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@xxxxxxxxx> Reviewed-by: Jarkko Sakkinen <jarkko@xxxxxxxxxx> Signed-off-by: Stefan Berger <stefanb@xxxxxxxxxxxxx> --- crypto/ecc.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) diff --git a/crypto/ecc.c b/crypto/ecc.c index 90a8c7ea9095..fe2ae2d4185c 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); -- 2.43.0
