Leaving aside the fact that Tarsnap is based in Canada (since really, I doubt CSIS has any more qualms about asking for data than the NSA does), the whole point

Leaving aside the fact that Tarsnap is based in Canada (since really, I doubt CSIS has any more qualms about asking for data than the NSA does), the whole point of Tarsnap is that I can't reveal customer data because -- unlike Dropbox -- data stored using Tarsnap is encrypted using keys which only the customer holds.