/* 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>
#ifndef OPENSSL_NO_RSA
#include <openssl/rsa.h>
#endif
#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 
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);
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 */
