[Barker, Elaine B.] NIST Publication Announcements

Perry E. Metzger perry at piermont.com
Thu Oct 1 12:49:26 EDT 2009

Stephan Neuhaus <neuhaus at st.cs.uni-sb.de> writes:
> On Oct 1, 2009, at 16:46, Perry E. Metzger wrote:
>> It is also completely impossible to prove you've deleted a
>> record. Someone who can read the record can always make a copy of
>> it. Cryptography can't fix the DRM problem.
> Sorry, I should have clarified that. We don't want to verify that Bob
> has in fact deleted the patient record, we just want to verify whether
> Bob *claims* to have deleted the patient record *within the time span
> given*. If Alice later finds out that Bob has lied, she will have this
> signed claim, with which she can take him to court.

If you have that more limited need, the Haber & Stornetta protocol will
likely do what you want, provided you can set something up to publish
the "widely witnessed events". (They had a company for a while to do
timestamping that published the hashes in the New York Times
classifieds. I think when they wrote their paper, the idea that
newspapers might soon cease to exist was not anticipated -- a more
modern system will need some sort of more durable model.)

Perry E. Metzger		perry at piermont.com

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