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>,
"Jason A . Donenfeld" <Jason@zx2c4.com>,
Greg Kaiser <gkaiser@google.com>,
Herbert Xu <herbert@gondor.apana.org.au>,
Samuel Neves <samuel.c.p.neves@gmail.com>,
Michael Halcrow <mhalcrow@google.com>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
linux-fscrypt@vger.kernel.org,
Tomer Ashur <tomer.ashur@esat.kuleuven.be>,
linux-arm-kernel <linux-arm-kernel@lists.infradead.org>,
Paul Crowley <paulcrowley@google.com>
Subject: Re: [RFC PATCH v2 01/12] crypto: chacha20-generic - add HChaCha20 library function
Date: Fri, 19 Oct 2018 22:13:00 +0800 [thread overview]
Message-ID: <CAKv+Gu8bYc_Ex4HjSasbBksj=w1KubVHtvWR=Wq1-65FPw8XBw@mail.gmail.com> (raw)
In-Reply-To: <20181015175424.97147-2-ebiggers@kernel.org>
On 16 October 2018 at 01:54, Eric Biggers <ebiggers@kernel.org> wrote:
> From: Eric Biggers <ebiggers@google.com>
>
> Refactor the unkeyed permutation part of chacha20_block() into its own
> function, then add hchacha20_block() which is the ChaCha equivalent of
> HSalsa20 and is an intermediate step towards XChaCha20 (see
> https://cr.yp.to/snuffle/xsalsa-20081128.pdf). HChaCha20 skips the
> final addition of the initial state, and outputs only certain words of
> the state. It should not be used for streaming directly.
>
> Signed-off-by: Eric Biggers <ebiggers@google.com>
Reviewed-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
> ---
> include/crypto/chacha20.h | 2 ++
> lib/chacha20.c | 50 ++++++++++++++++++++++++++++++++++-----
> 2 files changed, 46 insertions(+), 6 deletions(-)
>
> diff --git a/include/crypto/chacha20.h b/include/crypto/chacha20.h
> index f76302d99e2be..fbec4e6a87890 100644
> --- a/include/crypto/chacha20.h
> +++ b/include/crypto/chacha20.h
> @@ -19,6 +19,8 @@ struct chacha20_ctx {
> };
>
> void chacha20_block(u32 *state, u8 *stream);
> +void hchacha20_block(const u32 *in, u32 *out);
> +
> void crypto_chacha20_init(u32 *state, struct chacha20_ctx *ctx, u8 *iv);
> int crypto_chacha20_setkey(struct crypto_skcipher *tfm, const u8 *key,
> unsigned int keysize);
> diff --git a/lib/chacha20.c b/lib/chacha20.c
> index d907fec6a9ed1..6a484e16171d1 100644
> --- a/lib/chacha20.c
> +++ b/lib/chacha20.c
> @@ -1,5 +1,5 @@
> /*
> - * ChaCha20 256-bit cipher algorithm, RFC7539
> + * The "hash function" used as the core of the ChaCha20 stream cipher (RFC7539)
> *
> * Copyright (C) 2015 Martin Willi
> *
> @@ -16,14 +16,10 @@
> #include <asm/unaligned.h>
> #include <crypto/chacha20.h>
>
> -void chacha20_block(u32 *state, u8 *stream)
> +static void chacha20_permute(u32 *x)
> {
> - u32 x[16];
> int i;
>
> - for (i = 0; i < ARRAY_SIZE(x); i++)
> - x[i] = state[i];
> -
> for (i = 0; i < 20; i += 2) {
> x[0] += x[4]; x[12] = rol32(x[12] ^ x[0], 16);
> x[1] += x[5]; x[13] = rol32(x[13] ^ x[1], 16);
> @@ -65,6 +61,25 @@ void chacha20_block(u32 *state, u8 *stream)
> x[8] += x[13]; x[7] = rol32(x[7] ^ x[8], 7);
> x[9] += x[14]; x[4] = rol32(x[4] ^ x[9], 7);
> }
> +}
> +
> +/**
> + * chacha20_block - generate one keystream block and increment block counter
> + * @state: input state matrix (16 32-bit words)
> + * @stream: output keystream block (64 bytes)
> + *
> + * This is the ChaCha20 core, a function from 64-byte strings to 64-byte
> + * strings. The caller has already converted the endianness of the input. This
> + * function also handles incrementing the block counter in the input matrix.
> + */
> +void chacha20_block(u32 *state, u8 *stream)
> +{
> + u32 x[16];
> + int i;
> +
> + memcpy(x, state, 64);
> +
> + chacha20_permute(x);
>
> for (i = 0; i < ARRAY_SIZE(x); i++)
> put_unaligned_le32(x[i] + state[i], &stream[i * sizeof(u32)]);
> @@ -72,3 +87,26 @@ void chacha20_block(u32 *state, u8 *stream)
> state[12]++;
> }
> EXPORT_SYMBOL(chacha20_block);
> +
> +/**
> + * hchacha20_block - abbreviated ChaCha20 core, for XChaCha20
> + * @in: input state matrix (16 32-bit words)
> + * @out: output (8 32-bit words)
> + *
> + * HChaCha20 is the ChaCha equivalent of HSalsa20 and is an intermediate step
> + * towards XChaCha20 (see https://cr.yp.to/snuffle/xsalsa-20081128.pdf).
> + * HChaCha20 skips the final addition of the initial state, and outputs only
> + * certain words of the state. It should not be used for streaming directly.
> + */
> +void hchacha20_block(const u32 *in, u32 *out)
> +{
> + u32 x[16];
> +
> + memcpy(x, in, 64);
> +
> + chacha20_permute(x);
> +
> + memcpy(&out[0], &x[0], 16);
> + memcpy(&out[4], &x[12], 16);
> +}
> +EXPORT_SYMBOL(hchacha20_block);
> --
> 2.19.1.331.ge82ca0e54c-goog
>
>
> _______________________________________________
> linux-arm-kernel mailing list
> linux-arm-kernel@lists.infradead.org
> http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
next prev parent reply other threads:[~2018-10-19 14:13 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 [this message]
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
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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