From mboxrd@z Thu Jan 1 00:00:00 1970 X-Msuck: nntp://news.gmane.io/gmane.emacs.gnus.general/55125 Path: main.gmane.org!not-for-mail From: Lloyd Zusman Newsgroups: gmane.emacs.gnus.general Subject: Re: Encrypting outgoing message but not Gcc? Date: Sun, 07 Dec 2003 08:08:54 -0500 Sender: ding-owner@lists.math.uh.edu Message-ID: References: <87vfot99o1.fsf@virgil.koldfront.dk> <87r7zh8k9h.fsf@virgil.koldfront.dk> <87zne43mzs.fsf@shampoo.pants.nu> NNTP-Posting-Host: deer.gmane.org Mime-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Transfer-Encoding: quoted-printable X-Trace: sea.gmane.org 1070802692 9584 80.91.224.253 (7 Dec 2003 13:11:32 GMT) X-Complaints-To: usenet@sea.gmane.org NNTP-Posting-Date: Sun, 7 Dec 2003 13:11:32 +0000 (UTC) Original-X-From: ding-owner+M3665@lists.math.uh.edu Sun Dec 07 14:11:30 2003 Return-path: Original-Received: from malifon.math.uh.edu ([129.7.128.13]) by deer.gmane.org with esmtp (Exim 3.35 #1 (Debian)) id 1ASyh7-0003nU-00 for ; Sun, 07 Dec 2003 14:11:29 +0100 Original-Received: from localhost ([127.0.0.1] helo=lists.math.uh.edu) by malifon.math.uh.edu with smtp (Exim 3.20 #1) id 1ASygh-0000ey-00; Sun, 07 Dec 2003 07:11:03 -0600 Original-Received: from justine.libertine.org ([66.139.78.221] ident=postfix) by malifon.math.uh.edu with esmtp (Exim 3.20 #1) id 1ASygZ-0000es-00 for ding@lists.math.uh.edu; Sun, 07 Dec 2003 07:10:55 -0600 Original-Received: from main.gmane.org (main.gmane.org [80.91.224.249]) by justine.libertine.org (Postfix) with ESMTP id C411C3A0040 for ; Sun, 7 Dec 2003 07:10:54 -0600 (CST) Original-Received: from list by main.gmane.org with local (Exim 3.35 #1 (Debian)) id 1ASygX-0008Mg-00 for ; Sun, 07 Dec 2003 14:10:53 +0100 X-Injected-Via-Gmane: http://gmane.org/ Original-To: ding@gnus.org Original-Received: from sea.gmane.org ([80.91.224.252]) by main.gmane.org with esmtp (Exim 3.35 #1 (Debian)) id 1ASygU-0008MY-00 for ; Sun, 07 Dec 2003 14:10:50 +0100 Original-Received: from news by sea.gmane.org with local (Exim 3.35 #1 (Debian)) id 1ASygU-0002TH-00 for ; Sun, 07 Dec 2003 14:10:50 +0100 Original-Lines: 31 Original-X-Complaints-To: usenet@sea.gmane.org User-Agent: Gnus/5.1003 (Gnus v5.10.3) Emacs/21.2 (gnu/linux) Cancel-Lock: sha1:Em7ShKeMR0Cn++EKfGAuGNwtTfs= Precedence: bulk Xref: main.gmane.org gmane.emacs.gnus.general:55125 X-Report-Spam: http://spam.gmane.org/gmane.emacs.gnus.general:55125 Nathan Sullivan writes: > spamtrap@koldfront.dk (Adam Sj=F8gren) writes: > >> On Sat, 06 Dec 2003 13:35:21 -0500, Lloyd wrote: >> >>> Also, I think there's a gap somewhere in my understanding of all >>> this. How can it be that something encrypted twice, once with the >>> recipient's public key and once with yours, would only need your >>> private key to be decrypted? [ ... ] >> >> I'm not able to adequately and comprehensibly explain the theory, but >> I think it's a proporty of either assymetric key cryptography in >> general or the way PGP/GnuPG is constructed (the latter being less >> likely, probably, perhaps). > > It's a property of the way almost all assymetric cryptography is > implemented. The problem is that public key encryption is grotesquely > slow, so programs like PGP/GPG don't encrypt the entire message with > the public key. Instead, they encrypt the message with a symmetric > cypher, like IDEA or Blowfish, then encrypt the symmetric key with the > public key for the desired recipient. If you have multiple > recipients, then multiple copies of the encrypted symmetric key are > included, each encrypted for a specific public key pair. Thanks ... I had always wondered what symmetric cyphers like IDEA or Blowfish had to do with public key encryption. --=20 Lloyd Zusman ljz@asfast.com