Re: [pkix] Question about Curve P-192
Denis <denis.ietf@free.fr> Fri, 11 May 2018 10:09 UTC
Return-Path: <denis.ietf@free.fr>
X-Original-To: pkix@ietfa.amsl.com
Delivered-To: pkix@ietfa.amsl.com
Received: from localhost (localhost [127.0.0.1]) by ietfa.amsl.com (Postfix) with ESMTP id 5E03912D947 for <pkix@ietfa.amsl.com>; Fri, 11 May 2018 03:09:16 -0700 (PDT)
X-Virus-Scanned: amavisd-new at amsl.com
X-Spam-Flag: NO
X-Spam-Score: -0.23
X-Spam-Level:
X-Spam-Status: No, score=-0.23 tagged_above=-999 required=5 tests=[BAYES_00=-1.9, FREEMAIL_FROM=0.001, HTML_MESSAGE=0.001, MISSING_HEADERS=1.021, RCVD_IN_BL_SPAMCOP_NET=1.347, RCVD_IN_DNSWL_LOW=-0.7] autolearn=no autolearn_force=no
Received: from mail.ietf.org ([4.31.198.44]) by localhost (ietfa.amsl.com [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id yiX92sQtuZ3k for <pkix@ietfa.amsl.com>; Fri, 11 May 2018 03:09:13 -0700 (PDT)
Received: from smtp6-g21.free.fr (smtp6-g21.free.fr [212.27.42.6]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ietfa.amsl.com (Postfix) with ESMTPS id 5377A127078 for <pkix@ietf.org>; Fri, 11 May 2018 03:09:13 -0700 (PDT)
Received: from [192.168.0.13] (unknown [88.182.125.39]) by smtp6-g21.free.fr (Postfix) with ESMTP id 61DCA7803B2 for <pkix@ietf.org>; Fri, 11 May 2018 12:09:11 +0200 (CEST)
Cc: pkix@ietf.org
References: <5481b2bb-25cc-6d1f-d255-16403f2221de@free.fr> <38461622-c7e9-58f4-acd2-5451c37408ba@informatik.hu-berlin.de> <9721F6F1-BA0F-4A86-A1C9-7910003D00E8@vigilsec.com> <810C31990B57ED40B2062BA10D43FBF501C71CBD@XMB116CNC.rim.net> <77eb0920-c6a2-2697-46d0-b0ab0366d9da@free.fr> <CANeU+ZDJYqGJZrVk2GzfJ-TZYc+=ptqj1-+8Ko0s3TvK_jHLhw@mail.gmail.com>
From: Denis <denis.ietf@free.fr>
Message-ID: <689887b5-b034-5c4c-648c-3854321ce2c7@free.fr>
Date: Fri, 11 May 2018 12:09:13 +0200
User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:52.0) Gecko/20100101 Thunderbird/52.7.0
MIME-Version: 1.0
In-Reply-To: <CANeU+ZDJYqGJZrVk2GzfJ-TZYc+=ptqj1-+8Ko0s3TvK_jHLhw@mail.gmail.com>
Content-Type: multipart/alternative; boundary="------------8F5EBA53AE944EDAD9AE0BEA"
Content-Language: en-US
Archived-At: <https://mailarchive.ietf.org/arch/msg/pkix/0dziQ24uKuJpKPsjrS4A6z8VDDY>
Subject: Re: [pkix] Question about Curve P-192
X-BeenThere: pkix@ietf.org
X-Mailman-Version: 2.1.22
Precedence: list
List-Id: PKIX Working Group <pkix.ietf.org>
List-Unsubscribe: <https://www.ietf.org/mailman/options/pkix>, <mailto:pkix-request@ietf.org?subject=unsubscribe>
List-Archive: <https://mailarchive.ietf.org/arch/browse/pkix/>
List-Post: <mailto:pkix@ietf.org>
List-Help: <mailto:pkix-request@ietf.org?subject=help>
List-Subscribe: <https://www.ietf.org/mailman/listinfo/pkix>, <mailto:pkix-request@ietf.org?subject=subscribe>
X-List-Received-Date: Fri, 11 May 2018 10:09:16 -0000
Michael, I don't see how RFC 5480 can be used to obtain an *identifier* for a cryptographic *suite* for both P-192 and a SHA-256 hash function truncated to 192 bits. In between, I got a response why the leftmost bits shall be used. Close to the end of section 6.4NIST FIPS 186-4 <http://nvlpubs.nist.gov/nistpubs/FIPS/NIST.FIPS.186-4.pdf> states: When the length of the output of the hash function is greater than the bit length of /n/, then the *leftmost **/n/**bits* of the hash function output block *shall be used* in any calculation using the hash function output during the generation or verification of a digital signature. A hash function that provides a lower security strength than the security strength associated with the bit length of n ordinarily *should not* be used, since this would reduce the security strength of the digital signature process to a level no greater than that provided by the hash function. Denis > Actually see RFC5480. It describes a set of suggested pairings of > signature strengths and hashes and includes recommendations for P-192. > > Re Russ’s comment, the ECDSAWithShaxxx identifiers can be used with > any curve, (but follow the 5480 and other similar document pairing > recommendations) so it’s not exactly correct that there are no > algorithm identifiers. > > Lastly, AFAICT NIST didn’t originally define the P192 curve - it just > incorporated a previously defined curve in a set of acceptable > parameters when it was NISTifying EC cryptography. > > Mike > > On Thu, May 10, 2018 at 17:47 Denis <denis.ietf@free.fr > <mailto:denis.ietf@free.fr>> wrote: > > Hi Ernst, Russ and Dan, > > Thank your for your replies. This is what I feared : there is no > cryptographic suite defined for P-192. > Quite strange that NIST defined the algorithm and didn't defined a > hash function to go with it. > > Key sizes need to be appreciated relative to the environment where > they are used. > > P-192 would be used in a constrained environment where the size of > the digital signature matters (i.e. the smaller, the better). > > The verification of the digital signature would be real time. The > private key should resist one year, because it would be changed > every year. > > P-192 seems to be a good trade-off between the security level and > the size of the digital signature. > > A SHA-192 function has been defined in a paper available at: > http://www.ijctee.org/files/VOLUME2ISSUE3/IJCTEE_0612_24.pdf. > The title of this paper is : Performance Analysis of SHA > Algorithms (SHA-1 and SHA-192): A Review > However, I don't believe that any crypto-library supports it. > > So Ernst's method would certainly be one way to do it, but why not > take the 192 low bits ? > > The last question would be for Ernst who wrote: > > The corresponding signature suite can be defined with ISO > 14888-3, which allows the specification of the algo > > (e.g. EC-DSA, EC-KCDSA or whatsoever), the curve and the hash > function. > > What would the OID or the URI for this suite, if we take the 192 > left bits ? Same question if we take the 192 low bits ? > > > Denis > >> Hi Denis, >> >> Please, do not use P-192, unless there are some severe constraints. >> >> Even if you credit EC with a very generous 16 extra bits in >> security (compared to hashes & ciphers), P-192 would only reach >> 96+16=112-bit security, which does not meet the current best >> practice of 128 bit security. >> >> History as I understand it: NIST P-192 was meant for the 80-bit >> level (though it looks like 96-bit). This low security level has >> been widely deprecated since 2010, at least informally - to what >> extent it is formally deprecated, I don’t recall off-hand. I >> recall added text to ANSI X9.62/63 deprecating this security level. >> >> Anyway, originally, the idea was to use P-192 with SHA-1, P-224 >> with SHA-224, etc. >> >> I think that there were also OIDs for P-192, e.g. secp192k1, and >> OIDs for ECDSA-with-SHA1, which could be combined in some ways. >> I do not recall how far these OIDs made into IETF, i.e. as >> algorithm identifiers. >> >> Using 160-bit hash in ECDSA with P-192 renders the EU-CMA >> security to 80 bits, which is waste considering that P-192 >> potentially provides 96-bit security. As noted in the thread >> below, the standards have options to truncate a longer hash, >> which should correct this. >> >> Arguably, the security of P-192 has fared far better than SHA-1 >> in some ways, yet SHA-1 is probably much more widely used than >> P-192, though admittedly hashes are considered a general purpose >> tool. >> >> Best regards, >> >> Dan >> >> >> *From:* pkix [mailto:pkix-bounces@ietf.org] *On Behalf Of *Russ >> Housley >> *Sent:* Thursday, May 10, 2018 1:30 PM >> *To:* Ernst G Giessmann <giessman@informatik.hu-berlin.de> >> <mailto:giessman@informatik.hu-berlin.de> >> *Cc:* IETF PKIX <pkix@ietf.org> <mailto:pkix@ietf.org> >> *Subject:* Re: [pkix] Question about Curve P-192 >> >> Ernst: >> >> Of course, this technique works. That said, I am not aware of >> any algorithm identifiers that make use of the P-192 curve for >> digital signature or key agreement. >> >> Russ >> >> On May 10, 2018, at 1:24 PM, Ernst G Giessmann >> <giessman@informatik.hu-berlin.de >> <mailto:giessman@informatik.hu-berlin.de>> wrote: >> >> Yes, there is a standardized way: >> Pick up a corresponding hash function, in case of P-192 it >> should be SHA-224 and take the 192 left most bits of the hash >> value as the input to the EC sign primitive. >> The correspondig signature suite can be defined with ISO >> 14888-3, which allows the specification of the algo (e.g. >> EC-DSA, EC-KCDSA or whatsoever), the curve and the hash function. >> Kind regards, >> /Ernst. >> >> Am 2018-05-10 um 19:07 schrieb Denis: >> >> Hello everybody, >> >> Curve P-192 is specified in FIPS PUB 186-4 (Digital >> Signature Standard (DSS)). >> >> There is no "SHA-192" hash function defined in FIPS PUB >> 180-4 (Secure Hash Standard (SHS)). >> >> Is there any standardized way to use a hash function with >> Curve P-192 ? >> >> Is there any RFC or any another document that specifies a >> cryptographic suite for Curve P-192 ? >> >> Denis >> >>
- [pkix] Question about Curve P-192 Denis
- Re: [pkix] Question about Curve P-192 Ernst G Giessmann
- Re: [pkix] Question about Curve P-192 Russ Housley
- Re: [pkix] Question about Curve P-192 Dan Brown
- Re: [pkix] Question about Curve P-192 Denis
- Re: [pkix] Question about Curve P-192 Michael StJohns
- Re: [pkix] Question about Curve P-192 Denis
- Re: [pkix] Question about Curve P-192 Dan Brown
- Re: [pkix] Question about Curve P-192 Denis
- Re: [pkix] Question about Curve P-192 Dan Brown
- Re: [pkix] Question about Curve P-192 Ernst G Giessmann
- Re: [pkix] Question about Curve P-192 Michael StJohns
- Re: [pkix] Question about Curve P-192 Ernst G Giessmann