1 | /*
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2 | * Copyright 2001-2016 The OpenSSL Project Authors. All Rights Reserved.
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3 | *
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4 | * Licensed under the OpenSSL license (the "License"). You may not use
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5 | * this file except in compliance with the License. You can obtain a copy
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6 | * in the file LICENSE in the source distribution or at
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7 | * https://www.openssl.org/source/license.html
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8 | */
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9 |
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10 | /* ====================================================================
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11 | * Copyright 2002 Sun Microsystems, Inc. ALL RIGHTS RESERVED.
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12 | *
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13 | * Portions of the attached software ("Contribution") are developed by
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14 | * SUN MICROSYSTEMS, INC., and are contributed to the OpenSSL project.
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15 | *
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16 | * The Contribution is licensed pursuant to the OpenSSL open source
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17 | * license provided above.
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18 | *
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19 | * The elliptic curve binary polynomial software is originally written by
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20 | * Sheueling Chang Shantz and Douglas Stebila of Sun Microsystems Laboratories.
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21 | *
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22 | */
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23 |
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24 | #include <openssl/err.h>
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25 | #include "ec_lcl.h"
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26 |
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27 | EC_GROUP *EC_GROUP_new_curve_GFp(const BIGNUM *p, const BIGNUM *a,
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28 | const BIGNUM *b, BN_CTX *ctx)
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29 | {
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30 | const EC_METHOD *meth;
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31 | EC_GROUP *ret;
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32 |
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33 | #if defined(OPENSSL_BN_ASM_MONT)
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34 | /*
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35 | * This might appear controversial, but the fact is that generic
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36 | * prime method was observed to deliver better performance even
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37 | * for NIST primes on a range of platforms, e.g.: 60%-15%
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38 | * improvement on IA-64, ~25% on ARM, 30%-90% on P4, 20%-25%
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39 | * in 32-bit build and 35%--12% in 64-bit build on Core2...
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40 | * Coefficients are relative to optimized bn_nist.c for most
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41 | * intensive ECDSA verify and ECDH operations for 192- and 521-
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42 | * bit keys respectively. Choice of these boundary values is
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43 | * arguable, because the dependency of improvement coefficient
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44 | * from key length is not a "monotone" curve. For example while
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45 | * 571-bit result is 23% on ARM, 384-bit one is -1%. But it's
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46 | * generally faster, sometimes "respectfully" faster, sometimes
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47 | * "tolerably" slower... What effectively happens is that loop
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48 | * with bn_mul_add_words is put against bn_mul_mont, and the
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49 | * latter "wins" on short vectors. Correct solution should be
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50 | * implementing dedicated NxN multiplication subroutines for
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51 | * small N. But till it materializes, let's stick to generic
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52 | * prime method...
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53 | * <appro>
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54 | */
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55 | meth = EC_GFp_mont_method();
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56 | #else
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57 | if (BN_nist_mod_func(p))
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58 | meth = EC_GFp_nist_method();
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59 | else
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60 | meth = EC_GFp_mont_method();
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61 | #endif
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62 |
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63 | ret = EC_GROUP_new(meth);
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64 | if (ret == NULL)
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65 | return NULL;
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66 |
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67 | if (!EC_GROUP_set_curve_GFp(ret, p, a, b, ctx)) {
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68 | EC_GROUP_clear_free(ret);
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69 | return NULL;
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70 | }
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71 |
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72 | return ret;
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73 | }
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74 |
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75 | #ifndef OPENSSL_NO_EC2M
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76 | EC_GROUP *EC_GROUP_new_curve_GF2m(const BIGNUM *p, const BIGNUM *a,
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77 | const BIGNUM *b, BN_CTX *ctx)
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78 | {
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79 | const EC_METHOD *meth;
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80 | EC_GROUP *ret;
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81 |
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82 | meth = EC_GF2m_simple_method();
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83 |
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84 | ret = EC_GROUP_new(meth);
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85 | if (ret == NULL)
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86 | return NULL;
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87 |
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88 | if (!EC_GROUP_set_curve_GF2m(ret, p, a, b, ctx)) {
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89 | EC_GROUP_clear_free(ret);
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90 | return NULL;
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91 | }
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92 |
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93 | return ret;
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94 | }
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95 | #endif
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