- /* Originally written by Bodo Moeller for the OpenSSL project.
- * ====================================================================
- * Copyright (c) 1998-2005 The OpenSSL Project. All rights reserved.
- *
- * Redistribution and use in source and binary forms, with or without
- * modification, are permitted provided that the following conditions
- * are met:
- *
- * 1. Redistributions of source code must retain the above copyright
- * notice, this list of conditions and the following disclaimer.
- *
- * 2. Redistributions in binary form must reproduce the above copyright
- * notice, this list of conditions and the following disclaimer in
- * the documentation and/or other materials provided with the
- * distribution.
- *
- * 3. All advertising materials mentioning features or use of this
- * software must display the following acknowledgment:
- * "This product includes software developed by the OpenSSL Project
- * for use in the OpenSSL Toolkit. (http://www.openssl.org/)"
- *
- * 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to
- * endorse or promote products derived from this software without
- * prior written permission. For written permission, please contact
- * openssl-core@openssl.org.
- *
- * 5. Products derived from this software may not be called "OpenSSL"
- * nor may "OpenSSL" appear in their names without prior written
- * permission of the OpenSSL Project.
- *
- * 6. Redistributions of any form whatsoever must retain the following
- * acknowledgment:
- * "This product includes software developed by the OpenSSL Project
- * for use in the OpenSSL Toolkit (http://www.openssl.org/)"
- *
- * THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY
- * EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
- * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
- * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE OpenSSL PROJECT OR
- * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
- * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
- * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
- * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
- * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
- * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
- * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
- * OF THE POSSIBILITY OF SUCH DAMAGE.
- * ====================================================================
- *
- * This product includes cryptographic software written by Eric Young
- * (eay@cryptsoft.com). This product includes software written by Tim
- * Hudson (tjh@cryptsoft.com).
- *
- */
- /* ====================================================================
- * Copyright 2002 Sun Microsystems, Inc. ALL RIGHTS RESERVED.
- *
- * Portions of the attached software ("Contribution") are developed by
- * SUN MICROSYSTEMS, INC., and are contributed to the OpenSSL project.
- *
- * The Contribution is licensed pursuant to the OpenSSL open source
- * license provided above.
- *
- * The elliptic curve binary polynomial software is originally written by
- * Sheueling Chang Shantz and Douglas Stebila of Sun Microsystems
- * Laboratories. */
-
- #include <openssl/ec.h>
-
- #include <openssl/bn.h>
- #include <openssl/err.h>
-
- #include "internal.h"
-
-
- static size_t ec_GFp_simple_point2oct(const EC_GROUP *group,
- const EC_POINT *point,
- point_conversion_form_t form,
- uint8_t *buf, size_t len, BN_CTX *ctx) {
- size_t ret;
- BN_CTX *new_ctx = NULL;
- int used_ctx = 0;
- BIGNUM *x, *y;
- size_t field_len, i;
-
- if ((form != POINT_CONVERSION_COMPRESSED) &&
- (form != POINT_CONVERSION_UNCOMPRESSED)) {
- OPENSSL_PUT_ERROR(EC, EC_R_INVALID_FORM);
- goto err;
- }
-
- if (EC_POINT_is_at_infinity(group, point)) {
- /* encodes to a single 0 octet */
- if (buf != NULL) {
- if (len < 1) {
- OPENSSL_PUT_ERROR(EC, EC_R_BUFFER_TOO_SMALL);
- return 0;
- }
- buf[0] = 0;
- }
- return 1;
- }
-
-
- /* ret := required output buffer length */
- field_len = BN_num_bytes(&group->field);
- ret =
- (form == POINT_CONVERSION_COMPRESSED) ? 1 + field_len : 1 + 2 * field_len;
-
- /* if 'buf' is NULL, just return required length */
- if (buf != NULL) {
- if (len < ret) {
- OPENSSL_PUT_ERROR(EC, EC_R_BUFFER_TOO_SMALL);
- goto err;
- }
-
- if (ctx == NULL) {
- ctx = new_ctx = BN_CTX_new();
- if (ctx == NULL) {
- return 0;
- }
- }
-
- BN_CTX_start(ctx);
- used_ctx = 1;
- x = BN_CTX_get(ctx);
- y = BN_CTX_get(ctx);
- if (y == NULL) {
- goto err;
- }
-
- if (!EC_POINT_get_affine_coordinates_GFp(group, point, x, y, ctx)) {
- goto err;
- }
-
- if ((form == POINT_CONVERSION_COMPRESSED) &&
- BN_is_odd(y)) {
- buf[0] = form + 1;
- } else {
- buf[0] = form;
- }
- i = 1;
-
- if (!BN_bn2bin_padded(buf + i, field_len, x)) {
- OPENSSL_PUT_ERROR(EC, ERR_R_INTERNAL_ERROR);
- goto err;
- }
- i += field_len;
-
- if (form == POINT_CONVERSION_UNCOMPRESSED) {
- if (!BN_bn2bin_padded(buf + i, field_len, y)) {
- OPENSSL_PUT_ERROR(EC, ERR_R_INTERNAL_ERROR);
- goto err;
- }
- i += field_len;
- }
-
- if (i != ret) {
- OPENSSL_PUT_ERROR(EC, ERR_R_INTERNAL_ERROR);
- goto err;
- }
- }
-
- if (used_ctx) {
- BN_CTX_end(ctx);
- }
- BN_CTX_free(new_ctx);
- return ret;
-
- err:
- if (used_ctx) {
- BN_CTX_end(ctx);
- }
- BN_CTX_free(new_ctx);
- return 0;
- }
-
-
- static int ec_GFp_simple_oct2point(const EC_GROUP *group, EC_POINT *point,
- const uint8_t *buf, size_t len,
- BN_CTX *ctx) {
- point_conversion_form_t form;
- int y_bit;
- BN_CTX *new_ctx = NULL;
- BIGNUM *x, *y;
- size_t field_len, enc_len;
- int ret = 0;
-
- if (len == 0) {
- OPENSSL_PUT_ERROR(EC, EC_R_BUFFER_TOO_SMALL);
- return 0;
- }
- form = buf[0];
- y_bit = form & 1;
- form = form & ~1U;
- if ((form != 0) && (form != POINT_CONVERSION_COMPRESSED) &&
- (form != POINT_CONVERSION_UNCOMPRESSED)) {
- OPENSSL_PUT_ERROR(EC, EC_R_INVALID_ENCODING);
- return 0;
- }
- if ((form == 0 || form == POINT_CONVERSION_UNCOMPRESSED) && y_bit) {
- OPENSSL_PUT_ERROR(EC, EC_R_INVALID_ENCODING);
- return 0;
- }
-
- if (form == 0) {
- if (len != 1) {
- OPENSSL_PUT_ERROR(EC, EC_R_INVALID_ENCODING);
- return 0;
- }
-
- return EC_POINT_set_to_infinity(group, point);
- }
-
- field_len = BN_num_bytes(&group->field);
- enc_len =
- (form == POINT_CONVERSION_COMPRESSED) ? 1 + field_len : 1 + 2 * field_len;
-
- if (len != enc_len) {
- OPENSSL_PUT_ERROR(EC, EC_R_INVALID_ENCODING);
- return 0;
- }
-
- if (ctx == NULL) {
- ctx = new_ctx = BN_CTX_new();
- if (ctx == NULL) {
- return 0;
- }
- }
-
- BN_CTX_start(ctx);
- x = BN_CTX_get(ctx);
- y = BN_CTX_get(ctx);
- if (y == NULL) {
- goto err;
- }
-
- if (!BN_bin2bn(buf + 1, field_len, x)) {
- goto err;
- }
- if (BN_ucmp(x, &group->field) >= 0) {
- OPENSSL_PUT_ERROR(EC, EC_R_INVALID_ENCODING);
- goto err;
- }
-
- if (form == POINT_CONVERSION_COMPRESSED) {
- if (!EC_POINT_set_compressed_coordinates_GFp(group, point, x, y_bit, ctx)) {
- goto err;
- }
- } else {
- if (!BN_bin2bn(buf + 1 + field_len, field_len, y)) {
- goto err;
- }
- if (BN_ucmp(y, &group->field) >= 0) {
- OPENSSL_PUT_ERROR(EC, EC_R_INVALID_ENCODING);
- goto err;
- }
-
- if (!EC_POINT_set_affine_coordinates_GFp(group, point, x, y, ctx)) {
- goto err;
- }
- }
-
- /* test required by X9.62 */
- if (!EC_POINT_is_on_curve(group, point, ctx)) {
- OPENSSL_PUT_ERROR(EC, EC_R_POINT_IS_NOT_ON_CURVE);
- goto err;
- }
-
- ret = 1;
-
- err:
- BN_CTX_end(ctx);
- BN_CTX_free(new_ctx);
- return ret;
- }
-
- int EC_POINT_oct2point(const EC_GROUP *group, EC_POINT *point,
- const uint8_t *buf, size_t len, BN_CTX *ctx) {
- if (group->meth->oct2point == 0 &&
- !(group->meth->flags & EC_FLAGS_DEFAULT_OCT)) {
- OPENSSL_PUT_ERROR(EC, ERR_R_SHOULD_NOT_HAVE_BEEN_CALLED);
- return 0;
- }
- if (group->meth != point->meth) {
- OPENSSL_PUT_ERROR(EC, EC_R_INCOMPATIBLE_OBJECTS);
- return 0;
- }
- if (group->meth->flags & EC_FLAGS_DEFAULT_OCT) {
- return ec_GFp_simple_oct2point(group, point, buf, len, ctx);
- }
-
- return group->meth->oct2point(group, point, buf, len, ctx);
- }
-
- size_t EC_POINT_point2oct(const EC_GROUP *group, const EC_POINT *point,
- point_conversion_form_t form, uint8_t *buf,
- size_t len, BN_CTX *ctx) {
- if (group->meth->point2oct == 0 &&
- !(group->meth->flags & EC_FLAGS_DEFAULT_OCT)) {
- OPENSSL_PUT_ERROR(EC, ERR_R_SHOULD_NOT_HAVE_BEEN_CALLED);
- return 0;
- }
- if (group->meth != point->meth) {
- OPENSSL_PUT_ERROR(EC, EC_R_INCOMPATIBLE_OBJECTS);
- return 0;
- }
- if (group->meth->flags & EC_FLAGS_DEFAULT_OCT) {
- return ec_GFp_simple_point2oct(group, point, form, buf, len, ctx);
- }
-
- return group->meth->point2oct(group, point, form, buf, len, ctx);
- }
-
- int ec_GFp_simple_set_compressed_coordinates(const EC_GROUP *group,
- EC_POINT *point, const BIGNUM *x_,
- int y_bit, BN_CTX *ctx) {
- BN_CTX *new_ctx = NULL;
- BIGNUM *tmp1, *tmp2, *x, *y;
- int ret = 0;
-
- ERR_clear_error();
-
- if (ctx == NULL) {
- ctx = new_ctx = BN_CTX_new();
- if (ctx == NULL) {
- return 0;
- }
- }
-
- y_bit = (y_bit != 0);
-
- BN_CTX_start(ctx);
- tmp1 = BN_CTX_get(ctx);
- tmp2 = BN_CTX_get(ctx);
- x = BN_CTX_get(ctx);
- y = BN_CTX_get(ctx);
- if (y == NULL) {
- goto err;
- }
-
- /* Recover y. We have a Weierstrass equation
- * y^2 = x^3 + a*x + b,
- * so y is one of the square roots of x^3 + a*x + b. */
-
- /* tmp1 := x^3 */
- if (!BN_nnmod(x, x_, &group->field, ctx)) {
- goto err;
- }
-
- if (group->meth->field_decode == 0) {
- /* field_{sqr,mul} work on standard representation */
- if (!group->meth->field_sqr(group, tmp2, x_, ctx) ||
- !group->meth->field_mul(group, tmp1, tmp2, x_, ctx)) {
- goto err;
- }
- } else {
- if (!BN_mod_sqr(tmp2, x_, &group->field, ctx) ||
- !BN_mod_mul(tmp1, tmp2, x_, &group->field, ctx)) {
- goto err;
- }
- }
-
- /* tmp1 := tmp1 + a*x */
- if (group->a_is_minus3) {
- if (!BN_mod_lshift1_quick(tmp2, x, &group->field) ||
- !BN_mod_add_quick(tmp2, tmp2, x, &group->field) ||
- !BN_mod_sub_quick(tmp1, tmp1, tmp2, &group->field)) {
- goto err;
- }
- } else {
- if (group->meth->field_decode) {
- if (!group->meth->field_decode(group, tmp2, &group->a, ctx) ||
- !BN_mod_mul(tmp2, tmp2, x, &group->field, ctx)) {
- goto err;
- }
- } else {
- /* field_mul works on standard representation */
- if (!group->meth->field_mul(group, tmp2, &group->a, x, ctx)) {
- goto err;
- }
- }
-
- if (!BN_mod_add_quick(tmp1, tmp1, tmp2, &group->field)) {
- goto err;
- }
- }
-
- /* tmp1 := tmp1 + b */
- if (group->meth->field_decode) {
- if (!group->meth->field_decode(group, tmp2, &group->b, ctx) ||
- !BN_mod_add_quick(tmp1, tmp1, tmp2, &group->field)) {
- goto err;
- }
- } else {
- if (!BN_mod_add_quick(tmp1, tmp1, &group->b, &group->field)) {
- goto err;
- }
- }
-
- if (!BN_mod_sqrt(y, tmp1, &group->field, ctx)) {
- unsigned long err = ERR_peek_last_error();
-
- if (ERR_GET_LIB(err) == ERR_LIB_BN &&
- ERR_GET_REASON(err) == BN_R_NOT_A_SQUARE) {
- ERR_clear_error();
- OPENSSL_PUT_ERROR(EC, EC_R_INVALID_COMPRESSED_POINT);
- } else {
- OPENSSL_PUT_ERROR(EC, ERR_R_BN_LIB);
- }
- goto err;
- }
-
- if (y_bit != BN_is_odd(y)) {
- if (BN_is_zero(y)) {
- int kron;
-
- kron = BN_kronecker(x, &group->field, ctx);
- if (kron == -2) {
- goto err;
- }
-
- if (kron == 1) {
- OPENSSL_PUT_ERROR(EC, EC_R_INVALID_COMPRESSION_BIT);
- } else {
- /* BN_mod_sqrt() should have cought this error (not a square) */
- OPENSSL_PUT_ERROR(EC, EC_R_INVALID_COMPRESSED_POINT);
- }
- goto err;
- }
- if (!BN_usub(y, &group->field, y)) {
- goto err;
- }
- }
- if (y_bit != BN_is_odd(y)) {
- OPENSSL_PUT_ERROR(EC, ERR_R_INTERNAL_ERROR);
- goto err;
- }
-
- if (!EC_POINT_set_affine_coordinates_GFp(group, point, x, y, ctx)) {
- goto err;
- }
-
- ret = 1;
-
- err:
- BN_CTX_end(ctx);
- BN_CTX_free(new_ctx);
- return ret;
- }
-
- int EC_POINT_set_compressed_coordinates_GFp(const EC_GROUP *group,
- EC_POINT *point, const BIGNUM *x,
- int y_bit, BN_CTX *ctx) {
- if (group->meth->point_set_compressed_coordinates == 0 &&
- !(group->meth->flags & EC_FLAGS_DEFAULT_OCT)) {
- OPENSSL_PUT_ERROR(EC, ERR_R_SHOULD_NOT_HAVE_BEEN_CALLED);
- return 0;
- }
- if (group->meth != point->meth) {
- OPENSSL_PUT_ERROR(EC, EC_R_INCOMPATIBLE_OBJECTS);
- return 0;
- }
- if (group->meth->flags & EC_FLAGS_DEFAULT_OCT) {
- return ec_GFp_simple_set_compressed_coordinates(group, point, x, y_bit,
- ctx);
- }
- return group->meth->point_set_compressed_coordinates(group, point, x, y_bit,
- ctx);
- }
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