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/* $OpenBSD: cipher-3des1.c,v 1.10 2014/02/02 03:44:31 djm Exp $ */
/*
* 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 <sys/types.h>
#include <openssl/evp.h>
#include <string.h>
#include "xmalloc.h"
#include "log.h"
/*
* 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 = xcalloc(1, 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);
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) {
explicit_bzero(c, sizeof(*c));
free(c);
EVP_CIPHER_CTX_set_app_data(ctx, NULL);
return (0);
}
return (1);
}
static int
ssh1_3des_cbc(EVP_CIPHER_CTX *ctx, u_char *dest, const u_char *src, size_t len)
{
struct ssh1_3des_ctx *c;
if ((c = EVP_CIPHER_CTX_get_app_data(ctx)) == NULL) {
error("ssh1_3des_cbc: no context");
return (0);
}
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);
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);
explicit_bzero(c, sizeof(*c));
free(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;
ssh1_3des.flags = EVP_CIPH_CBC_MODE | EVP_CIPH_VARIABLE_LENGTH;
return (&ssh1_3des);
}
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