renato Renner2 Stefan Wolf 3 1 Computer Science Department, ETH Zurich, CH-8092 Zurich, Switzerland. E-mail: esther.haenggi@inf.ethz.ch 2 Institute for Theoretical Physics, ETH Zurich, CH-8093 Zurich, Switzerland. E-mail: renner@phys.ethz.ch 3 Computer Science Department, ETH Zurich, CH-8092 Zurich, Switzerland. E-mail: wolf@inf.ethz.ch Abstract. Information-theoretic key agreement is impossible to achieve from scratch and must be based on some — ultimately physical — premise. In 2005, Barrett, Hardy, and Kent showed that unconditional 0 security can be obtained in principle based on the impossibility of faster-than-light signaling; however, 1 their protocol is inefficient and cannot tolerate any noise. While their key-distribution scheme uses 0 quantum entanglement, its security only relies on the impossibility of superluminal signaling, rather 2 than the correctness and completeness of quantum theory. In particular, the resulting security is device independent. Here we introduce a new protocol which is efficient in terms of both classical and quantum n communication, and that can tolerate noise in the quantum channel. We prove that it offers device- a J independent security under the sole assumption that certain non-signaling conditions are satisfied. Our main insight is that the XOR of a number of bits that are partially secret according to the