lib/libcrypto/ec/ec_cvt.c

   1 /* $OpenBSD: ec_cvt.c,v 1.6 2014/07/10 22:45:57 jsing Exp $ */
   2 /*
   3  * Originally written by Bodo Moeller for the OpenSSL project.
   4  */
   5 /* ====================================================================
   6  * Copyright (c) 1998-2002 The OpenSSL Project.  All rights reserved.
   7  *
   8  * Redistribution and use in source and binary forms, with or without
   9  * modification, are permitted provided that the following conditions
  10  * are met:
  11  *
  12  * 1. Redistributions of source code must retain the above copyright
  13  *    notice, this list of conditions and the following disclaimer.
  14  *
  15  * 2. Redistributions in binary form must reproduce the above copyright
  16  *    notice, this list of conditions and the following disclaimer in
  17  *    the documentation and/or other materials provided with the
  18  *    distribution.
  19  *
  20  * 3. All advertising materials mentioning features or use of this
  21  *    software must display the following acknowledgment:
  22  *    "This product includes software developed by the OpenSSL Project
  23  *    for use in the OpenSSL Toolkit. (http://www.openssl.org/)"
  24  *
  25  * 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to
  26  *    endorse or promote products derived from this software without
  27  *    prior written permission. For written permission, please contact
  28  *    openssl-core@openssl.org.
  29  *
  30  * 5. Products derived from this software may not be called "OpenSSL"
  31  *    nor may "OpenSSL" appear in their names without prior written
  32  *    permission of the OpenSSL Project.
  33  *
  34  * 6. Redistributions of any form whatsoever must retain the following
  35  *    acknowledgment:
  36  *    "This product includes software developed by the OpenSSL Project
  37  *    for use in the OpenSSL Toolkit (http://www.openssl.org/)"
  38  *
  39  * THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY
  40  * EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  41  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
  42  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE OpenSSL PROJECT OR
  43  * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  44  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  45  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
  46  * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  47  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
  48  * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
  49  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
  50  * OF THE POSSIBILITY OF SUCH DAMAGE.
  51  * ====================================================================
  52  *
  53  * This product includes cryptographic software written by Eric Young
  54  * (eay@cryptsoft.com).  This product includes software written by Tim
  55  * Hudson (tjh@cryptsoft.com).
  56  *
  57  */
  58 /* ====================================================================
  59  * Copyright 2002 Sun Microsystems, Inc. ALL RIGHTS RESERVED.
  60  *
  61  * Portions of the attached software ("Contribution") are developed by
  62  * SUN MICROSYSTEMS, INC., and are contributed to the OpenSSL project.
  63  *
  64  * The Contribution is licensed pursuant to the OpenSSL open source
  65  * license provided above.
  66  *
  67  * The elliptic curve binary polynomial software is originally written by
  68  * Sheueling Chang Shantz and Douglas Stebila of Sun Microsystems Laboratories.
  69  *
  70  */
  71
  72 #include <openssl/opensslconf.h>
  73
  74 #include <openssl/err.h>
  75 #include "ec_lcl.h"
  76
  77 EC_GROUP *
  78 EC_GROUP_new_curve_GFp(const BIGNUM *p, const BIGNUM *a, const BIGNUM *b,
  79     BN_CTX *ctx)
  80 {
  81         const EC_METHOD *meth;
  82         EC_GROUP *ret;
  83
  84 #if defined(OPENSSL_BN_ASM_MONT)
  85         /*
  86          * This might appear controversial, but the fact is that generic
  87          * prime method was observed to deliver better performance even
  88          * for NIST primes on a range of platforms, e.g.: 60%-15%
  89          * improvement on IA-64, ~25% on ARM, 30%-90% on P4, 20%-25%
  90          * in 32-bit build and 35%--12% in 64-bit build on Core2...
  91          * Coefficients are relative to optimized bn_nist.c for most
  92          * intensive ECDSA verify and ECDH operations for 192- and 521-
  93          * bit keys respectively. Choice of these boundary values is
  94          * arguable, because the dependency of improvement coefficient
  95          * from key length is not a "monotone" curve. For example while
  96          * 571-bit result is 23% on ARM, 384-bit one is -1%. But it's
  97          * generally faster, sometimes "respectfully" faster, sometimes
  98          * "tolerably" slower... What effectively happens is that loop
  99          * with bn_mul_add_words is put against bn_mul_mont, and the
 100          * latter "wins" on short vectors. Correct solution should be
 101          * implementing dedicated NxN multiplication subroutines for
 102          * small N. But till it materializes, let's stick to generic
 103          * prime method...
 104          *                                              <appro>
 105          */
 106         meth = EC_GFp_mont_method();
 107 #else
 108         meth = EC_GFp_nist_method();
 109 #endif
 110
 111         ret = EC_GROUP_new(meth);
 112         if (ret == NULL)
 113                 return NULL;
 114
 115         if (!EC_GROUP_set_curve_GFp(ret, p, a, b, ctx)) {
 116                 unsigned long err;
 117
 118                 err = ERR_peek_last_error();
 119
 120                 if (!(ERR_GET_LIB(err) == ERR_LIB_EC &&
 121                     ((ERR_GET_REASON(err) == EC_R_NOT_A_NIST_PRIME) ||
 122                     (ERR_GET_REASON(err) == EC_R_NOT_A_SUPPORTED_NIST_PRIME)))) {
 123                         /* real error */
 124
 125                         EC_GROUP_clear_free(ret);
 126                         return NULL;
 127                 }
 128                 /* not an actual error, we just cannot use EC_GFp_nist_method */
 129
 130                 ERR_clear_error();
 131
 132                 EC_GROUP_clear_free(ret);
 133                 meth = EC_GFp_mont_method();
 134
 135                 ret = EC_GROUP_new(meth);
 136                 if (ret == NULL)
 137                         return NULL;
 138
 139                 if (!EC_GROUP_set_curve_GFp(ret, p, a, b, ctx)) {
 140                         EC_GROUP_clear_free(ret);
 141                         return NULL;
 142                 }
 143         }
 144         return ret;
 145 }
 146
 147 #ifndef OPENSSL_NO_EC2M
 148 EC_GROUP *
 149 EC_GROUP_new_curve_GF2m(const BIGNUM *p, const BIGNUM *a, const BIGNUM *b,
 150     BN_CTX *ctx)
 151 {
 152         const EC_METHOD *meth;
 153         EC_GROUP *ret;
 154
 155         meth = EC_GF2m_simple_method();
 156
 157         ret = EC_GROUP_new(meth);
 158         if (ret == NULL)
 159                 return NULL;
 160
 161         if (!EC_GROUP_set_curve_GF2m(ret, p, a, b, ctx)) {
 162                 EC_GROUP_clear_free(ret);
 163                 return NULL;
 164         }
 165         return ret;
 166 }
 167 #endif