Re: Timestamping
Mark Seiden (mis@seiden.com)
Sun, 28 Jan 1996 00:23:12 -0800 (PST)
> On Wed, 17 Jan 1996, Alex French wrote:
> > This is a little off the point, but does anyone know any secure
> > time-stamping systems for e-mail on a UNIX system?
> There is also a service that will time-stamp email for you. The URL is:
> http://www.itconsult.co.uk/stamper.htm
i also recommend to your attention the Digital Notary Service of
Surety Technologies, which is based on a set of really cute hacks
invented by Stuart Haber and Scott Stornetta when they were at
Bellcore
see http://www.surety.com
an few excerpts from their faq:
Q. How does the Digital Notary Service work?
Using the Digital Notary Software Developer's Kit, you can integrate
the Service into your enterprise. Each electronic record that you
generate will automatically be certified. The Service does this by
automatically producing a short, unique "fingerprint" of your document
through a mathematical process called "one-way hashing." This
fingerprint alone contains no information about your original
document; in other words, it can't be reverse-engineered.
The Digital Notary Server software running on your computer then uses
a patented synchronization protocol to transmit this fingerprint (via
Internet, dial-up, or leased line) to a Coordinating Server or CS. The
CS software mathematically links your certified records with all other
records certified within a common one-second time interval. Next,
unique identifying information about your records is transmitted back
to your application. The Digital Notary program then issues an
electronic, time-stamped certificate for your records. This
certificate, which is actually a small electronic file, is
automatically stored in your designated local database. During this
entire process,your actual record never leaves your hands; only the
fingerprint and other mathematical and timing information are
transmitted outside the walls of your company.
Later (which could be minutes, months, or years), anyone who needs to
verify the integrity of a certified digital document uses the Digital
Notary Service to validate that document. The Service quickly informs
the user if the record in question is valid or whether, instead, it
has been altered in content or time.
Q. How do I know that Surety itself won't backdate a certificate?
Because the nature of our patented Service means that we could not
backdate a certificate even if we tried our hardest. We like to say
that "You can trust us because you don't have to." In fact, even if we
collaborated with the certificate holder, we could not backdate the
certificate. The Service's patented mathematical algorithms ensure
that no one will be able to backdate any certified document.
In addition, Surety maintains a Universal Validation Record that
mathematically links together all certified records. Since the Record
contains no information whatsoever about our customers or their
documents, we will also publish certain of its contents at regular
intervals on the Internet and in The New York Times. These public,
widely-witnessed publishing events will irrevocably link the Record,
and every document represented in that Record, with the contents of
dated publications available on a world-wide basis. Falsifying the
Record would mean not only surmounting impossible mathematical odds,
but also altering the contents of already existing ,
widely-distributed copies of The New York Times. That's what we mean
when we say the Record is truly unimpeachable.
Q. So exactly how tamperproof is the Service?
Much more secure than even the most secret banking or government
transactions. That's because major banks and government agencies
utilize one-way hashing algorithms to secure their most important
transactions. In fact, one such algorithm, called SHA or SHS, was
designed by a super-secret government security agency. Digital Notary
Service uses two one-way hashing algorithms (SHA and another one
called MD5) to protect each and every document. Moreover, we have
developed techniques that will enable us to incorporate even more
secure algorithmic methods as they are developed. So even if MD5 and
SHS were replaced by better methods, we could easily use them and
continue to offer the highest possible level of security for digital
documents. Our using these methods means that Digital Notary
certificates provide a level of document unimpeachability unmet by any
industry today.