crypto/bn/bn_blind.c

   1 /*
   2  * Copyright 1998-2016 The OpenSSL Project Authors. All Rights Reserved.
   3  *
   4  * Licensed under the OpenSSL license (the "License").  You may not use
   5  * this file except in compliance with the License.  You can obtain a copy
   6  * in the file LICENSE in the source distribution or at
   7  * https://www.openssl.org/source/license.html
   8  */
   9
  10 #include <openssl/opensslconf.h>
  11 #include "internal/cryptlib.h"
  12 #include "bn_lcl.h"
  13
  14 #define BN_BLINDING_COUNTER     32
  15
  16 struct bn_blinding_st {
  17     BIGNUM *A;
  18     BIGNUM *Ai;
  19     BIGNUM *e;
  20     BIGNUM *mod;                /* just a reference */
  21     CRYPTO_THREAD_ID tid;
  22     int counter;
  23     unsigned long flags;
  24     BN_MONT_CTX *m_ctx;
  25     int (*bn_mod_exp) (BIGNUM *r, const BIGNUM *a, const BIGNUM *p,
  26                        const BIGNUM *m, BN_CTX *ctx, BN_MONT_CTX *m_ctx);
  27     CRYPTO_RWLOCK *lock;
  28 };
  29
  30 BN_BLINDING *BN_BLINDING_new(const BIGNUM *A, const BIGNUM *Ai, BIGNUM *mod)
  31 {
  32     BN_BLINDING *ret = NULL;
  33
  34     bn_check_top(mod);
  35
  36     if ((ret = OPENSSL_zalloc(sizeof(*ret))) == NULL) {
  37         BNerr(BN_F_BN_BLINDING_NEW, ERR_R_MALLOC_FAILURE);
  38         return NULL;
  39     }
  40
  41     ret->lock = CRYPTO_THREAD_lock_new();
  42     if (ret->lock == NULL) {
  43         BNerr(BN_F_BN_BLINDING_NEW, ERR_R_MALLOC_FAILURE);
  44         OPENSSL_free(ret);
  45         return NULL;
  46     }
  47
  48     BN_BLINDING_set_current_thread(ret);
  49
  50     if (A != NULL) {
  51         if ((ret->A = BN_dup(A)) == NULL)
  52             goto err;
  53     }
  54
  55     if (Ai != NULL) {
  56         if ((ret->Ai = BN_dup(Ai)) == NULL)
  57             goto err;
  58     }
  59
  60     /* save a copy of mod in the BN_BLINDING structure */
  61     if ((ret->mod = BN_dup(mod)) == NULL)
  62         goto err;
  63
  64     if (BN_get_flags(mod, BN_FLG_CONSTTIME) != 0)
  65         BN_set_flags(ret->mod, BN_FLG_CONSTTIME);
  66
  67     /*
  68      * Set the counter to the special value -1 to indicate that this is
  69      * never-used fresh blinding that does not need updating before first
  70      * use.
  71      */
  72     ret->counter = -1;
  73
  74     return ret;
  75
  76  err:
  77     BN_BLINDING_free(ret);
  78     return NULL;
  79 }
  80
  81 void BN_BLINDING_free(BN_BLINDING *r)
  82 {
  83     if (r == NULL)
  84         return;
  85
  86     BN_free(r->A);
  87     BN_free(r->Ai);
  88     BN_free(r->e);
  89     BN_free(r->mod);
  90     CRYPTO_THREAD_lock_free(r->lock);
  91     OPENSSL_free(r);
  92 }
  93
  94 int BN_BLINDING_update(BN_BLINDING *b, BN_CTX *ctx)
  95 {
  96     int ret = 0;
  97
  98     if ((b->A == NULL) || (b->Ai == NULL)) {
  99         BNerr(BN_F_BN_BLINDING_UPDATE, BN_R_NOT_INITIALIZED);
 100         goto err;
 101     }
 102
 103     if (b->counter == -1)
 104         b->counter = 0;
 105
 106     if (++b->counter == BN_BLINDING_COUNTER && b->e != NULL &&
 107         !(b->flags & BN_BLINDING_NO_RECREATE)) {
 108         /* re-create blinding parameters */
 109         if (!BN_BLINDING_create_param(b, NULL, NULL, ctx, NULL, NULL))
 110             goto err;
 111     } else if (!(b->flags & BN_BLINDING_NO_UPDATE)) {
 112         if (!BN_mod_mul(b->A, b->A, b->A, b->mod, ctx))
 113             goto err;
 114         if (!BN_mod_mul(b->Ai, b->Ai, b->Ai, b->mod, ctx))
 115             goto err;
 116     }
 117
 118     ret = 1;
 119  err:
 120     if (b->counter == BN_BLINDING_COUNTER)
 121         b->counter = 0;
 122     return ret;
 123 }
 124
 125 int BN_BLINDING_convert(BIGNUM *n, BN_BLINDING *b, BN_CTX *ctx)
 126 {
 127     return BN_BLINDING_convert_ex(n, NULL, b, ctx);
 128 }
 129
 130 int BN_BLINDING_convert_ex(BIGNUM *n, BIGNUM *r, BN_BLINDING *b, BN_CTX *ctx)
 131 {
 132     int ret = 1;
 133
 134     bn_check_top(n);
 135
 136     if ((b->A == NULL) || (b->Ai == NULL)) {
 137         BNerr(BN_F_BN_BLINDING_CONVERT_EX, BN_R_NOT_INITIALIZED);
 138         return 0;
 139     }
 140
 141     if (b->counter == -1)
 142         /* Fresh blinding, doesn't need updating. */
 143         b->counter = 0;
 144     else if (!BN_BLINDING_update(b, ctx))
 145         return 0;
 146
 147     if (r != NULL) {
 148         if (!BN_copy(r, b->Ai))
 149             ret = 0;
 150     }
 151
 152     if (!BN_mod_mul(n, n, b->A, b->mod, ctx))
 153         ret = 0;
 154
 155     return ret;
 156 }
 157
 158 int BN_BLINDING_invert(BIGNUM *n, BN_BLINDING *b, BN_CTX *ctx)
 159 {
 160     return BN_BLINDING_invert_ex(n, NULL, b, ctx);
 161 }
 162
 163 int BN_BLINDING_invert_ex(BIGNUM *n, const BIGNUM *r, BN_BLINDING *b,
 164                           BN_CTX *ctx)
 165 {
 166     int ret;
 167
 168     bn_check_top(n);
 169
 170     if (r != NULL)
 171         ret = BN_mod_mul(n, n, r, b->mod, ctx);
 172     else {
 173         if (b->Ai == NULL) {
 174             BNerr(BN_F_BN_BLINDING_INVERT_EX, BN_R_NOT_INITIALIZED);
 175             return 0;
 176         }
 177         ret = BN_mod_mul(n, n, b->Ai, b->mod, ctx);
 178     }
 179
 180     bn_check_top(n);
 181     return ret;
 182 }
 183
 184 int BN_BLINDING_is_current_thread(BN_BLINDING *b)
 185 {
 186     return CRYPTO_THREAD_compare_id(CRYPTO_THREAD_get_current_id(), b->tid);
 187 }
 188
 189 void BN_BLINDING_set_current_thread(BN_BLINDING *b)
 190 {
 191     b->tid = CRYPTO_THREAD_get_current_id();
 192 }
 193
 194 int BN_BLINDING_lock(BN_BLINDING *b)
 195 {
 196     return CRYPTO_THREAD_write_lock(b->lock);
 197 }
 198
 199 int BN_BLINDING_unlock(BN_BLINDING *b)
 200 {
 201     return CRYPTO_THREAD_unlock(b->lock);
 202 }
 203
 204 unsigned long BN_BLINDING_get_flags(const BN_BLINDING *b)
 205 {
 206     return b->flags;
 207 }
 208
 209 void BN_BLINDING_set_flags(BN_BLINDING *b, unsigned long flags)
 210 {
 211     b->flags = flags;
 212 }
 213
 214 BN_BLINDING *BN_BLINDING_create_param(BN_BLINDING *b,
 215                                       const BIGNUM *e, BIGNUM *m, BN_CTX *ctx,
 216                                       int (*bn_mod_exp) (BIGNUM *r,
 217                                                          const BIGNUM *a,
 218                                                          const BIGNUM *p,
 219                                                          const BIGNUM *m,
 220                                                          BN_CTX *ctx,
 221                                                          BN_MONT_CTX *m_ctx),
 222                                       BN_MONT_CTX *m_ctx)
 223 {
 224     int retry_counter = 32;
 225     BN_BLINDING *ret = NULL;
 226
 227     if (b == NULL)
 228         ret = BN_BLINDING_new(NULL, NULL, m);
 229     else
 230         ret = b;
 231
 232     if (ret == NULL)
 233         goto err;
 234
 235     if (ret->A == NULL && (ret->A = BN_new()) == NULL)
 236         goto err;
 237     if (ret->Ai == NULL && (ret->Ai = BN_new()) == NULL)
 238         goto err;
 239
 240     if (e != NULL) {
 241         BN_free(ret->e);
 242         ret->e = BN_dup(e);
 243     }
 244     if (ret->e == NULL)
 245         goto err;
 246
 247     if (bn_mod_exp != NULL)
 248         ret->bn_mod_exp = bn_mod_exp;
 249     if (m_ctx != NULL)
 250         ret->m_ctx = m_ctx;
 251
 252     do {
 253         int rv;
 254         if (!BN_rand_range(ret->A, ret->mod))
 255             goto err;
 256         if (!int_bn_mod_inverse(ret->Ai, ret->A, ret->mod, ctx, &rv)) {
 257             /*
 258              * this should almost never happen for good RSA keys
 259              */
 260             if (rv) {
 261                 if (retry_counter-- == 0) {
 262                     BNerr(BN_F_BN_BLINDING_CREATE_PARAM,
 263                           BN_R_TOO_MANY_ITERATIONS);
 264                     goto err;
 265                 }
 266             } else
 267                 goto err;
 268         } else
 269             break;
 270     } while (1);
 271
 272     if (ret->bn_mod_exp != NULL && ret->m_ctx != NULL) {
 273         if (!ret->bn_mod_exp
 274             (ret->A, ret->A, ret->e, ret->mod, ctx, ret->m_ctx))
 275             goto err;
 276     } else {
 277         if (!BN_mod_exp(ret->A, ret->A, ret->e, ret->mod, ctx))
 278             goto err;
 279     }
 280
 281     return ret;
 282  err:
 283     if (b == NULL) {
 284         BN_BLINDING_free(ret);
 285         ret = NULL;
 286     }
 287
 288     return ret;
 289 }