/* $OpenBSD: rsa_crpt.c,v 1.18 2017/01/29 17:49:23 beck Exp $ */
/* 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/bn.h>
#include <openssl/crypto.h>
#include <openssl/err.h>
#include <openssl/lhash.h>
#include <openssl/rsa.h>

#include "bn_lcl.h"

#ifndef OPENSSL_NO_ENGINE
#include <openssl/engine.h>
#endif

int
RSA_size(const RSA *r)
{
	return BN_num_bytes(r->n);
}

int
RSA_public_encrypt(int flen, const unsigned char *from, unsigned char *to,
    RSA *rsa, int padding)
{
	return rsa->meth->rsa_pub_enc(flen, from, to, rsa, padding);
}

int
RSA_private_encrypt(int flen, const unsigned char *from, unsigned char *to,
    RSA *rsa, int padding)
{
	return rsa->meth->rsa_priv_enc(flen, from, to, rsa, padding);
}

int
RSA_private_decrypt(int flen, const unsigned char *from, unsigned char *to,
    RSA *rsa, int padding)
{
	return rsa->meth->rsa_priv_dec(flen, from, to, rsa, padding);
}

int
RSA_public_decrypt(int flen, const unsigned char *from, unsigned char *to,
    RSA *rsa, int padding)
{
	return rsa->meth->rsa_pub_dec(flen, from, to, rsa, padding);
}

int
RSA_flags(const RSA *r)
{
	return r == NULL ? 0 : r->meth->flags;
}

void
RSA_blinding_off(RSA *rsa)
{
	BN_BLINDING_free(rsa->blinding);
	rsa->blinding = NULL;
	rsa->flags |= RSA_FLAG_NO_BLINDING;
}

int
RSA_blinding_on(RSA *rsa, BN_CTX *ctx)
{
	int ret = 0;

	if (rsa->blinding != NULL)
		RSA_blinding_off(rsa);

	rsa->blinding = RSA_setup_blinding(rsa, ctx);
	if (rsa->blinding == NULL)
		goto err;

	rsa->flags &= ~RSA_FLAG_NO_BLINDING;
	ret = 1;
err:
	return (ret);
}

static BIGNUM *
rsa_get_public_exp(const BIGNUM *d, const BIGNUM *p, const BIGNUM *q,
    BN_CTX *ctx)
{
	BIGNUM *ret = NULL, *r0, *r1, *r2;

	if (d == NULL || p == NULL || q == NULL)
		return NULL;

	BN_CTX_start(ctx);
	if ((r0 = BN_CTX_get(ctx)) == NULL)
		goto err;
	if ((r1 = BN_CTX_get(ctx)) == NULL)
		goto err;
	if ((r2 = BN_CTX_get(ctx)) == NULL)
		goto err;

	if (!BN_sub(r1, p, BN_value_one()))
		goto err;
	if (!BN_sub(r2, q, BN_value_one()))
		goto err;
	if (!BN_mul(r0, r1, r2, ctx))
		goto err;

	ret = BN_mod_inverse_ct(NULL, d, r0, ctx);
err:
	BN_CTX_end(ctx);
	return ret;
}

BN_BLINDING *
RSA_setup_blinding(RSA *rsa, BN_CTX *in_ctx)
{
	BIGNUM *e;
	BIGNUM n;
	BN_CTX *ctx;
	BN_BLINDING *ret = NULL;

	if (in_ctx == NULL) {
		if ((ctx = BN_CTX_new()) == NULL)
			return 0;
	} else
		ctx = in_ctx;

	BN_CTX_start(ctx);

	if (rsa->e == NULL) {
		e = rsa_get_public_exp(rsa->d, rsa->p, rsa->q, ctx);
		if (e == NULL) {
			RSAerror(RSA_R_NO_PUBLIC_EXPONENT);
			goto err;
		}
	} else
		e = rsa->e;

	BN_init(&n);
	BN_with_flags(&n, rsa->n, BN_FLG_CONSTTIME);

	ret = BN_BLINDING_create_param(NULL, e, &n, ctx, rsa->meth->bn_mod_exp,
	    rsa->_method_mod_n);

	if (ret == NULL) {
		RSAerror(ERR_R_BN_LIB);
		goto err;
	}
	CRYPTO_THREADID_current(BN_BLINDING_thread_id(ret));
err:
	BN_CTX_end(ctx);
	if (in_ctx == NULL)
		BN_CTX_free(ctx);
	if (rsa->e == NULL)
		BN_free(e);

	return ret;
}