On Quantum and Approximate Privacy (Extended Abstract)
Hartmut Klauck · 2002
This paper studies privacy and secure function evaluation in communication complexity. The focus is on quantum versions of the model and on protocols with only approximate privacy against honest players. We show that the privacy loss (the minimum divulged informa- tion) in computing a function can be decreased exponentially by using quantum protocols, while the class of privately computable functions (i.e., those with privacy loss 0) is not increased by quantum protocols. Quantum communication combined with small information leakage on the other hand makes certain functions computable (almost) privately which are not computable using quantum communication without leak- age or using classical communication with leakage. We also give an ex- ample of an exponential reduction of the communication complexity of a function by allowing a privacy loss of o(1) instead of privacy loss 0.