This system already exists. * Wuala (using encryption but somewhat insecure deduplication) * SpiderOak (using more secure deduplication: https://spideroak.com

This system already exists. * Wuala (using encryption but somewhat insecure deduplication) * SpiderOak (using more secure deduplication: https://spideroak.com/blog/20100827150530-why-spideroak-doesnt-de-duplicate-data-across-users-and-why-it-should-worry-you-if-we-did https://spideroak.com/blog/20100827150530-why-spideroak-does...)