From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from list by lists.gnu.org with archive (Exim 4.71) id 1TtnPH-0006yN-Pc for mharc-grub-devel@gnu.org; Fri, 11 Jan 2013 17:48:59 -0500 Received: from eggs.gnu.org ([208.118.235.92]:40527) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1TtnNd-0006SX-JV for grub-devel@gnu.org; Fri, 11 Jan 2013 17:48:57 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1TtnMl-0007q2-9o for grub-devel@gnu.org; Fri, 11 Jan 2013 17:47:17 -0500 Received: from mail-ee0-f44.google.com ([74.125.83.44]:53367) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1TtnMk-0007my-QG for grub-devel@gnu.org; Fri, 11 Jan 2013 17:46:23 -0500 Received: by mail-ee0-f44.google.com with SMTP id l10so1123600eei.31 for ; Fri, 11 Jan 2013 14:46:21 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=x-received:message-id:date:from:user-agent:mime-version:to:subject :references:in-reply-to:x-enigmail-version:content-type; bh=MBsLFW8mSTGyYo16WdtVTWNhgYIRjWK0Dv2a5CAQ/zE=; b=Mli/6F7ciZAdP9ZF4EzAmcp2i+BRi+4ZU9O9SqwUZv62fnkONESYaqYgD0DRI2l50B fEBAuzhjUDoCp+dfM1YszDad0eENxreRT5QgPIMFTnV21bk72d3sqWpwn/C+bmTpUKKf BFNFqaoCxcpqs3PmLdiaEftAA5s/7bOOV2r10LM0Mvjwsm5AeQpe/fKrxD0jtXU4lByc +4WeGw5/YbpIllWfAntmMxKoZ0+ajzTLsdvWcCCCv8pXhcDAEhwKN8k06iJLcipAZuGP /jqoRTM6imPzw1ofZEqm4wlQu7fVOijCc3rNUGdQEe+oPYeraci+RPXeK+wKrSYWmMe4 fV/w== X-Received: by 10.14.207.6 with SMTP id m6mr204499118eeo.10.1357944381914; Fri, 11 Jan 2013 14:46:21 -0800 (PST) Received: from debian.x201.phnet (127-197.203-62.cust.bluewin.ch. [62.203.197.127]) by mx.google.com with ESMTPS id f49sm10290999eep.12.2013.01.11.14.46.20 (version=TLSv1 cipher=ECDHE-RSA-RC4-SHA bits=128/128); Fri, 11 Jan 2013 14:46:21 -0800 (PST) Message-ID: <50F09635.7060207@gmail.com> Date: Fri, 11 Jan 2013 23:46:13 +0100 From: =?UTF-8?B?VmxhZGltaXIgJ8+GLWNvZGVyL3BoY29kZXInIFNlcmJpbmVua28=?= User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:10.0.11) Gecko/20121122 Icedove/10.0.11 MIME-Version: 1.0 To: The development of GNU GRUB Subject: Re: DSA GnuPG signatures References: <50F07BFE.4050800@gmail.com> <20130111221447.GA26172@riva.dynamic.greenend.org.uk> In-Reply-To: <20130111221447.GA26172@riva.dynamic.greenend.org.uk> X-Enigmail-Version: 1.4.1 Content-Type: multipart/signed; micalg=pgp-sha512; protocol="application/pgp-signature"; boundary="------------enig97A3D544094BCDE282F021D4" X-detected-operating-system: by eggs.gnu.org: GNU/Linux 3.x [fuzzy] X-Received-From: 74.125.83.44 X-BeenThere: grub-devel@gnu.org X-Mailman-Version: 2.1.14 Precedence: list Reply-To: The development of GNU GRUB List-Id: The development of GNU GRUB List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 11 Jan 2013 22:48:57 -0000 This is an OpenPGP/MIME signed message (RFC 2440 and 3156) --------------enig97A3D544094BCDE282F021D4 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable On 11.01.2013 23:14, Colin Watson wrote: > On Fri, Jan 11, 2013 at 09:54:22PM +0100, Vladimir '=CF=86-coder/phcode= r' Serbinenko wrote: >> 1) DSA keys only. RSA is more tricky since it needs padding and RSA >> should be progressively phased out, not put into new places due to som= e >> vulnerabilities (large classes of semiprimes are factorisable up to th= e >> point when a lot of care has to be taken to avoid them). >=20 > This is highly questionable. DSA is particularly sensitive to > low-entropy situations and has various other systemic vulnerabilities > that RSA doesn't have, mainly to do with the extreme sensitivity of k. > For example, when Debian had its notorious OpenSSL vulnerability > involving poor random number generation, RSA keys that were generated o= n > a system with the vulnerability were indeed compromised; but DSA keys > were compromised even if they were only ever used to generate a single > signature on a system with the vulnerability! Knowledge of even a few > bits of k is sufficient to recover a DSA private key if you collect a > relatively small number of signatures made by that key (say, rather les= s > than the number of modules shipped by GRUB). This is the sort of thing= > that makes me want to avoid a cipher, particularly for something like > GRUB where it's quite possible that you might find yourself needing to > sign things in situations where only limited entropy is available, even= > though the key might well have been generated in better conditions. >=20 Most schemes that need random, need a very good random numbers. That's why GRUB doesn't use anything needing random. And that's why sign functions are removed altogether. > RSA with a decent key length is perfectly fine and there is no call tha= t > I'm aware of to phase it out. Rather to the contrary, DSA is the one > that I would normally prefer to avoid except where dictated by > compatibility considerations. >=20 > Assuming that the semiprimes you're referring to are those in > https://en.wikipedia.org/wiki/RSA_numbers, nobody appears to have got > any further than 768 bits. That would be a tiny key by modern > standards; I've been using 4096 bits everywhere for a few years now, an= d > of course the difficulty of factoring scales up much faster than > linearly in the key length. I am not aware (and > https://en.wikipedia.org/wiki/RSA_%28algorithm%29#Integer_factorization= _and_RSA_problem > would appear to agree) of any suggestions that >=3D4096-bit keys might = be > considered weak any time soon. >=20 (AFAIR) Would need to recheck to be exact =46rom the p and q you can compute 2 numbers: 0 < alpha, beta < 1. And if= they are small, you can factorise pq even for long keys. There is a supposition that you could extend these algorithms up to when 0 Please reconsider. >=20 Ok. Let's move the "opinion" from "not accepted" to "patches are welcome". The missing part is mainly the padding which is detailed in RFC4880. --=20 Regards Vladimir '=CF=86-coder/phcoder' Serbinenko --------------enig97A3D544094BCDE282F021D4 Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.12 (GNU/Linux) Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org/ iF4EAREKAAYFAlDwljUACgkQNak7dOguQgn4xwD/Z3NOaA6iFmjaQ0QbuuMCVJmo 0yJSrM+MOqogZfVWnsoA/jY23x8c9jWw52wyosBghu5Q6Jb/3CM4eg40OUUw0KdA =5AVo -----END PGP SIGNATURE----- --------------enig97A3D544094BCDE282F021D4--