To: cypherpunks@toad.com ********** Original To: TCMAY@NETCOM.COM * CARBON * was By: WEIDAI * COPY * posted: On: ESKIMO ********** Conf: 0009 - Email ----------------------------------------------------------------------- -----BEGIN PGP SIGNED MESSAGE----- tcmay@netcom.com wrote:
The hard part is time stamper reliability, i.e., how does the world (and the courts) know that the time stamper(s) did not simply reset his clock and thus fake the times?
Another problem is security. Establishing a time stamping service can make you a good target for subversion.
1. Publish a one-way hash of the text to be stamped in a very public place, e.g., one's latest bestselling novel or the "New York Times." This is similar to the crypto methods used by scientists through the ages to prove ownership. H & S call this a "widely witnessed event," the idea being that millions of copies of archived issued of the NYT (or the novel!) would have to be retrieved and reprinted in order to change at a later date the text. Economically impractical.
Publishing a one-way hash of the text eliminates the role of the trusted time stamper. Alice can simply sign the text herself and then publish the hash right away (in a Usenet newsgroup for example). Trusted time stampers of course are trusted. It means they have reputations for being secure and reliable, and reputation is worth more to them than any possible benifit they can gain from abusing that trust. Of course, this may not work out in reality, but the theory sounds good to me. A way to convince the public that your time stamp is valid without publishing it at the time of the time stamp or absolute trust (on the public's part) on the time stampers is to use a large number of time stamping services. This way, they must all have colluded or been subverted in order to forge your time stamp. Therefore, the time stamp has a high probability of being valid. cc: CYPHERPUNKS MAILING LIST in 0009 on ESKIMO -----BEGIN PGP SIGNATURE----- Version: 2.3a iQCVAgUBLlUSnjl0sXKgdnV5AQFrkwQAopVBwQaFB5YkpKPkWfsOwA2xsTp4vNmZ SIfJDbhdEM2T2xRbGi9QEofADeIoISgVtN6hkhgeQnk5eyvI3EFL8K+ocqc5rYAQ mQAEsTY9sEvZ2CzQr8grayuvhSnnWRmQKSTsfELctWzZciqlDpHbhI++7G1c9hI+ 1zFEE/2HPoQ= =VtUy -----END PGP SIGNATURE----- PGP Public Key available