On Tue Mar 12, 2024 at 8:36 PM EET, Stefan Berger wrote: > From: Stefan Berger <stefanb@xxxxxxxxxxxxx> > > In ecc_point_mult use the number of bits of the NIST P521 curve + 2. The > change is required specifically for NIST P521 to pass mathematical tests > on the public key. > > Signed-off-by: Stefan Berger <stefanb@xxxxxxxxxxxxx> > Tested-by: Lukas Wunner <lukas@xxxxxxxxx> > --- > crypto/ecc.c | 5 ++++- > 1 file changed, 4 insertions(+), 1 deletion(-) > > diff --git a/crypto/ecc.c b/crypto/ecc.c > index 99d41887c005..ead40b5ebb46 100644 > --- a/crypto/ecc.c > +++ b/crypto/ecc.c > @@ -1320,7 +1320,10 @@ static void ecc_point_mult(struct ecc_point *result, > carry = vli_add(sk[0], scalar, curve->n, ndigits); > vli_add(sk[1], sk[0], curve->n, ndigits); > scalar = sk[!carry]; > - num_bits = sizeof(u64) * ndigits * 8 + 1; > + if (curve->nbits == 521) /* NIST P521 */ > + num_bits = curve->nbits + 2; > + else > + num_bits = sizeof(u64) * ndigits * 8 + 1; > > vli_set(rx[1], point->x, ndigits); > vli_set(ry[1], point->y, ndigits); Reviewed-by: Jarkko Sakkinen <jarkko@xxxxxxxxxx> BR, Jarkko
