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e_gmp.c

/* crypto/engine/e_gmp.c */
/* Written by Geoff Thorpe (geoff@geoffthorpe.net) for the OpenSSL
 * project 2003.
 */
/* ====================================================================
 * Copyright (c) 1999-2001 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
 *    licensing@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).
 *
 */

/* This engine is not (currently) compiled in by default. Do enable it,
 * reconfigure OpenSSL with "enable-gmp -lgmp". The GMP libraries and
 * headers must reside in one of the paths searched by the compiler/linker,
 * otherwise paths must be specified - eg. try configuring with
 * "enable-gmp -I<includepath> -L<libpath> -lgmp". YMMV. */

/* As for what this does - it's a largely unoptimised implementation of an
 * ENGINE that uses the GMP library to perform RSA private key operations. To
 * obtain more information about what "unoptimised" means, see my original mail
 * on the subject (though ignore the build instructions which have since
 * changed);
 *
 *    http://www.mail-archive.com/openssl-dev@openssl.org/msg12227.html
 *
 * On my athlon system at least, it appears the builtin OpenSSL code is now
 * slightly faster, which is to say that the RSA-related MPI performance
 * between OpenSSL's BIGNUM and GMP's mpz implementations is probably pretty
 * balanced for this chip, and so the performance degradation in this ENGINE by
 * having to convert to/from GMP formats (and not being able to cache
 * montgomery forms) is probably the difference. However, if some unconfirmed
 * reports from users is anything to go by, the situation on some other
 * chipsets might be a good deal more favourable to the GMP version (eg. PPC).
 * Feedback welcome. */

#include <stdio.h>
#include <string.h>
#include <openssl/crypto.h>
#include <openssl/buffer.h>
#include <openssl/engine.h>
#include <openssl/rsa.h>
#include <openssl/bn.h>

#ifndef OPENSSL_NO_HW
#ifndef OPENSSL_NO_GMP

#include <gmp.h>

#define E_GMP_LIB_NAME "gmp engine"
#include "e_gmp_err.c"

static int e_gmp_destroy(ENGINE *e);
static int e_gmp_init(ENGINE *e);
static int e_gmp_finish(ENGINE *e);
static int e_gmp_ctrl(ENGINE *e, int cmd, long i, void *p, void (*f)(void)); 

#ifndef OPENSSL_NO_RSA
/* RSA stuff */
static int e_gmp_rsa_mod_exp(BIGNUM *r, const BIGNUM *I, RSA *rsa, BN_CTX *ctx);
static int e_gmp_rsa_finish(RSA *r);
#endif

/* The definitions for control commands specific to this engine */
/* #define E_GMP_CMD_SO_PATH        ENGINE_CMD_BASE */
static const ENGINE_CMD_DEFN e_gmp_cmd_defns[] = {
#if 0
      {E_GMP_CMD_SO_PATH,
            "SO_PATH",
            "Specifies the path to the 'e_gmp' shared library",
            ENGINE_CMD_FLAG_STRING},
#endif
      {0, NULL, NULL, 0}
      };

#ifndef OPENSSL_NO_RSA
/* Our internal RSA_METHOD that we provide pointers to */
static RSA_METHOD e_gmp_rsa =
      {
      "GMP RSA method",
      NULL,
      NULL,
      NULL,
      NULL,
      e_gmp_rsa_mod_exp,
      NULL,
      NULL,
      e_gmp_rsa_finish,
      /* These flags initialise montgomery crud that GMP ignores, however it
       * makes sure the public key ops (which are done in openssl) don't seem
       * *slower* than usual :-) */
      RSA_FLAG_CACHE_PUBLIC|RSA_FLAG_CACHE_PRIVATE,
      NULL,
      NULL,
      NULL
      };
#endif

/* Constants used when creating the ENGINE */
static const char *engine_e_gmp_id = "gmp";
static const char *engine_e_gmp_name = "GMP engine support";

/* This internal function is used by ENGINE_gmp() and possibly by the
 * "dynamic" ENGINE support too */
static int bind_helper(ENGINE *e)
      {
#ifndef OPENSSL_NO_RSA
      const RSA_METHOD *meth1;
#endif
      if(!ENGINE_set_id(e, engine_e_gmp_id) ||
                  !ENGINE_set_name(e, engine_e_gmp_name) ||
#ifndef OPENSSL_NO_RSA
                  !ENGINE_set_RSA(e, &e_gmp_rsa) ||
#endif
                  !ENGINE_set_destroy_function(e, e_gmp_destroy) ||
                  !ENGINE_set_init_function(e, e_gmp_init) ||
                  !ENGINE_set_finish_function(e, e_gmp_finish) ||
                  !ENGINE_set_ctrl_function(e, e_gmp_ctrl) ||
                  !ENGINE_set_cmd_defns(e, e_gmp_cmd_defns))
            return 0;

#ifndef OPENSSL_NO_RSA
      meth1 = RSA_PKCS1_SSLeay();
      e_gmp_rsa.rsa_pub_enc = meth1->rsa_pub_enc;
      e_gmp_rsa.rsa_pub_dec = meth1->rsa_pub_dec;
      e_gmp_rsa.rsa_priv_enc = meth1->rsa_priv_enc;
      e_gmp_rsa.rsa_priv_dec = meth1->rsa_priv_dec;
      e_gmp_rsa.bn_mod_exp = meth1->bn_mod_exp;
#endif

      /* Ensure the e_gmp error handling is set up */
      ERR_load_GMP_strings();
      return 1;
      }

static ENGINE *engine_gmp(void)
      {
      ENGINE *ret = ENGINE_new();
      if(!ret)
            return NULL;
      if(!bind_helper(ret))
            {
            ENGINE_free(ret);
            return NULL;
            }
      return ret;
      }

void ENGINE_load_gmp(void)
      {
      /* Copied from eng_[openssl|dyn].c */
      ENGINE *toadd = engine_gmp();
      if(!toadd) return;
      ENGINE_add(toadd);
      ENGINE_free(toadd);
      ERR_clear_error();
      }

#ifndef OPENSSL_NO_RSA
/* Used to attach our own key-data to an RSA structure */
static int hndidx_rsa = -1;
#endif

static int e_gmp_destroy(ENGINE *e)
      {
      ERR_unload_GMP_strings();
      return 1;
      }

/* (de)initialisation functions. */
static int e_gmp_init(ENGINE *e)
      {
#ifndef OPENSSL_NO_RSA
      if (hndidx_rsa == -1)
            hndidx_rsa = RSA_get_ex_new_index(0,
                  "GMP-based RSA key handle",
                  NULL, NULL, NULL);
#endif
      if (hndidx_rsa == -1)
            return 0;
      return 1;
      }

static int e_gmp_finish(ENGINE *e)
      {
      return 1;
      }

static int e_gmp_ctrl(ENGINE *e, int cmd, long i, void *p, void (*f)(void))
      {
      int to_return = 1;

      switch(cmd)
            {
#if 0
      case E_GMP_CMD_SO_PATH:
            /* ... */
#endif
      /* The command isn't understood by this engine */
      default:
            GMPerr(GMP_F_E_GMP_CTRL,
                  GMP_R_CTRL_COMMAND_NOT_IMPLEMENTED);
            to_return = 0;
            break;
            }

      return to_return;
      }


/* Most often limb sizes will be the same. If not, we use hex conversion
 * which is neat, but extremely inefficient. */
static int bn2gmp(const BIGNUM *bn, mpz_t g)
      {
      bn_check_top(bn);
      if(((sizeof(bn->d[0]) * 8) == GMP_NUMB_BITS) &&
                  (BN_BITS2 == GMP_NUMB_BITS)) 
            {
            /* The common case */
            if(!_mpz_realloc (g, bn->top))
                  return 0;
            memcpy(&g->_mp_d[0], &bn->d[0], bn->top * sizeof(bn->d[0]));
            g->_mp_size = bn->top;
            if(bn->neg)
                  g->_mp_size = -g->_mp_size;
            return 1;
            }
      else
            {
            int toret;
            char *tmpchar = BN_bn2hex(bn);
            if(!tmpchar) return 0;
            toret = (mpz_set_str(g, tmpchar, 16) == 0 ? 1 : 0);
            OPENSSL_free(tmpchar);
            return toret;
            }
      }

static int gmp2bn(mpz_t g, BIGNUM *bn)
      {
      if(((sizeof(bn->d[0]) * 8) == GMP_NUMB_BITS) &&
                  (BN_BITS2 == GMP_NUMB_BITS))
            {
            /* The common case */
            int s = (g->_mp_size >= 0) ? g->_mp_size : -g->_mp_size;
            BN_zero(bn);
            if(bn_expand2 (bn, s) == NULL)
                  return 0;
            bn->top = s;
            memcpy(&bn->d[0], &g->_mp_d[0], s * sizeof(bn->d[0]));
            bn_correct_top(bn);
            bn->neg = g->_mp_size >= 0 ? 0 : 1;
            return 1;
            }
      else
            {
            int toret;
            char *tmpchar = OPENSSL_malloc(mpz_sizeinbase(g, 16) + 10);
            if(!tmpchar) return 0;
            mpz_get_str(tmpchar, 16, g);
            toret = BN_hex2bn(&bn, tmpchar);
            OPENSSL_free(tmpchar);
            return toret;
            }
      }

#ifndef OPENSSL_NO_RSA 
00314 typedef struct st_e_gmp_rsa_ctx
      {
      int public_only;
      mpz_t n;
      mpz_t d;
      mpz_t e;
      mpz_t p;
      mpz_t q;
      mpz_t dmp1;
      mpz_t dmq1;
      mpz_t iqmp;
      mpz_t r0, r1, I0, m1;
      } E_GMP_RSA_CTX;

static E_GMP_RSA_CTX *e_gmp_get_rsa(RSA *rsa)
      {
      E_GMP_RSA_CTX *hptr = RSA_get_ex_data(rsa, hndidx_rsa);
      if(hptr) return hptr;
      hptr = OPENSSL_malloc(sizeof(E_GMP_RSA_CTX));
      if(!hptr) return NULL;
      /* These inits could probably be replaced by more intelligent
       * mpz_init2() versions, to reduce malloc-thrashing. */
      mpz_init(hptr->n);
      mpz_init(hptr->d);
      mpz_init(hptr->e);
      mpz_init(hptr->p);
      mpz_init(hptr->q);
      mpz_init(hptr->dmp1);
      mpz_init(hptr->dmq1);
      mpz_init(hptr->iqmp);
      mpz_init(hptr->r0);
      mpz_init(hptr->r1);
      mpz_init(hptr->I0);
      mpz_init(hptr->m1);
      if(!bn2gmp(rsa->n, hptr->n) || !bn2gmp(rsa->e, hptr->e))
            goto err;
      if(!rsa->p || !rsa->q || !rsa->d || !rsa->dmp1 || !rsa->dmq1 || !rsa->iqmp)
            {
            hptr->public_only = 1;
            return hptr;
            }
      if(!bn2gmp(rsa->d, hptr->d) || !bn2gmp(rsa->p, hptr->p) ||
                  !bn2gmp(rsa->q, hptr->q) || !bn2gmp(rsa->dmp1, hptr->dmp1) ||
                  !bn2gmp(rsa->dmq1, hptr->dmq1) || !bn2gmp(rsa->iqmp, hptr->iqmp))
            goto err;
      hptr->public_only = 0;
      RSA_set_ex_data(rsa, hndidx_rsa, hptr);
      return hptr;
err:
      mpz_clear(hptr->n);
      mpz_clear(hptr->d);
      mpz_clear(hptr->e);
      mpz_clear(hptr->p);
      mpz_clear(hptr->q);
      mpz_clear(hptr->dmp1);
      mpz_clear(hptr->dmq1);
      mpz_clear(hptr->iqmp);
      mpz_clear(hptr->r0);
      mpz_clear(hptr->r1);
      mpz_clear(hptr->I0);
      mpz_clear(hptr->m1);
      OPENSSL_free(hptr);
      return NULL;
      }

static int e_gmp_rsa_finish(RSA *rsa)
      {
      E_GMP_RSA_CTX *hptr = RSA_get_ex_data(rsa, hndidx_rsa);
      if(!hptr) return 0;
      mpz_clear(hptr->n);
      mpz_clear(hptr->d);
      mpz_clear(hptr->e);
      mpz_clear(hptr->p);
      mpz_clear(hptr->q);
      mpz_clear(hptr->dmp1);
      mpz_clear(hptr->dmq1);
      mpz_clear(hptr->iqmp);
      mpz_clear(hptr->r0);
      mpz_clear(hptr->r1);
      mpz_clear(hptr->I0);
      mpz_clear(hptr->m1);
      OPENSSL_free(hptr);
      RSA_set_ex_data(rsa, hndidx_rsa, NULL);
      return 1;
      }

static int e_gmp_rsa_mod_exp(BIGNUM *r, const BIGNUM *I, RSA *rsa, BN_CTX *ctx)
      {
      E_GMP_RSA_CTX *hptr;
      int to_return = 0;

      hptr = e_gmp_get_rsa(rsa);
      if(!hptr)
            {
            GMPerr(GMP_F_E_GMP_RSA_MOD_EXP,
                        GMP_R_KEY_CONTEXT_ERROR);
            return 0;
            }
      if(hptr->public_only)
            {
            GMPerr(GMP_F_E_GMP_RSA_MOD_EXP,
                        GMP_R_MISSING_KEY_COMPONENTS);
            return 0;
            }

      /* ugh!!! */
      if(!bn2gmp(I, hptr->I0))
            return 0;

      /* This is basically the CRT logic in crypto/rsa/rsa_eay.c reworded into
       * GMP-speak. It may be that GMP's API facilitates cleaner formulations
       * of this stuff, eg. better handling of negatives, or functions that
       * combine operations. */

      mpz_mod(hptr->r1, hptr->I0, hptr->q);
      mpz_powm(hptr->m1, hptr->r1, hptr->dmq1, hptr->q);

      mpz_mod(hptr->r1, hptr->I0, hptr->p);
      mpz_powm(hptr->r0, hptr->r1, hptr->dmp1, hptr->p);

      mpz_sub(hptr->r0, hptr->r0, hptr->m1);

      if(mpz_sgn(hptr->r0) < 0)
            mpz_add(hptr->r0, hptr->r0, hptr->p);
      mpz_mul(hptr->r1, hptr->r0, hptr->iqmp);
      mpz_mod(hptr->r0, hptr->r1, hptr->p);

      if(mpz_sgn(hptr->r0) < 0)
            mpz_add(hptr->r0, hptr->r0, hptr->p);
      mpz_mul(hptr->r1, hptr->r0, hptr->q);
      mpz_add(hptr->r0, hptr->r1, hptr->m1);

      /* ugh!!! */
      if(gmp2bn(hptr->r0, r))
            to_return = 1;

      return 1;
      }
#endif

#endif /* !OPENSSL_NO_GMP */

/* This stuff is needed if this ENGINE is being compiled into a self-contained
 * shared-library. */      
#ifndef OPENSSL_NO_DYNAMIC_ENGINE
IMPLEMENT_DYNAMIC_CHECK_FN()
#ifndef OPENSSL_NO_GMP
static int bind_fn(ENGINE *e, const char *id)
      {
      if(id && (strcmp(id, engine_e_gmp_id) != 0))
            return 0;
      if(!bind_helper(e))
            return 0;
      return 1;
      }       
IMPLEMENT_DYNAMIC_BIND_FN(bind_fn)
#else
OPENSSL_EXPORT
int bind_engine(ENGINE *e, const char *id, const dynamic_fns *fns) { return 0; }
#endif
#endif /* OPENSSL_NO_DYNAMIC_ENGINE */

#endif /* !OPENSSL_NO_HW */

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