linux-kernel.vger.kernel.org archive mirror
 help / color / mirror / Atom feed
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

  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

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to='CAKv+Gu8bYc_Ex4HjSasbBksj=w1KubVHtvWR=Wq1-65FPw8XBw@mail.gmail.com' \
    --to=ard.biesheuvel@linaro.org \
    --cc=Jason@zx2c4.com \
    --cc=ebiggers@kernel.org \
    --cc=gkaiser@google.com \
    --cc=herbert@gondor.apana.org.au \
    --cc=linux-arm-kernel@lists.infradead.org \
    --cc=linux-crypto@vger.kernel.org \
    --cc=linux-fscrypt@vger.kernel.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=mhalcrow@google.com \
    --cc=paulcrowley@google.com \
    --cc=samuel.c.p.neves@gmail.com \
    --cc=tomer.ashur@esat.kuleuven.be \
    --subject='Re: [RFC PATCH v2 01/12] crypto: chacha20-generic - add HChaCha20 library function' \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).