--- /dev/null
+/* 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 = 0;
+ BN_CTX *new_ctx = NULL;
+ int used_ctx = 0;
+
+ 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)) {
+ OPENSSL_PUT_ERROR(EC, EC_R_POINT_AT_INFINITY);
+ goto err;
+ }
+
+ const size_t field_len = BN_num_bytes(&group->field);
+ size_t output_len = 1 /* type byte */ + field_len;
+ if (form == POINT_CONVERSION_UNCOMPRESSED) {
+ // Uncompressed points have a second coordinate.
+ output_len += field_len;
+ }
+
+ // if 'buf' is NULL, just return required length
+ if (buf != NULL) {
+ if (len < output_len) {
+ OPENSSL_PUT_ERROR(EC, EC_R_BUFFER_TOO_SMALL);
+ goto err;
+ }
+
+ if (ctx == NULL) {
+ ctx = new_ctx = BN_CTX_new();
+ if (ctx == NULL) {
+ goto err;
+ }
+ }
+
+ BN_CTX_start(ctx);
+ used_ctx = 1;
+ BIGNUM *x = BN_CTX_get(ctx);
+ BIGNUM *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;
+ }
+ size_t 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 != output_len) {
+ OPENSSL_PUT_ERROR(EC, ERR_R_INTERNAL_ERROR);
+ goto err;
+ }
+ }
+
+ ret = output_len;
+
+err:
+ if (used_ctx) {
+ BN_CTX_end(ctx);
+ }
+ BN_CTX_free(new_ctx);
+ return ret;
+}
+
+static int ec_GFp_simple_oct2point(const EC_GROUP *group, EC_POINT *point,
+ const uint8_t *buf, size_t len,
+ BN_CTX *ctx) {
+ BN_CTX *new_ctx = NULL;
+ int ret = 0, used_ctx = 0;
+
+ if (len == 0) {
+ OPENSSL_PUT_ERROR(EC, EC_R_BUFFER_TOO_SMALL);
+ goto err;
+ }
+
+ point_conversion_form_t form = buf[0];
+ const int y_bit = form & 1;
+ form = form & ~1U;
+ if ((form != POINT_CONVERSION_COMPRESSED &&
+ form != POINT_CONVERSION_UNCOMPRESSED) ||
+ (form == POINT_CONVERSION_UNCOMPRESSED && y_bit)) {
+ OPENSSL_PUT_ERROR(EC, EC_R_INVALID_ENCODING);
+ goto err;
+ }
+
+ const size_t field_len = BN_num_bytes(&group->field);
+ size_t enc_len = 1 /* type byte */ + field_len;
+ if (form == POINT_CONVERSION_UNCOMPRESSED) {
+ // Uncompressed points have a second coordinate.
+ enc_len += field_len;
+ }
+
+ if (len != enc_len) {
+ OPENSSL_PUT_ERROR(EC, EC_R_INVALID_ENCODING);
+ goto err;
+ }
+
+ if (ctx == NULL) {
+ ctx = new_ctx = BN_CTX_new();
+ if (ctx == NULL) {
+ goto err;
+ }
+ }
+
+ BN_CTX_start(ctx);
+ used_ctx = 1;
+ BIGNUM *x = BN_CTX_get(ctx);
+ BIGNUM *y = BN_CTX_get(ctx);
+ if (x == NULL || 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;
+ }
+ }
+
+ ret = 1;
+
+err:
+ if (used_ctx) {
+ 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 (EC_GROUP_cmp(group, point->group, NULL) != 0) {
+ OPENSSL_PUT_ERROR(EC, EC_R_INCOMPATIBLE_OBJECTS);
+ return 0;
+ }
+ return ec_GFp_simple_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 (EC_GROUP_cmp(group, point->group, NULL) != 0) {
+ OPENSSL_PUT_ERROR(EC, EC_R_INCOMPATIBLE_OBJECTS);
+ return 0;
+ }
+ return ec_GFp_simple_point2oct(group, point, form, buf, len, ctx);
+}
+
+int EC_POINT_set_compressed_coordinates_GFp(const EC_GROUP *group,
+ EC_POINT *point, const BIGNUM *x,
+ int y_bit, BN_CTX *ctx) {
+ if (EC_GROUP_cmp(group, point->group, NULL) != 0) {
+ OPENSSL_PUT_ERROR(EC, EC_R_INCOMPATIBLE_OBJECTS);
+ return 0;
+ }
+
+ if (BN_is_negative(x) || BN_cmp(x, &group->field) >= 0) {
+ OPENSSL_PUT_ERROR(EC, EC_R_INVALID_COMPRESSED_POINT);
+ return 0;
+ }
+
+ BN_CTX *new_ctx = NULL;
+ 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);
+ BIGNUM *tmp1 = BN_CTX_get(ctx);
+ BIGNUM *tmp2 = BN_CTX_get(ctx);
+ BIGNUM *a = BN_CTX_get(ctx);
+ BIGNUM *b = BN_CTX_get(ctx);
+ BIGNUM *y = BN_CTX_get(ctx);
+ if (y == NULL ||
+ !EC_GROUP_get_curve_GFp(group, NULL, a, b, ctx)) {
+ 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_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_consttime(tmp2, x, &group->field, ctx) ||
+ !bn_mod_add_consttime(tmp2, tmp2, x, &group->field, ctx) ||
+ !bn_mod_sub_consttime(tmp1, tmp1, tmp2, &group->field, ctx)) {
+ goto err;
+ }
+ } else {
+ if (!BN_mod_mul(tmp2, a, x, &group->field, ctx) ||
+ !bn_mod_add_consttime(tmp1, tmp1, tmp2, &group->field, ctx)) {
+ goto err;
+ }
+ }
+
+ // tmp1 := tmp1 + b
+ if (!bn_mod_add_consttime(tmp1, tmp1, b, &group->field, ctx)) {
+ 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)) {
+ OPENSSL_PUT_ERROR(EC, EC_R_INVALID_COMPRESSION_BIT);
+ 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;
+}
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