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[thirdparty/openssl.git] / crypto / ec / ec2_oct.c
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DSH
1/* crypto/ec/ec2_oct.c */
2/* ====================================================================
3 * Copyright 2002 Sun Microsystems, Inc. ALL RIGHTS RESERVED.
4 *
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.
8 *
9 * The ECC Code is licensed pursuant to the OpenSSL open source
10 * license provided below.
11 *
12 * The software is originally written by Sheueling Chang Shantz and
13 * Douglas Stebila of Sun Microsystems Laboratories.
14 *
15 */
16/* ====================================================================
17 * Copyright (c) 1998-2005 The OpenSSL Project. All rights reserved.
18 *
19 * Redistribution and use in source and binary forms, with or without
20 * modification, are permitted provided that the following conditions
21 * are met:
22 *
23 * 1. Redistributions of source code must retain the above copyright
0f113f3e 24 * notice, this list of conditions and the following disclaimer.
84b08eee
DSH
25 *
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
29 * distribution.
30 *
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/)"
35 *
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.
40 *
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.
44 *
45 * 6. Redistributions of any form whatsoever must retain the following
46 * acknowledgment:
47 * "This product includes software developed by the OpenSSL Project
48 * for use in the OpenSSL Toolkit (http://www.openssl.org/)"
49 *
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 * ====================================================================
63 *
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).
67 *
68 */
69
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DSH
70#include <openssl/err.h>
71
72#include "ec_lcl.h"
73
74#ifndef OPENSSL_NO_EC2M
75
3a83462d
MC
76/*-
77 * Calculates and sets the affine coordinates of an EC_POINT from the given
0f113f3e 78 * compressed coordinates. Uses algorithm 2.3.4 of SEC 1.
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DSH
79 * Note that the simple implementation only uses affine coordinates.
80 *
81 * The method is from the following publication:
0f113f3e 82 *
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DSH
83 * Harper, Menezes, Vanstone:
84 * "Public-Key Cryptosystems with Very Small Key Lengths",
85 * EUROCRYPT '92, Springer-Verlag LNCS 658,
86 * published February 1993
87 *
88 * US Patents 6,141,420 and 6,618,483 (Vanstone, Mullin, Agnew) describe
89 * the same method, but claim no priority date earlier than July 29, 1994
90 * (and additionally fail to cite the EUROCRYPT '92 publication as prior art).
91 */
0f113f3e
MC
92int ec_GF2m_simple_set_compressed_coordinates(const EC_GROUP *group,
93 EC_POINT *point,
94 const BIGNUM *x_, int y_bit,
95 BN_CTX *ctx)
96{
97 BN_CTX *new_ctx = NULL;
98 BIGNUM *tmp, *x, *y, *z;
99 int ret = 0, z0;
100
101 /* clear error queue */
102 ERR_clear_error();
103
104 if (ctx == NULL) {
105 ctx = new_ctx = BN_CTX_new();
106 if (ctx == NULL)
107 return 0;
108 }
109
110 y_bit = (y_bit != 0) ? 1 : 0;
111
112 BN_CTX_start(ctx);
113 tmp = BN_CTX_get(ctx);
114 x = BN_CTX_get(ctx);
115 y = BN_CTX_get(ctx);
116 z = BN_CTX_get(ctx);
117 if (z == NULL)
118 goto err;
119
120 if (!BN_GF2m_mod_arr(x, x_, group->poly))
121 goto err;
122 if (BN_is_zero(x)) {
123 if (!BN_GF2m_mod_sqrt_arr(y, group->b, group->poly, ctx))
124 goto err;
125 } else {
126 if (!group->meth->field_sqr(group, tmp, x, ctx))
127 goto err;
128 if (!group->meth->field_div(group, tmp, group->b, tmp, ctx))
129 goto err;
130 if (!BN_GF2m_add(tmp, group->a, tmp))
131 goto err;
132 if (!BN_GF2m_add(tmp, x, tmp))
133 goto err;
134 if (!BN_GF2m_mod_solve_quad_arr(z, tmp, group->poly, ctx)) {
135 unsigned long err = ERR_peek_last_error();
136
137 if (ERR_GET_LIB(err) == ERR_LIB_BN
138 && ERR_GET_REASON(err) == BN_R_NO_SOLUTION) {
139 ERR_clear_error();
140 ECerr(EC_F_EC_GF2M_SIMPLE_SET_COMPRESSED_COORDINATES,
141 EC_R_INVALID_COMPRESSED_POINT);
142 } else
143 ECerr(EC_F_EC_GF2M_SIMPLE_SET_COMPRESSED_COORDINATES,
144 ERR_R_BN_LIB);
145 goto err;
146 }
147 z0 = (BN_is_odd(z)) ? 1 : 0;
148 if (!group->meth->field_mul(group, y, x, z, ctx))
149 goto err;
150 if (z0 != y_bit) {
151 if (!BN_GF2m_add(y, y, x))
152 goto err;
153 }
154 }
155
156 if (!EC_POINT_set_affine_coordinates_GF2m(group, point, x, y, ctx))
157 goto err;
158
159 ret = 1;
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DSH
160
161 err:
0f113f3e 162 BN_CTX_end(ctx);
23a1d5e9 163 BN_CTX_free(new_ctx);
0f113f3e
MC
164 return ret;
165}
166
167/*
168 * Converts an EC_POINT to an octet string. If buf is NULL, the encoded
169 * length will be returned. If the length len of buf is smaller than required
170 * an error will be returned.
84b08eee 171 */
0f113f3e
MC
172size_t 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)
175{
176 size_t ret;
177 BN_CTX *new_ctx = NULL;
178 int used_ctx = 0;
179 BIGNUM *x, *y, *yxi;
180 size_t field_len, i, skip;
181
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);
186 goto err;
187 }
188
189 if (EC_POINT_is_at_infinity(group, point)) {
190 /* encodes to a single 0 octet */
191 if (buf != NULL) {
192 if (len < 1) {
193 ECerr(EC_F_EC_GF2M_SIMPLE_POINT2OCT, EC_R_BUFFER_TOO_SMALL);
194 return 0;
195 }
196 buf[0] = 0;
197 }
198 return 1;
199 }
200
201 /* ret := required output buffer length */
202 field_len = (EC_GROUP_get_degree(group) + 7) / 8;
203 ret =
204 (form ==
205 POINT_CONVERSION_COMPRESSED) ? 1 + field_len : 1 + 2 * field_len;
206
207 /* if 'buf' is NULL, just return required length */
208 if (buf != NULL) {
209 if (len < ret) {
210 ECerr(EC_F_EC_GF2M_SIMPLE_POINT2OCT, EC_R_BUFFER_TOO_SMALL);
211 goto err;
212 }
213
214 if (ctx == NULL) {
215 ctx = new_ctx = BN_CTX_new();
216 if (ctx == NULL)
217 return 0;
218 }
219
220 BN_CTX_start(ctx);
221 used_ctx = 1;
222 x = BN_CTX_get(ctx);
223 y = BN_CTX_get(ctx);
224 yxi = BN_CTX_get(ctx);
225 if (yxi == NULL)
226 goto err;
227
228 if (!EC_POINT_get_affine_coordinates_GF2m(group, point, x, y, ctx))
229 goto err;
230
231 buf[0] = form;
232 if ((form != POINT_CONVERSION_UNCOMPRESSED) && !BN_is_zero(x)) {
233 if (!group->meth->field_div(group, yxi, y, x, ctx))
234 goto err;
235 if (BN_is_odd(yxi))
236 buf[0]++;
237 }
238
239 i = 1;
240
241 skip = field_len - BN_num_bytes(x);
242 if (skip > field_len) {
243 ECerr(EC_F_EC_GF2M_SIMPLE_POINT2OCT, ERR_R_INTERNAL_ERROR);
244 goto err;
245 }
246 while (skip > 0) {
247 buf[i++] = 0;
248 skip--;
249 }
250 skip = BN_bn2bin(x, buf + i);
251 i += skip;
252 if (i != 1 + field_len) {
253 ECerr(EC_F_EC_GF2M_SIMPLE_POINT2OCT, ERR_R_INTERNAL_ERROR);
254 goto err;
255 }
256
257 if (form == POINT_CONVERSION_UNCOMPRESSED
258 || form == POINT_CONVERSION_HYBRID) {
259 skip = field_len - BN_num_bytes(y);
260 if (skip > field_len) {
261 ECerr(EC_F_EC_GF2M_SIMPLE_POINT2OCT, ERR_R_INTERNAL_ERROR);
262 goto err;
263 }
264 while (skip > 0) {
265 buf[i++] = 0;
266 skip--;
267 }
268 skip = BN_bn2bin(y, buf + i);
269 i += skip;
270 }
271
272 if (i != ret) {
273 ECerr(EC_F_EC_GF2M_SIMPLE_POINT2OCT, ERR_R_INTERNAL_ERROR);
274 goto err;
275 }
276 }
277
278 if (used_ctx)
279 BN_CTX_end(ctx);
23a1d5e9 280 BN_CTX_free(new_ctx);
0f113f3e 281 return ret;
84b08eee
DSH
282
283 err:
0f113f3e
MC
284 if (used_ctx)
285 BN_CTX_end(ctx);
23a1d5e9 286 BN_CTX_free(new_ctx);
0f113f3e
MC
287 return 0;
288}
289
290/*
291 * Converts an octet string representation to an EC_POINT. Note that the
292 * simple implementation only uses affine coordinates.
84b08eee
DSH
293 */
294int ec_GF2m_simple_oct2point(const EC_GROUP *group, EC_POINT *point,
0f113f3e
MC
295 const unsigned char *buf, size_t len,
296 BN_CTX *ctx)
297{
298 point_conversion_form_t form;
299 int y_bit;
300 BN_CTX *new_ctx = NULL;
301 BIGNUM *x, *y, *yxi;
302 size_t field_len, enc_len;
303 int ret = 0;
304
305 if (len == 0) {
306 ECerr(EC_F_EC_GF2M_SIMPLE_OCT2POINT, EC_R_BUFFER_TOO_SMALL);
307 return 0;
308 }
309 form = buf[0];
310 y_bit = form & 1;
311 form = form & ~1U;
312 if ((form != 0) && (form != POINT_CONVERSION_COMPRESSED)
313 && (form != POINT_CONVERSION_UNCOMPRESSED)
314 && (form != POINT_CONVERSION_HYBRID)) {
315 ECerr(EC_F_EC_GF2M_SIMPLE_OCT2POINT, EC_R_INVALID_ENCODING);
316 return 0;
317 }
318 if ((form == 0 || form == POINT_CONVERSION_UNCOMPRESSED) && y_bit) {
319 ECerr(EC_F_EC_GF2M_SIMPLE_OCT2POINT, EC_R_INVALID_ENCODING);
320 return 0;
321 }
322
323 if (form == 0) {
324 if (len != 1) {
325 ECerr(EC_F_EC_GF2M_SIMPLE_OCT2POINT, EC_R_INVALID_ENCODING);
326 return 0;
327 }
328
329 return EC_POINT_set_to_infinity(group, point);
330 }
331
332 field_len = (EC_GROUP_get_degree(group) + 7) / 8;
333 enc_len =
334 (form ==
335 POINT_CONVERSION_COMPRESSED) ? 1 + field_len : 1 + 2 * field_len;
336
337 if (len != enc_len) {
338 ECerr(EC_F_EC_GF2M_SIMPLE_OCT2POINT, EC_R_INVALID_ENCODING);
339 return 0;
340 }
341
342 if (ctx == NULL) {
343 ctx = new_ctx = BN_CTX_new();
344 if (ctx == NULL)
345 return 0;
346 }
347
348 BN_CTX_start(ctx);
349 x = BN_CTX_get(ctx);
350 y = BN_CTX_get(ctx);
351 yxi = BN_CTX_get(ctx);
352 if (yxi == NULL)
353 goto err;
354
355 if (!BN_bin2bn(buf + 1, field_len, x))
356 goto err;
357 if (BN_ucmp(x, group->field) >= 0) {
358 ECerr(EC_F_EC_GF2M_SIMPLE_OCT2POINT, EC_R_INVALID_ENCODING);
359 goto err;
360 }
361
362 if (form == POINT_CONVERSION_COMPRESSED) {
363 if (!EC_POINT_set_compressed_coordinates_GF2m
364 (group, point, x, y_bit, ctx))
365 goto err;
366 } else {
367 if (!BN_bin2bn(buf + 1 + field_len, field_len, y))
368 goto err;
369 if (BN_ucmp(y, group->field) >= 0) {
370 ECerr(EC_F_EC_GF2M_SIMPLE_OCT2POINT, EC_R_INVALID_ENCODING);
371 goto err;
372 }
373 if (form == POINT_CONVERSION_HYBRID) {
374 if (!group->meth->field_div(group, yxi, y, x, ctx))
375 goto err;
376 if (y_bit != BN_is_odd(yxi)) {
377 ECerr(EC_F_EC_GF2M_SIMPLE_OCT2POINT, EC_R_INVALID_ENCODING);
378 goto err;
379 }
380 }
381
382 if (!EC_POINT_set_affine_coordinates_GF2m(group, point, x, y, ctx))
383 goto err;
384 }
385
386 /* test required by X9.62 */
387 if (!EC_POINT_is_on_curve(group, point, ctx)) {
388 ECerr(EC_F_EC_GF2M_SIMPLE_OCT2POINT, EC_R_POINT_IS_NOT_ON_CURVE);
389 goto err;
390 }
391
392 ret = 1;
393
84b08eee 394 err:
0f113f3e 395 BN_CTX_end(ctx);
23a1d5e9 396 BN_CTX_free(new_ctx);
0f113f3e
MC
397 return ret;
398}
84b08eee 399#endif