From: Vitaly Chikunov <vt@altlinux.org>
To: Jarkko Sakkinen <jarkko@kernel.org>,
Stefan Berger <stefanb@linux.ibm.com>
Cc: keyrings@vger.kernel.org, linux-crypto@vger.kernel.org,
herbert@gondor.apana.org.au, davem@davemloft.net,
linux-kernel@vger.kernel.org, saulo.alessandre@tse.jus.br,
lukas@wunner.de
Subject: Re: [PATCH v5 09/12] crypto: ecdsa - Rename keylen to bufsize where necessary
Date: Fri, 8 Mar 2024 10:48:42 +0300 [thread overview]
Message-ID: <20240308074842.g25bsphtbwdzzo4l@altlinux.org> (raw)
In-Reply-To: <571aa199-00cc-4153-9424-0012d20dc6f6@linux.ibm.com>
Jarkko,
On Thu, Mar 07, 2024 at 02:20:12PM -0500, Stefan Berger wrote:
> On 3/7/24 14:13, Jarkko Sakkinen wrote:
> > On Thu Mar 7, 2024 at 12:22 AM EET, Stefan Berger wrote:
> > > In some cases the name keylen does not reflect the purpose of the variable
> > > anymore once NIST P521 is used but it is the size of the buffer. There-
> > > for, rename keylen to bufsize where appropriate.
> > >
> > > Signed-off-by: Stefan Berger <stefanb@linux.ibm.com>
> > > Tested-by: Lukas Wunner <lukas@wunner.de>
> > > ---
> > > crypto/ecdsa.c | 12 ++++++------
> > > 1 file changed, 6 insertions(+), 6 deletions(-)
> > >
> > > diff --git a/crypto/ecdsa.c b/crypto/ecdsa.c
> > > index 4daefb40c37a..4e847b59622a 100644
> > > --- a/crypto/ecdsa.c
> > > +++ b/crypto/ecdsa.c
> > > @@ -35,8 +35,8 @@ struct ecdsa_signature_ctx {
> > > static int ecdsa_get_signature_rs(u64 *dest, size_t hdrlen, unsigned char tag,
> > > const void *value, size_t vlen, unsigned int ndigits)
> > > {
> > > - size_t keylen = ndigits * sizeof(u64);
> >
> > nit: still don't get why "* sizeof(u64)" would ever be more readable
> > thean "* 8".
>
> Because existing code in crypto uses sizeof(u64) when converting ndigits to
> number of bytes and '8' is not used for converting to bytes. Do we need to
> change this now ? No, I think it's better to conform to existing code.
`sizeof(u64)` is easily read as `8` by reviewers, but just `8` will
require inline comments because it's magic number isn't it? So this will
not even decrease number of letters.
`sizeof(u64)` is self-documenting code and you don't even need to
interpret it as `8` for review as you don't need number from any
sizeof(struct ..).
Also, possible we need to calculate number of bits in the big number, so
this would become `* 8 * 8`, in that case how would you distinguish
omission of one `* 8` by a typo.
Overall it's quite common in the whole tree
linux/torvalds$ git grep -e '\* sizeof(u64)' -e 'sizeof(u64) \*' | wc -l
551
So this is perhaps acceptable and depends on point of view. crypto
subsystem coders seems to prefer not to save on letters and type
`sizeof(u64)`.
Thanks,
>
> # grep -rI ndigits crypto/ | grep sizeof\(u64\)
> crypto/ecrdsa.c: unsigned int ndigits = req->dst_len / sizeof(u64);
> crypto/ecrdsa.c: req->dst_len != ctx->curve->g.ndigits *
> sizeof(u64) ||
> crypto/ecrdsa.c: vli_from_be64(r, sig + ndigits * sizeof(u64),
> ndigits);
> crypto/ecrdsa.c: ctx->curve->g.ndigits * sizeof(u64) !=
> ctx->digest_len)
> crypto/ecrdsa.c: ctx->key_len != ctx->curve->g.ndigits *
> sizeof(u64) * 2)
> crypto/ecrdsa.c: ndigits = ctx->key_len / sizeof(u64) / 2;
> crypto/ecrdsa.c: vli_from_le64(ctx->pub_key.y, ctx->key + ndigits *
> sizeof(u64),
> crypto/ecrdsa.c: return ctx->pub_key.ndigits * sizeof(u64);
> crypto/ecdh.c: params.key_size > sizeof(u64) * ctx->ndigits)
> crypto/ecc.c: size_t len = ndigits * sizeof(u64);
> crypto/ecc.c: num_bits = sizeof(u64) * ndigits * 8 + 1;
> crypto/ecdsa.c: size_t bufsize = ndigits * sizeof(u64);
> crypto/ecdsa.c: size_t bufsize = ctx->curve->g.ndigits * sizeof(u64);
> crypto/ecdsa.c: ndigits = DIV_ROUND_UP(digitlen, sizeof(u64));
>
> Stefan
>
> >
> > BR, Jarkko
next prev parent reply other threads:[~2024-03-08 7:56 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
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 [this message]
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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