02103nas a2200229 4500008004100000022001400041245010900055210006900164260001500233300001700248490000700265520140200272653002101674653001901695653001201714653002501726653002901751653002101780100001701801700001601818856003901834 2016 eng d a0004-541100aRobust Protocols for Securely Expanding Randomness and Distributing Keys Using Untrusted Quantum Devices0 aRobust Protocols for Securely Expanding Randomness and Distribut c2016/10/26 a33:1–33:630 v633 a
Randomness is a vital resource for modern-day information processing, especially for cryptography. A wide range of applications critically rely on abundant, high-quality random numbers generated securely. Here, we show how to expand a random seed at an exponential rate without trusting the underlying quantum devices. Our approach is secure against the most general adversaries, and has the following new features: cryptographic level of security, tolerating a constant level of imprecision in devices, requiring only unit size quantum memory (for each device component) in an honest implementation, and allowing a large natural class of constructions for the protocol. In conjunction with a recent work by Chung et al. [2014], it also leads to robust unbounded expansion using just 2 multipart devices. When adapted for distributing cryptographic keys, our method achieves, for the first time, exponential expansion combined with cryptographic security and noise tolerance. The proof proceeds by showing that the Rényi divergence of the outputs of the protocol (for a specific bounding operator) decreases linearly as the protocol iterates. At the heart of the proof are a new uncertainty principle on quantum measurements and a method for simulating trusted measurements with untrusted devices.
10akey distribution10anonlocal games10aprivacy10aquantum cryptography10arandom-number generation10auntrusted device1 aMiller, Carl1 aShi, Yaoyun uhttp://doi.acm.org/10.1145/2885493