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crypto: ecc - Add special case for NIST P521 in ecc_point_mult

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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.

Tested-by: Lukas Wunner <lukas@wunner.de>
Reviewed-by: Jarkko Sakkinen <jarkko@kernel.org>
Signed-off-by: Stefan Berger <stefanb@linux.ibm.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
This commit is contained in:
Stefan Berger 2024-04-04 10:18:50 -04:00 committed by Herbert Xu
parent e7fb062754
commit 114e80437e
1 changed files with 4 additions and 1 deletions
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crypto/ecc.c
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@ -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);