Stefan,
On Sat, Mar 06, 2021 at 06:29:18PM -0500, Stefan Berger wrote:
> On 3/6/21 2:25 PM, Vitaly Chikunov wrote:
> >
> > On Thu, Mar 04, 2021 at 07:51:57PM -0500, Stefan Berger wrote:
> > > From: Saulo Alessandre <saulo.alessandre@xxxxxxxxxx>
> > >
> > > * crypto/ecc.c
> > > - add vli_mmod_fast_384
> > > - change some routines to pass ecc_curve forward until vli_mmod_fast
> > >
> > > * crypto/ecc.h
> > > - add ECC_CURVE_NIST_P384_DIGITS
> > > - change ECC_MAX_DIGITS to P384 size
> > >
> > > Signed-off-by: Saulo Alessandre <saulo.alessandre@xxxxxxxxxx>
> > > Tested-by: Stefan Berger <stefanb@xxxxxxxxxxxxx>
> > > ---
> > > crypto/ecc.c | 266 +++++++++++++++++++++++++++++++++++++--------------
> > > crypto/ecc.h | 3 +-
> > > 2 files changed, 194 insertions(+), 75 deletions(-)
> > >
> > > diff --git a/crypto/ecc.c b/crypto/ecc.c
> > > index f6cef5a7942d..c125576cda6b 100644
> > > --- a/crypto/ecc.c
> > > +++ b/crypto/ecc.c
> > > @@ -778,18 +778,133 @@ static void vli_mmod_fast_256(u64 *result, const u64 *product,
> > > ...
> > > /* Computes result = product % curve_prime for different curve_primes.
> > > *
> > > * Note that curve_primes are distinguished just by heuristic check and
> > > * not by complete conformance check.
> > > */
> > > static bool vli_mmod_fast(u64 *result, u64 *product,
> > > - const u64 *curve_prime, unsigned int ndigits)
> > > + const struct ecc_curve *curve)
> > > {
> > > u64 tmp[2 * ECC_MAX_DIGITS];
> > > + const u64 *curve_prime = curve->p;
> > > + const unsigned int ndigits = curve->g.ndigits;
> > > - /* Currently, both NIST primes have -1 in lowest qword. */
> > > - if (curve_prime[0] != -1ull) {
> > > + /* Currently, all NIST have name nist_.* */
> > > + if (strncmp(curve->name, "nist_", 5) != 0) {
> > I am not sure, but maybe this strncmp should not be optimized somehow,
> > since vli_mmod_fast could be called quite frequently. Perhaps by integer
> > algo id or even callback?
>
> Should be optimized or should not be? You seem to say both.
Excuse me for the typo. I meant "should be optimized". I think, maybe
it's time to add algo selector id (for the case statement, for example
instead of `switch (ndigits)') or just callback for a low level mmod
function.
If you think this would not impact performance then nevermind.
Thanks,
>
> The code code here is shared with ecrdsa. The comparison won't go beyond a
> single letter considering the naming of the curves define here:
>
> "cp256a":
> https://elixir.bootlin.com/linux/v5.11.3/source/crypto/ecrdsa_defs.h#L49
>
> "cp256b":
> https://elixir.bootlin.com/linux/v5.11.3/source/crypto/ecrdsa_defs.h#L82
>
> "cp256c":
> https://elixir.bootlin.com/linux/v5.11.3/source/crypto/ecrdsa_defs.h#L119
>
> "tc512a":
> https://elixir.bootlin.com/linux/v5.11.3/source/crypto/ecrdsa_defs.h#L168
>
> and here:
>
> "nist_192":
> https://elixir.bootlin.com/linux/v5.11.3/source/crypto/ecc_curve_defs.h#L18
>
> "nist_256":
> https://elixir.bootlin.com/linux/v5.11.3/source/crypto/ecc_curve_defs.h#L45
>
>
> All the ecrdsa curves were previously evaluating 'curve_prime[0] != -1ull',
> so it doesn't change anything.
>
> Stefan
>
