Efficient Methods for Privacy Preserving Face Detection

Bob offers a face-detection web service where clients can submit their images for analysis. Alice would very much like to use the service, but is reluctant to reveal the content of her images to Bob. Bob, for his part, is reluctant to release his face detector, as he spent a lot of time, energy and money constructing it. Secure Multi- Party computations use cryptographic tools to solve this problem without leaking any information. Unfortunately, these methods are slow to compute and we intro- duce a couple of machine learning techniques that allow the parties to solve the problem while leaking a controlled amount of information.