If you use Carbonite, you're considerably braver than I am. Carbonite has no effective technological security, so you'd better hope that nobody breaks into their offices, none of their employees "go bad", and they're never confronted by a subpoena or have the PATRIOT act invoked against them; and they only keep the latest version of any file, so if you ever accidentally mangle a file you'd better hope that you can retrieve the unmangled version before Carbonite backs up the mangled version and throws away the older copy.
Right, but they're secure enough for most people. Think about it, the chances that someone gets access to my own computer (stealing it, breaking into my home, or hacking it over the Internet) are higher than the chances of that happening to a professional service provider. At least that's the case for most computer users. I heard recently that 25% of all computers in the world are zombified. So much for security on your own computer.
But anyway, that's why I said if you can improve on their offering then go for it. Given the current options, they're the best that I know of; and I say that knowing that they have a lot to improve. So, if you build a better service, I'd consider switching.
If you get a subpoena for a passphrase for a client, you will give it up. Yes you will. Now, if someone was holding terroristic bombcodes or whatever and REALLY didn't want people getting them, they ain't backing up anything online. The same people who need real security aren't going to be uploading their data anywhere .
"If you get a subpoena for a passphrase for a client, you will give it up."
Not if I don't have it. This is the point of strong security -- you don't NEED to trust me, because I am not technically capable (nor, unless I'm quite mistaken, is the NSA) of decrypting data backed up using tarsnap.
