/* $OpenBSD: bn_blind.c,v 1.17 2017/01/29 17:49:22 beck Exp $ */

/* ====================================================================

 * Copyright (c) 1998-2006 The OpenSSL Project.  All rights reserved.

 *

 * Redistribution and use in source and binary forms, with or without

 * modification, are permitted provided that the following conditions

 * are met:

 *

 * 1. Redistributions of source code must retain the above copyright

 *    notice, this list of conditions and the following disclaimer.

 *

 * 2. Redistributions in binary form must reproduce the above copyright

 *    notice, this list of conditions and the following disclaimer in

 *    the documentation and/or other materials provided with the

 *    distribution.

 *

 * 3. All advertising materials mentioning features or use of this

 *    software must display the following acknowledgment:

 *    "This product includes software developed by the OpenSSL Project

 *    for use in the OpenSSL Toolkit. (http://www.openssl.org/)"

 *

 * 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to

 *    endorse or promote products derived from this software without

 *    prior written permission. For written permission, please contact

 *    openssl-core@openssl.org.

 *

 * 5. Products derived from this software may not be called "OpenSSL"

 *    nor may "OpenSSL" appear in their names without prior written

 *    permission of the OpenSSL Project.

 *

 * 6. Redistributions of any form whatsoever must retain the following

 *    acknowledgment:

 *    "This product includes software developed by the OpenSSL Project

 *    for use in the OpenSSL Toolkit (http://www.openssl.org/)"

 *

 * THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY

 * EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE

 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR

 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE OpenSSL PROJECT OR

 * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,

 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT

 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;

 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)

 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,

 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)

 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED

 * OF THE POSSIBILITY OF SUCH DAMAGE.

 * ====================================================================

 *

 * This product includes cryptographic software written by Eric Young

 * (eay@cryptsoft.com).  This product includes software written by Tim

 * Hudson (tjh@cryptsoft.com).

 *

 */

/* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)

 * All rights reserved.

 *

 * This package is an SSL implementation written

 * by Eric Young (eay@cryptsoft.com).

 * The implementation was written so as to conform with Netscapes SSL.

 *

 * This library is free for commercial and non-commercial use as long as

 * the following conditions are aheared to.  The following conditions

 * apply to all code found in this distribution, be it the RC4, RSA,

 * lhash, DES, etc., code; not just the SSL code.  The SSL documentation

 * included with this distribution is covered by the same copyright terms

 * except that the holder is Tim Hudson (tjh@cryptsoft.com).

 *

 * Copyright remains Eric Young's, and as such any Copyright notices in

 * the code are not to be removed.

 * If this package is used in a product, Eric Young should be given attribution

 * as the author of the parts of the library used.

 * This can be in the form of a textual message at program startup or

 * in documentation (online or textual) provided with the package.

 *

 * Redistribution and use in source and binary forms, with or without

 * modification, are permitted provided that the following conditions

 * are met:

 * 1. Redistributions of source code must retain the copyright

 *    notice, this list of conditions and the following disclaimer.

 * 2. Redistributions in binary form must reproduce the above copyright

 *    notice, this list of conditions and the following disclaimer in the

 *    documentation and/or other materials provided with the distribution.

 * 3. All advertising materials mentioning features or use of this software

 *    must display the following acknowledgement:

 *    "This product includes cryptographic software written by

 *     Eric Young (eay@cryptsoft.com)"

 *    The word 'cryptographic' can be left out if the rouines from the library

 *    being used are not cryptographic related :-).

 * 4. If you include any Windows specific code (or a derivative thereof) from

 *    the apps directory (application code) you must include an acknowledgement:

 *    "This product includes software written by Tim Hudson (tjh@cryptsoft.com)"

 *

 * THIS SOFTWARE IS PROVIDED BY ERIC YOUNG ``AS IS'' AND

 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE

 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE

 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE

 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL

 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS

 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)

 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT

 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY

 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF

 * SUCH DAMAGE.

 *

 * The licence and distribution terms for any publically available version or

 * derivative of this code cannot be changed.  i.e. this code cannot simply be

 * copied and put under another distribution licence

 * [including the GNU Public Licence.]

 */

#include <stdio.h>

#include <openssl/opensslconf.h>

#include <openssl/err.h>

#include "bn_lcl.h"

#define BN_BLINDING_COUNTER 32

struct bn_blinding_st {

  BIGNUM *A;

  BIGNUM *Ai;

  BIGNUM *e;

  BIGNUM *mod; /* just a reference */

#ifndef OPENSSL_NO_DEPRECATED

  unsigned long thread_id; /* added in OpenSSL 0.9.6j and 0.9.7b;

          * used only by crypto/rsa/rsa_eay.c, rsa_lib.c */

#endif

  CRYPTO_THREADID tid;

  int counter;

  unsigned long flags;

  BN_MONT_CTX *m_ctx;

  int (*bn_mod_exp)(BIGNUM *r, const BIGNUM *a, const BIGNUM *p,

      const BIGNUM *m, BN_CTX *ctx, BN_MONT_CTX *m_ctx);

};

BN_BLINDING *

BN_BLINDING_new(const BIGNUM *A, const BIGNUM *Ai, BIGNUM *mod)

{

  BN_BLINDING *ret = NULL;

  bn_check_top(mod);

  if ((ret = calloc(1, sizeof(BN_BLINDING))) == NULL) {

    BNerror(ERR_R_MALLOC_FAILURE);

    return (NULL);

  }

  if (A != NULL) {

    if ((ret->A = BN_dup(A))  == NULL)

      goto err;

  }

  if (Ai != NULL) {

    if ((ret->Ai = BN_dup(Ai)) == NULL)

      goto err;

  }

  /* save a copy of mod in the BN_BLINDING structure */

  if ((ret->mod = BN_dup(mod)) == NULL)

    goto err;

  if (BN_get_flags(mod, BN_FLG_CONSTTIME) != 0)

    BN_set_flags(ret->mod, BN_FLG_CONSTTIME);

  /* Set the counter to the special value -1

   * to indicate that this is never-used fresh blinding

   * that does not need updating before first use. */

  ret->counter = -1;

  CRYPTO_THREADID_current(&ret->tid);

  return (ret);

err:

  if (ret != NULL)

    BN_BLINDING_free(ret);

  return (NULL);

}

void

BN_BLINDING_free(BN_BLINDING *r)

{

  if (r == NULL)

    return;

  BN_clear_free(r->A);

  BN_clear_free(r->Ai);

  BN_clear_free(r->e);

  BN_clear_free(r->mod);

  free(r);

}

int

BN_BLINDING_update(BN_BLINDING *b, BN_CTX *ctx)

{

  int ret = 0;

  if ((b->A == NULL) || (b->Ai == NULL)) {

    BNerror(BN_R_NOT_INITIALIZED);

    goto err;

  }

  if (b->counter == -1)

    b->counter = 0;

  if (++b->counter == BN_BLINDING_COUNTER && b->e != NULL &&

      !(b->flags & BN_BLINDING_NO_RECREATE)) {

    /* re-create blinding parameters */

    if (!BN_BLINDING_create_param(b, NULL, NULL, ctx, NULL, NULL))

      goto err;

  } else if (!(b->flags & BN_BLINDING_NO_UPDATE)) {

    if (!BN_mod_mul(b->A, b->A, b->A, b->mod, ctx))

      goto err;

    if (!BN_mod_mul(b->Ai, b->Ai, b->Ai, b->mod, ctx))

      goto err;

  }

  ret = 1;

err:

  if (b->counter == BN_BLINDING_COUNTER)

    b->counter = 0;

  return (ret);

}

int

BN_BLINDING_convert(BIGNUM *n, BN_BLINDING *b, BN_CTX *ctx)

{

  return BN_BLINDING_convert_ex(n, NULL, b, ctx);

}

int

BN_BLINDING_convert_ex(BIGNUM *n, BIGNUM *r, BN_BLINDING *b, BN_CTX *ctx)

{

  int ret = 1;

  bn_check_top(n);

  if ((b->A == NULL) || (b->Ai == NULL)) {

    BNerror(BN_R_NOT_INITIALIZED);

    return (0);

  }

  if (b->counter == -1)

    /* Fresh blinding, doesn't need updating. */

    b->counter = 0;

  else if (!BN_BLINDING_update(b, ctx))

    return (0);

  if (r != NULL) {

    if (!BN_copy(r, b->Ai))

      ret = 0;

  }

  if (!BN_mod_mul(n, n,b->A, b->mod, ctx))

    ret = 0;

  return ret;

}

int

BN_BLINDING_invert(BIGNUM *n, BN_BLINDING *b, BN_CTX *ctx)

{

  return BN_BLINDING_invert_ex(n, NULL, b, ctx);

}

int

BN_BLINDING_invert_ex(BIGNUM *n, const BIGNUM *r, BN_BLINDING *b, BN_CTX *ctx)

{

  int ret;

  bn_check_top(n);

  if (r != NULL)

    ret = BN_mod_mul(n, n, r, b->mod, ctx);

  else {

    if (b->Ai == NULL) {

      BNerror(BN_R_NOT_INITIALIZED);

      return (0);

    }

    ret = BN_mod_mul(n, n, b->Ai, b->mod, ctx);

  }

  bn_check_top(n);

  return (ret);

}

#ifndef OPENSSL_NO_DEPRECATED

unsigned long

BN_BLINDING_get_thread_id(const BN_BLINDING *b)

{

  return b->thread_id;

}

void

BN_BLINDING_set_thread_id(BN_BLINDING *b, unsigned long n)

{

  b->thread_id = n;

}

#endif

CRYPTO_THREADID *

BN_BLINDING_thread_id(BN_BLINDING *b)

{

  return &b->tid;

}

unsigned long

BN_BLINDING_get_flags(const BN_BLINDING *b)

{

  return b->flags;

}

void

BN_BLINDING_set_flags(BN_BLINDING *b, unsigned long flags)

{

  b->flags = flags;

}

BN_BLINDING *

BN_BLINDING_create_param(BN_BLINDING *b, const BIGNUM *e, BIGNUM *m,

    BN_CTX *ctx, int (*bn_mod_exp)(BIGNUM *r, const BIGNUM *a, const BIGNUM *p,

    const BIGNUM *m, BN_CTX *ctx, BN_MONT_CTX *m_ctx), BN_MONT_CTX *m_ctx)

{

  int    retry_counter = 32;

  BN_BLINDING *ret = NULL;

  if (b == NULL)

    ret = BN_BLINDING_new(NULL, NULL, m);

  else

    ret = b;

  if (ret == NULL)

    goto err;

  if (ret->A  == NULL && (ret->A = BN_new()) == NULL)

    goto err;

  if (ret->Ai == NULL && (ret->Ai = BN_new()) == NULL)

    goto err;

  if (e != NULL) {

    BN_free(ret->e);

    ret->e = BN_dup(e);

  }

  if (ret->e == NULL)

    goto err;

  if (bn_mod_exp != NULL)

    ret->bn_mod_exp = bn_mod_exp;

  if (m_ctx != NULL)

    ret->m_ctx = m_ctx;

  do {

    if (!BN_rand_range(ret->A, ret->mod))

      goto err;

    if (BN_mod_inverse_ct(ret->Ai, ret->A, ret->mod, ctx) == NULL) {

      /* this should almost never happen for good RSA keys */

      unsigned long error = ERR_peek_last_error();

      if (ERR_GET_REASON(error) == BN_R_NO_INVERSE) {

        if (retry_counter-- == 0) {

          BNerror(BN_R_TOO_MANY_ITERATIONS);

          goto err;

        }

        ERR_clear_error();

      } else

        goto err;

    } else

      break;

  } while (1);

  if (ret->bn_mod_exp != NULL && ret->m_ctx != NULL) {

    if (!ret->bn_mod_exp(ret->A, ret->A, ret->e, ret->mod,

        ctx, ret->m_ctx))

      goto err;

  } else {

    if (!BN_mod_exp_ct(ret->A, ret->A, ret->e, ret->mod, ctx))

      goto err;

  }

  return ret;

err:

  if (b == NULL && ret != NULL) {

    BN_BLINDING_free(ret);

    ret = NULL;

  }

  return ret;

}