[331] | 1 | /*
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| 2 | * Copyright 1998-2016 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 | #include <openssl/opensslconf.h>
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| 11 | #include "internal/cryptlib.h"
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| 12 | #include "bn_lcl.h"
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| 13 |
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| 14 | #define BN_BLINDING_COUNTER 32
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| 15 |
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| 16 | struct bn_blinding_st {
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| 17 | BIGNUM *A;
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| 18 | BIGNUM *Ai;
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| 19 | BIGNUM *e;
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| 20 | BIGNUM *mod; /* just a reference */
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| 21 | CRYPTO_THREAD_ID tid;
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| 22 | int counter;
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| 23 | unsigned long flags;
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| 24 | BN_MONT_CTX *m_ctx;
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| 25 | int (*bn_mod_exp) (BIGNUM *r, const BIGNUM *a, const BIGNUM *p,
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| 26 | const BIGNUM *m, BN_CTX *ctx, BN_MONT_CTX *m_ctx);
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| 27 | CRYPTO_RWLOCK *lock;
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| 28 | };
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| 29 |
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| 30 | BN_BLINDING *BN_BLINDING_new(const BIGNUM *A, const BIGNUM *Ai, BIGNUM *mod)
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| 31 | {
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| 32 | BN_BLINDING *ret = NULL;
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| 33 |
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| 34 | bn_check_top(mod);
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| 35 |
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| 36 | if ((ret = OPENSSL_zalloc(sizeof(*ret))) == NULL) {
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| 37 | BNerr(BN_F_BN_BLINDING_NEW, ERR_R_MALLOC_FAILURE);
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| 38 | return NULL;
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| 39 | }
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| 40 |
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| 41 | ret->lock = CRYPTO_THREAD_lock_new();
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| 42 | if (ret->lock == NULL) {
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| 43 | BNerr(BN_F_BN_BLINDING_NEW, ERR_R_MALLOC_FAILURE);
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| 44 | OPENSSL_free(ret);
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| 45 | return NULL;
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| 46 | }
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| 47 |
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| 48 | BN_BLINDING_set_current_thread(ret);
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| 49 |
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| 50 | if (A != NULL) {
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| 51 | if ((ret->A = BN_dup(A)) == NULL)
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| 52 | goto err;
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| 53 | }
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| 54 |
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| 55 | if (Ai != NULL) {
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| 56 | if ((ret->Ai = BN_dup(Ai)) == NULL)
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| 57 | goto err;
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| 58 | }
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| 59 |
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| 60 | /* save a copy of mod in the BN_BLINDING structure */
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| 61 | if ((ret->mod = BN_dup(mod)) == NULL)
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| 62 | goto err;
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| 63 |
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| 64 | if (BN_get_flags(mod, BN_FLG_CONSTTIME) != 0)
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| 65 | BN_set_flags(ret->mod, BN_FLG_CONSTTIME);
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| 66 |
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| 67 | /*
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| 68 | * Set the counter to the special value -1 to indicate that this is
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| 69 | * never-used fresh blinding that does not need updating before first
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| 70 | * use.
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| 71 | */
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| 72 | ret->counter = -1;
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| 73 |
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| 74 | return ret;
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| 75 |
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| 76 | err:
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| 77 | BN_BLINDING_free(ret);
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| 78 | return NULL;
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| 79 | }
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| 80 |
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| 81 | void BN_BLINDING_free(BN_BLINDING *r)
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| 82 | {
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| 83 | if (r == NULL)
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| 84 | return;
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| 85 |
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| 86 | BN_free(r->A);
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| 87 | BN_free(r->Ai);
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| 88 | BN_free(r->e);
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| 89 | BN_free(r->mod);
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| 90 | CRYPTO_THREAD_lock_free(r->lock);
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| 91 | OPENSSL_free(r);
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| 92 | }
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| 93 |
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| 94 | int BN_BLINDING_update(BN_BLINDING *b, BN_CTX *ctx)
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| 95 | {
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| 96 | int ret = 0;
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| 97 |
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| 98 | if ((b->A == NULL) || (b->Ai == NULL)) {
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| 99 | BNerr(BN_F_BN_BLINDING_UPDATE, BN_R_NOT_INITIALIZED);
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| 100 | goto err;
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| 101 | }
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| 102 |
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| 103 | if (b->counter == -1)
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| 104 | b->counter = 0;
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| 105 |
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| 106 | if (++b->counter == BN_BLINDING_COUNTER && b->e != NULL &&
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| 107 | !(b->flags & BN_BLINDING_NO_RECREATE)) {
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| 108 | /* re-create blinding parameters */
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| 109 | if (!BN_BLINDING_create_param(b, NULL, NULL, ctx, NULL, NULL))
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| 110 | goto err;
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| 111 | } else if (!(b->flags & BN_BLINDING_NO_UPDATE)) {
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| 112 | if (!BN_mod_mul(b->A, b->A, b->A, b->mod, ctx))
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| 113 | goto err;
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| 114 | if (!BN_mod_mul(b->Ai, b->Ai, b->Ai, b->mod, ctx))
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| 115 | goto err;
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| 116 | }
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| 117 |
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| 118 | ret = 1;
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| 119 | err:
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| 120 | if (b->counter == BN_BLINDING_COUNTER)
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| 121 | b->counter = 0;
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| 122 | return (ret);
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| 123 | }
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| 124 |
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| 125 | int BN_BLINDING_convert(BIGNUM *n, BN_BLINDING *b, BN_CTX *ctx)
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| 126 | {
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| 127 | return BN_BLINDING_convert_ex(n, NULL, b, ctx);
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| 128 | }
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| 129 |
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| 130 | int BN_BLINDING_convert_ex(BIGNUM *n, BIGNUM *r, BN_BLINDING *b, BN_CTX *ctx)
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| 131 | {
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| 132 | int ret = 1;
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| 133 |
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| 134 | bn_check_top(n);
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| 135 |
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| 136 | if ((b->A == NULL) || (b->Ai == NULL)) {
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| 137 | BNerr(BN_F_BN_BLINDING_CONVERT_EX, BN_R_NOT_INITIALIZED);
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| 138 | return (0);
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| 139 | }
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| 140 |
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| 141 | if (b->counter == -1)
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| 142 | /* Fresh blinding, doesn't need updating. */
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| 143 | b->counter = 0;
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| 144 | else if (!BN_BLINDING_update(b, ctx))
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| 145 | return (0);
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| 146 |
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| 147 | if (r != NULL) {
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| 148 | if (!BN_copy(r, b->Ai))
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| 149 | ret = 0;
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| 150 | }
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| 151 |
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| 152 | if (!BN_mod_mul(n, n, b->A, b->mod, ctx))
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| 153 | ret = 0;
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| 154 |
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| 155 | return ret;
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| 156 | }
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| 157 |
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| 158 | int BN_BLINDING_invert(BIGNUM *n, BN_BLINDING *b, BN_CTX *ctx)
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| 159 | {
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| 160 | return BN_BLINDING_invert_ex(n, NULL, b, ctx);
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| 161 | }
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| 162 |
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| 163 | int BN_BLINDING_invert_ex(BIGNUM *n, const BIGNUM *r, BN_BLINDING *b,
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| 164 | BN_CTX *ctx)
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| 165 | {
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| 166 | int ret;
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| 167 |
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| 168 | bn_check_top(n);
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| 169 |
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| 170 | if (r != NULL)
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| 171 | ret = BN_mod_mul(n, n, r, b->mod, ctx);
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| 172 | else {
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| 173 | if (b->Ai == NULL) {
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| 174 | BNerr(BN_F_BN_BLINDING_INVERT_EX, BN_R_NOT_INITIALIZED);
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| 175 | return (0);
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| 176 | }
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| 177 | ret = BN_mod_mul(n, n, b->Ai, b->mod, ctx);
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| 178 | }
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| 179 |
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| 180 | bn_check_top(n);
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| 181 | return (ret);
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| 182 | }
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| 183 |
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| 184 | int BN_BLINDING_is_current_thread(BN_BLINDING *b)
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| 185 | {
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| 186 | return CRYPTO_THREAD_compare_id(CRYPTO_THREAD_get_current_id(), b->tid);
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| 187 | }
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| 188 |
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| 189 | void BN_BLINDING_set_current_thread(BN_BLINDING *b)
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| 190 | {
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| 191 | b->tid = CRYPTO_THREAD_get_current_id();
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| 192 | }
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| 193 |
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| 194 | int BN_BLINDING_lock(BN_BLINDING *b)
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| 195 | {
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| 196 | return CRYPTO_THREAD_write_lock(b->lock);
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| 197 | }
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| 198 |
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| 199 | int BN_BLINDING_unlock(BN_BLINDING *b)
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| 200 | {
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| 201 | return CRYPTO_THREAD_unlock(b->lock);
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| 202 | }
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| 203 |
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| 204 | unsigned long BN_BLINDING_get_flags(const BN_BLINDING *b)
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| 205 | {
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| 206 | return b->flags;
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| 207 | }
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| 208 |
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| 209 | void BN_BLINDING_set_flags(BN_BLINDING *b, unsigned long flags)
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| 210 | {
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| 211 | b->flags = flags;
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| 212 | }
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| 213 |
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| 214 | BN_BLINDING *BN_BLINDING_create_param(BN_BLINDING *b,
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| 215 | const BIGNUM *e, BIGNUM *m, BN_CTX *ctx,
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| 216 | int (*bn_mod_exp) (BIGNUM *r,
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| 217 | const BIGNUM *a,
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| 218 | const BIGNUM *p,
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| 219 | const BIGNUM *m,
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| 220 | BN_CTX *ctx,
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| 221 | BN_MONT_CTX *m_ctx),
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| 222 | BN_MONT_CTX *m_ctx)
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| 223 | {
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| 224 | int retry_counter = 32;
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| 225 | BN_BLINDING *ret = NULL;
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| 226 |
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| 227 | if (b == NULL)
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| 228 | ret = BN_BLINDING_new(NULL, NULL, m);
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| 229 | else
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| 230 | ret = b;
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| 231 |
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| 232 | if (ret == NULL)
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| 233 | goto err;
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| 234 |
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| 235 | if (ret->A == NULL && (ret->A = BN_new()) == NULL)
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| 236 | goto err;
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| 237 | if (ret->Ai == NULL && (ret->Ai = BN_new()) == NULL)
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| 238 | goto err;
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| 239 |
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| 240 | if (e != NULL) {
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| 241 | BN_free(ret->e);
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| 242 | ret->e = BN_dup(e);
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| 243 | }
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| 244 | if (ret->e == NULL)
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| 245 | goto err;
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| 246 |
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| 247 | if (bn_mod_exp != NULL)
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| 248 | ret->bn_mod_exp = bn_mod_exp;
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| 249 | if (m_ctx != NULL)
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| 250 | ret->m_ctx = m_ctx;
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| 251 |
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| 252 | do {
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| 253 | int rv;
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| 254 | if (!BN_rand_range(ret->A, ret->mod))
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| 255 | goto err;
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| 256 | if (!int_bn_mod_inverse(ret->Ai, ret->A, ret->mod, ctx, &rv)) {
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| 257 | /*
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| 258 | * this should almost never happen for good RSA keys
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| 259 | */
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| 260 | if (rv) {
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| 261 | if (retry_counter-- == 0) {
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| 262 | BNerr(BN_F_BN_BLINDING_CREATE_PARAM,
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| 263 | BN_R_TOO_MANY_ITERATIONS);
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| 264 | goto err;
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| 265 | }
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| 266 | } else
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| 267 | goto err;
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| 268 | } else
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| 269 | break;
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| 270 | } while (1);
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| 271 |
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| 272 | if (ret->bn_mod_exp != NULL && ret->m_ctx != NULL) {
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| 273 | if (!ret->bn_mod_exp
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| 274 | (ret->A, ret->A, ret->e, ret->mod, ctx, ret->m_ctx))
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| 275 | goto err;
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| 276 | } else {
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| 277 | if (!BN_mod_exp(ret->A, ret->A, ret->e, ret->mod, ctx))
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| 278 | goto err;
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| 279 | }
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| 280 |
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| 281 | return ret;
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| 282 | err:
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| 283 | if (b == NULL) {
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| 284 | BN_BLINDING_free(ret);
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| 285 | ret = NULL;
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| 286 | }
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| 287 |
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| 288 | return ret;
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| 289 | }
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