From: "Jarkko Sakkinen" <jarkko@kernel.org>
To: "Stefan Berger" <stefanb@linux.ibm.com>,
<keyrings@vger.kernel.org>, <linux-crypto@vger.kernel.org>,
<herbert@gondor.apana.org.au>, <davem@davemloft.net>
Cc: <linux-kernel@vger.kernel.org>, <saulo.alessandre@tse.jus.br>,
<lukas@wunner.de>
Subject: Re: [PATCH v5 05/12] crypto: ecc - Implement vli_mmod_fast_521 for NIST p521
Date: Thu, 07 Mar 2024 21:11:37 +0200 [thread overview]
Message-ID: <CZNR8E07IQ14.301SKAK0CJX1G@kernel.org> (raw)
In-Reply-To: <20240306222257.979304-6-stefanb@linux.ibm.com>
On Thu Mar 7, 2024 at 12:22 AM EET, Stefan Berger wrote:
> Implement vli_mmod_fast_521 following the description for how to calculate
> the modulus for NIST P521 in the NIST publication "Recommendations for
> Discrete Logarithm-Based Cryptography: Elliptic Curve Domain Parameters"
> section G.1.4.
>
> NIST p521 requires 9 64bit digits, so increase the ECC_MAX_DIGITS so that
> arrays fit the larger numbers.
>
> Signed-off-by: Stefan Berger <stefanb@linux.ibm.com>
> Tested-by: Lukas Wunner <lukas@wunner.de>
> ---
> crypto/ecc.c | 31 +++++++++++++++++++++++++++++++
> include/crypto/internal/ecc.h | 2 +-
> 2 files changed, 32 insertions(+), 1 deletion(-)
>
> diff --git a/crypto/ecc.c b/crypto/ecc.c
> index f53fb4d6af99..373660e7b19d 100644
> --- a/crypto/ecc.c
> +++ b/crypto/ecc.c
> @@ -902,6 +902,31 @@ static void vli_mmod_fast_384(u64 *result, const u64 *product,
> #undef AND64H
> #undef AND64L
>
> +/* Computes result = product % curve_prime
Missing empty comment line:
/*
*
> + * from "Recommendations for Discrete Logarithm-Based Cryptography:
> + * Elliptic Curve Domain Parameters" G.1.4
> + */
> +static void vli_mmod_fast_521(u64 *result, const u64 *product,
> + const u64 *curve_prime, u64 *tmp)
> +{
> + const unsigned int ndigits = 9;
> + size_t i;
> +
> + for (i = 0; i < ndigits; i++)
> + tmp[i] = product[i];
> + tmp[8] &= 0x1ff;
> +
> + vli_set(result, tmp, ndigits);
> +
> +
> + for (i = 0; i < ndigits; i++)
> + tmp[i] = (product[8 + i] >> 9) | (product[9 + i] << 55);
> + tmp[8] &= 0x1ff;
> +
> + vli_mod_add(result, result, tmp, curve_prime, ndigits);
> +}
> +
> +
> /* Computes result = product % curve_prime for different curve_primes.
> *
> * Note that curve_primes are distinguished just by heuristic check and
> @@ -941,6 +966,12 @@ static bool vli_mmod_fast(u64 *result, u64 *product,
> case 6:
> vli_mmod_fast_384(result, product, curve_prime, tmp);
> break;
> + case 9:
> + if (curve->nbits == 521) {
Missing inline comment about the branching decision, and has a magic
number.
> + vli_mmod_fast_521(result, product, curve_prime, tmp);
> + break;
> + }
> + fallthrough;
> default:
> pr_err_ratelimited("ecc: unsupported digits size!\n");
> return false;
> diff --git a/include/crypto/internal/ecc.h b/include/crypto/internal/ecc.h
> index 4a556b41873e..de17bcdeb53a 100644
> --- a/include/crypto/internal/ecc.h
> +++ b/include/crypto/internal/ecc.h
> @@ -33,7 +33,7 @@
> #define ECC_CURVE_NIST_P192_DIGITS 3
> #define ECC_CURVE_NIST_P256_DIGITS 4
> #define ECC_CURVE_NIST_P384_DIGITS 6
> -#define ECC_MAX_DIGITS (512 / 64) /* due to ecrdsa */
> +#define ECC_MAX_DIGITS DIV_ROUND_UP(521, 64) /* NIST P521 */
>
> #define ECC_DIGITS_TO_BYTES_SHIFT 3
>
BR, Jarkko
next prev parent reply other threads:[~2024-03-07 19:11 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-03-06 22:22 [PATCH v4 00/12] Add support for NIST P521 to ecdsa Stefan Berger
2024-03-06 22:22 ` [PATCH v5 01/12] crypto: ecdsa - Convert byte arrays with key coordinates to digits Stefan Berger
2024-03-08 8:41 ` Lukas Wunner
2024-03-08 12:11 ` Stefan Berger
2024-03-06 22:22 ` [PATCH v5 02/12] crypto: ecdsa - Adjust tests on length of key parameters Stefan Berger
2024-03-06 22:22 ` [PATCH v5 03/12] crypto: ecdsa - Extend res.x mod n calculation for NIST P521 Stefan Berger
2024-03-06 22:22 ` [PATCH v5 04/12] crypto: ecc - Add nbits field to ecc_curve structure Stefan Berger
2024-03-06 22:22 ` [PATCH v5 05/12] crypto: ecc - Implement vli_mmod_fast_521 for NIST p521 Stefan Berger
2024-03-07 19:11 ` Jarkko Sakkinen [this message]
2024-03-07 20:37 ` Stefan Berger
2024-03-11 5:07 ` [EXTERNAL] " Bharat Bhushan
2024-03-11 14:03 ` Stefan Berger
2024-03-11 16:11 ` [EXTERNAL] " Bharat Bhushan
2024-03-06 22:22 ` [PATCH v5 06/12] crypto: ecc - Add special case for NIST P521 in ecc_point_mult Stefan Berger
2024-03-06 22:22 ` [PATCH v5 07/12] crypto: ecc - Add NIST P521 curve parameters Stefan Berger
2024-03-06 22:22 ` [PATCH v5 08/12] crypto: ecdsa - Replace ndigits with nbits where precision is needed Stefan Berger
2024-03-06 22:22 ` [PATCH v5 09/12] crypto: ecdsa - Rename keylen to bufsize where necessary Stefan Berger
2024-03-07 19:13 ` Jarkko Sakkinen
2024-03-07 19:20 ` Stefan Berger
2024-03-08 7:48 ` Vitaly Chikunov
2024-03-06 22:22 ` [PATCH v5 10/12] crypto: ecdsa - Register NIST P521 and extend test suite Stefan Berger
2024-03-06 22:22 ` [PATCH v5 11/12] crypto: asymmetric_keys - Adjust signature size calculation for NIST P521 Stefan Berger
2024-03-06 22:22 ` [PATCH v5 12/12] crypto: x509 - Add OID for NIST P521 and extend parser for it Stefan Berger
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