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Improve doc on special use of A in ecp group structure

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Signed-off-by: Chien Wong <m@xv97.com>
This commit is contained in:
Chien Wong
2023-01-31 23:27:03 +08:00
parent 3b5e8aa05c
commit 153ae464db
2 changed files with 44 additions and 4 deletions
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4
library/ecp.c
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@ -1255,7 +1255,7 @@ static int ecp_sw_rhs(const mbedtls_ecp_group *grp,
MPI_ECP_SQR(rhs, X);
/* Special case for A = -3 */
if (grp->A.p == NULL) {
if (mbedtls_ecp_group_a_is_minus_3(grp)) {
MPI_ECP_SUB_INT(rhs, rhs, 3);
} else {
MPI_ECP_ADD(rhs, rhs, &grp->A);
@ -1526,7 +1526,7 @@ static int ecp_double_jac(const mbedtls_ecp_group *grp, mbedtls_ecp_point *R,
int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
/* Special case for A = -3 */
if (grp->A.p == NULL) {
if (mbedtls_ecp_group_a_is_minus_3(grp)) {
/* tmp[0] <- M = 3(X + Z^2)(X - Z^2) */
MPI_ECP_SQR(&tmp[1], &P->Z);
MPI_ECP_ADD(&tmp[2], &P->X, &tmp[1]);