IETF Logo Mail Archive

Re: [kitten] DES enctypes are not PKCS#7 padded (Re: Input on Paul's concerns about aes-cbc)

Luke Howard <lukeh@padl.com> Wed, 09 October 2013 13:21 UTC

Return-Path: <lukeh@padl.com>
X-Original-To: kitten@ietfa.amsl.com
Delivered-To: kitten@ietfa.amsl.com
Received: from localhost (localhost [127.0.0.1]) by ietfa.amsl.com (Postfix) with ESMTP id 336C211E8183 for <kitten@ietfa.amsl.com>; Wed, 9 Oct 2013 06:21:23 -0700 (PDT)
X-Virus-Scanned: amavisd-new at amsl.com
X-Spam-Flag: NO
X-Spam-Score: -2.599
X-Spam-Level:
X-Spam-Status: No, score=-2.599 tagged_above=-999 required=5 tests=[AWL=0.000, BAYES_00=-2.599]
Received: from mail.ietf.org ([12.22.58.30]) by localhost (ietfa.amsl.com [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id 9zU1liJNZHLg for <kitten@ietfa.amsl.com>; Wed, 9 Oct 2013 06:21:18 -0700 (PDT)
Received: from us.padl.com (us.padl.com [216.154.215.154]) by ietfa.amsl.com (Postfix) with ESMTP id 1517C21F841A for <kitten@ietf.org>; Wed, 9 Oct 2013 06:21:17 -0700 (PDT)
Received: by us.padl.com with ESMTP id r99DL64b028522; Wed, 9 Oct 2013 09:21:08 -0400
Content-Type: text/plain; charset="us-ascii"
Mime-Version: 1.0 (Mac OS X Mail 6.6 \(1510\))
From: Luke Howard <lukeh@padl.com>
In-Reply-To: <ldvzjqik2qb.fsf_-_@cathode-dark-space.mit.edu>
Date: Thu, 10 Oct 2013 00:21:05 +1100
Content-Transfer-Encoding: quoted-printable
Message-Id: <A86BAEC9-A792-43BF-ACFE-93A4206EC01A@padl.com>
References: <20131009022305.BD1FB1A9E6@ld9781.wdf.sap.corp> <B1237751-AD3C-4A09-93DF-8CE56B746499@padl.com> <ldvzjqik2qb.fsf_-_@cathode-dark-space.mit.edu>
To: Tom Yu <tlyu@mit.edu>
X-Mailer: Apple Mail (2.1510)
X-SMTP-Vilter-Version: 1.3.6
X-Spamd-Symbols: AWL,BAYES_00,RDNS_NONE,USER_IN_WHITELIST
X-SMTP-Vilter-Spam-Backend: spamd
X-Spam-Threshold: 5.0
X-Spam-Probability: -20.5
Cc: "kitten@ietf.org" <kitten@ietf.org>, Sam Hartman <hartmans-ietf@mit.edu>
Subject: Re: [kitten] DES enctypes are not PKCS#7 padded (Re: Input on Paul's concerns about aes-cbc)
X-BeenThere: kitten@ietf.org
X-Mailman-Version: 2.1.12
Precedence: list
List-Id: Common Authentication Technologies - Next Generation <kitten.ietf.org>
List-Unsubscribe: <https://www.ietf.org/mailman/options/kitten>, <mailto:kitten-request@ietf.org?subject=unsubscribe>
List-Archive: <http://www.ietf.org/mail-archive/web/kitten>
List-Post: <mailto:kitten@ietf.org>
List-Help: <mailto:kitten-request@ietf.org?subject=help>
List-Subscribe: <https://www.ietf.org/mailman/listinfo/kitten>, <mailto:kitten-request@ietf.org?subject=subscribe>
X-List-Received-Date: Wed, 09 Oct 2013 13:21:23 -0000

>> Because this sample was geared towards GSS-API interoperability (which was DES only at the time, hence required PKCS#7 padding), it's no surprise that it correctly uses SECBUFFER_PADDING.
> 
> The DES enctypes used in Kerberos are not PKCS#7 padding.  When the
> plaintext is an exact multiple of the block size, there is no padding
> for DES.  PKCS#7 type padding requires a full block of padding in that
> case, because it is self-describing.

Ah, my (long-term) bad.

What about RFC 4757?

Greg: in the MIT implementation, make_seal_token_v1_iov()/kg_fixup_padding_iov() may be  wrong then for DES, I believe I assumed PKCS#7 when implementing it.

-- Luke

v2.46.0 | Report a Bug | By Email | System Status