496 lines
13 KiB
C
496 lines
13 KiB
C
/* $NetBSD: cipher.c,v 1.1.1.1 2000/09/28 22:09:53 thorpej 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.
|
|
* Copyright (c) 1999,2000 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.
|
|
*/
|
|
|
|
/* from OpenBSD: cipher.c,v 1.31 2000/09/12 00:38:32 deraadt Exp */
|
|
|
|
#include <sys/cdefs.h>
|
|
#ifndef lint
|
|
__RCSID("$NetBSD: cipher.c,v 1.1.1.1 2000/09/28 22:09:53 thorpej Exp $");
|
|
#endif
|
|
|
|
#include "includes.h"
|
|
|
|
#include "ssh.h"
|
|
#include "cipher.h"
|
|
#include "xmalloc.h"
|
|
|
|
#include <openssl/md5.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.
|
|
*/
|
|
static void
|
|
SSH_3CBC_ENCRYPT(des_key_schedule ks1,
|
|
des_key_schedule ks2, des_cblock * iv2,
|
|
des_key_schedule ks3, des_cblock * iv3,
|
|
unsigned char *dest, unsigned char *src,
|
|
unsigned int len)
|
|
{
|
|
des_cblock iv1;
|
|
|
|
memcpy(&iv1, iv2, 8);
|
|
|
|
des_cbc_encrypt(src, dest, len, ks1, &iv1, DES_ENCRYPT);
|
|
memcpy(&iv1, dest + len - 8, 8);
|
|
|
|
des_cbc_encrypt(dest, dest, len, ks2, iv2, DES_DECRYPT);
|
|
memcpy(iv2, &iv1, 8); /* Note how iv1 == iv2 on entry and exit. */
|
|
|
|
des_cbc_encrypt(dest, dest, len, ks3, iv3, DES_ENCRYPT);
|
|
memcpy(iv3, dest + len - 8, 8);
|
|
}
|
|
|
|
static void
|
|
SSH_3CBC_DECRYPT(des_key_schedule ks1,
|
|
des_key_schedule ks2, des_cblock * iv2,
|
|
des_key_schedule ks3, des_cblock * iv3,
|
|
unsigned char *dest, unsigned char *src,
|
|
unsigned int len)
|
|
{
|
|
des_cblock iv1;
|
|
|
|
memcpy(&iv1, iv2, 8);
|
|
|
|
des_cbc_encrypt(src, dest, len, ks3, iv3, DES_DECRYPT);
|
|
memcpy(iv3, src + len - 8, 8);
|
|
|
|
des_cbc_encrypt(dest, dest, len, ks2, iv2, DES_ENCRYPT);
|
|
memcpy(iv2, dest + len - 8, 8);
|
|
|
|
des_cbc_encrypt(dest, dest, len, ks1, &iv1, DES_DECRYPT);
|
|
/* memcpy(&iv1, iv2, 8); */
|
|
/* Note how iv1 == iv2 on entry and exit. */
|
|
}
|
|
|
|
/*
|
|
* SSH1 uses a variation on Blowfish, all bytes must be swapped before
|
|
* and after encryption/decryption. Thus the swap_bytes stuff (yuk).
|
|
*/
|
|
static void
|
|
swap_bytes(const unsigned char *src, unsigned char *dst_, int n)
|
|
{
|
|
/* dst must be properly aligned. */
|
|
u_int32_t *dst = (u_int32_t *) dst_;
|
|
union {
|
|
u_int32_t i;
|
|
char c[4];
|
|
} t;
|
|
|
|
/* Process 8 bytes every lap. */
|
|
for (n = n / 8; n > 0; n--) {
|
|
t.c[3] = *src++;
|
|
t.c[2] = *src++;
|
|
t.c[1] = *src++;
|
|
t.c[0] = *src++;
|
|
*dst++ = t.i;
|
|
|
|
t.c[3] = *src++;
|
|
t.c[2] = *src++;
|
|
t.c[1] = *src++;
|
|
t.c[0] = *src++;
|
|
*dst++ = t.i;
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Names of all encryption algorithms.
|
|
* These must match the numbers defined in cipher.h.
|
|
*/
|
|
static char *cipher_names[] =
|
|
{
|
|
"none",
|
|
"idea",
|
|
"des",
|
|
"3des",
|
|
"tss",
|
|
"rc4", /* Alleged RC4 */
|
|
"blowfish",
|
|
"reserved",
|
|
"blowfish-cbc",
|
|
"3des-cbc",
|
|
"arcfour",
|
|
"cast128-cbc"
|
|
};
|
|
|
|
/*
|
|
* Returns a bit mask indicating which ciphers are supported by this
|
|
* implementation. The bit mask has the corresponding bit set of each
|
|
* supported cipher.
|
|
*/
|
|
|
|
unsigned int
|
|
cipher_mask1()
|
|
{
|
|
unsigned int mask = 0;
|
|
mask |= 1 << SSH_CIPHER_3DES; /* Mandatory */
|
|
mask |= 1 << SSH_CIPHER_BLOWFISH;
|
|
return mask;
|
|
}
|
|
unsigned int
|
|
cipher_mask2()
|
|
{
|
|
unsigned int mask = 0;
|
|
mask |= 1 << SSH_CIPHER_BLOWFISH_CBC;
|
|
mask |= 1 << SSH_CIPHER_3DES_CBC;
|
|
mask |= 1 << SSH_CIPHER_ARCFOUR;
|
|
mask |= 1 << SSH_CIPHER_CAST128_CBC;
|
|
return mask;
|
|
}
|
|
unsigned int
|
|
cipher_mask()
|
|
{
|
|
return cipher_mask1() | cipher_mask2();
|
|
}
|
|
|
|
/* Returns the name of the cipher. */
|
|
|
|
const char *
|
|
cipher_name(int cipher)
|
|
{
|
|
if (cipher < 0 || cipher >= sizeof(cipher_names) / sizeof(cipher_names[0]) ||
|
|
cipher_names[cipher] == NULL)
|
|
fatal("cipher_name: bad cipher name: %d", cipher);
|
|
return cipher_names[cipher];
|
|
}
|
|
|
|
/* Returns 1 if the name of the ciphers are valid. */
|
|
|
|
#define CIPHER_SEP ","
|
|
int
|
|
ciphers_valid(const char *names)
|
|
{
|
|
char *ciphers, *cp;
|
|
char *p;
|
|
int i;
|
|
|
|
if (names == NULL || strcmp(names, "") == 0)
|
|
return 0;
|
|
ciphers = cp = xstrdup(names);
|
|
for ((p = strsep(&cp, CIPHER_SEP)); p && *p != '\0';
|
|
(p = strsep(&cp, CIPHER_SEP))) {
|
|
i = cipher_number(p);
|
|
if (i == -1 || !(cipher_mask2() & (1 << i))) {
|
|
xfree(ciphers);
|
|
return 0;
|
|
}
|
|
}
|
|
xfree(ciphers);
|
|
return 1;
|
|
}
|
|
|
|
/*
|
|
* Parses the name of the cipher. Returns the number of the corresponding
|
|
* cipher, or -1 on error.
|
|
*/
|
|
|
|
int
|
|
cipher_number(const char *name)
|
|
{
|
|
int i;
|
|
if (name == NULL)
|
|
return -1;
|
|
for (i = 0; i < sizeof(cipher_names) / sizeof(cipher_names[0]); i++)
|
|
if (strcmp(cipher_names[i], name) == 0 &&
|
|
(cipher_mask() & (1 << i)))
|
|
return i;
|
|
return -1;
|
|
}
|
|
|
|
/*
|
|
* Selects the cipher, and keys if by computing the MD5 checksum of the
|
|
* passphrase and using the resulting 16 bytes as the key.
|
|
*/
|
|
|
|
void
|
|
cipher_set_key_string(CipherContext *context, int cipher, const char *passphrase)
|
|
{
|
|
MD5_CTX md;
|
|
unsigned char digest[16];
|
|
|
|
MD5_Init(&md);
|
|
MD5_Update(&md, (const unsigned char *) passphrase, strlen(passphrase));
|
|
MD5_Final(digest, &md);
|
|
|
|
cipher_set_key(context, cipher, digest, 16);
|
|
|
|
memset(digest, 0, sizeof(digest));
|
|
memset(&md, 0, sizeof(md));
|
|
}
|
|
|
|
/* Selects the cipher to use and sets the key. */
|
|
|
|
void
|
|
cipher_set_key(CipherContext *context, int cipher, const unsigned char *key,
|
|
int keylen)
|
|
{
|
|
unsigned char padded[32];
|
|
|
|
/* Set cipher type. */
|
|
context->type = cipher;
|
|
|
|
/* Get 32 bytes of key data. Pad if necessary. (So that code
|
|
below does not need to worry about key size). */
|
|
memset(padded, 0, sizeof(padded));
|
|
memcpy(padded, key, keylen < sizeof(padded) ? keylen : sizeof(padded));
|
|
|
|
/* Initialize the initialization vector. */
|
|
switch (cipher) {
|
|
case SSH_CIPHER_NONE:
|
|
/*
|
|
* Has to stay for authfile saving of private key with no
|
|
* passphrase
|
|
*/
|
|
break;
|
|
|
|
case SSH_CIPHER_3DES:
|
|
/*
|
|
* Note: the least significant bit of each byte of key is
|
|
* parity, and must be ignored by the implementation. 16
|
|
* bytes of key are used (first and last keys are the same).
|
|
*/
|
|
if (keylen < 16)
|
|
error("Key length %d is insufficient for 3DES.", keylen);
|
|
des_set_key((void *) padded, context->u.des3.key1);
|
|
des_set_key((void *) (padded + 8), context->u.des3.key2);
|
|
if (keylen <= 16)
|
|
des_set_key((void *) padded, context->u.des3.key3);
|
|
else
|
|
des_set_key((void *) (padded + 16), context->u.des3.key3);
|
|
memset(context->u.des3.iv2, 0, sizeof(context->u.des3.iv2));
|
|
memset(context->u.des3.iv3, 0, sizeof(context->u.des3.iv3));
|
|
break;
|
|
|
|
case SSH_CIPHER_BLOWFISH:
|
|
if (keylen < 16)
|
|
error("Key length %d is insufficient for blowfish.", keylen);
|
|
BF_set_key(&context->u.bf.key, keylen, padded);
|
|
memset(context->u.bf.iv, 0, 8);
|
|
break;
|
|
|
|
case SSH_CIPHER_3DES_CBC:
|
|
case SSH_CIPHER_BLOWFISH_CBC:
|
|
case SSH_CIPHER_ARCFOUR:
|
|
case SSH_CIPHER_CAST128_CBC:
|
|
fatal("cipher_set_key: illegal cipher: %s", cipher_name(cipher));
|
|
break;
|
|
|
|
default:
|
|
fatal("cipher_set_key: unknown cipher: %s", cipher_name(cipher));
|
|
}
|
|
memset(padded, 0, sizeof(padded));
|
|
}
|
|
|
|
void
|
|
cipher_set_key_iv(CipherContext * context, int cipher,
|
|
const unsigned char *key, int keylen,
|
|
const unsigned char *iv, int ivlen)
|
|
{
|
|
/* Set cipher type. */
|
|
context->type = cipher;
|
|
|
|
/* Initialize the initialization vector. */
|
|
switch (cipher) {
|
|
case SSH_CIPHER_NONE:
|
|
break;
|
|
|
|
case SSH_CIPHER_3DES:
|
|
case SSH_CIPHER_BLOWFISH:
|
|
fatal("cipher_set_key_iv: illegal cipher: %s", cipher_name(cipher));
|
|
break;
|
|
|
|
case SSH_CIPHER_3DES_CBC:
|
|
if (keylen < 24)
|
|
error("Key length %d is insufficient for 3des-cbc.", keylen);
|
|
des_set_key((void *) key, context->u.des3.key1);
|
|
des_set_key((void *) (key+8), context->u.des3.key2);
|
|
des_set_key((void *) (key+16), context->u.des3.key3);
|
|
if (ivlen < 8)
|
|
error("IV length %d is insufficient for 3des-cbc.", ivlen);
|
|
memcpy(context->u.des3.iv3, (char *)iv, 8);
|
|
break;
|
|
|
|
case SSH_CIPHER_BLOWFISH_CBC:
|
|
if (keylen < 16)
|
|
error("Key length %d is insufficient for blowfish.", keylen);
|
|
if (ivlen < 8)
|
|
error("IV length %d is insufficient for blowfish.", ivlen);
|
|
BF_set_key(&context->u.bf.key, keylen, (unsigned char *)key);
|
|
memcpy(context->u.bf.iv, (char *)iv, 8);
|
|
break;
|
|
|
|
case SSH_CIPHER_ARCFOUR:
|
|
if (keylen < 16)
|
|
error("Key length %d is insufficient for arcfour.", keylen);
|
|
RC4_set_key(&context->u.rc4, keylen, (unsigned char *)key);
|
|
break;
|
|
|
|
case SSH_CIPHER_CAST128_CBC:
|
|
if (keylen < 16)
|
|
error("Key length %d is insufficient for cast128.", keylen);
|
|
if (ivlen < 8)
|
|
error("IV length %d is insufficient for cast128.", ivlen);
|
|
CAST_set_key(&context->u.cast.key, keylen, (unsigned char *) key);
|
|
memcpy(context->u.cast.iv, (char *)iv, 8);
|
|
break;
|
|
|
|
default:
|
|
fatal("cipher_set_key: unknown cipher: %s", cipher_name(cipher));
|
|
}
|
|
}
|
|
|
|
/* Encrypts data using the cipher. */
|
|
|
|
void
|
|
cipher_encrypt(CipherContext *context, unsigned char *dest,
|
|
const unsigned char *src, unsigned int len)
|
|
{
|
|
if ((len & 7) != 0)
|
|
fatal("cipher_encrypt: bad plaintext length %d", len);
|
|
|
|
switch (context->type) {
|
|
case SSH_CIPHER_NONE:
|
|
memcpy(dest, src, len);
|
|
break;
|
|
|
|
case SSH_CIPHER_3DES:
|
|
SSH_3CBC_ENCRYPT(context->u.des3.key1,
|
|
context->u.des3.key2, &context->u.des3.iv2,
|
|
context->u.des3.key3, &context->u.des3.iv3,
|
|
dest, (unsigned char *) src, len);
|
|
break;
|
|
|
|
case SSH_CIPHER_BLOWFISH:
|
|
swap_bytes(src, dest, len);
|
|
BF_cbc_encrypt(dest, dest, len,
|
|
&context->u.bf.key, context->u.bf.iv,
|
|
BF_ENCRYPT);
|
|
swap_bytes(dest, dest, len);
|
|
break;
|
|
|
|
case SSH_CIPHER_BLOWFISH_CBC:
|
|
BF_cbc_encrypt((void *)src, dest, len,
|
|
&context->u.bf.key, context->u.bf.iv,
|
|
BF_ENCRYPT);
|
|
break;
|
|
|
|
case SSH_CIPHER_3DES_CBC:
|
|
des_ede3_cbc_encrypt(src, dest, len,
|
|
context->u.des3.key1, context->u.des3.key2,
|
|
context->u.des3.key3, &context->u.des3.iv3, DES_ENCRYPT);
|
|
break;
|
|
|
|
case SSH_CIPHER_ARCFOUR:
|
|
RC4(&context->u.rc4, len, (unsigned char *)src, dest);
|
|
break;
|
|
|
|
case SSH_CIPHER_CAST128_CBC:
|
|
CAST_cbc_encrypt(src, dest, len,
|
|
&context->u.cast.key, context->u.cast.iv, CAST_ENCRYPT);
|
|
break;
|
|
|
|
default:
|
|
fatal("cipher_encrypt: unknown cipher: %s", cipher_name(context->type));
|
|
}
|
|
}
|
|
|
|
/* Decrypts data using the cipher. */
|
|
|
|
void
|
|
cipher_decrypt(CipherContext *context, unsigned char *dest,
|
|
const unsigned char *src, unsigned int len)
|
|
{
|
|
if ((len & 7) != 0)
|
|
fatal("cipher_decrypt: bad ciphertext length %d", len);
|
|
|
|
switch (context->type) {
|
|
case SSH_CIPHER_NONE:
|
|
memcpy(dest, src, len);
|
|
break;
|
|
|
|
case SSH_CIPHER_3DES:
|
|
SSH_3CBC_DECRYPT(context->u.des3.key1,
|
|
context->u.des3.key2, &context->u.des3.iv2,
|
|
context->u.des3.key3, &context->u.des3.iv3,
|
|
dest, (unsigned char *) src, len);
|
|
break;
|
|
|
|
case SSH_CIPHER_BLOWFISH:
|
|
swap_bytes(src, dest, len);
|
|
BF_cbc_encrypt((void *) dest, dest, len,
|
|
&context->u.bf.key, context->u.bf.iv,
|
|
BF_DECRYPT);
|
|
swap_bytes(dest, dest, len);
|
|
break;
|
|
|
|
case SSH_CIPHER_BLOWFISH_CBC:
|
|
BF_cbc_encrypt((void *) src, dest, len,
|
|
&context->u.bf.key, context->u.bf.iv,
|
|
BF_DECRYPT);
|
|
break;
|
|
|
|
case SSH_CIPHER_3DES_CBC:
|
|
des_ede3_cbc_encrypt(src, dest, len,
|
|
context->u.des3.key1, context->u.des3.key2,
|
|
context->u.des3.key3, &context->u.des3.iv3, DES_DECRYPT);
|
|
break;
|
|
|
|
case SSH_CIPHER_ARCFOUR:
|
|
RC4(&context->u.rc4, len, (unsigned char *)src, dest);
|
|
break;
|
|
|
|
case SSH_CIPHER_CAST128_CBC:
|
|
CAST_cbc_encrypt(src, dest, len,
|
|
&context->u.cast.key, context->u.cast.iv, CAST_DECRYPT);
|
|
break;
|
|
|
|
default:
|
|
fatal("cipher_decrypt: unknown cipher: %s", cipher_name(context->type));
|
|
}
|
|
}
|