From: Ard Biesheuvel <ard.biesheuvel@linaro.org>
To: Eric Biggers <ebiggers@kernel.org>
Cc: "open list:HARDWARE RANDOM NUMBER GENERATOR CORE"
<linux-crypto@vger.kernel.org>,
linux-fscrypt@vger.kernel.org,
linux-arm-kernel <linux-arm-kernel@lists.infradead.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
Herbert Xu <herbert@gondor.apana.org.au>,
Paul Crowley <paulcrowley@google.com>,
Greg Kaiser <gkaiser@google.com>,
Michael Halcrow <mhalcrow@google.com>,
"Jason A . Donenfeld" <Jason@zx2c4.com>,
Samuel Neves <samuel.c.p.neves@gmail.com>,
Tomer Ashur <tomer.ashur@esat.kuleuven.be>
Subject: Re: [RFC PATCH v2 09/12] crypto: nhpoly1305 - add NHPoly1305 support
Date: Mon, 22 Oct 2018 19:43:01 -0300 [thread overview]
Message-ID: <CAKv+Gu-6JCQ=f=Qy8DCLAN4V56HbXAG9Wr2Tb7Zm25HLKuG4Lg@mail.gmail.com> (raw)
In-Reply-To: <20181022224008.GB59695@gmail.com>
On 22 October 2018 at 19:40, Eric Biggers <ebiggers@kernel.org> wrote:
> Hi Ard,
>
> On Mon, Oct 22, 2018 at 07:25:27PM -0300, Ard Biesheuvel wrote:
>> >
>> > Hmm, I'm actually leaning towards the following instead. Unrolling multiple
>> > strides to try to reduce loads of the keys doesn't seem worthwhile in the C
>> > implementation; for one, it bloats the code size a lot
>> > (412 => 2332 bytes on arm32).
>> >
>> > static void nh_generic(const u32 *key, const u8 *message, size_t message_len,
>> > __le64 hash[NH_NUM_PASSES])
>> > {
>> > u64 sums[4] = { 0, 0, 0, 0 };
>> >
>> > BUILD_BUG_ON(NH_PAIR_STRIDE != 2);
>> > BUILD_BUG_ON(NH_NUM_PASSES != 4);
>> >
>> > while (message_len) {
>> > u32 m0 = get_unaligned_le32(message + 0);
>> > u32 m1 = get_unaligned_le32(message + 4);
>> > u32 m2 = get_unaligned_le32(message + 8);
>> > u32 m3 = get_unaligned_le32(message + 12);
>> >
>> > sums[0] += (u64)(u32)(m0 + key[ 0]) * (u32)(m2 + key[ 2]);
>> > sums[1] += (u64)(u32)(m0 + key[ 4]) * (u32)(m2 + key[ 6]);
>> > sums[2] += (u64)(u32)(m0 + key[ 8]) * (u32)(m2 + key[10]);
>> > sums[3] += (u64)(u32)(m0 + key[12]) * (u32)(m2 + key[14]);
>> > sums[0] += (u64)(u32)(m1 + key[ 1]) * (u32)(m3 + key[ 3]);
>> > sums[1] += (u64)(u32)(m1 + key[ 5]) * (u32)(m3 + key[ 7]);
>> > sums[2] += (u64)(u32)(m1 + key[ 9]) * (u32)(m3 + key[11]);
>> > sums[3] += (u64)(u32)(m1 + key[13]) * (u32)(m3 + key[15]);
>>
>> Are these (u32) casts really necessary? All the addends are u32 types,
>> so I'd expect each (x + y) subexpression to have a u32 type already as
>> well. Or am I missing something?
>>
>
> The (u32) casts are only necessary when sizeof(int) > sizeof(u32), as then the
> addends will be promoted to 'int'. Of course, that's never the case for the
> Linux kernel. But I prefer it to be as robust and well-defined as possible,
> since people might use this as a reference when coding other implementations,
> which could end up finding their way into unusual and/or future platforms.
>
Fair enough.
next prev parent reply other threads:[~2018-10-22 22:43 UTC|newest]
Thread overview: 54+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-10-15 17:54 [RFC PATCH v2 00/12] crypto: Adiantum support Eric Biggers
2018-10-15 17:54 ` [RFC PATCH v2 01/12] crypto: chacha20-generic - add HChaCha20 library function Eric Biggers
2018-10-19 14:13 ` Ard Biesheuvel
2018-10-15 17:54 ` [RFC PATCH v2 02/12] crypto: chacha20-generic - add XChaCha20 support Eric Biggers
2018-10-19 14:24 ` Ard Biesheuvel
2018-10-15 17:54 ` [RFC PATCH v2 03/12] crypto: chacha20-generic - refactor to allow varying number of rounds Eric Biggers
2018-10-19 14:25 ` Ard Biesheuvel
2018-10-15 17:54 ` [RFC PATCH v2 04/12] crypto: chacha - add XChaCha12 support Eric Biggers
2018-10-19 14:34 ` Ard Biesheuvel
2018-10-19 18:28 ` Eric Biggers
2018-10-15 17:54 ` [RFC PATCH v2 05/12] crypto: arm/chacha20 - add XChaCha20 support Eric Biggers
2018-10-20 2:29 ` Ard Biesheuvel
2018-10-15 17:54 ` [RFC PATCH v2 06/12] crypto: arm/chacha20 - refactor to allow varying number of rounds Eric Biggers
2018-10-20 3:35 ` Ard Biesheuvel
2018-10-20 5:26 ` Eric Biggers
2018-10-15 17:54 ` [RFC PATCH v2 07/12] crypto: arm/chacha - add XChaCha12 support Eric Biggers
2018-10-20 3:36 ` Ard Biesheuvel
2018-10-15 17:54 ` [RFC PATCH v2 08/12] crypto: poly1305 - add Poly1305 core API Eric Biggers
2018-10-20 3:45 ` Ard Biesheuvel
2018-10-15 17:54 ` [RFC PATCH v2 09/12] crypto: nhpoly1305 - add NHPoly1305 support Eric Biggers
2018-10-20 4:00 ` Ard Biesheuvel
2018-10-20 5:38 ` Eric Biggers
2018-10-20 15:06 ` Ard Biesheuvel
2018-10-22 18:42 ` Eric Biggers
2018-10-22 22:25 ` Ard Biesheuvel
2018-10-22 22:40 ` Eric Biggers
2018-10-22 22:43 ` Ard Biesheuvel [this message]
2018-10-15 17:54 ` [RFC PATCH v2 10/12] crypto: arm/nhpoly1305 - add NEON-accelerated NHPoly1305 Eric Biggers
2018-10-20 4:12 ` Ard Biesheuvel
2018-10-20 5:51 ` Eric Biggers
2018-10-20 15:00 ` Ard Biesheuvel
2018-10-15 17:54 ` [RFC PATCH v2 11/12] crypto: adiantum - add Adiantum support Eric Biggers
2018-10-20 4:17 ` Ard Biesheuvel
2018-10-20 7:12 ` Eric Biggers
2018-10-23 10:40 ` Ard Biesheuvel
2018-10-24 22:06 ` Eric Biggers
2018-10-30 8:17 ` Herbert Xu
2018-10-15 17:54 ` [RFC PATCH v2 12/12] fscrypt: " Eric Biggers
2018-10-19 15:58 ` [RFC PATCH v2 00/12] crypto: " Jason A. Donenfeld
2018-10-19 18:19 ` Paul Crowley
2018-10-20 3:24 ` Ard Biesheuvel
2018-10-20 5:22 ` Eric Biggers
[not found] ` <2395454e-a0dc-408f-4138-9d15ab5f20b8@esat.kuleuven.be>
2018-10-22 11:20 ` Tomer Ashur
2018-10-19 19:04 ` Eric Biggers
2018-10-20 10:26 ` Milan Broz
2018-10-20 13:47 ` Jason A. Donenfeld
2018-11-16 21:52 ` Eric Biggers
2018-11-17 10:29 ` Milan Broz
2018-11-19 19:28 ` Eric Biggers
2018-11-19 20:05 ` Milan Broz
2018-11-19 20:30 ` Jason A. Donenfeld
2018-10-21 22:23 ` Eric Biggers
2018-10-21 22:51 ` Jason A. Donenfeld
2018-10-22 17:17 ` Paul Crowley
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