Mike Ingle writes:
There are a lot of additions being talked about for the remailers, and timestamping is another which could be put in. With commercial PGP coming out, people may soon be doing "real business" using PGP. In this case, timestamps can be a problem. A simple example: you sign an electronic
New ideas for "Mom and Pop Timestapping Services" are useful to discuss, but be aware that several papers on exactly this kind of digital timestamping have been presented at conferences, mostly by Stu Haber and Scott Stornetta of Bellcore. Their system involves a hash of some document which is then published in an effectively unchangeable place: the pages of the "New York Times," Sunday edition, form a pretty good "widely witnessed event," to use their terminology. A digital contract timestamped (to the "granularity" of the publishing schedule, clearly) could not easily be disavowed. There are some other details. To reduce storage/publishing requirements, a binary tree of other documents can all be hashed together, so that only a single number need be published. Anyone trying to alter a contract, or to claim the given contract was not in fact timestamped when it was, would have to produce the same hash value with a different input...this can be made intractable with a good hash function. The hash function hides the content of course, so privacy is maintained. Bellcore is offering a commercial service to do this. An Internet service might be exciting (the distribution of NetNews to many thousands of sites, for archiving on CD-ROMs, tapes, etc., is a lot like the "widely witnessed event" of publishing in the "New York Times"). Alternatives to Bellcore may run afoul of patents, though. -Tim May -- .......................................................................... Timothy C. May | Crypto Anarchy: encryption, digital money, tcmay@netcom.com | anonymous networks, digital pseudonyms, zero 408-688-5409 | knowledge, reputations, information markets, W.A.S.T.E.: Aptos, CA | black markets, collapse of governments. Higher Power: 2^756839 | Public Key: PGP and MailSafe available. Note: I put time and money into writing this posting. I hope you enjoy it.