At 10:47 AM 10/4/95 EDT, dlv@bwalk.dm.com (Dr. Dimitri Vulis) wrote:
When an article is posted, two quantities are computed by the posting program: M1 = H(article body + newsgroups + message-id + date + passphrase) and M2 = H(M1). The posted article contains the header "Cancel-lock: M2". [.. Cancel-key: M1 to cancel or supersede.] [..Daemons forward suspected forged cancels to originator]
Aside from the forged-From:-bogus-cancel spam /r$ proposed, this has the problem that it still only allows the originator to cancel a message, and not either the moderator of a moderated group or a Good Spam-canceller like CancelMoose, as well as stopping censors and cancel-spammers. Cancellation is a sufficiently local-policy-dependent issue, and reasonably low volume compared to the rest of news, that it probably makes sense for the various news programs to hand cancellation requests off to an external program, which can be locally modified as desired. One approach is to add digital signature and verification capability to News, at least to support cancels; doing this in an outboard cancel-daemon is obviously easier. RIPEM-SIG is a signature-only version of RIPEM which is exportable, probably just in binaries. The local cancel-daemon could accept cancellation requests that were signed by anybody on the list of locally-approved cancellers; one site could accept cancels from Cancelmoose, newsgroup moderators, and Helena Kobrin; another could do authors only. This would, of course, encourage people to get their digital signatures out there to allow themselves to cancel their own messages. ---------------- BTW, on the general topic of spam, I got a nice note back from the Johnson-Grace folks saying they were sorry they posted their ad/announcement to the list and it won't happen again. And you can download their compression stuff from www.jgc.com but they're not actually making the algorithms public... ----- #--- # Thanks; Bill # Bill Stewart, Freelance Information Architect, stewarts@ix.netcom.com # Phone +1-510-247-0664 Pager/Voicemail 1-408-787-1281 #---