Re: More thoughts about digital postage (was Re: Digital postage and remailer abuse)

[Adam Shostack <adam@lighthouse.homeport.org>]

Alan Bostick wrote:

| People asked in earlier in this thread how remailers could issue digital
| postage stamps without being able to know who is using which stamp issued.
| 
| One obvious approach is to use blind signatures.  Rather than issuing
| a stamp to the user who requests/purchases it, the user could send
| an unsigned stamp, encrypted in an RSA envelope, to the remailer.  The
| remailer would then blind-sign the envelope and return it to the user.
| The user then decrypts the envelope and has a stamp ready for use.

This is a lot of public key work for the remailer.

Take a look at Shamir's Micromint scheme, and sell coins for ecash on
the web.  Micromint coins are easy to verify, and thus could be resold
on peoples web pages.  They do have expiry dates though.

Adam


-- 
"It is seldom that liberty of any kind is lost all at once."
					               -Hume