Do we need another version of digital timestamps?

06 Nov 2003
Microsoft and the U.S. Postal Service (USPS) have announced an "Electronic Postmark (EPM)" plug-in for Office 2003 and Windows XP. The plug-in allows a user to get a digital signature for a document that signifies a timestamp for it, similar to a postmark. This feature is completely compatible with PGP security solutions, which can encrypt a document and also sign it for transport.

This isn't the first time someone has tried to start a business with digital timestamps. There are a number of standards for them, including one that is part of OpenPGP. In fact, one of the authors of the OpenPGP standard runs an OpenPGP-based timestamping service in Germany.

There are several issues I see with the new EPM plug-in:

• It requires that users be running Windows XP and Office 2003, meaning an outlay of money to upgrade software for most people. Of course, as time goes on and people replace their computers with new ones that have Windows XP and Office 2003, the plug-in becomes more viable. If this toolkit spreads to other systems such as PDAs, cell phones, and Macs as well, it also becomes more viable.

• It requires purchasing a certificate, which seems odd, seeing that it's the Postal Service that needs the certificates to make a timestamping signature. There is, of course, goodness in signing documents, but conflating a postmark with a document signature blurs the distinction between the two. It also slows deployment.

• The postmarks cost 80 cents in lumps of 25 or as little as a dime if you buy a million of them. This seems a bit high because it's well more than first-class postage (and more than bulk postage if you're sending a million letters), yet they're advertised as a money-saving device. If you send paper mail, at least the Postal Service actually delivers something for you, instead of just stamping it. Charging more for doing less is nice for them, but what does it mean for us end users?

To me, this seems like a solution in search of a problem. I can think of times when a postmark would be useful, such as when submitting a paper to a conference. In those cases, Microsoft Word is not considered an acceptable format because many of these people want non-proprietary formats such as PDF or HTML. I can think of other times when the postmarks would be useful, such as when responding to a government RFP that requires submission by a specific deadline. However, as the articles describing them point out, these electronic postmarks have no legal standing, so there's no benefit to using them.

Email has as an advantage over paper mail because it is easier to use, faster, and cheaper. Faxes are somewhere between the two; they are often as easy to send as email, often cost less than postage, and are immediate. A signature postmark doesn't offer the advantages of registered paper mail, but brings in added cost.

Background reading
" AuthentiDate, Inc. Signs Strategic Agreement With U.S. Postal Service to Provide Electronic Postmark Service," August 6, 2003.

" Protect the integrity of your data," U.S. Postal Service.

Roberts, Paul, " Microsoft, U.S. Postal Service offer electronic postmarking," Computerworld, October 21, 2003.

" USPS Electronic Postmark® (USPS EPM)," AuthentiDate [PDF: 200KB], 2003.

" USPS Electronic Postmark® (USPS EPM®) White Paper," [PDF: 196KB], September 2003.