1 /* $OpenBSD: ec2_oct.c,v 1.6 2015/02/08 22:25:03 miod Exp $ */
2 /* ====================================================================
3 * Copyright 2002 Sun Microsystems, Inc. ALL RIGHTS RESERVED.
5 * The Elliptic Curve Public-Key Crypto Library (ECC Code) included
6 * herein is developed by SUN MICROSYSTEMS, INC., and is contributed
7 * to the OpenSSL project.
9 * The ECC Code is licensed pursuant to the OpenSSL open source
10 * license provided below.
12 * The software is originally written by Sheueling Chang Shantz and
13 * Douglas Stebila of Sun Microsystems Laboratories.
16 /* ====================================================================
17 * Copyright (c) 1998-2005 The OpenSSL Project. All rights reserved.
19 * Redistribution and use in source and binary forms, with or without
20 * modification, are permitted provided that the following conditions
23 * 1. Redistributions of source code must retain the above copyright
24 * notice, this list of conditions and the following disclaimer.
26 * 2. Redistributions in binary form must reproduce the above copyright
27 * notice, this list of conditions and the following disclaimer in
28 * the documentation and/or other materials provided with the
31 * 3. All advertising materials mentioning features or use of this
32 * software must display the following acknowledgment:
33 * "This product includes software developed by the OpenSSL Project
34 * for use in the OpenSSL Toolkit. (http://www.openssl.org/)"
36 * 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to
37 * endorse or promote products derived from this software without
38 * prior written permission. For written permission, please contact
39 * openssl-core@openssl.org.
41 * 5. Products derived from this software may not be called "OpenSSL"
42 * nor may "OpenSSL" appear in their names without prior written
43 * permission of the OpenSSL Project.
45 * 6. Redistributions of any form whatsoever must retain the following
47 * "This product includes software developed by the OpenSSL Project
48 * for use in the OpenSSL Toolkit (http://www.openssl.org/)"
50 * THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY
51 * EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
52 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
53 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE OpenSSL PROJECT OR
54 * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
55 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
56 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
57 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
58 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
59 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
60 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
61 * OF THE POSSIBILITY OF SUCH DAMAGE.
62 * ====================================================================
64 * This product includes cryptographic software written by Eric Young
65 * (eay@cryptsoft.com). This product includes software written by Tim
66 * Hudson (tjh@cryptsoft.com).
70 #include <openssl/opensslconf.h>
72 #include <openssl/err.h>
76 #ifndef OPENSSL_NO_EC2M
78 /* Calculates and sets the affine coordinates of an EC_POINT from the given
79 * compressed coordinates. Uses algorithm 2.3.4 of SEC 1.
80 * Note that the simple implementation only uses affine coordinates.
82 * The method is from the following publication:
84 * Harper, Menezes, Vanstone:
85 * "Public-Key Cryptosystems with Very Small Key Lengths",
86 * EUROCRYPT '92, Springer-Verlag LNCS 658,
87 * published February 1993
89 * US Patents 6,141,420 and 6,618,483 (Vanstone, Mullin, Agnew) describe
90 * the same method, but claim no priority date earlier than July 29, 1994
91 * (and additionally fail to cite the EUROCRYPT '92 publication as prior art).
94 ec_GF2m_simple_set_compressed_coordinates(const EC_GROUP *group, EC_POINT *point,
95 const BIGNUM *x_, int y_bit, BN_CTX *ctx)
97 BN_CTX *new_ctx = NULL;
98 BIGNUM *tmp, *x, *y, *z;
101 /* clear error queue */
105 ctx = new_ctx = BN_CTX_new();
109 y_bit = (y_bit != 0) ? 1 : 0;
112 if ((tmp = BN_CTX_get(ctx)) == NULL)
114 if ((x = BN_CTX_get(ctx)) == NULL)
116 if ((y = BN_CTX_get(ctx)) == NULL)
118 if ((z = BN_CTX_get(ctx)) == NULL)
121 if (!BN_GF2m_mod_arr(x, x_, group->poly))
124 if (!BN_GF2m_mod_sqrt_arr(y, &group->b, group->poly, ctx))
127 if (!group->meth->field_sqr(group, tmp, x, ctx))
129 if (!group->meth->field_div(group, tmp, &group->b, tmp, ctx))
131 if (!BN_GF2m_add(tmp, &group->a, tmp))
133 if (!BN_GF2m_add(tmp, x, tmp))
135 if (!BN_GF2m_mod_solve_quad_arr(z, tmp, group->poly, ctx)) {
136 unsigned long err = ERR_peek_last_error();
138 if (ERR_GET_LIB(err) == ERR_LIB_BN &&
139 ERR_GET_REASON(err) == BN_R_NO_SOLUTION) {
141 ECerr(EC_F_EC_GF2M_SIMPLE_SET_COMPRESSED_COORDINATES, EC_R_INVALID_COMPRESSED_POINT);
143 ECerr(EC_F_EC_GF2M_SIMPLE_SET_COMPRESSED_COORDINATES, ERR_R_BN_LIB);
146 z0 = (BN_is_odd(z)) ? 1 : 0;
147 if (!group->meth->field_mul(group, y, x, z, ctx))
150 if (!BN_GF2m_add(y, y, x))
155 if (!EC_POINT_set_affine_coordinates_GF2m(group, point, x, y, ctx))
162 BN_CTX_free(new_ctx);
167 /* Converts an EC_POINT to an octet string.
168 * If buf is NULL, the encoded length will be returned.
169 * If the length len of buf is smaller than required an error will be returned.
172 ec_GF2m_simple_point2oct(const EC_GROUP *group, const EC_POINT *point,
173 point_conversion_form_t form,
174 unsigned char *buf, size_t len, BN_CTX * ctx)
177 BN_CTX *new_ctx = NULL;
180 size_t field_len, i, skip;
182 if ((form != POINT_CONVERSION_COMPRESSED)
183 && (form != POINT_CONVERSION_UNCOMPRESSED)
184 && (form != POINT_CONVERSION_HYBRID)) {
185 ECerr(EC_F_EC_GF2M_SIMPLE_POINT2OCT, EC_R_INVALID_FORM);
188 if (EC_POINT_is_at_infinity(group, point) > 0) {
189 /* encodes to a single 0 octet */
192 ECerr(EC_F_EC_GF2M_SIMPLE_POINT2OCT, EC_R_BUFFER_TOO_SMALL);
199 /* ret := required output buffer length */
200 field_len = (EC_GROUP_get_degree(group) + 7) / 8;
201 ret = (form == POINT_CONVERSION_COMPRESSED) ? 1 + field_len :
204 /* if 'buf' is NULL, just return required length */
207 ECerr(EC_F_EC_GF2M_SIMPLE_POINT2OCT, EC_R_BUFFER_TOO_SMALL);
211 ctx = new_ctx = BN_CTX_new();
217 if ((x = BN_CTX_get(ctx)) == NULL)
219 if ((y = BN_CTX_get(ctx)) == NULL)
221 if ((yxi = BN_CTX_get(ctx)) == NULL)
224 if (!EC_POINT_get_affine_coordinates_GF2m(group, point, x, y, ctx))
228 if ((form != POINT_CONVERSION_UNCOMPRESSED) && !BN_is_zero(x)) {
229 if (!group->meth->field_div(group, yxi, y, x, ctx))
236 skip = field_len - BN_num_bytes(x);
237 if (skip > field_len) {
238 ECerr(EC_F_EC_GF2M_SIMPLE_POINT2OCT, ERR_R_INTERNAL_ERROR);
245 skip = BN_bn2bin(x, buf + i);
247 if (i != 1 + field_len) {
248 ECerr(EC_F_EC_GF2M_SIMPLE_POINT2OCT, ERR_R_INTERNAL_ERROR);
251 if (form == POINT_CONVERSION_UNCOMPRESSED ||
252 form == POINT_CONVERSION_HYBRID) {
253 skip = field_len - BN_num_bytes(y);
254 if (skip > field_len) {
255 ECerr(EC_F_EC_GF2M_SIMPLE_POINT2OCT, ERR_R_INTERNAL_ERROR);
262 skip = BN_bn2bin(y, buf + i);
266 ECerr(EC_F_EC_GF2M_SIMPLE_POINT2OCT, ERR_R_INTERNAL_ERROR);
272 BN_CTX_free(new_ctx);
278 BN_CTX_free(new_ctx);
283 /* Converts an octet string representation to an EC_POINT.
284 * Note that the simple implementation only uses affine coordinates.
287 ec_GF2m_simple_oct2point(const EC_GROUP *group, EC_POINT *point,
288 const unsigned char *buf, size_t len, BN_CTX *ctx)
290 point_conversion_form_t form;
292 BN_CTX *new_ctx = NULL;
294 size_t field_len, enc_len;
298 ECerr(EC_F_EC_GF2M_SIMPLE_OCT2POINT, EC_R_BUFFER_TOO_SMALL);
304 if ((form != 0) && (form != POINT_CONVERSION_COMPRESSED) &&
305 (form != POINT_CONVERSION_UNCOMPRESSED) &&
306 (form != POINT_CONVERSION_HYBRID)) {
307 ECerr(EC_F_EC_GF2M_SIMPLE_OCT2POINT, EC_R_INVALID_ENCODING);
310 if ((form == 0 || form == POINT_CONVERSION_UNCOMPRESSED) && y_bit) {
311 ECerr(EC_F_EC_GF2M_SIMPLE_OCT2POINT, EC_R_INVALID_ENCODING);
316 ECerr(EC_F_EC_GF2M_SIMPLE_OCT2POINT, EC_R_INVALID_ENCODING);
319 return EC_POINT_set_to_infinity(group, point);
321 field_len = (EC_GROUP_get_degree(group) + 7) / 8;
322 enc_len = (form == POINT_CONVERSION_COMPRESSED) ? 1 + field_len :
325 if (len != enc_len) {
326 ECerr(EC_F_EC_GF2M_SIMPLE_OCT2POINT, EC_R_INVALID_ENCODING);
330 ctx = new_ctx = BN_CTX_new();
335 if ((x = BN_CTX_get(ctx)) == NULL)
337 if ((y = BN_CTX_get(ctx)) == NULL)
339 if ((yxi = BN_CTX_get(ctx)) == NULL)
342 if (!BN_bin2bn(buf + 1, field_len, x))
344 if (BN_ucmp(x, &group->field) >= 0) {
345 ECerr(EC_F_EC_GF2M_SIMPLE_OCT2POINT, EC_R_INVALID_ENCODING);
348 if (form == POINT_CONVERSION_COMPRESSED) {
349 if (!EC_POINT_set_compressed_coordinates_GF2m(group, point, x, y_bit, ctx))
352 if (!BN_bin2bn(buf + 1 + field_len, field_len, y))
354 if (BN_ucmp(y, &group->field) >= 0) {
355 ECerr(EC_F_EC_GF2M_SIMPLE_OCT2POINT, EC_R_INVALID_ENCODING);
358 if (form == POINT_CONVERSION_HYBRID) {
359 if (!group->meth->field_div(group, yxi, y, x, ctx))
361 if (y_bit != BN_is_odd(yxi)) {
362 ECerr(EC_F_EC_GF2M_SIMPLE_OCT2POINT, EC_R_INVALID_ENCODING);
366 if (!EC_POINT_set_affine_coordinates_GF2m(group, point, x, y, ctx))
370 /* test required by X9.62 */
371 if (EC_POINT_is_on_curve(group, point, ctx) <= 0) {
372 ECerr(EC_F_EC_GF2M_SIMPLE_OCT2POINT, EC_R_POINT_IS_NOT_ON_CURVE);
379 BN_CTX_free(new_ctx);