From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from pigeon.gentoo.org ([69.77.167.62] helo=lists.gentoo.org) by finch.gentoo.org with esmtp (Exim 4.60) (envelope-from ) id 1KCDu1-0004I4-6B for garchives@archives.gentoo.org; Fri, 27 Jun 2008 13:22:13 +0000 Received: from pigeon.gentoo.org (localhost [127.0.0.1]) by pigeon.gentoo.org (Postfix) with SMTP id 055D5E02F4; Fri, 27 Jun 2008 13:22:11 +0000 (UTC) Received: from mail.gmx.net (mail.gmx.net [213.165.64.20]) by pigeon.gentoo.org (Postfix) with SMTP id 9A52EE02F4 for ; Fri, 27 Jun 2008 13:22:10 +0000 (UTC) Received: (qmail invoked by alias); 27 Jun 2008 13:22:09 -0000 Received: from p3E9E6FAC.dip.t-dialin.net (EHLO nargond.local) [62.158.111.172] by mail.gmx.net (mp013) with SMTP; 27 Jun 2008 15:22:09 +0200 X-Authenticated: #26187417 X-Provags-ID: V01U2FsdGVkX1/UZS1OFPzUdTKnjvKxPFx4rXm3yizP2yCgaUgzr6 NWgo412wFqNm5u From: Sebastian Wiesner To: gentoo-user@lists.gentoo.org Subject: Re: [gentoo-user] h Date: Fri, 27 Jun 2008 15:21:23 +0200 User-Agent: KMail/1.9.9 References: <4861AB64.9000709@comcast.net> <20080626224734.GA30511@marvin.heimnetz.local> <48643425.10206@badapple.net> In-Reply-To: <48643425.10206@badapple.net> Precedence: bulk List-Post: List-Help: List-Unsubscribe: List-Subscribe: List-Id: Gentoo Linux mail X-BeenThere: gentoo-user@lists.gentoo.org Reply-to: gentoo-user@lists.gentoo.org MIME-Version: 1.0 Content-Type: multipart/signed; boundary="nextPart20590974.d8sQWhFq5I"; protocol="application/pgp-signature"; micalg=pgp-sha1 Content-Transfer-Encoding: 7bit Message-Id: <200806271521.23592.basti.wiesner@gmx.net> X-Y-GMX-Trusted: 0 X-FuHaFi: 0.67 X-Archives-Salt: 5fb76ccc-d9f4-4204-a027-1a265ae3418e X-Archives-Hash: 1a47d2deb28cd50ce7a8a9e823dc9325 --nextPart20590974.d8sQWhFq5I Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable Content-Disposition: inline kashani at Friday 27 June 2008, 02:28:21 > Here's a reference to the interesting meet-in-the-middle attack which > reduced 3DES key space down to 112 bits from 192.=20 3DES always had an effective key size of 112 bits, because it uses the=20 original DES algorithm applied in the following scheme E1(D2(E1(M)) with=20 two different 56-bit DES keys. 3DES never had 192 bit keys. The meet-in-the-middle attack has nothing to do with 3DES. In fact, 3DES=20 was designed the way it works now to _prevent_ meet-in-the-middle attacks. = =20 Such attacks can be applied to ciphers, that apply a single algorithm with= =20 two different keys: E1(E2(M)) =20 Mathematical, the key size of the latter cipher is equal to 3DES: 56+56 = =3D=20 112. But the latter cipher is vulnerable to meet-in-the-middle attacks,=20 which is why 3DES uses the second key to apply the DES decryption function= =20 with a different key right between the consecutive DES encryptions. > Obviously that was unknown when 3DES was built. I doubt. If meet in the middle was unknown at the time of 3DES development= ,=20 we wouldn't have 3DES today, but 2DES, being as simple as E1(E2(M)). =2D-=20 =46reedom is always the freedom of dissenters. (Rosa Luxemburg) --nextPart20590974.d8sQWhFq5I Content-Type: application/pgp-signature; name=signature.asc Content-Description: This is a digitally signed message part. -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.9 (GNU/Linux) iEYEABECAAYFAkhk6VMACgkQn3IEGILecb6hEgCfeQroQ1Hr336AMzvX+xT45FOF yVAAmwWx8B9ERN3rXJrOhisjNpb9Sfwi =58Ac -----END PGP SIGNATURE----- --nextPart20590974.d8sQWhFq5I-- -- gentoo-user@lists.gentoo.org mailing list