On Sep 29, 2009, at 10:31 AM, Perry E. Metzger wrote:
Stephan Neuhaus <neuh...@st.cs.uni-sb.de> writes:
For business reasons,
Alice can't force Bob to use a particular TTA, and it's also
impossible to stipulate a particular TTA as part of the job
description (the reason is that Alice and the Bobs----great band name
BTW---won't agree to trust any particular TTA and also don't want to
operate their own).
You don't need such a complicated description -- you're just asking
"can
I do secure timestamping without requiring significant trust in the
timestamping authority."
The Haber & Stornetta scheme provides a timestamping service that
doesn't require terribly much trust, since hard to forge widely
witnessed events delimit particular sets of timestamps. The only issue
is getting sufficient granularity.
I don't know if their scheme was patented in Germany. It was in the
U.S., though I think that at least some of the patents expire within
the year.
--Steve Bellovin, http://www.cs.columbia.edu/~smb
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