-----BEGIN PGP SIGNED MESSAGE----- I think we're pretty well agreed that Dave's DataHaven can't ensure that files are encrypted without looking inside them at some point. It's a dilemma: Dave wants to be sure he can't read something, but the only way he can be sure is by reading it. But suppose that Dave's good friend Ender Trent decides to set up a new service, Ender Trent's Trusted Encryption. It's a simple job: people send files to Ender and he returns them encrypted and signed. Now, all Dave needs do is check Ender's signature before accepting a file. At no point does Dave ever decrypt or attempt to decrypt such a file. Ender offers encryption in many different forms. In the simplest, Alice sends the file to Ender, Ender generates a random key, encrypts the file, and sends both back to Alice. Almost as simple, Ender uses the hash of the original file as the key. Presumably, Alice already knows the hash and so Ender doesn't send that back. Alice could supply a public PGP (or other asymmetrical algorithm) key with the file and Ender uses that. If Alice is a frequent customer and likes this method, she might register the key with Ender. Lastly, Alice might want to supply a symmetric key of her own. Because Ender wants to protect people like Dave, he can either print a warning that the key used for encryption might not be secure, or run a password-cracking algorithm on it, or both. Because of the extra effort and reduced security, Ender might not want to offer this, or charge an arm and a leg for it. And Dave might not be willing to accept such files, anyway. How is it better to have Ender do all this rather than Dave? Essentially, it splits the risk. Dave never sees the files, and therefore can't be responsible for their contents. Nor could he make sense out of them, even if he tried really, really hard. He could operate his data haven in all but the most repressive parts of the world. Ender's risk is slim to none. Were he to be held accountable for files he encrypts, public notaries would likewise have to be held accountable for everything they notarize. I don't see that as a problem. Dave might wish to offer an encryption service, as Ender might want to offer a data haven, but, if they're smart, they won't accept files that they themselves encrypted. Ender's encryption need not only be for data havens, of course. Nervous remailer operators might want proof of encryption. Escrow services will likely like Ender. And probably more. If there is a demand for a trusted encryption service, I'll create one after the second trumpet audition for the Oregon Symphony on the first of the month. That's the main reason I'm signing this--to hold myself to it. b& -----BEGIN PGP SIGNATURE----- Version: 2.6.2 iQEUAwUBLxrj5a7gd9aHWwWVAQH2Hgf0CF+0CIMWiK7d52Gaa8fPpMQy+qAYOBj+ MxJPZJpwxLEzmdT8n+dWjz2+0uPbIXXYa8yEM86UeV9++BzNM7WkOr5tezUuUrYa aM+I4yWJEz/oUpURxi4tt1Jmxn4F0IGQENBweIw+lsgU/TyNweCerKoShLpP4zca iZr1HtkK/7KdEi/wmADtfI6aUHytRyMXYvwKhKiy23eAFyNtZgAz4i77p2Kw6iM6 aTGsQQVjda6AYcVlIcLAJN8v+pQV+RGKA4FGACsxEGHDCQvFd3/WvCD4pupPm80E 9QLhQ2zLIjAkSmkO9flndXq6TOcCtMd3f6u/oGCx1EHKUTdP8nbg =svFy -----END PGP SIGNATURE----- -- Ben.Goren@asu.edu, Arizona State University School of Music Finger ben@tux.music.asu.edu for PGP public key ID 0x875B059.