[openssh.git] / cipher.c

/*
 * 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 1.52 2002/02/18 13:05:32 markus Exp $");

#include "xmalloc.h"
#include "log.h"
#include "cipher.h"

#include <openssl/md5.h>
#include "rijndael.h"

static EVP_CIPHER *evp_ssh1_3des(void);
static EVP_CIPHER *evp_ssh1_bf(void);
static EVP_CIPHER *evp_rijndael(void);

struct Cipher {
	char	*name;
	int	number;		/* for ssh1 only */
	u_int	block_size;
	u_int	key_len;
	EVP_CIPHER	*(*evptype)(void);
} ciphers[] = {
	{ "none", 		SSH_CIPHER_NONE, 8, 0, EVP_enc_null },
	{ "des", 		SSH_CIPHER_DES, 8, 8, EVP_des_cbc },
	{ "3des", 		SSH_CIPHER_3DES, 8, 16, evp_ssh1_3des },
	{ "blowfish", 		SSH_CIPHER_BLOWFISH, 8, 32, evp_ssh1_bf },

	{ "3des-cbc", 		SSH_CIPHER_SSH2, 8, 24, EVP_des_ede3_cbc },
	{ "blowfish-cbc", 	SSH_CIPHER_SSH2, 8, 16, EVP_bf_cbc },
	{ "cast128-cbc", 	SSH_CIPHER_SSH2, 8, 16, EVP_cast5_cbc },
	{ "arcfour", 		SSH_CIPHER_SSH2, 8, 16, EVP_rc4 },
	{ "aes128-cbc", 	SSH_CIPHER_SSH2, 16, 16, evp_rijndael },
	{ "aes192-cbc", 	SSH_CIPHER_SSH2, 16, 24, evp_rijndael },
	{ "aes256-cbc", 	SSH_CIPHER_SSH2, 16, 32, evp_rijndael },

	{ NULL,			SSH_CIPHER_ILLEGAL, 0, 0, NULL }
};

/*--*/

u_int	
cipher_blocksize(Cipher *c)
{
	return (c->block_size);
}
u_int	
cipher_keylen(Cipher *c)
{
	return (c->key_len);
}

u_int
cipher_mask_ssh1(int client)
{
	u_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 {
			debug3("cipher ok: %s [%s]", p, names);
		}
	}
	debug3("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,
    int encrypt)
{
	static int dowarn = 1;
	const EVP_CIPHER *type;
	int klen;

	if (cipher->number == SSH_CIPHER_DES) {
		if (dowarn) {
			error("Warning: use of DES is strongly discouraged "
			    "due to cryptographic weaknesses");
			dowarn = 0;
		}
		if (keylen > 8)
			keylen = 8;
	}
	cc->plaintext = (cipher->number == SSH_CIPHER_NONE);

	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;

	type = (*cipher->evptype)();

	EVP_CIPHER_CTX_init(&cc->evp);
	if (EVP_CipherInit(&cc->evp, type, NULL, (u_char *)iv,
	    (encrypt == CIPHER_ENCRYPT)) == 0)
		fatal("cipher_init: EVP_CipherInit failed for %s",
		    cipher->name);
	klen = EVP_CIPHER_CTX_key_length(&cc->evp);
	if (klen > 0 && keylen != klen) {
		debug("cipher_init: set keylen (%d -> %d)", klen, keylen);
		if (EVP_CIPHER_CTX_set_key_length(&cc->evp, keylen) == 0)
			fatal("cipher_init: set keylen failed (%d -> %d)",
			    klen, keylen);
	}
	if (EVP_CipherInit(&cc->evp, NULL, (u_char *)key, NULL, -1) == 0)
		fatal("cipher_init: EVP_CipherInit: set key failed for %s",
		    cipher->name);
}

void
cipher_crypt(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);
	if (EVP_Cipher(&cc->evp, dest, (u_char *)src, len) == 0)
		fatal("evp_crypt: EVP_Cipher failed");
}

void
cipher_cleanup(CipherContext *cc)
{
	if (EVP_CIPHER_CTX_cleanup(&cc->evp) == 0)
		error("cipher_cleanup: EVP_CIPHER_CTX_cleanup failed");
}

/*
 * 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, int encrypt)
{
	MD5_CTX md;
	u_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, encrypt);

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

/* Implementations for other non-EVP ciphers */

/*
 * 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;
};
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);
	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);
	}
	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);
	}
	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) {
		memset(c, 0, sizeof(*c));
		xfree(c);
		EVP_CIPHER_CTX_set_app_data(ctx, NULL);
	}
	return (1);
}
static 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);
}

/*
 * 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 u_char *src, u_char *dst, int n)
{
	u_char c[4];

	/* Process 4 bytes every lap. */
	for (n = n / 4; n > 0; n--) {
		c[3] = *src++;
		c[2] = *src++;
		c[1] = *src++;
		c[0] = *src++;

		*dst++ = c[0];
		*dst++ = c[1];
		*dst++ = c[2];
		*dst++ = c[3];
	}
}
static int (*orig_bf)(EVP_CIPHER_CTX *, u_char *, const u_char *, u_int) = NULL;
static int
bf_ssh1_cipher(EVP_CIPHER_CTX *ctx, u_char *out, const u_char *in, u_int len)
{
	int ret;

	swap_bytes(in, out, len);
	ret = (*orig_bf)(ctx, out, out, len);
	swap_bytes(out, out, len);
	return (ret);
}
static EVP_CIPHER *
evp_ssh1_bf(void)
{
	static EVP_CIPHER ssh1_bf;

	memcpy(&ssh1_bf, EVP_bf_cbc(), sizeof(EVP_CIPHER));
	orig_bf = ssh1_bf.do_cipher;
	ssh1_bf.nid = NID_undef;
	ssh1_bf.do_cipher = bf_ssh1_cipher;
	ssh1_bf.key_len = 32;
	return (&ssh1_bf);
}

/* RIJNDAEL */
#define RIJNDAEL_BLOCKSIZE 16
struct ssh_rijndael_ctx
{
	rijndael_ctx	r_ctx;
	u_char		r_iv[RIJNDAEL_BLOCKSIZE];
};

static int
ssh_rijndael_init(EVP_CIPHER_CTX *ctx, const u_char *key, const u_char *iv,
    int enc)
{
	struct ssh_rijndael_ctx *c;

	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) {
		if (enc == -1)
			enc = ctx->encrypt;
		rijndael_set_key(&c->r_ctx, (u_char *)key,
		    8*EVP_CIPHER_CTX_key_length(ctx), enc);
	}
	if (iv != NULL)
		memcpy(c->r_iv, iv, RIJNDAEL_BLOCKSIZE);
	return (1);
}
static int
ssh_rijndael_cbc(EVP_CIPHER_CTX *ctx, u_char *dest, const u_char *src,
    u_int len)
{
	struct ssh_rijndael_ctx *c;
	u_char buf[RIJNDAEL_BLOCKSIZE];
	u_char *cprev, *cnow, *plain, *ivp;
	int i, j, blocks = len / RIJNDAEL_BLOCKSIZE;

	if (len == 0)
		return (1);
	if (len % RIJNDAEL_BLOCKSIZE)
		fatal("ssh_rijndael_cbc: bad len %d", len);
	if ((c = EVP_CIPHER_CTX_get_app_data(ctx)) == NULL) {
		error("ssh_rijndael_cbc: no context");
		return (0);
	}
	if (ctx->encrypt) {
		cnow  = dest;
		plain = (u_char *)src;
		cprev = c->r_iv;
		for (i = 0; i < blocks; i++, plain+=RIJNDAEL_BLOCKSIZE,
		    cnow+=RIJNDAEL_BLOCKSIZE) {
			for (j = 0; j < RIJNDAEL_BLOCKSIZE; j++)
				buf[j] = plain[j] ^ cprev[j];
			rijndael_encrypt(&c->r_ctx, buf, cnow);
			cprev = cnow;
		}
		memcpy(c->r_iv, cprev, RIJNDAEL_BLOCKSIZE);
	} else {
		cnow  = (u_char *) (src+len-RIJNDAEL_BLOCKSIZE);
		plain = dest+len-RIJNDAEL_BLOCKSIZE;

		memcpy(buf, cnow, RIJNDAEL_BLOCKSIZE);
		for (i = blocks; i > 0; i--, cnow-=RIJNDAEL_BLOCKSIZE,
		    plain-=RIJNDAEL_BLOCKSIZE) {
			rijndael_decrypt(&c->r_ctx, cnow, plain);
			ivp = (i == 1) ? c->r_iv : cnow-RIJNDAEL_BLOCKSIZE;
			for (j = 0; j < RIJNDAEL_BLOCKSIZE; j++)
				plain[j] ^= ivp[j];
		}
		memcpy(c->r_iv, buf, RIJNDAEL_BLOCKSIZE);
	}
	return (1);
}
static int
ssh_rijndael_cleanup(EVP_CIPHER_CTX *ctx)
{
	struct ssh_rijndael_ctx *c;

	if ((c = EVP_CIPHER_CTX_get_app_data(ctx)) != NULL) {
		memset(c, 0, sizeof(*c));
		xfree(c);
		EVP_CIPHER_CTX_set_app_data(ctx, NULL);
	}
	return (1);
}
static EVP_CIPHER *
evp_rijndael(void)
{
	static EVP_CIPHER rijndal_cbc;

	memset(&rijndal_cbc, 0, sizeof(EVP_CIPHER));
	rijndal_cbc.nid = NID_undef;
	rijndal_cbc.block_size = RIJNDAEL_BLOCKSIZE;
	rijndal_cbc.iv_len = RIJNDAEL_BLOCKSIZE;
	rijndal_cbc.key_len = 16;
	rijndal_cbc.init = ssh_rijndael_init;
	rijndal_cbc.cleanup = ssh_rijndael_cleanup;
	rijndal_cbc.do_cipher = ssh_rijndael_cbc;
	rijndal_cbc.flags = EVP_CIPH_CBC_MODE | EVP_CIPH_VARIABLE_LENGTH |
	    EVP_CIPH_ALWAYS_CALL_INIT;
	return (&rijndal_cbc);
}
Commit	Line	Data
8efc0c15	1	/*
5260325f	2	* Author: Tatu Ylonen <ylo@cs.hut.fi>
5260325f	3	* Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
5260325f	4	* All rights reserved
6ae2364d	5	*
bcbf86ec	6	* As far as I am concerned, the code I have written for this software
	7	* can be used freely for any purpose. Any derived versions of this
	8	* software must be clearly marked as such, and if the derived work is
	9	* incompatible with the protocol description in the RFC file, it must be
	10	* called by a name other than "ssh" or "Secure Shell".
	11	*
	12	*
	13	* Copyright (c) 1999 Niels Provos. All rights reserved.
a96070d4	14	* Copyright (c) 1999, 2000 Markus Friedl. All rights reserved.
bcbf86ec	15	*
	16	* Redistribution and use in source and binary forms, with or without
	17	* modification, are permitted provided that the following conditions
	18	* are met:
	19	* 1. Redistributions of source code must retain the above copyright
	20	* notice, this list of conditions and the following disclaimer.
	21	* 2. Redistributions in binary form must reproduce the above copyright
	22	* notice, this list of conditions and the following disclaimer in the
	23	* documentation and/or other materials provided with the distribution.
6ae2364d	24	*
bcbf86ec	25	* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
	26	* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
	27	* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
	28	* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
	29	* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
	30	* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
	31	* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
	32	* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
	33	* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
	34	* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
5260325f	35	*/
8efc0c15	36
8efc0c15	37	#include "includes.h"
70fc1609	38	RCSID("$OpenBSD: cipher.c,v 1.52 2002/02/18 13:05:32 markus Exp $");
8efc0c15	39
a8be9f80	40	#include "xmalloc.h"
42f11eb2	41	#include "log.h"
42f11eb2	42	#include "cipher.h"
8efc0c15	43
8efc0c15	44	#include <openssl/md5.h>
70fc1609	45	#include "rijndael.h"
	46
	47	static EVP_CIPHER *evp_ssh1_3des(void);
	48	static EVP_CIPHER *evp_ssh1_bf(void);
	49	static EVP_CIPHER *evp_rijndael(void);
8efc0c15	50
3ee832e5	51	struct Cipher {
	52	char *name;
	53	int number; /* for ssh1 only */
	54	u_int block_size;
	55	u_int key_len;
70fc1609	56	EVP_CIPHER (evptype)(void);
	57	} ciphers[] = {
	58	{ "none", SSH_CIPHER_NONE, 8, 0, EVP_enc_null },
	59	{ "des", SSH_CIPHER_DES, 8, 8, EVP_des_cbc },
	60	{ "3des", SSH_CIPHER_3DES, 8, 16, evp_ssh1_3des },
	61	{ "blowfish", SSH_CIPHER_BLOWFISH, 8, 32, evp_ssh1_bf },
	62
	63	{ "3des-cbc", SSH_CIPHER_SSH2, 8, 24, EVP_des_ede3_cbc },
	64	{ "blowfish-cbc", SSH_CIPHER_SSH2, 8, 16, EVP_bf_cbc },
	65	{ "cast128-cbc", SSH_CIPHER_SSH2, 8, 16, EVP_cast5_cbc },
	66	{ "arcfour", SSH_CIPHER_SSH2, 8, 16, EVP_rc4 },
	67	{ "aes128-cbc", SSH_CIPHER_SSH2, 16, 16, evp_rijndael },
	68	{ "aes192-cbc", SSH_CIPHER_SSH2, 16, 24, evp_rijndael },
	69	{ "aes256-cbc", SSH_CIPHER_SSH2, 16, 32, evp_rijndael },
	70
	71	{ NULL, SSH_CIPHER_ILLEGAL, 0, 0, NULL }
94ec8c6b	72	};
	73
	74	/--/
	75
70fc1609	76	u_int
3ee832e5	77	cipher_blocksize(Cipher *c)
	78	{
	79	return (c->block_size);
	80	}
70fc1609	81	u_int
3ee832e5	82	cipher_keylen(Cipher *c)
	83	{
	84	return (c->key_len);
	85	}
	86
1e3b8b07	87	u_int
94ec8c6b	88	cipher_mask_ssh1(int client)
8ce64345	89	{
1e3b8b07	90	u_int mask = 0;
184eed6a	91	mask \|= 1 << SSH_CIPHER_3DES; /* Mandatory */
94ec8c6b	92	mask \|= 1 << SSH_CIPHER_BLOWFISH;
	93	if (client) {
	94	mask \|= 1 << SSH_CIPHER_DES;
	95	}
5260325f	96	return mask;
8efc0c15	97	}
94ec8c6b	98
	99	Cipher *
	100	cipher_by_name(const char *name)
8ce64345	101	{
94ec8c6b	102	Cipher *c;
	103	for (c = ciphers; c->name != NULL; c++)
	104	if (strcasecmp(c->name, name) == 0)
	105	return c;
	106	return NULL;
8ce64345	107	}
8efc0c15	108
94ec8c6b	109	Cipher *
94ec8c6b	110	cipher_by_number(int id)
8efc0c15	111	{
94ec8c6b	112	Cipher *c;
	113	for (c = ciphers; c->name != NULL; c++)
	114	if (c->number == id)
	115	return c;
	116	return NULL;
8efc0c15	117	}
8efc0c15	118
a8be9f80	119	#define CIPHER_SEP ","
	120	int
	121	ciphers_valid(const char *names)
	122	{
94ec8c6b	123	Cipher *c;
089fbbd2	124	char ciphers, cp;
a8be9f80	125	char *p;
a8be9f80	126
71276795	127	if (names == NULL \|\| strcmp(names, "") == 0)
a8be9f80	128	return 0;
089fbbd2	129	ciphers = cp = xstrdup(names);
94ec8c6b	130	for ((p = strsep(&cp, CIPHER_SEP)); p && *p != '\0';
184eed6a	131	(p = strsep(&cp, CIPHER_SEP))) {
94ec8c6b	132	c = cipher_by_name(p);
	133	if (c == NULL \|\| c->number != SSH_CIPHER_SSH2) {
	134	debug("bad cipher %s [%s]", p, names);
a8be9f80	135	xfree(ciphers);
a8be9f80	136	return 0;
94ec8c6b	137	} else {
33de75a3	138	debug3("cipher ok: %s [%s]", p, names);
a8be9f80	139	}
a8be9f80	140	}
33de75a3	141	debug3("ciphers ok: [%s]", names);
a8be9f80	142	xfree(ciphers);
	143	return 1;
	144	}
	145
aa3378df	146	/*
	147	* Parses the name of the cipher. Returns the number of the corresponding
	148	* cipher, or -1 on error.
	149	*/
8efc0c15	150
	151	int
	152	cipher_number(const char *name)
	153	{
94ec8c6b	154	Cipher *c;
71276795	155	if (name == NULL)
71276795	156	return -1;
94ec8c6b	157	c = cipher_by_name(name);
	158	return (c==NULL) ? -1 : c->number;
	159	}
	160
	161	char *
	162	cipher_name(int id)
	163	{
	164	Cipher *c = cipher_by_number(id);
	165	return (c==NULL) ? "<unknown>" : c->name;
	166	}
	167
	168	void
70fc1609	169	cipher_init(CipherContext cc, Cipher cipher,
	170	const u_char key, u_int keylen, const u_char iv, u_int ivlen,
	171	int encrypt)
94ec8c6b	172	{
70fc1609	173	static int dowarn = 1;
	174	const EVP_CIPHER *type;
	175	int klen;
	176
	177	if (cipher->number == SSH_CIPHER_DES) {
	178	if (dowarn) {
	179	error("Warning: use of DES is strongly discouraged "
	180	"due to cryptographic weaknesses");
	181	dowarn = 0;
	182	}
	183	if (keylen > 8)
	184	keylen = 8;
	185	}
	186	cc->plaintext = (cipher->number == SSH_CIPHER_NONE);
	187
94ec8c6b	188	if (keylen < cipher->key_len)
	189	fatal("cipher_init: key length %d is insufficient for %s.",
	190	keylen, cipher->name);
	191	if (iv != NULL && ivlen < cipher->block_size)
	192	fatal("cipher_init: iv length %d is insufficient for %s.",
	193	ivlen, cipher->name);
	194	cc->cipher = cipher;
70fc1609	195
	196	type = (*cipher->evptype)();
	197
	198	EVP_CIPHER_CTX_init(&cc->evp);
	199	if (EVP_CipherInit(&cc->evp, type, NULL, (u_char *)iv,
	200	(encrypt == CIPHER_ENCRYPT)) == 0)
	201	fatal("cipher_init: EVP_CipherInit failed for %s",
	202	cipher->name);
	203	klen = EVP_CIPHER_CTX_key_length(&cc->evp);
	204	if (klen > 0 && keylen != klen) {
	205	debug("cipher_init: set keylen (%d -> %d)", klen, keylen);
	206	if (EVP_CIPHER_CTX_set_key_length(&cc->evp, keylen) == 0)
	207	fatal("cipher_init: set keylen failed (%d -> %d)",
	208	klen, keylen);
	209	}
	210	if (EVP_CipherInit(&cc->evp, NULL, (u_char *)key, NULL, -1) == 0)
	211	fatal("cipher_init: EVP_CipherInit: set key failed for %s",
	212	cipher->name);
94ec8c6b	213	}
	214
	215	void
3ee832e5	216	cipher_crypt(CipherContext cc, u_char dest, const u_char *src, u_int len)
94ec8c6b	217	{
	218	if (len % cc->cipher->block_size)
	219	fatal("cipher_encrypt: bad plaintext length %d", len);
70fc1609	220	if (EVP_Cipher(&cc->evp, dest, (u_char *)src, len) == 0)
70fc1609	221	fatal("evp_crypt: EVP_Cipher failed");
94ec8c6b	222	}
	223
	224	void
3ee832e5	225	cipher_cleanup(CipherContext *cc)
94ec8c6b	226	{
70fc1609	227	if (EVP_CIPHER_CTX_cleanup(&cc->evp) == 0)
70fc1609	228	error("cipher_cleanup: EVP_CIPHER_CTX_cleanup failed");
8efc0c15	229	}
8efc0c15	230
aa3378df	231	/*
	232	* Selects the cipher, and keys if by computing the MD5 checksum of the
	233	* passphrase and using the resulting 16 bytes as the key.
	234	*/
8efc0c15	235
6ae2364d	236	void
94ec8c6b	237	cipher_set_key_string(CipherContext cc, Cipher cipher,
3ee832e5	238	const char *passphrase, int encrypt)
8efc0c15	239	{
5260325f	240	MD5_CTX md;
1e3b8b07	241	u_char digest[16];
5260325f	242
5260325f	243	MD5_Init(&md);
94ec8c6b	244	MD5_Update(&md, (const u_char *)passphrase, strlen(passphrase));
5260325f	245	MD5_Final(digest, &md);
5260325f	246
3ee832e5	247	cipher_init(cc, cipher, digest, 16, NULL, 0, encrypt);
5260325f	248
	249	memset(digest, 0, sizeof(digest));
	250	memset(&md, 0, sizeof(md));
8efc0c15	251	}
70fc1609	252
	253	/* Implementations for other non-EVP ciphers */
	254
	255	/*
	256	* This is used by SSH1:
	257	*
	258	* What kind of triple DES are these 2 routines?
	259	*
	260	* Why is there a redundant initialization vector?
	261	*
	262	* If only iv3 was used, then, this would till effect have been
	263	* outer-cbc. However, there is also a private iv1 == iv2 which
	264	* perhaps makes differential analysis easier. On the other hand, the
	265	* private iv1 probably makes the CRC-32 attack ineffective. This is a
	266	* result of that there is no longer any known iv1 to use when
	267	* choosing the X block.
	268	*/
	269	struct ssh1_3des_ctx
	270	{
	271	EVP_CIPHER_CTX k1, k2, k3;
	272	};
	273	static int
	274	ssh1_3des_init(EVP_CIPHER_CTX ctx, const u_char key, const u_char *iv,
	275	int enc)
	276	{
	277	struct ssh1_3des_ctx *c;
	278	u_char k1, k2, *k3;
	279
	280	if ((c = EVP_CIPHER_CTX_get_app_data(ctx)) == NULL) {
	281	c = xmalloc(sizeof(*c));
	282	EVP_CIPHER_CTX_set_app_data(ctx, c);
	283	}
	284	if (key == NULL)
	285	return (1);
	286	if (enc == -1)
	287	enc = ctx->encrypt;
	288	k1 = k2 = k3 = (u_char *) key;
	289	k2 += 8;
	290	if (EVP_CIPHER_CTX_key_length(ctx) >= 16+8) {
	291	if (enc)
	292	k3 += 16;
	293	else
	294	k1 += 16;
	295	}
	296	EVP_CIPHER_CTX_init(&c->k1);
	297	EVP_CIPHER_CTX_init(&c->k2);
	298	EVP_CIPHER_CTX_init(&c->k3);
	299	if (EVP_CipherInit(&c->k1, EVP_des_cbc(), k1, NULL, enc) == 0 \|\|
	300	EVP_CipherInit(&c->k2, EVP_des_cbc(), k2, NULL, !enc) == 0 \|\|
	301	EVP_CipherInit(&c->k3, EVP_des_cbc(), k3, NULL, enc) == 0) {
	302	memset(c, 0, sizeof(*c));
	303	xfree(c);
	304	EVP_CIPHER_CTX_set_app_data(ctx, NULL);
	305	return (0);
	306	}
	307	return (1);
	308	}
	309	static int
	310	ssh1_3des_cbc(EVP_CIPHER_CTX ctx, u_char dest, const u_char *src, u_int len)
	311	{
	312	struct ssh1_3des_ctx *c;
	313
	314	if ((c = EVP_CIPHER_CTX_get_app_data(ctx)) == NULL) {
	315	error("ssh1_3des_cbc: no context");
316	return (0);
317	}
318	if (EVP_Cipher(&c->k1, dest, (u_char *)src, len) == 0 \|\|
319	EVP_Cipher(&c->k2, dest, dest, len) == 0 \|\|
320	EVP_Cipher(&c->k3, dest, dest, len) == 0)
321	return (0);
322	return (1);
323	}
324	static int
325	ssh1_3des_cleanup(EVP_CIPHER_CTX *ctx)
326	{
327	struct ssh1_3des_ctx *c;
328
329	if ((c = EVP_CIPHER_CTX_get_app_data(ctx)) != NULL) {
330	memset(c, 0, sizeof(*c));
331	xfree(c);
332	EVP_CIPHER_CTX_set_app_data(ctx, NULL);
333	}
334	return (1);
335	}
336	static EVP_CIPHER *
337	evp_ssh1_3des(void)
338	{
339	static EVP_CIPHER ssh1_3des;
340
341	memset(&ssh1_3des, 0, sizeof(EVP_CIPHER));
342	ssh1_3des.nid = NID_undef;
343	ssh1_3des.block_size = 8;
344	ssh1_3des.iv_len = 0;
345	ssh1_3des.key_len = 16;
346	ssh1_3des.init = ssh1_3des_init;
347	ssh1_3des.cleanup = ssh1_3des_cleanup;
348	ssh1_3des.do_cipher = ssh1_3des_cbc;
349	ssh1_3des.flags = EVP_CIPH_CBC_MODE \| EVP_CIPH_VARIABLE_LENGTH;
350	return (&ssh1_3des);
351	}
352
353	/*
354	* SSH1 uses a variation on Blowfish, all bytes must be swapped before
355	* and after encryption/decryption. Thus the swap_bytes stuff (yuk).
356	*/
357	static void
358	swap_bytes(const u_char src, u_char dst, int n)
359	{
360	u_char c[4];
361
362	/* Process 4 bytes every lap. */
363	for (n = n / 4; n > 0; n--) {
364	c[3] = *src++;
365	c[2] = *src++;
366	c[1] = *src++;
367	c[0] = *src++;
368
369	*dst++ = c[0];
370	*dst++ = c[1];
371	*dst++ = c[2];
372	*dst++ = c[3];
373	}
374	}
375	static int (orig_bf)(EVP_CIPHER_CTX , u_char , const u_char , u_int) = NULL;
376	static int
377	bf_ssh1_cipher(EVP_CIPHER_CTX ctx, u_char out, const u_char *in, u_int len)
378	{
379	int ret;
380
381	swap_bytes(in, out, len);
382	ret = (*orig_bf)(ctx, out, out, len);
383	swap_bytes(out, out, len);
384	return (ret);
385	}
386	static EVP_CIPHER *
387	evp_ssh1_bf(void)
388	{
389	static EVP_CIPHER ssh1_bf;
390
391	memcpy(&ssh1_bf, EVP_bf_cbc(), sizeof(EVP_CIPHER));
392	orig_bf = ssh1_bf.do_cipher;
393	ssh1_bf.nid = NID_undef;
394	ssh1_bf.do_cipher = bf_ssh1_cipher;
395	ssh1_bf.key_len = 32;
396	return (&ssh1_bf);
397	}
398
399	/* RIJNDAEL */
400	#define RIJNDAEL_BLOCKSIZE 16
401	struct ssh_rijndael_ctx
402	{
403	rijndael_ctx r_ctx;
404	u_char r_iv[RIJNDAEL_BLOCKSIZE];
405	};
406
407	static int
408	ssh_rijndael_init(EVP_CIPHER_CTX ctx, const u_char key, const u_char *iv,
409	int enc)
410	{
411	struct ssh_rijndael_ctx *c;
412
413	if ((c = EVP_CIPHER_CTX_get_app_data(ctx)) == NULL) {
414	c = xmalloc(sizeof(*c));
415	EVP_CIPHER_CTX_set_app_data(ctx, c);
416	}
417	if (key != NULL) {
418	if (enc == -1)
419	enc = ctx->encrypt;
420	rijndael_set_key(&c->r_ctx, (u_char *)key,
421	8*EVP_CIPHER_CTX_key_length(ctx), enc);
422	}
423	if (iv != NULL)
424	memcpy(c->r_iv, iv, RIJNDAEL_BLOCKSIZE);
425	return (1);
426	}
427	static int
428	ssh_rijndael_cbc(EVP_CIPHER_CTX ctx, u_char dest, const u_char *src,
429	u_int len)
430	{
431	struct ssh_rijndael_ctx *c;
432	u_char buf[RIJNDAEL_BLOCKSIZE];
433	u_char cprev, cnow, plain, ivp;
434	int i, j, blocks = len / RIJNDAEL_BLOCKSIZE;
435
436	if (len == 0)
437	return (1);
438	if (len % RIJNDAEL_BLOCKSIZE)
439	fatal("ssh_rijndael_cbc: bad len %d", len);
440	if ((c = EVP_CIPHER_CTX_get_app_data(ctx)) == NULL) {
441	error("ssh_rijndael_cbc: no context");
442	return (0);
443	}
444	if (ctx->encrypt) {
445	cnow = dest;
446	plain = (u_char *)src;
447	cprev = c->r_iv;
448	for (i = 0; i < blocks; i++, plain+=RIJNDAEL_BLOCKSIZE,
449	cnow+=RIJNDAEL_BLOCKSIZE) {
450	for (j = 0; j < RIJNDAEL_BLOCKSIZE; j++)
451	buf[j] = plain[j] ^ cprev[j];
452	rijndael_encrypt(&c->r_ctx, buf, cnow);
453	cprev = cnow;
454	}
455	memcpy(c->r_iv, cprev, RIJNDAEL_BLOCKSIZE);
456	} else {
457	cnow = (u_char *) (src+len-RIJNDAEL_BLOCKSIZE);
458	plain = dest+len-RIJNDAEL_BLOCKSIZE;
459
460	memcpy(buf, cnow, RIJNDAEL_BLOCKSIZE);
461	for (i = blocks; i > 0; i--, cnow-=RIJNDAEL_BLOCKSIZE,
462	plain-=RIJNDAEL_BLOCKSIZE) {
463	rijndael_decrypt(&c->r_ctx, cnow, plain);
464	ivp = (i == 1) ? c->r_iv : cnow-RIJNDAEL_BLOCKSIZE;
465	for (j = 0; j < RIJNDAEL_BLOCKSIZE; j++)
466	plain[j] ^= ivp[j];
467	}
468	memcpy(c->r_iv, buf, RIJNDAEL_BLOCKSIZE);
469	}
470	return (1);
471	}
472	static int
473	ssh_rijndael_cleanup(EVP_CIPHER_CTX *ctx)
474	{
475	struct ssh_rijndael_ctx *c;
476
477	if ((c = EVP_CIPHER_CTX_get_app_data(ctx)) != NULL) {
478	memset(c, 0, sizeof(*c));
479	xfree(c);
480	EVP_CIPHER_CTX_set_app_data(ctx, NULL);
481	}
482	return (1);
483	}
484	static EVP_CIPHER *
485	evp_rijndael(void)
486	{
487	static EVP_CIPHER rijndal_cbc;
488
489	memset(&rijndal_cbc, 0, sizeof(EVP_CIPHER));
490	rijndal_cbc.nid = NID_undef;
491	rijndal_cbc.block_size = RIJNDAEL_BLOCKSIZE;
492	rijndal_cbc.iv_len = RIJNDAEL_BLOCKSIZE;
493	rijndal_cbc.key_len = 16;
494	rijndal_cbc.init = ssh_rijndael_init;
495	rijndal_cbc.cleanup = ssh_rijndael_cleanup;
496	rijndal_cbc.do_cipher = ssh_rijndael_cbc;
497	rijndal_cbc.flags = EVP_CIPH_CBC_MODE \| EVP_CIPH_VARIABLE_LENGTH \|
498	EVP_CIPH_ALWAYS_CALL_INIT;
499	return (&rijndal_cbc);
500	}