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/*

 * Copyright (c) 2003 Markus Friedl.  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.

 */

#include "includes.h"

RCSID("$OpenBSD: cipher-3des1.c,v 1.2 2003/12/22 20:29:55 markus Exp $");

#include <openssl/evp.h>

#include "xmalloc.h"

#include "log.h"

#if OPENSSL_VERSION_NUMBER < 0x00906000L

#define SSH_OLD_EVP

#endif

/*

 * This is used by SSH1:

 *

 * What kind of triple DES are these 2 routines?

 *

 * Why is there a redundant initialization vector?

 *

 * If only iv3 was used, then, this would till effect have been

 * outer-cbc. However, there is also a private iv1 == iv2 which

 * perhaps makes differential analysis easier. On the other hand, the

 * private iv1 probably makes the CRC-32 attack ineffective. This is a

 * result of that there is no longer any known iv1 to use when

 * choosing the X block.

 */

struct ssh1_3des_ctx

{

	EVP_CIPHER_CTX	k1, k2, k3;

};

const EVP_CIPHER * evp_ssh1_3des(void);

void ssh1_3des_iv(EVP_CIPHER_CTX *, int, u_char *, int);

static int

ssh1_3des_init(EVP_CIPHER_CTX *ctx, const u_char *key, const u_char *iv,

    int enc)

{

	struct ssh1_3des_ctx *c;

	u_char *k1, *k2, *k3;

	if ((c = EVP_CIPHER_CTX_get_app_data(ctx)) == NULL) {

		c = xmalloc(sizeof(*c));

		EVP_CIPHER_CTX_set_app_data(ctx, c);

	}

	if (key == NULL)

		return (1);

	if (enc == -1)

		enc = ctx->encrypt;

	k1 = k2 = k3 = (u_char *) key;

	k2 += 8;

	if (EVP_CIPHER_CTX_key_length(ctx) >= 16+8) {

		if (enc)

			k3 += 16;

		else

			k1 += 16;

	}

	EVP_CIPHER_CTX_init(&c->k1);

	EVP_CIPHER_CTX_init(&c->k2);

	EVP_CIPHER_CTX_init(&c->k3);

#ifdef SSH_OLD_EVP

	EVP_CipherInit(&c->k1, EVP_des_cbc(), k1, NULL, enc);

	EVP_CipherInit(&c->k2, EVP_des_cbc(), k2, NULL, !enc);

	EVP_CipherInit(&c->k3, EVP_des_cbc(), k3, NULL, enc);

#else

	if (EVP_CipherInit(&c->k1, EVP_des_cbc(), k1, NULL, enc) == 0 ||

	    EVP_CipherInit(&c->k2, EVP_des_cbc(), k2, NULL, !enc) == 0 ||

	    EVP_CipherInit(&c->k3, EVP_des_cbc(), k3, NULL, enc) == 0) {

		memset(c, 0, sizeof(*c));

		xfree(c);

		EVP_CIPHER_CTX_set_app_data(ctx, NULL);

		return (0);

	}

#endif

	return (1);

}

static int

ssh1_3des_cbc(EVP_CIPHER_CTX *ctx, u_char *dest, const u_char *src, u_int len)

{

	struct ssh1_3des_ctx *c;

	if ((c = EVP_CIPHER_CTX_get_app_data(ctx)) == NULL) {

		error("ssh1_3des_cbc: no context");

		return (0);

	}

#ifdef SSH_OLD_EVP

	EVP_Cipher(&c->k1, dest, (u_char *)src, len);

	EVP_Cipher(&c->k2, dest, dest, len);

	EVP_Cipher(&c->k3, dest, dest, len);

#else

	if (EVP_Cipher(&c->k1, dest, (u_char *)src, len) == 0 ||

	    EVP_Cipher(&c->k2, dest, dest, len) == 0 ||

	    EVP_Cipher(&c->k3, dest, dest, len) == 0)

		return (0);

#endif

	return (1);

}

static int

ssh1_3des_cleanup(EVP_CIPHER_CTX *ctx)

{

	struct ssh1_3des_ctx *c;

	if ((c = EVP_CIPHER_CTX_get_app_data(ctx)) != NULL) {

		EVP_CIPHER_CTX_cleanup(&c->k1);

		EVP_CIPHER_CTX_cleanup(&c->k2);

		EVP_CIPHER_CTX_cleanup(&c->k3);

		memset(c, 0, sizeof(*c));

		xfree(c);

		EVP_CIPHER_CTX_set_app_data(ctx, NULL);

	}

	return (1);

}

void

ssh1_3des_iv(EVP_CIPHER_CTX *evp, int doset, u_char *iv, int len)

{

	struct ssh1_3des_ctx *c;

	if (len != 24)

		fatal("%s: bad 3des iv length: %d", __func__, len);

	if ((c = EVP_CIPHER_CTX_get_app_data(evp)) == NULL)

		fatal("%s: no 3des context", __func__);

	if (doset) {

		debug3("%s: Installed 3DES IV", __func__);

		memcpy(c->k1.iv, iv, 8);

		memcpy(c->k2.iv, iv + 8, 8);

		memcpy(c->k3.iv, iv + 16, 8);

	} else {

		debug3("%s: Copying 3DES IV", __func__);

		memcpy(iv, c->k1.iv, 8);

		memcpy(iv + 8, c->k2.iv, 8);

		memcpy(iv + 16, c->k3.iv, 8);

	}

}

const EVP_CIPHER *

evp_ssh1_3des(void)

{

	static EVP_CIPHER ssh1_3des;

	memset(&ssh1_3des, 0, sizeof(EVP_CIPHER));

	ssh1_3des.nid = NID_undef;

	ssh1_3des.block_size = 8;

	ssh1_3des.iv_len = 0;

	ssh1_3des.key_len = 16;

	ssh1_3des.init = ssh1_3des_init;

	ssh1_3des.cleanup = ssh1_3des_cleanup;

	ssh1_3des.do_cipher = ssh1_3des_cbc;

#ifndef SSH_OLD_EVP

	ssh1_3des.flags = EVP_CIPH_CBC_MODE | EVP_CIPH_VARIABLE_LENGTH;

#endif

	return (&ssh1_3des);

}