release/src/router/openssl/crypto/ec/ec2_oct.c

   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 *point,
  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)) goto 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_COORDINATES, EC_R_INVALID_COMPRESSED_POINT);
 136                                 }
 137                         else
 138                                 ECerr(EC_F_EC_GF2M_SIMPLE_SET_COMPRESSED_COORDINATES, 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, point_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*field_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_SMALL);
 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, ctx)) 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_ERROR);
 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_ERROR);
 252                         goto err;
 253                         }
 254
 255                 if (form == POINT_CONVERSION_UNCOMPRESSED || form == POINT_CONVERSION_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_INTERNAL_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_ERROR);
 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_ENCODING);
 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_ENCODING);
 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_INVALID_ENCODING);
 386                                 goto err;
 387                                 }
 388                         }
 389
 390                 if (!EC_POINT_set_affine_coordinates_GF2m(group, point, x, y, ctx)) 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