As long as BTSync does not betray you.<p>The idea is discussed for syncthing, <a href="https:&#x2F;&#x2F;github.com&#x2F;syncthing&#x2F;syncthing&#x2F;issues&#x2F;109" rel="nofollow">https:&#x2F;&#x2F;github.com&#x2F;syncthing&#x2F;syncthing&#x2F;issues&#x2F;109</a><p>There is a 880 USD bounty on it at <a href="https:&#x2F;&#x2F;www.bountysource.com&#x2F;issues&#x2F;1474343-support-for-file-encryption-e-g-non-trusted-servers" rel="nofollow">https:&#x2F;&#x2F;www.bountysource.com&#x2F;issues&#x2F;1474343-support-for-file...</a>