Additional comment changes for reformat of 1.0.2
[openssl.git] / crypto / ec / ecp_oct.c
1 /* crypto/ec/ecp_oct.c */
2 /* Includes code written by Lenka Fibikova <fibikova@exp-math.uni-essen.de>
3  * for the OpenSSL project. 
4  * Includes code written by Bodo Moeller for the OpenSSL project.
5 */
6 /* ====================================================================
7  * Copyright (c) 1998-2002 The OpenSSL Project.  All rights reserved.
8  *
9  * Redistribution and use in source and binary forms, with or without
10  * modification, are permitted provided that the following conditions
11  * are met:
12  *
13  * 1. Redistributions of source code must retain the above copyright
14  *    notice, this list of conditions and the following disclaimer. 
15  *
16  * 2. Redistributions in binary form must reproduce the above copyright
17  *    notice, this list of conditions and the following disclaimer in
18  *    the documentation and/or other materials provided with the
19  *    distribution.
20  *
21  * 3. All advertising materials mentioning features or use of this
22  *    software must display the following acknowledgment:
23  *    "This product includes software developed by the OpenSSL Project
24  *    for use in the OpenSSL Toolkit. (http://www.openssl.org/)"
25  *
26  * 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to
27  *    endorse or promote products derived from this software without
28  *    prior written permission. For written permission, please contact
29  *    openssl-core@openssl.org.
30  *
31  * 5. Products derived from this software may not be called "OpenSSL"
32  *    nor may "OpenSSL" appear in their names without prior written
33  *    permission of the OpenSSL Project.
34  *
35  * 6. Redistributions of any form whatsoever must retain the following
36  *    acknowledgment:
37  *    "This product includes software developed by the OpenSSL Project
38  *    for use in the OpenSSL Toolkit (http://www.openssl.org/)"
39  *
40  * THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY
41  * EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
42  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
43  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE OpenSSL PROJECT OR
44  * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
45  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
46  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
47  * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
48  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
49  * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
50  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
51  * OF THE POSSIBILITY OF SUCH DAMAGE.
52  * ====================================================================
53  *
54  * This product includes cryptographic software written by Eric Young
55  * (eay@cryptsoft.com).  This product includes software written by Tim
56  * Hudson (tjh@cryptsoft.com).
57  *
58  */
59 /* ====================================================================
60  * Copyright 2002 Sun Microsystems, Inc. ALL RIGHTS RESERVED.
61  * Portions of this software developed by SUN MICROSYSTEMS, INC.,
62  * and contributed to the OpenSSL project.
63  */
64
65 #include <openssl/err.h>
66 #include <openssl/symhacks.h>
67
68 #include "ec_lcl.h"
69
70 int ec_GFp_simple_set_compressed_coordinates(const EC_GROUP *group, EC_POINT *point,
71         const BIGNUM *x_, int y_bit, BN_CTX *ctx)
72         {
73         BN_CTX *new_ctx = NULL;
74         BIGNUM *tmp1, *tmp2, *x, *y;
75         int ret = 0;
76
77         /* clear error queue*/
78         ERR_clear_error();
79
80         if (ctx == NULL)
81                 {
82                 ctx = new_ctx = BN_CTX_new();
83                 if (ctx == NULL)
84                         return 0;
85                 }
86
87         y_bit = (y_bit != 0);
88
89         BN_CTX_start(ctx);
90         tmp1 = BN_CTX_get(ctx);
91         tmp2 = BN_CTX_get(ctx);
92         x = BN_CTX_get(ctx);
93         y = BN_CTX_get(ctx);
94         if (y == NULL) goto err;
95
96         /*-
97          * Recover y.  We have a Weierstrass equation
98          *     y^2 = x^3 + a*x + b,
99          * so  y  is one of the square roots of  x^3 + a*x + b.
100          */
101
102         /* tmp1 := x^3 */
103         if (!BN_nnmod(x, x_, &group->field,ctx)) goto err;
104         if (group->meth->field_decode == 0)
105                 {
106                 /* field_{sqr,mul} work on standard representation */
107                 if (!group->meth->field_sqr(group, tmp2, x_, ctx)) goto err;
108                 if (!group->meth->field_mul(group, tmp1, tmp2, x_, ctx)) goto err;
109                 }
110         else
111                 {
112                 if (!BN_mod_sqr(tmp2, x_, &group->field, ctx)) goto err;
113                 if (!BN_mod_mul(tmp1, tmp2, x_, &group->field, ctx)) goto err;
114                 }
115         
116         /* tmp1 := tmp1 + a*x */
117         if (group->a_is_minus3)
118                 {
119                 if (!BN_mod_lshift1_quick(tmp2, x, &group->field)) goto err;
120                 if (!BN_mod_add_quick(tmp2, tmp2, x, &group->field)) goto err;
121                 if (!BN_mod_sub_quick(tmp1, tmp1, tmp2, &group->field)) goto err;
122                 }
123         else
124                 {
125                 if (group->meth->field_decode)
126                         {
127                         if (!group->meth->field_decode(group, tmp2, &group->a, ctx)) goto err;
128                         if (!BN_mod_mul(tmp2, tmp2, x, &group->field, ctx)) goto err;
129                         }
130                 else
131                         {
132                         /* field_mul works on standard representation */
133                         if (!group->meth->field_mul(group, tmp2, &group->a, x, ctx)) goto err;
134                         }
135                 
136                 if (!BN_mod_add_quick(tmp1, tmp1, tmp2, &group->field)) goto err;
137                 }
138         
139         /* tmp1 := tmp1 + b */
140         if (group->meth->field_decode)
141                 {
142                 if (!group->meth->field_decode(group, tmp2, &group->b, ctx)) goto err;
143                 if (!BN_mod_add_quick(tmp1, tmp1, tmp2, &group->field)) goto err;
144                 }
145         else
146                 {
147                 if (!BN_mod_add_quick(tmp1, tmp1, &group->b, &group->field)) goto err;
148                 }
149         
150         if (!BN_mod_sqrt(y, tmp1, &group->field, ctx))
151                 {
152                 unsigned long err = ERR_peek_last_error();
153                 
154                 if (ERR_GET_LIB(err) == ERR_LIB_BN && ERR_GET_REASON(err) == BN_R_NOT_A_SQUARE)
155                         {
156                         ERR_clear_error();
157                         ECerr(EC_F_EC_GFP_SIMPLE_SET_COMPRESSED_COORDINATES, EC_R_INVALID_COMPRESSED_POINT);
158                         }
159                 else
160                         ECerr(EC_F_EC_GFP_SIMPLE_SET_COMPRESSED_COORDINATES, ERR_R_BN_LIB);
161                 goto err;
162                 }
163
164         if (y_bit != BN_is_odd(y))
165                 {
166                 if (BN_is_zero(y))
167                         {
168                         int kron;
169
170                         kron = BN_kronecker(x, &group->field, ctx);
171                         if (kron == -2) goto err;
172
173                         if (kron == 1)
174                                 ECerr(EC_F_EC_GFP_SIMPLE_SET_COMPRESSED_COORDINATES, EC_R_INVALID_COMPRESSION_BIT);
175                         else
176                                 /* BN_mod_sqrt() should have cought this error (not a square) */
177                                 ECerr(EC_F_EC_GFP_SIMPLE_SET_COMPRESSED_COORDINATES, EC_R_INVALID_COMPRESSED_POINT);
178                         goto err;
179                         }
180                 if (!BN_usub(y, &group->field, y)) goto err;
181                 }
182         if (y_bit != BN_is_odd(y))
183                 {
184                 ECerr(EC_F_EC_GFP_SIMPLE_SET_COMPRESSED_COORDINATES, ERR_R_INTERNAL_ERROR);
185                 goto err;
186                 }
187
188         if (!EC_POINT_set_affine_coordinates_GFp(group, point, x, y, ctx)) goto err;
189
190         ret = 1;
191
192  err:
193         BN_CTX_end(ctx);
194         if (new_ctx != NULL)
195                 BN_CTX_free(new_ctx);
196         return ret;
197         }
198
199
200 size_t ec_GFp_simple_point2oct(const EC_GROUP *group, const EC_POINT *point, point_conversion_form_t form,
201         unsigned char *buf, size_t len, BN_CTX *ctx)
202         {
203         size_t ret;
204         BN_CTX *new_ctx = NULL;
205         int used_ctx = 0;
206         BIGNUM *x, *y;
207         size_t field_len, i, skip;
208
209         if ((form != POINT_CONVERSION_COMPRESSED)
210                 && (form != POINT_CONVERSION_UNCOMPRESSED)
211                 && (form != POINT_CONVERSION_HYBRID))
212                 {
213                 ECerr(EC_F_EC_GFP_SIMPLE_POINT2OCT, EC_R_INVALID_FORM);
214                 goto err;
215                 }
216
217         if (EC_POINT_is_at_infinity(group, point))
218                 {
219                 /* encodes to a single 0 octet */
220                 if (buf != NULL)
221                         {
222                         if (len < 1)
223                                 {
224                                 ECerr(EC_F_EC_GFP_SIMPLE_POINT2OCT, EC_R_BUFFER_TOO_SMALL);
225                                 return 0;
226                                 }
227                         buf[0] = 0;
228                         }
229                 return 1;
230                 }
231
232
233         /* ret := required output buffer length */
234         field_len = BN_num_bytes(&group->field);
235         ret = (form == POINT_CONVERSION_COMPRESSED) ? 1 + field_len : 1 + 2*field_len;
236
237         /* if 'buf' is NULL, just return required length */
238         if (buf != NULL)
239                 {
240                 if (len < ret)
241                         {
242                         ECerr(EC_F_EC_GFP_SIMPLE_POINT2OCT, EC_R_BUFFER_TOO_SMALL);
243                         goto err;
244                         }
245
246                 if (ctx == NULL)
247                         {
248                         ctx = new_ctx = BN_CTX_new();
249                         if (ctx == NULL)
250                                 return 0;
251                         }
252
253                 BN_CTX_start(ctx);
254                 used_ctx = 1;
255                 x = BN_CTX_get(ctx);
256                 y = BN_CTX_get(ctx);
257                 if (y == NULL) goto err;
258
259                 if (!EC_POINT_get_affine_coordinates_GFp(group, point, x, y, ctx)) goto err;
260
261                 if ((form == POINT_CONVERSION_COMPRESSED || form == POINT_CONVERSION_HYBRID) && BN_is_odd(y))
262                         buf[0] = form + 1;
263                 else
264                         buf[0] = form;
265         
266                 i = 1;
267                 
268                 skip = field_len - BN_num_bytes(x);
269                 if (skip > field_len)
270                         {
271                         ECerr(EC_F_EC_GFP_SIMPLE_POINT2OCT, ERR_R_INTERNAL_ERROR);
272                         goto err;
273                         }
274                 while (skip > 0)
275                         {
276                         buf[i++] = 0;
277                         skip--;
278                         }
279                 skip = BN_bn2bin(x, buf + i);
280                 i += skip;
281                 if (i != 1 + field_len)
282                         {
283                         ECerr(EC_F_EC_GFP_SIMPLE_POINT2OCT, ERR_R_INTERNAL_ERROR);
284                         goto err;
285                         }
286
287                 if (form == POINT_CONVERSION_UNCOMPRESSED || form == POINT_CONVERSION_HYBRID)
288                         {
289                         skip = field_len - BN_num_bytes(y);
290                         if (skip > field_len)
291                                 {
292                                 ECerr(EC_F_EC_GFP_SIMPLE_POINT2OCT, ERR_R_INTERNAL_ERROR);
293                                 goto err;
294                                 }
295                         while (skip > 0)
296                                 {
297                                 buf[i++] = 0;
298                                 skip--;
299                                 }
300                         skip = BN_bn2bin(y, buf + i);
301                         i += skip;
302                         }
303
304                 if (i != ret)
305                         {
306                         ECerr(EC_F_EC_GFP_SIMPLE_POINT2OCT, ERR_R_INTERNAL_ERROR);
307                         goto err;
308                         }
309                 }
310         
311         if (used_ctx)
312                 BN_CTX_end(ctx);
313         if (new_ctx != NULL)
314                 BN_CTX_free(new_ctx);
315         return ret;
316
317  err:
318         if (used_ctx)
319                 BN_CTX_end(ctx);
320         if (new_ctx != NULL)
321                 BN_CTX_free(new_ctx);
322         return 0;
323         }
324
325
326 int ec_GFp_simple_oct2point(const EC_GROUP *group, EC_POINT *point,
327         const unsigned char *buf, size_t len, BN_CTX *ctx)
328         {
329         point_conversion_form_t form;
330         int y_bit;
331         BN_CTX *new_ctx = NULL;
332         BIGNUM *x, *y;
333         size_t field_len, enc_len;
334         int ret = 0;
335
336         if (len == 0)
337                 {
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                 {
348                 ECerr(EC_F_EC_GFP_SIMPLE_OCT2POINT, EC_R_INVALID_ENCODING);
349                 return 0;
350                 }
351         if ((form == 0 || form == POINT_CONVERSION_UNCOMPRESSED) && y_bit)
352                 {
353                 ECerr(EC_F_EC_GFP_SIMPLE_OCT2POINT, EC_R_INVALID_ENCODING);
354                 return 0;
355                 }
356
357         if (form == 0)
358                 {
359                 if (len != 1)
360                         {
361                         ECerr(EC_F_EC_GFP_SIMPLE_OCT2POINT, EC_R_INVALID_ENCODING);
362                         return 0;
363                         }
364
365                 return EC_POINT_set_to_infinity(group, point);
366                 }
367         
368         field_len = BN_num_bytes(&group->field);
369         enc_len = (form == POINT_CONVERSION_COMPRESSED) ? 1 + field_len : 1 + 2*field_len;
370
371         if (len != enc_len)
372                 {
373                 ECerr(EC_F_EC_GFP_SIMPLE_OCT2POINT, EC_R_INVALID_ENCODING);
374                 return 0;
375                 }
376
377         if (ctx == NULL)
378                 {
379                 ctx = new_ctx = BN_CTX_new();
380                 if (ctx == NULL)
381                         return 0;
382                 }
383
384         BN_CTX_start(ctx);
385         x = BN_CTX_get(ctx);
386         y = BN_CTX_get(ctx);
387         if (y == NULL) goto err;
388
389         if (!BN_bin2bn(buf + 1, field_len, x)) goto err;
390         if (BN_ucmp(x, &group->field) >= 0)
391                 {
392                 ECerr(EC_F_EC_GFP_SIMPLE_OCT2POINT, EC_R_INVALID_ENCODING);
393                 goto err;
394                 }
395
396         if (form == POINT_CONVERSION_COMPRESSED)
397                 {
398                 if (!EC_POINT_set_compressed_coordinates_GFp(group, point, x, y_bit, ctx)) goto err;
399                 }
400         else
401                 {
402                 if (!BN_bin2bn(buf + 1 + field_len, field_len, y)) goto err;
403                 if (BN_ucmp(y, &group->field) >= 0)
404                         {
405                         ECerr(EC_F_EC_GFP_SIMPLE_OCT2POINT, EC_R_INVALID_ENCODING);
406                         goto err;
407                         }
408                 if (form == POINT_CONVERSION_HYBRID)
409                         {
410                         if (y_bit != BN_is_odd(y))
411                                 {
412                                 ECerr(EC_F_EC_GFP_SIMPLE_OCT2POINT, EC_R_INVALID_ENCODING);
413                                 goto err;
414                                 }
415                         }
416
417                 if (!EC_POINT_set_affine_coordinates_GFp(group, point, x, y, ctx)) goto err;
418                 }
419         
420         if (!EC_POINT_is_on_curve(group, point, ctx)) /* test required by X9.62 */
421                 {
422                 ECerr(EC_F_EC_GFP_SIMPLE_OCT2POINT, EC_R_POINT_IS_NOT_ON_CURVE);
423                 goto err;
424                 }
425
426         ret = 1;
427         
428  err:
429         BN_CTX_end(ctx);
430         if (new_ctx != NULL)
431                 BN_CTX_free(new_ctx);
432         return ret;
433         }
434