[90900] in Cypherpunks
Re: Quoting Portions of a Signed Document
daemon@ATHENA.MIT.EDU (Randall Farmer)
Tue Nov 25 21:18:00 1997
Date: Tue, 25 Nov 1997 19:53:39 -0600 (CST)
From: Randall Farmer <rfarmer@HiWAAY.net>
cc: cypherpunks@Algebra.COM
In-Reply-To: <199711252109.WAA05443@basement.replay.com>
Reply-To: Randall Farmer <rfarmer@HiWAAY.net>
> It would be neat if you could quote people and prove that they signed
> the particular paragraph quoted without supplying the entire text. Is
> there a way to do this?
Yes. To do it using standard proggies, hash each of your paragraphs and put the
results in a PGP-signed message. Quoter provides signature and signed hashes.
Reader hashes your quoted paragraph and checks the signed message to see if it
was one of the original paragraphs. So simple I can do it. :)
[Disclaimer: I think.]
A more cool-sounding solution would be to concatenate those hashes and sign
them (not a hash of them) as one packet. Since RSA sigs are secret-key
decryptions (right?), the reader can re-encrypt it and check any individual
hash. Not more secure, though, and it takes a lot of processor time.
No idea how to do it with bit-level granularity.
> (It seems impossible, but so does mental poker.)
Mental poker? Easy.
>
> A crude approach would be to sign every paragraph or line separately,
> but that's obviously inelegant.
Allows you a tad too much freedom with their quotes, too...
>
> Monty Cantsin
> Editor in Chief
> Smile Magazine
> http://www.neoism.org/squares/smile_index.html
> http://www.neoism.org/squares/cantsin_10.htm
---------------------------------------------------------------------------
Randall Farmer
rfarmer@hiwaay.net
http://hiwaay.net/~rfarmer
