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/* $OpenBSD: rsa.c,v 1.29 2006/11/06 21:25:28 markus Exp $ */

/*

 * Author: Tatu Ylonen <ylo@cs.hut.fi>

 * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland

 *                    All rights reserved

 *

 * As far as I am concerned, the code I have written for this software

 * can be used freely for any purpose.  Any derived versions of this

 * software must be clearly marked as such, and if the derived work is

 * incompatible with the protocol description in the RFC file, it must be

 * called by a name other than "ssh" or "Secure Shell".

 *

 *

 * Copyright (c) 1999 Niels Provos.  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.

 *

 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``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 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.

 *

 *

 * Description of the RSA algorithm can be found e.g. from the following

 * sources:

 *

 *   Bruce Schneier: Applied Cryptography.  John Wiley & Sons, 1994.

 *

 *   Jennifer Seberry and Josed Pieprzyk: Cryptography: An Introduction to

 *   Computer Security.  Prentice-Hall, 1989.

 *

 *   Man Young Rhee: Cryptography and Secure Data Communications.  McGraw-Hill,

 *   1994.

 *

 *   R. Rivest, A. Shamir, and L. M. Adleman: Cryptographic Communications

 *   System and Method.  US Patent 4,405,829, 1983.

 *

 *   Hans Riesel: Prime Numbers and Computer Methods for Factorization.

 *   Birkhauser, 1994.

 *

 *   The RSA Frequently Asked Questions document by RSA Data Security,

 *   Inc., 1995.

 *

 *   RSA in 3 lines of perl by Adam Back <aba@atlax.ex.ac.uk>, 1995, as

 * included below:

 *

 *     [gone - had to be deleted - what a pity]

 */

#include "includes.h"

#include <sys/types.h>

#include <stdarg.h>

#include <string.h>

#include "xmalloc.h"

#include "rsa.h"

#include "log.h"

void

rsa_public_encrypt(BIGNUM *out, BIGNUM *in, RSA *key)

{

	u_char *inbuf, *outbuf;

	int len, ilen, olen;

	if (BN_num_bits(key->e) < 2 || !BN_is_odd(key->e))

		fatal("rsa_public_encrypt() exponent too small or not odd");

	olen = BN_num_bytes(key->n);

	outbuf = xmalloc(olen);

	ilen = BN_num_bytes(in);

	inbuf = xmalloc(ilen);

	BN_bn2bin(in, inbuf);

	if ((len = RSA_public_encrypt(ilen, inbuf, outbuf, key,

	    RSA_PKCS1_PADDING)) <= 0)

		fatal("rsa_public_encrypt() failed");

	if (BN_bin2bn(outbuf, len, out) == NULL)

		fatal("rsa_public_encrypt: BN_bin2bn failed");

	memset(outbuf, 0, olen);

	memset(inbuf, 0, ilen);

	xfree(outbuf);

	xfree(inbuf);

}

int

rsa_private_decrypt(BIGNUM *out, BIGNUM *in, RSA *key)

{

	u_char *inbuf, *outbuf;

	int len, ilen, olen;

	olen = BN_num_bytes(key->n);

	outbuf = xmalloc(olen);

	ilen = BN_num_bytes(in);

	inbuf = xmalloc(ilen);

	BN_bn2bin(in, inbuf);

	if ((len = RSA_private_decrypt(ilen, inbuf, outbuf, key,

	    RSA_PKCS1_PADDING)) <= 0) {

		error("rsa_private_decrypt() failed");

	} else {

		if (BN_bin2bn(outbuf, len, out) == NULL)

			fatal("rsa_private_decrypt: BN_bin2bn failed");

	}

	memset(outbuf, 0, olen);

	memset(inbuf, 0, ilen);

	xfree(outbuf);

	xfree(inbuf);

	return len;

}

/* calculate p-1 and q-1 */

void

rsa_generate_additional_parameters(RSA *rsa)

{

	BIGNUM *aux;

	BN_CTX *ctx;

	if ((aux = BN_new()) == NULL)

		fatal("rsa_generate_additional_parameters: BN_new failed");

	if ((ctx = BN_CTX_new()) == NULL)

		fatal("rsa_generate_additional_parameters: BN_CTX_new failed");

	if ((BN_sub(aux, rsa->q, BN_value_one()) == 0) ||

	    (BN_mod(rsa->dmq1, rsa->d, aux, ctx) == 0) ||

	    (BN_sub(aux, rsa->p, BN_value_one()) == 0) ||

	    (BN_mod(rsa->dmp1, rsa->d, aux, ctx) == 0))

		fatal("rsa_generate_additional_parameters: BN_sub/mod failed");

	BN_clear_free(aux);

	BN_CTX_free(ctx);

}