patent of the day

[Dirk-Willem van Gulik]

On Wed, 23 Jan 2008, Leichter, Jerry wrote:

> well be prior art, but the idea of erasing information by deliberately
> discarding a key is certainly not completely obvious except in
> retrospect.  If you look at any traditional crypto text, you won't

Hmm - it is commonly mentioned that (early) hardware based trusted
computer environments store a small key (or part thereof, the other part
beeing some PIN, etc) in their tamperproof environment (wired as to be
ereased when any tampering, xraying, temp shock, etc is detected) which is
during normal operations used to decrypt some flash or disk based larger
bit of key material inside the secure environment.

The other senario is that of using a multitude of public keys (with some
organisational semantic) which are used to encrypt a backup; destruction
of a specific private key then selectively takes out a certain set of
file(s) from the backup tape without having to drag that tape out of the
vault and having to erase a small piece of it.

Dw

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