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69e2ec63 | 1 | /* crypto/ec/ecp_oct.c */ |
ae5c8664 MC |
2 | /* |
3 | * Includes code written by Lenka Fibikova <fibikova@exp-math.uni-essen.de> | |
4 | * for the OpenSSL project. Includes code written by Bodo Moeller for the | |
5 | * OpenSSL project. | |
6 | */ | |
69e2ec63 DSH |
7 | /* ==================================================================== |
8 | * Copyright (c) 1998-2002 The OpenSSL Project. All rights reserved. | |
9 | * | |
10 | * Redistribution and use in source and binary forms, with or without | |
11 | * modification, are permitted provided that the following conditions | |
12 | * are met: | |
13 | * | |
14 | * 1. Redistributions of source code must retain the above copyright | |
ae5c8664 | 15 | * notice, this list of conditions and the following disclaimer. |
69e2ec63 DSH |
16 | * |
17 | * 2. Redistributions in binary form must reproduce the above copyright | |
18 | * notice, this list of conditions and the following disclaimer in | |
19 | * the documentation and/or other materials provided with the | |
20 | * distribution. | |
21 | * | |
22 | * 3. All advertising materials mentioning features or use of this | |
23 | * software must display the following acknowledgment: | |
24 | * "This product includes software developed by the OpenSSL Project | |
25 | * for use in the OpenSSL Toolkit. (http://www.openssl.org/)" | |
26 | * | |
27 | * 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to | |
28 | * endorse or promote products derived from this software without | |
29 | * prior written permission. For written permission, please contact | |
30 | * openssl-core@openssl.org. | |
31 | * | |
32 | * 5. Products derived from this software may not be called "OpenSSL" | |
33 | * nor may "OpenSSL" appear in their names without prior written | |
34 | * permission of the OpenSSL Project. | |
35 | * | |
36 | * 6. Redistributions of any form whatsoever must retain the following | |
37 | * acknowledgment: | |
38 | * "This product includes software developed by the OpenSSL Project | |
39 | * for use in the OpenSSL Toolkit (http://www.openssl.org/)" | |
40 | * | |
41 | * THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY | |
42 | * EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE | |
43 | * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR | |
44 | * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE OpenSSL PROJECT OR | |
45 | * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, | |
46 | * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT | |
47 | * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; | |
48 | * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) | |
49 | * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, | |
50 | * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) | |
51 | * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED | |
52 | * OF THE POSSIBILITY OF SUCH DAMAGE. | |
53 | * ==================================================================== | |
54 | * | |
55 | * This product includes cryptographic software written by Eric Young | |
56 | * (eay@cryptsoft.com). This product includes software written by Tim | |
57 | * Hudson (tjh@cryptsoft.com). | |
58 | * | |
59 | */ | |
60 | /* ==================================================================== | |
61 | * Copyright 2002 Sun Microsystems, Inc. ALL RIGHTS RESERVED. | |
62 | * Portions of this software developed by SUN MICROSYSTEMS, INC., | |
63 | * and contributed to the OpenSSL project. | |
64 | */ | |
65 | ||
66 | #include <openssl/err.h> | |
67 | #include <openssl/symhacks.h> | |
68 | ||
69 | #include "ec_lcl.h" | |
70 | ||
ae5c8664 MC |
71 | int ec_GFp_simple_set_compressed_coordinates(const EC_GROUP *group, |
72 | EC_POINT *point, | |
73 | const BIGNUM *x_, int y_bit, | |
74 | BN_CTX *ctx) | |
75 | { | |
76 | BN_CTX *new_ctx = NULL; | |
77 | BIGNUM *tmp1, *tmp2, *x, *y; | |
78 | int ret = 0; | |
79 | ||
80 | /* clear error queue */ | |
81 | ERR_clear_error(); | |
82 | ||
83 | if (ctx == NULL) { | |
84 | ctx = new_ctx = BN_CTX_new(); | |
85 | if (ctx == NULL) | |
86 | return 0; | |
87 | } | |
88 | ||
89 | y_bit = (y_bit != 0); | |
90 | ||
91 | BN_CTX_start(ctx); | |
92 | tmp1 = BN_CTX_get(ctx); | |
93 | tmp2 = BN_CTX_get(ctx); | |
94 | x = BN_CTX_get(ctx); | |
95 | y = BN_CTX_get(ctx); | |
96 | if (y == NULL) | |
97 | goto err; | |
98 | ||
99 | /*- | |
100 | * Recover y. We have a Weierstrass equation | |
101 | * y^2 = x^3 + a*x + b, | |
102 | * so y is one of the square roots of x^3 + a*x + b. | |
103 | */ | |
104 | ||
105 | /* tmp1 := x^3 */ | |
106 | if (!BN_nnmod(x, x_, &group->field, ctx)) | |
107 | goto err; | |
108 | if (group->meth->field_decode == 0) { | |
109 | /* field_{sqr,mul} work on standard representation */ | |
110 | if (!group->meth->field_sqr(group, tmp2, x_, ctx)) | |
111 | goto err; | |
112 | if (!group->meth->field_mul(group, tmp1, tmp2, x_, ctx)) | |
113 | goto err; | |
114 | } else { | |
115 | if (!BN_mod_sqr(tmp2, x_, &group->field, ctx)) | |
116 | goto err; | |
117 | if (!BN_mod_mul(tmp1, tmp2, x_, &group->field, ctx)) | |
118 | goto err; | |
119 | } | |
120 | ||
121 | /* tmp1 := tmp1 + a*x */ | |
122 | if (group->a_is_minus3) { | |
123 | if (!BN_mod_lshift1_quick(tmp2, x, &group->field)) | |
124 | goto err; | |
125 | if (!BN_mod_add_quick(tmp2, tmp2, x, &group->field)) | |
126 | goto err; | |
127 | if (!BN_mod_sub_quick(tmp1, tmp1, tmp2, &group->field)) | |
128 | goto err; | |
129 | } else { | |
130 | if (group->meth->field_decode) { | |
131 | if (!group->meth->field_decode(group, tmp2, &group->a, ctx)) | |
132 | goto err; | |
133 | if (!BN_mod_mul(tmp2, tmp2, x, &group->field, ctx)) | |
134 | goto err; | |
135 | } else { | |
136 | /* field_mul works on standard representation */ | |
137 | if (!group->meth->field_mul(group, tmp2, &group->a, x, ctx)) | |
138 | goto err; | |
139 | } | |
140 | ||
141 | if (!BN_mod_add_quick(tmp1, tmp1, tmp2, &group->field)) | |
142 | goto err; | |
143 | } | |
144 | ||
145 | /* tmp1 := tmp1 + b */ | |
146 | if (group->meth->field_decode) { | |
147 | if (!group->meth->field_decode(group, tmp2, &group->b, ctx)) | |
148 | goto err; | |
149 | if (!BN_mod_add_quick(tmp1, tmp1, tmp2, &group->field)) | |
150 | goto err; | |
151 | } else { | |
152 | if (!BN_mod_add_quick(tmp1, tmp1, &group->b, &group->field)) | |
153 | goto err; | |
154 | } | |
155 | ||
156 | if (!BN_mod_sqrt(y, tmp1, &group->field, ctx)) { | |
157 | unsigned long err = ERR_peek_last_error(); | |
158 | ||
159 | if (ERR_GET_LIB(err) == ERR_LIB_BN | |
160 | && ERR_GET_REASON(err) == BN_R_NOT_A_SQUARE) { | |
161 | ERR_clear_error(); | |
162 | ECerr(EC_F_EC_GFP_SIMPLE_SET_COMPRESSED_COORDINATES, | |
163 | EC_R_INVALID_COMPRESSED_POINT); | |
164 | } else | |
165 | ECerr(EC_F_EC_GFP_SIMPLE_SET_COMPRESSED_COORDINATES, | |
166 | ERR_R_BN_LIB); | |
167 | goto err; | |
168 | } | |
169 | ||
170 | if (y_bit != BN_is_odd(y)) { | |
171 | if (BN_is_zero(y)) { | |
172 | int kron; | |
173 | ||
174 | kron = BN_kronecker(x, &group->field, ctx); | |
175 | if (kron == -2) | |
176 | goto err; | |
177 | ||
178 | if (kron == 1) | |
179 | ECerr(EC_F_EC_GFP_SIMPLE_SET_COMPRESSED_COORDINATES, | |
180 | EC_R_INVALID_COMPRESSION_BIT); | |
181 | else | |
182 | /* | |
183 | * BN_mod_sqrt() should have cought this error (not a square) | |
184 | */ | |
185 | ECerr(EC_F_EC_GFP_SIMPLE_SET_COMPRESSED_COORDINATES, | |
186 | EC_R_INVALID_COMPRESSED_POINT); | |
187 | goto err; | |
188 | } | |
189 | if (!BN_usub(y, &group->field, y)) | |
190 | goto err; | |
191 | } | |
192 | if (y_bit != BN_is_odd(y)) { | |
193 | ECerr(EC_F_EC_GFP_SIMPLE_SET_COMPRESSED_COORDINATES, | |
194 | ERR_R_INTERNAL_ERROR); | |
195 | goto err; | |
196 | } | |
197 | ||
198 | if (!EC_POINT_set_affine_coordinates_GFp(group, point, x, y, ctx)) | |
199 | goto err; | |
200 | ||
201 | ret = 1; | |
69e2ec63 DSH |
202 | |
203 | err: | |
ae5c8664 MC |
204 | BN_CTX_end(ctx); |
205 | if (new_ctx != NULL) | |
206 | BN_CTX_free(new_ctx); | |
207 | return ret; | |
208 | } | |
209 | ||
210 | size_t ec_GFp_simple_point2oct(const EC_GROUP *group, const EC_POINT *point, | |
211 | point_conversion_form_t form, | |
212 | unsigned char *buf, size_t len, BN_CTX *ctx) | |
213 | { | |
214 | size_t ret; | |
215 | BN_CTX *new_ctx = NULL; | |
216 | int used_ctx = 0; | |
217 | BIGNUM *x, *y; | |
218 | size_t field_len, i, skip; | |
219 | ||
220 | if ((form != POINT_CONVERSION_COMPRESSED) | |
221 | && (form != POINT_CONVERSION_UNCOMPRESSED) | |
222 | && (form != POINT_CONVERSION_HYBRID)) { | |
223 | ECerr(EC_F_EC_GFP_SIMPLE_POINT2OCT, EC_R_INVALID_FORM); | |
224 | goto err; | |
225 | } | |
226 | ||
227 | if (EC_POINT_is_at_infinity(group, point)) { | |
228 | /* encodes to a single 0 octet */ | |
229 | if (buf != NULL) { | |
230 | if (len < 1) { | |
231 | ECerr(EC_F_EC_GFP_SIMPLE_POINT2OCT, EC_R_BUFFER_TOO_SMALL); | |
232 | return 0; | |
233 | } | |
234 | buf[0] = 0; | |
235 | } | |
236 | return 1; | |
237 | } | |
238 | ||
239 | /* ret := required output buffer length */ | |
240 | field_len = BN_num_bytes(&group->field); | |
241 | ret = | |
242 | (form == | |
243 | POINT_CONVERSION_COMPRESSED) ? 1 + field_len : 1 + 2 * field_len; | |
244 | ||
245 | /* if 'buf' is NULL, just return required length */ | |
246 | if (buf != NULL) { | |
247 | if (len < ret) { | |
248 | ECerr(EC_F_EC_GFP_SIMPLE_POINT2OCT, EC_R_BUFFER_TOO_SMALL); | |
249 | goto err; | |
250 | } | |
251 | ||
252 | if (ctx == NULL) { | |
253 | ctx = new_ctx = BN_CTX_new(); | |
254 | if (ctx == NULL) | |
255 | return 0; | |
256 | } | |
257 | ||
258 | BN_CTX_start(ctx); | |
259 | used_ctx = 1; | |
260 | x = BN_CTX_get(ctx); | |
261 | y = BN_CTX_get(ctx); | |
262 | if (y == NULL) | |
263 | goto err; | |
264 | ||
265 | if (!EC_POINT_get_affine_coordinates_GFp(group, point, x, y, ctx)) | |
266 | goto err; | |
267 | ||
268 | if ((form == POINT_CONVERSION_COMPRESSED | |
269 | || form == POINT_CONVERSION_HYBRID) && BN_is_odd(y)) | |
270 | buf[0] = form + 1; | |
271 | else | |
272 | buf[0] = form; | |
273 | ||
274 | i = 1; | |
275 | ||
276 | skip = field_len - BN_num_bytes(x); | |
277 | if (skip > field_len) { | |
278 | ECerr(EC_F_EC_GFP_SIMPLE_POINT2OCT, ERR_R_INTERNAL_ERROR); | |
279 | goto err; | |
280 | } | |
281 | while (skip > 0) { | |
282 | buf[i++] = 0; | |
283 | skip--; | |
284 | } | |
285 | skip = BN_bn2bin(x, buf + i); | |
286 | i += skip; | |
287 | if (i != 1 + field_len) { | |
288 | ECerr(EC_F_EC_GFP_SIMPLE_POINT2OCT, ERR_R_INTERNAL_ERROR); | |
289 | goto err; | |
290 | } | |
291 | ||
292 | if (form == POINT_CONVERSION_UNCOMPRESSED | |
293 | || form == POINT_CONVERSION_HYBRID) { | |
294 | skip = field_len - BN_num_bytes(y); | |
295 | if (skip > field_len) { | |
296 | ECerr(EC_F_EC_GFP_SIMPLE_POINT2OCT, ERR_R_INTERNAL_ERROR); | |
297 | goto err; | |
298 | } | |
299 | while (skip > 0) { | |
300 | buf[i++] = 0; | |
301 | skip--; | |
302 | } | |
303 | skip = BN_bn2bin(y, buf + i); | |
304 | i += skip; | |
305 | } | |
306 | ||
307 | if (i != ret) { | |
308 | ECerr(EC_F_EC_GFP_SIMPLE_POINT2OCT, ERR_R_INTERNAL_ERROR); | |
309 | goto err; | |
310 | } | |
311 | } | |
312 | ||
313 | if (used_ctx) | |
314 | BN_CTX_end(ctx); | |
315 | if (new_ctx != NULL) | |
316 | BN_CTX_free(new_ctx); | |
317 | return ret; | |
69e2ec63 DSH |
318 | |
319 | err: | |
ae5c8664 MC |
320 | if (used_ctx) |
321 | BN_CTX_end(ctx); | |
322 | if (new_ctx != NULL) | |
323 | BN_CTX_free(new_ctx); | |
324 | return 0; | |
325 | } | |
69e2ec63 DSH |
326 | |
327 | int ec_GFp_simple_oct2point(const EC_GROUP *group, EC_POINT *point, | |
ae5c8664 MC |
328 | const unsigned char *buf, size_t len, BN_CTX *ctx) |
329 | { | |
330 | point_conversion_form_t form; | |
331 | int y_bit; | |
332 | BN_CTX *new_ctx = NULL; | |
333 | BIGNUM *x, *y; | |
334 | size_t field_len, enc_len; | |
335 | int ret = 0; | |
336 | ||
337 | if (len == 0) { | |
338 | ECerr(EC_F_EC_GFP_SIMPLE_OCT2POINT, EC_R_BUFFER_TOO_SMALL); | |
339 | return 0; | |
340 | } | |
341 | form = buf[0]; | |
342 | y_bit = form & 1; | |
343 | form = form & ~1U; | |
344 | if ((form != 0) && (form != POINT_CONVERSION_COMPRESSED) | |
345 | && (form != POINT_CONVERSION_UNCOMPRESSED) | |
346 | && (form != POINT_CONVERSION_HYBRID)) { | |
347 | ECerr(EC_F_EC_GFP_SIMPLE_OCT2POINT, EC_R_INVALID_ENCODING); | |
348 | return 0; | |
349 | } | |
350 | if ((form == 0 || form == POINT_CONVERSION_UNCOMPRESSED) && y_bit) { | |
351 | ECerr(EC_F_EC_GFP_SIMPLE_OCT2POINT, EC_R_INVALID_ENCODING); | |
352 | return 0; | |
353 | } | |
354 | ||
355 | if (form == 0) { | |
356 | if (len != 1) { | |
357 | ECerr(EC_F_EC_GFP_SIMPLE_OCT2POINT, EC_R_INVALID_ENCODING); | |
358 | return 0; | |
359 | } | |
360 | ||
361 | return EC_POINT_set_to_infinity(group, point); | |
362 | } | |
363 | ||
364 | field_len = BN_num_bytes(&group->field); | |
365 | enc_len = | |
366 | (form == | |
367 | POINT_CONVERSION_COMPRESSED) ? 1 + field_len : 1 + 2 * field_len; | |
368 | ||
369 | if (len != enc_len) { | |
370 | ECerr(EC_F_EC_GFP_SIMPLE_OCT2POINT, EC_R_INVALID_ENCODING); | |
371 | return 0; | |
372 | } | |
373 | ||
374 | if (ctx == NULL) { | |
375 | ctx = new_ctx = BN_CTX_new(); | |
376 | if (ctx == NULL) | |
377 | return 0; | |
378 | } | |
379 | ||
380 | BN_CTX_start(ctx); | |
381 | x = BN_CTX_get(ctx); | |
382 | y = BN_CTX_get(ctx); | |
383 | if (y == NULL) | |
384 | goto err; | |
385 | ||
386 | if (!BN_bin2bn(buf + 1, field_len, x)) | |
387 | goto err; | |
388 | if (BN_ucmp(x, &group->field) >= 0) { | |
389 | ECerr(EC_F_EC_GFP_SIMPLE_OCT2POINT, EC_R_INVALID_ENCODING); | |
390 | goto err; | |
391 | } | |
392 | ||
393 | if (form == POINT_CONVERSION_COMPRESSED) { | |
394 | if (!EC_POINT_set_compressed_coordinates_GFp | |
395 | (group, point, x, y_bit, ctx)) | |
396 | goto err; | |
397 | } else { | |
398 | if (!BN_bin2bn(buf + 1 + field_len, field_len, y)) | |
399 | goto err; | |
400 | if (BN_ucmp(y, &group->field) >= 0) { | |
401 | ECerr(EC_F_EC_GFP_SIMPLE_OCT2POINT, EC_R_INVALID_ENCODING); | |
402 | goto err; | |
403 | } | |
404 | if (form == POINT_CONVERSION_HYBRID) { | |
405 | if (y_bit != BN_is_odd(y)) { | |
406 | ECerr(EC_F_EC_GFP_SIMPLE_OCT2POINT, EC_R_INVALID_ENCODING); | |
407 | goto err; | |
408 | } | |
409 | } | |
410 | ||
411 | if (!EC_POINT_set_affine_coordinates_GFp(group, point, x, y, ctx)) | |
412 | goto err; | |
413 | } | |
414 | ||
415 | /* test required by X9.62 */ | |
416 | if (!EC_POINT_is_on_curve(group, point, ctx)) { | |
417 | ECerr(EC_F_EC_GFP_SIMPLE_OCT2POINT, EC_R_POINT_IS_NOT_ON_CURVE); | |
418 | goto err; | |
419 | } | |
420 | ||
421 | ret = 1; | |
69e2ec63 | 422 | |
ae5c8664 MC |
423 | err: |
424 | BN_CTX_end(ctx); | |
425 | if (new_ctx != NULL) | |
426 | BN_CTX_free(new_ctx); | |
427 | return ret; | |
428 | } |