cipher.c - security/openssh-library - Rivoreo Source Code Repositories

 /*
  * 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.
  */

 #include "includes.h"
 RCSID("$OpenBSD: cipher.c,v 1.35 2000/10/13 18:59:13 markus Exp $");

 #include "ssh.h"
 #include "xmalloc.h"

 #include <openssl/md5.h>


 /* no encryption */
 void
 none_setkey(CipherContext *cc, const u_char *key, u_int keylen)
 {
 }
 void
 none_setiv(CipherContext *cc, const u_char *iv, u_int ivlen)
 {
 }
 void
 none_crypt(CipherContext *cc, u_char *dest, const u_char *src, u_int len)
 {
 	memcpy(dest, src, len);
 }

 /* DES */
 void
 des_ssh1_setkey(CipherContext *cc, const u_char *key, u_int keylen)
 {
 	static int dowarn = 1;
 	if (dowarn) {
 		error("Warning: use of DES is strongly discouraged "
 		    "due to cryptographic weaknesses");
 		dowarn = 0;
 	}
 	des_set_key((void *)key, cc->u.des.key);
 }
 void
 des_ssh1_setiv(CipherContext *cc, const u_char *iv, u_int ivlen)
 {
 	memset(cc->u.des.iv, 0, sizeof(cc->u.des.iv));
 }
 void
 des_ssh1_encrypt(CipherContext *cc, u_char *dest, const u_char *src, u_int len)
 {
 	des_ncbc_encrypt(src, dest, len, cc->u.des.key, &cc->u.des.iv,
 	    DES_ENCRYPT);
 }
 void
 des_ssh1_decrypt(CipherContext *cc, u_char *dest, const u_char *src, u_int len)
 {
 	des_ncbc_encrypt(src, dest, len, cc->u.des.key, &cc->u.des.iv,
 	    DES_DECRYPT);
 }

 /* 3DES */
 void
 des3_setkey(CipherContext *cc, const u_char *key, u_int keylen)
 {
 	des_set_key((void *) key, cc->u.des3.key1);
 	des_set_key((void *) (key+8), cc->u.des3.key2);
 	des_set_key((void *) (key+16), cc->u.des3.key3);
 }
 void
 des3_setiv(CipherContext *cc, const u_char *iv, u_int ivlen)
 {
 	memset(cc->u.des3.iv2, 0, sizeof(cc->u.des3.iv2));
 	memset(cc->u.des3.iv3, 0, sizeof(cc->u.des3.iv3));
 	if (iv == NULL)
 		return;
 	memcpy(cc->u.des3.iv3, (char *)iv, 8);
 }
 void
 des3_cbc_encrypt(CipherContext *cc, u_char *dest, const u_char *src, u_int len)
 {
 	des_ede3_cbc_encrypt(src, dest, len,
 	    cc->u.des3.key1, cc->u.des3.key2, cc->u.des3.key3,
 	    &cc->u.des3.iv3, DES_ENCRYPT);
 }
 void
 des3_cbc_decrypt(CipherContext *cc, u_char *dest, const u_char *src, u_int len)
 {
 	des_ede3_cbc_encrypt(src, dest, len,
 	    cc->u.des3.key1, cc->u.des3.key2, cc->u.des3.key3,
 	    &cc->u.des3.iv3, DES_DECRYPT);
 }

 /*
  * 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.
  */
 void
 des3_ssh1_setkey(CipherContext *cc, const u_char *key, u_int keylen)
 {
 	des_set_key((void *) key, cc->u.des3.key1);
 	des_set_key((void *) (key+8), cc->u.des3.key2);
 	if (keylen <= 16)
 		des_set_key((void *) key, cc->u.des3.key3);
 	else
 		des_set_key((void *) (key+16), cc->u.des3.key3);
 }
 void
 des3_ssh1_encrypt(CipherContext *cc, u_char *dest, const u_char *src,
     u_int len)
 {
 	des_cblock iv1;
 	des_cblock *iv2 = &cc->u.des3.iv2;
 	des_cblock *iv3 = &cc->u.des3.iv3;

 	memcpy(&iv1, iv2, 8);

 	des_cbc_encrypt(src, dest, len, cc->u.des3.key1, &iv1, DES_ENCRYPT);
 	memcpy(&iv1, dest + len - 8, 8);

 	des_cbc_encrypt(dest, dest, len, cc->u.des3.key2, iv2, DES_DECRYPT);
 	memcpy(iv2, &iv1, 8);	/* Note how iv1 == iv2 on entry and exit. */

 	des_cbc_encrypt(dest, dest, len, cc->u.des3.key3, iv3, DES_ENCRYPT);
 	memcpy(iv3, dest + len - 8, 8);
 }
 void
 des3_ssh1_decrypt(CipherContext *cc, u_char *dest, const u_char *src,
     u_int len)
 {
 	des_cblock iv1;
 	des_cblock *iv2 = &cc->u.des3.iv2;
 	des_cblock *iv3 = &cc->u.des3.iv3;

 	memcpy(&iv1, iv2, 8);

 	des_cbc_encrypt(src, dest, len, cc->u.des3.key3, iv3, DES_DECRYPT);
 	memcpy(iv3, src + len - 8, 8);

 	des_cbc_encrypt(dest, dest, len, cc->u.des3.key2, iv2, DES_ENCRYPT);
 	memcpy(iv2, dest + len - 8, 8);

 	des_cbc_encrypt(dest, dest, len, cc->u.des3.key1, &iv1, DES_DECRYPT);
 	/* memcpy(&iv1, iv2, 8); */
 	/* Note how iv1 == iv2 on entry and exit. */
 }

 /* Blowfish */
 void
 blowfish_setkey(CipherContext *cc, const u_char *key, u_int keylen)
 {
 	BF_set_key(&cc->u.bf.key, keylen, (unsigned char *)key);
 }
 void
 blowfish_setiv(CipherContext *cc, const u_char *iv, u_int ivlen)
 {
 	if (iv == NULL)
 		memset(cc->u.bf.iv, 0, 8);
 	else
 		memcpy(cc->u.bf.iv, (char *)iv, 8);
 }
 void
 blowfish_cbc_encrypt(CipherContext *cc, u_char *dest, const u_char *src,
      u_int len)
 {
 	BF_cbc_encrypt((void *)src, dest, len, &cc->u.bf.key, cc->u.bf.iv,
 	    BF_ENCRYPT);
 }
 void
 blowfish_cbc_decrypt(CipherContext *cc, u_char *dest, const u_char *src,
      u_int len)
 {
 	BF_cbc_encrypt((void *)src, dest, len, &cc->u.bf.key, cc->u.bf.iv,
 	    BF_DECRYPT);
 }

 /*
  * 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;
 	}
 }

 void
 blowfish_ssh1_encrypt(CipherContext *cc, u_char *dest, const u_char *src,
     u_int len)
 {
 	swap_bytes(src, dest, len);
 	BF_cbc_encrypt((void *)dest, dest, len, &cc->u.bf.key, cc->u.bf.iv,
 	    BF_ENCRYPT);
 	swap_bytes(dest, dest, len);
 }
 void
 blowfish_ssh1_decrypt(CipherContext *cc, u_char *dest, const u_char *src,
     u_int len)
 {
 	swap_bytes(src, dest, len);
 	BF_cbc_encrypt((void *)dest, dest, len, &cc->u.bf.key, cc->u.bf.iv,
 	    BF_DECRYPT);
 	swap_bytes(dest, dest, len);
 }

 /* alleged rc4 */
 void
 arcfour_setkey(CipherContext *cc, const u_char *key, u_int keylen)
 {
 	RC4_set_key(&cc->u.rc4, keylen, (u_char *)key);
 }
 void
 arcfour_crypt(CipherContext *cc, u_char *dest, const u_char *src, u_int len)
 {
 	RC4(&cc->u.rc4, len, (u_char *)src, dest);
 }

 /* CAST */
 void
 cast_setkey(CipherContext *cc, const u_char *key, u_int keylen)
 {
 	CAST_set_key(&cc->u.cast.key, keylen, (unsigned char *) key);
 }
 void
 cast_setiv(CipherContext *cc, const u_char *iv, u_int ivlen)
 {
 	if (iv == NULL)
 		fatal("no IV for %s.", cc->cipher->name);
 	memcpy(cc->u.cast.iv, (char *)iv, 8);
 }
 void
 cast_cbc_encrypt(CipherContext *cc, u_char *dest, const u_char *src, u_int len)
 {
 	CAST_cbc_encrypt(src, dest, len, &cc->u.cast.key, cc->u.cast.iv,
 	    CAST_ENCRYPT);
 }
 void
 cast_cbc_decrypt(CipherContext *cc, u_char *dest, const u_char *src, u_int len)
 {
 	CAST_cbc_encrypt(src, dest, len, &cc->u.cast.key, cc->u.cast.iv,
 	    CAST_DECRYPT);
 }

 /* RIJNDAEL */

 #define RIJNDAEL_BLOCKSIZE 16
 void
 rijndael_setkey(CipherContext *cc, const u_char *key, u_int keylen)
 {
 	rijndael_set_key(&cc->u.rijndael.enc, (u4byte *)key, 8*keylen, 1);
 	rijndael_set_key(&cc->u.rijndael.dec, (u4byte *)key, 8*keylen, 0);
 }
 void
 rijndael_setiv(CipherContext *cc, const u_char *iv, u_int ivlen)
 {
 	if (iv == NULL)
 		fatal("no IV for %s.", cc->cipher->name);
 	memcpy((u_char *)cc->u.rijndael.iv, iv, RIJNDAEL_BLOCKSIZE);
 }
 void
 rijndael_cbc_encrypt(CipherContext *cc, u_char *dest, const u_char *src,
     u_int len)
 {
 	rijndael_ctx *ctx = &cc->u.rijndael.enc;
 	u4byte *iv = cc->u.rijndael.iv;
 	u4byte in[4];
 	u4byte *cprev, *cnow, *plain;
 	int i, blocks = len / RIJNDAEL_BLOCKSIZE;
 	if (len == 0)
 		return;
 	if (len % RIJNDAEL_BLOCKSIZE)
 		fatal("rijndael_cbc_encrypt: bad len %d", len);
 	cnow  = (u4byte*) dest;
 	plain = (u4byte*) src;
 	cprev = iv;
 	for(i = 0; i < blocks; i++, plain+=4, cnow+=4) {
 		in[0] = plain[0] ^ cprev[0];
 		in[1] = plain[1] ^ cprev[1];
 		in[2] = plain[2] ^ cprev[2];
 		in[3] = plain[3] ^ cprev[3];
 		rijndael_encrypt(ctx, in, cnow);
 		cprev = cnow;
 	}
 	memcpy(iv, cprev, RIJNDAEL_BLOCKSIZE);
 }

 void
 rijndael_cbc_decrypt(CipherContext *cc, u_char *dest, const u_char *src,
     u_int len)
 {
 	rijndael_ctx *ctx = &cc->u.rijndael.dec;
 	u4byte *iv = cc->u.rijndael.iv;
 	u4byte ivsaved[4];
 	u4byte *cnow =  (u4byte*) (src+len-RIJNDAEL_BLOCKSIZE);
 	u4byte *plain = (u4byte*) (dest+len-RIJNDAEL_BLOCKSIZE);
 	u4byte *ivp;
 	int i, blocks = len / RIJNDAEL_BLOCKSIZE;
 	if (len == 0)
 		return;
 	if (len % RIJNDAEL_BLOCKSIZE)
 		fatal("rijndael_cbc_decrypt: bad len %d", len);
 	memcpy(ivsaved, cnow, RIJNDAEL_BLOCKSIZE);
 	for(i = blocks; i > 0; i--, cnow-=4, plain-=4) {
 		rijndael_decrypt(ctx, cnow, plain);
 		ivp =  (i == 1) ? iv : cnow-4;
 		plain[0] ^= ivp[0];
 		plain[1] ^= ivp[1];
 		plain[2] ^= ivp[2];
 		plain[3] ^= ivp[3];
 	}
 	memcpy(iv, ivsaved, RIJNDAEL_BLOCKSIZE);
 }

 Cipher ciphers[] = {
 	{ "none",
 		SSH_CIPHER_NONE, 8, 0,
 		none_setkey, none_setiv,
 		none_crypt, none_crypt },
 	{ "des",
 		SSH_CIPHER_DES, 8, 8,
 		des_ssh1_setkey, des_ssh1_setiv,
 		des_ssh1_encrypt, des_ssh1_decrypt },
 	{ "3des",
 		SSH_CIPHER_3DES, 8, 16,
 		des3_ssh1_setkey, des3_setiv,
 		des3_ssh1_encrypt, des3_ssh1_decrypt },
 	{ "blowfish",
 		SSH_CIPHER_BLOWFISH, 8, 16,
 		blowfish_setkey, blowfish_setiv,
 		blowfish_ssh1_encrypt, blowfish_ssh1_decrypt },

 	{ "3des-cbc",
 		SSH_CIPHER_SSH2, 8, 24,
 		des3_setkey, des3_setiv,
 		des3_cbc_encrypt, des3_cbc_decrypt },
 	{ "blowfish-cbc",
 		SSH_CIPHER_SSH2, 8, 16,
 		blowfish_setkey, blowfish_setiv,
 		blowfish_cbc_encrypt, blowfish_cbc_decrypt },
 	{ "cast128-cbc",
 		SSH_CIPHER_SSH2, 8, 16,
 		cast_setkey, cast_setiv,
 		cast_cbc_encrypt, cast_cbc_decrypt },
 	{ "arcfour",
 		SSH_CIPHER_SSH2, 8, 16,
 		arcfour_setkey, none_setiv,
 		arcfour_crypt, arcfour_crypt },
 	{ "aes128-cbc",
 		SSH_CIPHER_SSH2, 16, 16,
 		rijndael_setkey, rijndael_setiv,
 		rijndael_cbc_encrypt, rijndael_cbc_decrypt },
 	{ "aes192-cbc",
 		SSH_CIPHER_SSH2, 16, 24,
 		rijndael_setkey, rijndael_setiv,
 		rijndael_cbc_encrypt, rijndael_cbc_decrypt },
 	{ "aes256-cbc",
 		SSH_CIPHER_SSH2, 16, 32,
 		rijndael_setkey, rijndael_setiv,
 		rijndael_cbc_encrypt, rijndael_cbc_decrypt },
 	{ "rijndael128-cbc",
 		SSH_CIPHER_SSH2, 16, 16,
 		rijndael_setkey, rijndael_setiv,
 		rijndael_cbc_encrypt, rijndael_cbc_decrypt },
 	{ "rijndael192-cbc",
 		SSH_CIPHER_SSH2, 16, 24,
 		rijndael_setkey, rijndael_setiv,
 		rijndael_cbc_encrypt, rijndael_cbc_decrypt },
 	{ "rijndael256-cbc",
 		SSH_CIPHER_SSH2, 16, 32,
 		rijndael_setkey, rijndael_setiv,
 		rijndael_cbc_encrypt, rijndael_cbc_decrypt },
 	{ "rijndael-cbc@lysator.liu.se",
 		SSH_CIPHER_SSH2, 16, 32,
 		rijndael_setkey, rijndael_setiv,
 		rijndael_cbc_encrypt, rijndael_cbc_decrypt },
         { NULL, SSH_CIPHER_ILLEGAL, 0, 0, NULL, NULL, NULL, NULL }
 };

 /*--*/

 unsigned int
 cipher_mask_ssh1(int client)
 {
 	unsigned int mask = 0;
 	mask |= 1 << SSH_CIPHER_3DES;           /* Mandatory */
 	mask |= 1 << SSH_CIPHER_BLOWFISH;
 	if (client) {
 		mask |= 1 << SSH_CIPHER_DES;
 	}
 	return mask;
 }

 Cipher *
 cipher_by_name(const char *name)
 {
 	Cipher *c;
 	for (c = ciphers; c->name != NULL; c++)
 		if (strcasecmp(c->name, name) == 0)
 			return c;
 	return NULL;
 }

 Cipher *
 cipher_by_number(int id)
 {
 	Cipher *c;
 	for (c = ciphers; c->name != NULL; c++)
 		if (c->number == id)
 			return c;
 	return NULL;
 }

 #define	CIPHER_SEP	","
 int
 ciphers_valid(const char *names)
 {
 	Cipher *c;
 	char *ciphers, *cp;
 	char *p;

 	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))) {
 		c = cipher_by_name(p);
 		if (c == NULL || c->number != SSH_CIPHER_SSH2) {
 			debug("bad cipher %s [%s]", p, names);
 			xfree(ciphers);
 			return 0;
 		} else {
 			debug("cipher ok: %s [%s]", p, names);
 		}
 	}
 	debug("ciphers ok: [%s]", names);
 	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)
 {
 	Cipher *c;
 	if (name == NULL)
 		return -1;
 	c = cipher_by_name(name);
 	return (c==NULL) ? -1 : c->number;
 }

 char *
 cipher_name(int id)
 {
 	Cipher *c = cipher_by_number(id);
 	return (c==NULL) ? "<unknown>" : c->name;
 }

 void
 cipher_init(CipherContext *cc, Cipher *cipher,
     const u_char *key, u_int keylen, const u_char *iv, u_int ivlen)
 {
 	if (keylen < cipher->key_len)
 		fatal("cipher_init: key length %d is insufficient for %s.",
 		    keylen, cipher->name);
 	if (iv != NULL && ivlen < cipher->block_size)
 		fatal("cipher_init: iv length %d is insufficient for %s.",
 		    ivlen, cipher->name);
 	cc->cipher = cipher;
 	cipher->setkey(cc, key, keylen);
 	cipher->setiv(cc, iv, ivlen);
 }

 void
 cipher_encrypt(CipherContext *cc, u_char *dest, const u_char *src, u_int len)
 {
 	if (len % cc->cipher->block_size)
 		fatal("cipher_encrypt: bad plaintext length %d", len);
 	cc->cipher->encrypt(cc, dest, src, len);
 }

 void
 cipher_decrypt(CipherContext *cc, u_char *dest, const u_char *src, u_int len)
 {
 	if (len % cc->cipher->block_size)
 		fatal("cipher_decrypt: bad ciphertext length %d", len);
 	cc->cipher->decrypt(cc, dest, src, len);
 }

 /*
  * 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 *cc, Cipher *cipher,
     const char *passphrase)
 {
 	MD5_CTX md;
 	unsigned char digest[16];

 	MD5_Init(&md);
 	MD5_Update(&md, (const u_char *)passphrase, strlen(passphrase));
 	MD5_Final(digest, &md);

 	cipher_init(cc, cipher, digest, 16, NULL, 0);

 	memset(digest, 0, sizeof(digest));
 	memset(&md, 0, sizeof(md));
 }
	/*
	* 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.
	*/

	#include "includes.h"
	RCSID("$OpenBSD: cipher.c,v 1.35 2000/10/13 18:59:13 markus Exp $");

	#include "ssh.h"
	#include "xmalloc.h"

	#include <openssl/md5.h>


	/* no encryption */
	void
	none_setkey(CipherContext cc, const u_char key, u_int keylen)
	{
	}
	void
	none_setiv(CipherContext cc, const u_char iv, u_int ivlen)
	{
	}
	void
	none_crypt(CipherContext cc, u_char dest, const u_char *src, u_int len)
	{
	memcpy(dest, src, len);
	}

	/* DES */
	void
	des_ssh1_setkey(CipherContext cc, const u_char key, u_int keylen)
	{
	static int dowarn = 1;
	if (dowarn) {
	error("Warning: use of DES is strongly discouraged "
	"due to cryptographic weaknesses");
	dowarn = 0;
	}
	des_set_key((void *)key, cc->u.des.key);
	}
	void
	des_ssh1_setiv(CipherContext cc, const u_char iv, u_int ivlen)
	{
	memset(cc->u.des.iv, 0, sizeof(cc->u.des.iv));
	}
	void
	des_ssh1_encrypt(CipherContext cc, u_char dest, const u_char *src, u_int len)
	{
	des_ncbc_encrypt(src, dest, len, cc->u.des.key, &cc->u.des.iv,
	DES_ENCRYPT);
	}
	void
	des_ssh1_decrypt(CipherContext cc, u_char dest, const u_char *src, u_int len)
	{
	des_ncbc_encrypt(src, dest, len, cc->u.des.key, &cc->u.des.iv,
	DES_DECRYPT);
	}

	/* 3DES */
	void
	des3_setkey(CipherContext cc, const u_char key, u_int keylen)
	{
	des_set_key((void *) key, cc->u.des3.key1);
	des_set_key((void *) (key+8), cc->u.des3.key2);
	des_set_key((void *) (key+16), cc->u.des3.key3);
	}
	void
	des3_setiv(CipherContext cc, const u_char iv, u_int ivlen)
	{
	memset(cc->u.des3.iv2, 0, sizeof(cc->u.des3.iv2));
	memset(cc->u.des3.iv3, 0, sizeof(cc->u.des3.iv3));
	if (iv == NULL)
	return;
	memcpy(cc->u.des3.iv3, (char *)iv, 8);
	}
	void
	des3_cbc_encrypt(CipherContext cc, u_char dest, const u_char *src, u_int len)
	{
	des_ede3_cbc_encrypt(src, dest, len,
	cc->u.des3.key1, cc->u.des3.key2, cc->u.des3.key3,
	&cc->u.des3.iv3, DES_ENCRYPT);
	}
	void
	des3_cbc_decrypt(CipherContext cc, u_char dest, const u_char *src, u_int len)
	{
	des_ede3_cbc_encrypt(src, dest, len,
	cc->u.des3.key1, cc->u.des3.key2, cc->u.des3.key3,
	&cc->u.des3.iv3, DES_DECRYPT);
	}

	/*
	* 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.
	*/
	void
	des3_ssh1_setkey(CipherContext cc, const u_char key, u_int keylen)
	{
	des_set_key((void *) key, cc->u.des3.key1);
	des_set_key((void *) (key+8), cc->u.des3.key2);
	if (keylen <= 16)
	des_set_key((void *) key, cc->u.des3.key3);
	else
	des_set_key((void *) (key+16), cc->u.des3.key3);
	}
	void
	des3_ssh1_encrypt(CipherContext cc, u_char dest, const u_char *src,
	u_int len)
	{
	des_cblock iv1;
	des_cblock *iv2 = &cc->u.des3.iv2;
	des_cblock *iv3 = &cc->u.des3.iv3;

	memcpy(&iv1, iv2, 8);

	des_cbc_encrypt(src, dest, len, cc->u.des3.key1, &iv1, DES_ENCRYPT);
	memcpy(&iv1, dest + len - 8, 8);

	des_cbc_encrypt(dest, dest, len, cc->u.des3.key2, iv2, DES_DECRYPT);
	memcpy(iv2, &iv1, 8); /* Note how iv1 == iv2 on entry and exit. */

	des_cbc_encrypt(dest, dest, len, cc->u.des3.key3, iv3, DES_ENCRYPT);
	memcpy(iv3, dest + len - 8, 8);
	}
	void
	des3_ssh1_decrypt(CipherContext cc, u_char dest, const u_char *src,
	u_int len)
	{
	des_cblock iv1;
	des_cblock *iv2 = &cc->u.des3.iv2;
	des_cblock *iv3 = &cc->u.des3.iv3;

	memcpy(&iv1, iv2, 8);

	des_cbc_encrypt(src, dest, len, cc->u.des3.key3, iv3, DES_DECRYPT);
	memcpy(iv3, src + len - 8, 8);

	des_cbc_encrypt(dest, dest, len, cc->u.des3.key2, iv2, DES_ENCRYPT);
	memcpy(iv2, dest + len - 8, 8);

	des_cbc_encrypt(dest, dest, len, cc->u.des3.key1, &iv1, DES_DECRYPT);
	/* memcpy(&iv1, iv2, 8); */
	/* Note how iv1 == iv2 on entry and exit. */
	}

	/* Blowfish */
	void
	blowfish_setkey(CipherContext cc, const u_char key, u_int keylen)
	{
	BF_set_key(&cc->u.bf.key, keylen, (unsigned char *)key);
	}
	void
	blowfish_setiv(CipherContext cc, const u_char iv, u_int ivlen)
	{
	if (iv == NULL)
	memset(cc->u.bf.iv, 0, 8);
	else
	memcpy(cc->u.bf.iv, (char *)iv, 8);
	}
	void
	blowfish_cbc_encrypt(CipherContext cc, u_char dest, const u_char *src,
	u_int len)
	{
	BF_cbc_encrypt((void *)src, dest, len, &cc->u.bf.key, cc->u.bf.iv,
	BF_ENCRYPT);
	}
	void
	blowfish_cbc_decrypt(CipherContext cc, u_char dest, const u_char *src,
	u_int len)
	{
	BF_cbc_encrypt((void *)src, dest, len, &cc->u.bf.key, cc->u.bf.iv,
	BF_DECRYPT);
	}

	/*
	* 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;
	}
	}

	void
	blowfish_ssh1_encrypt(CipherContext cc, u_char dest, const u_char *src,
	u_int len)
	{
	swap_bytes(src, dest, len);
	BF_cbc_encrypt((void *)dest, dest, len, &cc->u.bf.key, cc->u.bf.iv,
	BF_ENCRYPT);
	swap_bytes(dest, dest, len);
	}
	void
	blowfish_ssh1_decrypt(CipherContext cc, u_char dest, const u_char *src,
	u_int len)
	{
	swap_bytes(src, dest, len);
	BF_cbc_encrypt((void *)dest, dest, len, &cc->u.bf.key, cc->u.bf.iv,
	BF_DECRYPT);
	swap_bytes(dest, dest, len);
	}

	/* alleged rc4 */
	void
	arcfour_setkey(CipherContext cc, const u_char key, u_int keylen)
	{
	RC4_set_key(&cc->u.rc4, keylen, (u_char *)key);
	}
	void
	arcfour_crypt(CipherContext cc, u_char dest, const u_char *src, u_int len)
	{
	RC4(&cc->u.rc4, len, (u_char *)src, dest);
	}

	/* CAST */
	void
	cast_setkey(CipherContext cc, const u_char key, u_int keylen)
	{
	CAST_set_key(&cc->u.cast.key, keylen, (unsigned char *) key);
	}
	void
	cast_setiv(CipherContext cc, const u_char iv, u_int ivlen)
	{
	if (iv == NULL)
	fatal("no IV for %s.", cc->cipher->name);
	memcpy(cc->u.cast.iv, (char *)iv, 8);
	}
	void
	cast_cbc_encrypt(CipherContext cc, u_char dest, const u_char *src, u_int len)
	{
	CAST_cbc_encrypt(src, dest, len, &cc->u.cast.key, cc->u.cast.iv,
	CAST_ENCRYPT);
	}
	void
	cast_cbc_decrypt(CipherContext cc, u_char dest, const u_char *src, u_int len)
	{
	CAST_cbc_encrypt(src, dest, len, &cc->u.cast.key, cc->u.cast.iv,
	CAST_DECRYPT);
	}

	/* RIJNDAEL */

	#define RIJNDAEL_BLOCKSIZE 16
	void
	rijndael_setkey(CipherContext cc, const u_char key, u_int keylen)
	{
	rijndael_set_key(&cc->u.rijndael.enc, (u4byte )key, 8keylen, 1);
	rijndael_set_key(&cc->u.rijndael.dec, (u4byte )key, 8keylen, 0);
	}
	void
	rijndael_setiv(CipherContext cc, const u_char iv, u_int ivlen)
	{
	if (iv == NULL)
	fatal("no IV for %s.", cc->cipher->name);
	memcpy((u_char *)cc->u.rijndael.iv, iv, RIJNDAEL_BLOCKSIZE);
	}
	void
	rijndael_cbc_encrypt(CipherContext cc, u_char dest, const u_char *src,
	u_int len)
	{
	rijndael_ctx *ctx = &cc->u.rijndael.enc;
	u4byte *iv = cc->u.rijndael.iv;
	u4byte in[4];
	u4byte cprev, cnow, *plain;
	int i, blocks = len / RIJNDAEL_BLOCKSIZE;
	if (len == 0)
	return;
	if (len % RIJNDAEL_BLOCKSIZE)
	fatal("rijndael_cbc_encrypt: bad len %d", len);
	cnow = (u4byte*) dest;
	plain = (u4byte*) src;
	cprev = iv;
	for(i = 0; i < blocks; i++, plain+=4, cnow+=4) {
	in[0] = plain[0] ^ cprev[0];
	in[1] = plain[1] ^ cprev[1];
	in[2] = plain[2] ^ cprev[2];
	in[3] = plain[3] ^ cprev[3];
	rijndael_encrypt(ctx, in, cnow);
	cprev = cnow;
	}
	memcpy(iv, cprev, RIJNDAEL_BLOCKSIZE);
	}

	void
	rijndael_cbc_decrypt(CipherContext cc, u_char dest, const u_char *src,
	u_int len)
	{
	rijndael_ctx *ctx = &cc->u.rijndael.dec;
	u4byte *iv = cc->u.rijndael.iv;
	u4byte ivsaved[4];
	u4byte cnow = (u4byte) (src+len-RIJNDAEL_BLOCKSIZE);
	u4byte plain = (u4byte) (dest+len-RIJNDAEL_BLOCKSIZE);
	u4byte *ivp;
	int i, blocks = len / RIJNDAEL_BLOCKSIZE;
	if (len == 0)
	return;
	if (len % RIJNDAEL_BLOCKSIZE)
	fatal("rijndael_cbc_decrypt: bad len %d", len);
	memcpy(ivsaved, cnow, RIJNDAEL_BLOCKSIZE);
	for(i = blocks; i > 0; i--, cnow-=4, plain-=4) {
	rijndael_decrypt(ctx, cnow, plain);
	ivp = (i == 1) ? iv : cnow-4;
	plain[0] ^= ivp[0];
	plain[1] ^= ivp[1];
	plain[2] ^= ivp[2];
	plain[3] ^= ivp[3];
	}
	memcpy(iv, ivsaved, RIJNDAEL_BLOCKSIZE);
	}

	Cipher ciphers[] = {
	{ "none",
	SSH_CIPHER_NONE, 8, 0,
	none_setkey, none_setiv,
	none_crypt, none_crypt },
	{ "des",
	SSH_CIPHER_DES, 8, 8,
	des_ssh1_setkey, des_ssh1_setiv,
	des_ssh1_encrypt, des_ssh1_decrypt },
	{ "3des",
	SSH_CIPHER_3DES, 8, 16,
	des3_ssh1_setkey, des3_setiv,
	des3_ssh1_encrypt, des3_ssh1_decrypt },
	{ "blowfish",
	SSH_CIPHER_BLOWFISH, 8, 16,
	blowfish_setkey, blowfish_setiv,
	blowfish_ssh1_encrypt, blowfish_ssh1_decrypt },

	{ "3des-cbc",
	SSH_CIPHER_SSH2, 8, 24,
	des3_setkey, des3_setiv,
	des3_cbc_encrypt, des3_cbc_decrypt },
	{ "blowfish-cbc",
	SSH_CIPHER_SSH2, 8, 16,
	blowfish_setkey, blowfish_setiv,
	blowfish_cbc_encrypt, blowfish_cbc_decrypt },
	{ "cast128-cbc",
	SSH_CIPHER_SSH2, 8, 16,
	cast_setkey, cast_setiv,
	cast_cbc_encrypt, cast_cbc_decrypt },
	{ "arcfour",
	SSH_CIPHER_SSH2, 8, 16,
	arcfour_setkey, none_setiv,
	arcfour_crypt, arcfour_crypt },
	{ "aes128-cbc",
	SSH_CIPHER_SSH2, 16, 16,
	rijndael_setkey, rijndael_setiv,
	rijndael_cbc_encrypt, rijndael_cbc_decrypt },
	{ "aes192-cbc",
	SSH_CIPHER_SSH2, 16, 24,
	rijndael_setkey, rijndael_setiv,
	rijndael_cbc_encrypt, rijndael_cbc_decrypt },
	{ "aes256-cbc",
	SSH_CIPHER_SSH2, 16, 32,
	rijndael_setkey, rijndael_setiv,
	rijndael_cbc_encrypt, rijndael_cbc_decrypt },
	{ "rijndael128-cbc",
	SSH_CIPHER_SSH2, 16, 16,
	rijndael_setkey, rijndael_setiv,
	rijndael_cbc_encrypt, rijndael_cbc_decrypt },
	{ "rijndael192-cbc",
	SSH_CIPHER_SSH2, 16, 24,
	rijndael_setkey, rijndael_setiv,
	rijndael_cbc_encrypt, rijndael_cbc_decrypt },
	{ "rijndael256-cbc",
	SSH_CIPHER_SSH2, 16, 32,
	rijndael_setkey, rijndael_setiv,
	rijndael_cbc_encrypt, rijndael_cbc_decrypt },
	{ "rijndael-cbc@lysator.liu.se",
	SSH_CIPHER_SSH2, 16, 32,
	rijndael_setkey, rijndael_setiv,
	rijndael_cbc_encrypt, rijndael_cbc_decrypt },
	{ NULL, SSH_CIPHER_ILLEGAL, 0, 0, NULL, NULL, NULL, NULL }
	};

	/--/

	unsigned int
	cipher_mask_ssh1(int client)
	{
	unsigned int mask = 0;
	mask \|= 1 << SSH_CIPHER_3DES; /* Mandatory */
	mask \|= 1 << SSH_CIPHER_BLOWFISH;
	if (client) {
	mask \|= 1 << SSH_CIPHER_DES;
	}
	return mask;
	}

	Cipher *
	cipher_by_name(const char *name)
	{
	Cipher *c;
	for (c = ciphers; c->name != NULL; c++)
	if (strcasecmp(c->name, name) == 0)
	return c;
	return NULL;
	}

	Cipher *
	cipher_by_number(int id)
	{
	Cipher *c;
	for (c = ciphers; c->name != NULL; c++)
	if (c->number == id)
	return c;
	return NULL;
	}

	#define CIPHER_SEP ","
	int
	ciphers_valid(const char *names)
	{
	Cipher *c;
	char ciphers, cp;
	char *p;

	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))) {
	c = cipher_by_name(p);
	if (c == NULL \|\| c->number != SSH_CIPHER_SSH2) {
	debug("bad cipher %s [%s]", p, names);
	xfree(ciphers);
	return 0;
	} else {
	debug("cipher ok: %s [%s]", p, names);
	}
	}
	debug("ciphers ok: [%s]", names);
	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)
	{
	Cipher *c;
	if (name == NULL)
	return -1;
	c = cipher_by_name(name);
	return (c==NULL) ? -1 : c->number;
	}

	char *
	cipher_name(int id)
	{
	Cipher *c = cipher_by_number(id);
	return (c==NULL) ? "<unknown>" : c->name;
	}

	void
	cipher_init(CipherContext cc, Cipher cipher,
	const u_char key, u_int keylen, const u_char iv, u_int ivlen)
	{
	if (keylen < cipher->key_len)
	fatal("cipher_init: key length %d is insufficient for %s.",
	keylen, cipher->name);
	if (iv != NULL && ivlen < cipher->block_size)
	fatal("cipher_init: iv length %d is insufficient for %s.",
	ivlen, cipher->name);
	cc->cipher = cipher;
	cipher->setkey(cc, key, keylen);
	cipher->setiv(cc, iv, ivlen);
	}

	void
	cipher_encrypt(CipherContext cc, u_char dest, const u_char *src, u_int len)
	{
	if (len % cc->cipher->block_size)
	fatal("cipher_encrypt: bad plaintext length %d", len);
	cc->cipher->encrypt(cc, dest, src, len);
	}

	void
	cipher_decrypt(CipherContext cc, u_char dest, const u_char *src, u_int len)
	{
	if (len % cc->cipher->block_size)
	fatal("cipher_decrypt: bad ciphertext length %d", len);
	cc->cipher->decrypt(cc, dest, src, len);
	}

	/*
	* 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 cc, Cipher cipher,
	const char *passphrase)
	{
	MD5_CTX md;
	unsigned char digest[16];

	MD5_Init(&md);
	MD5_Update(&md, (const u_char *)passphrase, strlen(passphrase));
	MD5_Final(digest, &md);

	cipher_init(cc, cipher, digest, 16, NULL, 0);

	memset(digest, 0, sizeof(digest));
	memset(&md, 0, sizeof(md));
	}