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Align various point_get_affine_coordinates implementations.

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The P-224 implementation was missing the optimization to avoid doing
extra work when asking for only one coordinate (ECDH and ECDSA both
involve an x-coordinate query). The P-256 implementation was missing the
optimization to do one less Montgomery reduction.

TODO - Benchmarks

Change-Id: I268d9c24737c6da9efaf1c73395b73dd97355de7
Reviewed-on: https://boringssl-review.googlesource.com/24690
Reviewed-by: Adam Langley <agl@google.com>
Commit-Queue: Adam Langley <agl@google.com>
CQ-Verified: CQ bot account: commit-bot@chromium.org <commit-bot@chromium.org>
This commit is contained in:
David Benjamin 2017-12-30 00:33:54 -05:00 committed by CQ bot account: commit-bot@chromium.org
parent 9112631c1f
commit 0c9b7b5de2
2 changed files with 24 additions and 16 deletions
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33
crypto/fipsmodule/ec/p224-64.c
View File

@ -1015,22 +1015,27 @@ static int ec_GFp_nistp224_point_get_affine_coordinates(const EC_GROUP *group,
p224_felem_inv(z2, z1);
p224_felem_square(tmp, z2);
p224_felem_reduce(z1, tmp);
p224_felem_mul(tmp, x_in, z1);
p224_felem_reduce(x_in, tmp);
p224_felem_contract(x_out, x_in);
if (x != NULL && !p224_felem_to_BN(x, x_out)) {
OPENSSL_PUT_ERROR(EC, ERR_R_BN_LIB);
return 0;
if (x != NULL) {
p224_felem_mul(tmp, x_in, z1);
p224_felem_reduce(x_in, tmp);
p224_felem_contract(x_out, x_in);
if (!p224_felem_to_BN(x, x_out)) {
OPENSSL_PUT_ERROR(EC, ERR_R_BN_LIB);
return 0;
}
}
p224_felem_mul(tmp, z1, z2);
p224_felem_reduce(z1, tmp);
p224_felem_mul(tmp, y_in, z1);
p224_felem_reduce(y_in, tmp);
p224_felem_contract(y_out, y_in);
if (y != NULL && !p224_felem_to_BN(y, y_out)) {
OPENSSL_PUT_ERROR(EC, ERR_R_BN_LIB);
return 0;
if (y != NULL) {
p224_felem_mul(tmp, z1, z2);
p224_felem_reduce(z1, tmp);
p224_felem_mul(tmp, y_in, z1);
p224_felem_reduce(y_in, tmp);
p224_felem_contract(y_out, y_in);
if (!p224_felem_to_BN(y, y_out)) {
OPENSSL_PUT_ERROR(EC, ERR_R_BN_LIB);
return 0;
}
}
return 1;

7
third_party/fiat/p256.c vendored
View File

@ -1645,9 +1645,13 @@ static int ec_GFp_nistp256_point_get_affine_coordinates(const EC_GROUP *group,
fe_inv(z2, z1);
fe_sqr(z1, z2);
// Instead of using |fe_from_montgomery| to convert the |x| coordinate and
// then calling |fe_from_montgomery| again to convert the |y| coordinate
// below, convert the common factor |z1| once now, saving one reduction.
fe_from_montgomery(z1);
if (x_out != NULL) {
fe_mul(x, x, z1);
fe_from_montgomery(x);
if (!fe_to_BN(x_out, x)) {
OPENSSL_PUT_ERROR(EC, ERR_R_BN_LIB);
return 0;
@ -1657,7 +1661,6 @@ static int ec_GFp_nistp256_point_get_affine_coordinates(const EC_GROUP *group,
if (y_out != NULL) {
fe_mul(z1, z1, z2);
fe_mul(y, y, z1);
fe_from_montgomery(y);
if (!fe_to_BN(y_out, y)) {
OPENSSL_PUT_ERROR(EC, ERR_R_BN_LIB);
return 0;