Re: lockable trapdoor one-way function

From: Peter Fairbrother (zenadsl6186_at_zen.co.uk)
Date: 11/27/03 

Date: Thu, 27 Nov 2003 19:57:40 +0000

Paul Rubin wrote

> Peter Fairbrother <zenadsl6186@zen.co.uk> writes:
>> Does anyone know of a trapdoor one-way function whose trapdoor can be locked
>> after use?
>>
>> It can be done with secure hardware and/or distributed trust, just delete
>> the trapdoor key, and prove (somehow?) you've deleted it.
>>
>> It looks hard to do in "trust-the-math-only" mode...
>
> Um, using the trapdoor means using a secret parameter that it has.

But not necessarily a calculateable secret parameter. Or a secret parameter
that you actually know.

> Locking it means proving you no longer know the secret parameter.
> Without secure hardware, how do you prove you don't know something?

By proving you couldn't have known it in the first place; or that it would
be as hard for you to know the secret parameter as for you to break the
one-wayness of the function.

:)

I feel a paper coming on. It's a lot-of-work one tho'. Any volunteers to
help?

Peter