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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 | |
24 * notice, this list of conditions and the following disclaimer. | |
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 | |
70 #include <openssl/err.h> | |
71 | |
72 #include "ec_lcl.h" | |
73 | |
74 #ifndef OPENSSL_NO_EC2M | |
75 | |
76 /* Calculates and sets the affine coordinates of an EC_POINT from the given | |
77 * compressed coordinates. Uses algorithm 2.3.4 of SEC 1. | |
78 * Note that the simple implementation only uses affine coordinates. | |
79 * | |
80 * The method is from the following publication: | |
81 * | |
82 * Harper, Menezes, Vanstone: | |
83 * "Public-Key Cryptosystems with Very Small Key Lengths", | |
84 * EUROCRYPT '92, Springer-Verlag LNCS 658, | |
85 * published February 1993 | |
86 * | |
87 * US Patents 6,141,420 and 6,618,483 (Vanstone, Mullin, Agnew) describe | |
88 * the same method, but claim no priority date earlier than July 29, 1994 | |
89 * (and additionally fail to cite the EUROCRYPT '92 publication as prior art). | |
90 */ | |
91 int ec_GF2m_simple_set_compressed_coordinates(const EC_GROUP *group, EC_POINT *p
oint, | |
92 const BIGNUM *x_, int y_bit, BN_CTX *ctx) | |
93 { | |
94 BN_CTX *new_ctx = NULL; | |
95 BIGNUM *tmp, *x, *y, *z; | |
96 int ret = 0, z0; | |
97 | |
98 /* clear error queue */ | |
99 ERR_clear_error(); | |
100 | |
101 if (ctx == NULL) | |
102 { | |
103 ctx = new_ctx = BN_CTX_new(); | |
104 if (ctx == NULL) | |
105 return 0; | |
106 } | |
107 | |
108 y_bit = (y_bit != 0) ? 1 : 0; | |
109 | |
110 BN_CTX_start(ctx); | |
111 tmp = BN_CTX_get(ctx); | |
112 x = BN_CTX_get(ctx); | |
113 y = BN_CTX_get(ctx); | |
114 z = BN_CTX_get(ctx); | |
115 if (z == NULL) goto err; | |
116 | |
117 if (!BN_GF2m_mod_arr(x, x_, group->poly)) goto err; | |
118 if (BN_is_zero(x)) | |
119 { | |
120 if (!BN_GF2m_mod_sqrt_arr(y, &group->b, group->poly, ctx)) goto
err; | |
121 } | |
122 else | |
123 { | |
124 if (!group->meth->field_sqr(group, tmp, x, ctx)) goto err; | |
125 if (!group->meth->field_div(group, tmp, &group->b, tmp, ctx)) go
to err; | |
126 if (!BN_GF2m_add(tmp, &group->a, tmp)) goto err; | |
127 if (!BN_GF2m_add(tmp, x, tmp)) goto err; | |
128 if (!BN_GF2m_mod_solve_quad_arr(z, tmp, group->poly, ctx)) | |
129 { | |
130 unsigned long err = ERR_peek_last_error(); | |
131 | |
132 if (ERR_GET_LIB(err) == ERR_LIB_BN && ERR_GET_REASON(err
) == BN_R_NO_SOLUTION) | |
133 { | |
134 ERR_clear_error(); | |
135 ECerr(EC_F_EC_GF2M_SIMPLE_SET_COMPRESSED_COORDIN
ATES, EC_R_INVALID_COMPRESSED_POINT); | |
136 } | |
137 else | |
138 ECerr(EC_F_EC_GF2M_SIMPLE_SET_COMPRESSED_COORDIN
ATES, ERR_R_BN_LIB); | |
139 goto err; | |
140 } | |
141 z0 = (BN_is_odd(z)) ? 1 : 0; | |
142 if (!group->meth->field_mul(group, y, x, z, ctx)) goto err; | |
143 if (z0 != y_bit) | |
144 { | |
145 if (!BN_GF2m_add(y, y, x)) goto err; | |
146 } | |
147 } | |
148 | |
149 if (!EC_POINT_set_affine_coordinates_GF2m(group, point, x, y, ctx)) goto
err; | |
150 | |
151 ret = 1; | |
152 | |
153 err: | |
154 BN_CTX_end(ctx); | |
155 if (new_ctx != NULL) | |
156 BN_CTX_free(new_ctx); | |
157 return ret; | |
158 } | |
159 | |
160 | |
161 /* Converts an EC_POINT to an octet string. | |
162 * If buf is NULL, the encoded length will be returned. | |
163 * If the length len of buf is smaller than required an error will be returned. | |
164 */ | |
165 size_t ec_GF2m_simple_point2oct(const EC_GROUP *group, const EC_POINT *point, po
int_conversion_form_t form, | |
166 unsigned char *buf, size_t len, BN_CTX *ctx) | |
167 { | |
168 size_t ret; | |
169 BN_CTX *new_ctx = NULL; | |
170 int used_ctx = 0; | |
171 BIGNUM *x, *y, *yxi; | |
172 size_t field_len, i, skip; | |
173 | |
174 if ((form != POINT_CONVERSION_COMPRESSED) | |
175 && (form != POINT_CONVERSION_UNCOMPRESSED) | |
176 && (form != POINT_CONVERSION_HYBRID)) | |
177 { | |
178 ECerr(EC_F_EC_GF2M_SIMPLE_POINT2OCT, EC_R_INVALID_FORM); | |
179 goto err; | |
180 } | |
181 | |
182 if (EC_POINT_is_at_infinity(group, point)) | |
183 { | |
184 /* encodes to a single 0 octet */ | |
185 if (buf != NULL) | |
186 { | |
187 if (len < 1) | |
188 { | |
189 ECerr(EC_F_EC_GF2M_SIMPLE_POINT2OCT, EC_R_BUFFER
_TOO_SMALL); | |
190 return 0; | |
191 } | |
192 buf[0] = 0; | |
193 } | |
194 return 1; | |
195 } | |
196 | |
197 | |
198 /* ret := required output buffer length */ | |
199 field_len = (EC_GROUP_get_degree(group) + 7) / 8; | |
200 ret = (form == POINT_CONVERSION_COMPRESSED) ? 1 + field_len : 1 + 2*fiel
d_len; | |
201 | |
202 /* if 'buf' is NULL, just return required length */ | |
203 if (buf != NULL) | |
204 { | |
205 if (len < ret) | |
206 { | |
207 ECerr(EC_F_EC_GF2M_SIMPLE_POINT2OCT, EC_R_BUFFER_TOO_SMA
LL); | |
208 goto err; | |
209 } | |
210 | |
211 if (ctx == NULL) | |
212 { | |
213 ctx = new_ctx = BN_CTX_new(); | |
214 if (ctx == NULL) | |
215 return 0; | |
216 } | |
217 | |
218 BN_CTX_start(ctx); | |
219 used_ctx = 1; | |
220 x = BN_CTX_get(ctx); | |
221 y = BN_CTX_get(ctx); | |
222 yxi = BN_CTX_get(ctx); | |
223 if (yxi == NULL) goto err; | |
224 | |
225 if (!EC_POINT_get_affine_coordinates_GF2m(group, point, x, y, ct
x)) goto err; | |
226 | |
227 buf[0] = form; | |
228 if ((form != POINT_CONVERSION_UNCOMPRESSED) && !BN_is_zero(x)) | |
229 { | |
230 if (!group->meth->field_div(group, yxi, y, x, ctx)) goto
err; | |
231 if (BN_is_odd(yxi)) buf[0]++; | |
232 } | |
233 | |
234 i = 1; | |
235 | |
236 skip = field_len - BN_num_bytes(x); | |
237 if (skip > field_len) | |
238 { | |
239 ECerr(EC_F_EC_GF2M_SIMPLE_POINT2OCT, ERR_R_INTERNAL_ERRO
R); | |
240 goto err; | |
241 } | |
242 while (skip > 0) | |
243 { | |
244 buf[i++] = 0; | |
245 skip--; | |
246 } | |
247 skip = BN_bn2bin(x, buf + i); | |
248 i += skip; | |
249 if (i != 1 + field_len) | |
250 { | |
251 ECerr(EC_F_EC_GF2M_SIMPLE_POINT2OCT, ERR_R_INTERNAL_ERRO
R); | |
252 goto err; | |
253 } | |
254 | |
255 if (form == POINT_CONVERSION_UNCOMPRESSED || form == POINT_CONVE
RSION_HYBRID) | |
256 { | |
257 skip = field_len - BN_num_bytes(y); | |
258 if (skip > field_len) | |
259 { | |
260 ECerr(EC_F_EC_GF2M_SIMPLE_POINT2OCT, ERR_R_INTER
NAL_ERROR); | |
261 goto err; | |
262 } | |
263 while (skip > 0) | |
264 { | |
265 buf[i++] = 0; | |
266 skip--; | |
267 } | |
268 skip = BN_bn2bin(y, buf + i); | |
269 i += skip; | |
270 } | |
271 | |
272 if (i != ret) | |
273 { | |
274 ECerr(EC_F_EC_GF2M_SIMPLE_POINT2OCT, ERR_R_INTERNAL_ERRO
R); | |
275 goto err; | |
276 } | |
277 } | |
278 | |
279 if (used_ctx) | |
280 BN_CTX_end(ctx); | |
281 if (new_ctx != NULL) | |
282 BN_CTX_free(new_ctx); | |
283 return ret; | |
284 | |
285 err: | |
286 if (used_ctx) | |
287 BN_CTX_end(ctx); | |
288 if (new_ctx != NULL) | |
289 BN_CTX_free(new_ctx); | |
290 return 0; | |
291 } | |
292 | |
293 | |
294 /* Converts an octet string representation to an EC_POINT. | |
295 * Note that the simple implementation only uses affine coordinates. | |
296 */ | |
297 int ec_GF2m_simple_oct2point(const EC_GROUP *group, EC_POINT *point, | |
298 const unsigned char *buf, size_t len, BN_CTX *ctx) | |
299 { | |
300 point_conversion_form_t form; | |
301 int y_bit; | |
302 BN_CTX *new_ctx = NULL; | |
303 BIGNUM *x, *y, *yxi; | |
304 size_t field_len, enc_len; | |
305 int ret = 0; | |
306 | |
307 if (len == 0) | |
308 { | |
309 ECerr(EC_F_EC_GF2M_SIMPLE_OCT2POINT, EC_R_BUFFER_TOO_SMALL); | |
310 return 0; | |
311 } | |
312 form = buf[0]; | |
313 y_bit = form & 1; | |
314 form = form & ~1U; | |
315 if ((form != 0) && (form != POINT_CONVERSION_COMPRESSED) | |
316 && (form != POINT_CONVERSION_UNCOMPRESSED) | |
317 && (form != POINT_CONVERSION_HYBRID)) | |
318 { | |
319 ECerr(EC_F_EC_GF2M_SIMPLE_OCT2POINT, EC_R_INVALID_ENCODING); | |
320 return 0; | |
321 } | |
322 if ((form == 0 || form == POINT_CONVERSION_UNCOMPRESSED) && y_bit) | |
323 { | |
324 ECerr(EC_F_EC_GF2M_SIMPLE_OCT2POINT, EC_R_INVALID_ENCODING); | |
325 return 0; | |
326 } | |
327 | |
328 if (form == 0) | |
329 { | |
330 if (len != 1) | |
331 { | |
332 ECerr(EC_F_EC_GF2M_SIMPLE_OCT2POINT, EC_R_INVALID_ENCODI
NG); | |
333 return 0; | |
334 } | |
335 | |
336 return EC_POINT_set_to_infinity(group, point); | |
337 } | |
338 | |
339 field_len = (EC_GROUP_get_degree(group) + 7) / 8; | |
340 enc_len = (form == POINT_CONVERSION_COMPRESSED) ? 1 + field_len : 1 + 2*
field_len; | |
341 | |
342 if (len != enc_len) | |
343 { | |
344 ECerr(EC_F_EC_GF2M_SIMPLE_OCT2POINT, EC_R_INVALID_ENCODING); | |
345 return 0; | |
346 } | |
347 | |
348 if (ctx == NULL) | |
349 { | |
350 ctx = new_ctx = BN_CTX_new(); | |
351 if (ctx == NULL) | |
352 return 0; | |
353 } | |
354 | |
355 BN_CTX_start(ctx); | |
356 x = BN_CTX_get(ctx); | |
357 y = BN_CTX_get(ctx); | |
358 yxi = BN_CTX_get(ctx); | |
359 if (yxi == NULL) goto err; | |
360 | |
361 if (!BN_bin2bn(buf + 1, field_len, x)) goto err; | |
362 if (BN_ucmp(x, &group->field) >= 0) | |
363 { | |
364 ECerr(EC_F_EC_GF2M_SIMPLE_OCT2POINT, EC_R_INVALID_ENCODING); | |
365 goto err; | |
366 } | |
367 | |
368 if (form == POINT_CONVERSION_COMPRESSED) | |
369 { | |
370 if (!EC_POINT_set_compressed_coordinates_GF2m(group, point, x, y
_bit, ctx)) goto err; | |
371 } | |
372 else | |
373 { | |
374 if (!BN_bin2bn(buf + 1 + field_len, field_len, y)) goto err; | |
375 if (BN_ucmp(y, &group->field) >= 0) | |
376 { | |
377 ECerr(EC_F_EC_GF2M_SIMPLE_OCT2POINT, EC_R_INVALID_ENCODI
NG); | |
378 goto err; | |
379 } | |
380 if (form == POINT_CONVERSION_HYBRID) | |
381 { | |
382 if (!group->meth->field_div(group, yxi, y, x, ctx)) goto
err; | |
383 if (y_bit != BN_is_odd(yxi)) | |
384 { | |
385 ECerr(EC_F_EC_GF2M_SIMPLE_OCT2POINT, EC_R_INVALI
D_ENCODING); | |
386 goto err; | |
387 } | |
388 } | |
389 | |
390 if (!EC_POINT_set_affine_coordinates_GF2m(group, point, x, y, ct
x)) goto err; | |
391 } | |
392 | |
393 if (!EC_POINT_is_on_curve(group, point, ctx)) /* test required by X9.62
*/ | |
394 { | |
395 ECerr(EC_F_EC_GF2M_SIMPLE_OCT2POINT, EC_R_POINT_IS_NOT_ON_CURVE)
; | |
396 goto err; | |
397 } | |
398 | |
399 ret = 1; | |
400 | |
401 err: | |
402 BN_CTX_end(ctx); | |
403 if (new_ctx != NULL) | |
404 BN_CTX_free(new_ctx); | |
405 return ret; | |
406 } | |
407 #endif | |
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