Return-Path: <linux-kernel-owner@vger.kernel.org>
Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand
        id S1760363AbcLPKkM convert rfc822-to-8bit (ORCPT <rfc822;w@1wt.eu>);
        Fri, 16 Dec 2016 05:40:12 -0500
Received: from smtp-out6.electric.net ([192.162.217.194]:55795 "EHLO
        smtp-out6.electric.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org
        with ESMTP id S1759719AbcLPKjq (ORCPT
        <rfc822;linux-kernel@vger.kernel.org>);
        Fri, 16 Dec 2016 05:39:46 -0500
From: David Laight <David.Laight@ACULAB.COM>
To: "'Jason A. Donenfeld'" <Jason@zx2c4.com>,
        Netdev <netdev@vger.kernel.org>,
        "kernel-hardening@lists.openwall.com" 
        <kernel-hardening@lists.openwall.com>,
        LKML <linux-kernel@vger.kernel.org>,
        "linux-crypto@vger.kernel.org" <linux-crypto@vger.kernel.org>,
        Ted Tso <tytso@mit.edu>,
        Hannes Frederic Sowa <hannes@stressinduktion.org>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Eric Biggers <ebiggers3@gmail.com>, Tom Herbert <tom@herbertland.com>,
        "George Spelvin" <linux@sciencehorizons.net>,
        Vegard Nossum <vegard.nossum@gmail.com>,
        "ak@linux.intel.com" <ak@linux.intel.com>,
        "davem@davemloft.net" <davem@davemloft.net>,
        "luto@amacapital.net" <luto@amacapital.net>
Subject: RE: [PATCH v5 2/4] siphash: add Nu{32,64} helpers
Thread-Topic: [PATCH v5 2/4] siphash: add Nu{32,64} helpers
Thread-Index: AQHSVxIWOaxCO9WcYUmYSehpaG9H2KEKYf9A
Date: Fri, 16 Dec 2016 10:39:35 +0000
Message-ID: <063D6719AE5E284EB5DD2968C1650D6DB0240EFA@AcuExch.aculab.com>
References: <20161215203003.31989-1-Jason@zx2c4.com>
 <20161215203003.31989-3-Jason@zx2c4.com>
In-Reply-To: <20161215203003.31989-3-Jason@zx2c4.com>
Accept-Language: en-GB, en-US
Content-Language: en-US
X-MS-Has-Attach: 
X-MS-TNEF-Correlator: 
x-originating-ip: [10.202.99.200]
Content-Type: text/plain; charset="Windows-1252"
Content-Transfer-Encoding: 8BIT
MIME-Version: 1.0
X-Outbound-IP: 213.249.233.130
X-Env-From: David.Laight@ACULAB.COM
X-Proto: esmtps
X-Revdns: 
X-HELO: AcuExch.aculab.com
X-TLS: TLSv1:AES128-SHA:128
X-Authenticated_ID: 
X-PolicySMART: 3396946, 3397078
Sender: linux-kernel-owner@vger.kernel.org
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org
Content-Length: 756
Lines: 26

From: Jason A. Donenfeld
> Sent: 15 December 2016 20:30
> These restore parity with the jhash interface by providing high
> performance helpers for common input sizes.
...
> +#define PREAMBLE(len) \
> +	u64 v0 = 0x736f6d6570736575ULL; \
> +	u64 v1 = 0x646f72616e646f6dULL; \
> +	u64 v2 = 0x6c7967656e657261ULL; \
> +	u64 v3 = 0x7465646279746573ULL; \
> +	u64 b = ((u64)len) << 56; \
> +	v3 ^= key[1]; \
> +	v2 ^= key[0]; \
> +	v1 ^= key[1]; \
> +	v0 ^= key[0];

Isn't that equivalent to:
	v0 = key[0];
	v1 = key[1];
	v2 = key[0] ^ (0x736f6d6570736575ULL ^ 0x646f72616e646f6dULL);
	v3 = key[1] ^ (0x646f72616e646f6dULL ^ 0x7465646279746573ULL);

Those constants also look like ASCII strings.
What cryptographic analysis has been done on the values?

	David