[FDE] administrative recovery

[Mike Markowitz]

At 09:34 AM 4/24/2007, dan at geer.org wrote:

>So far as I know, no recovery mechanism uses threshhold
>cryptography ("split-key"), but I'd be intrigued if any
>did.

While not exactly an FDE product, SecretAgent has supported a DH/ECDH
certificate-based split-key (or secret sharing) scheme for key recovery
since sometime in the mid '90s. Idea is simply to successively wrap
the "session key" in each key recovery agent's public key using ElGamal
(assuming, of course, that all use the same DH or ECDH parameters).
While an arbitrary number of KRAs may be used, it's a pretty trivial
threshold scheme as *all* KRA private keys are required to unwrap --
we don't support a true 'n of m' solution.

This scheme was first used by the FBI and SBA in their KRDP pilots,
which ISC supplied under contract to GITS.
http://csrc.nist.gov/krdp/
http://csrc.nist.gov/krdp/eadpps.html

It's still available in the current version of SecretAgent.
http://www.infoseccorp.com/products/secretagent/contents.htm

-mjm