2 * Author: Tatu Ylonen <ylo@cs.hut.fi>
3 * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
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".
13 * Copyright (c) 1999 Niels Provos. All rights reserved.
14 * Copyright (c) 1999, 2000 Markus Friedl. All rights reserved.
16 * Redistribution and use in source and binary forms, with or without
17 * modification, are permitted provided that the following conditions
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.
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.
38 RCSID("$OpenBSD: cipher.c,v 1.61 2002/07/12 15:50:17 markus Exp $");
44 #include <openssl/md5.h>
46 #if OPENSSL_VERSION_NUMBER < 0x00906000L
48 #define EVP_CIPHER_CTX_get_app_data(e) ((e)->app_data)
51 #if OPENSSL_VERSION_NUMBER < 0x00907000L
53 static const EVP_CIPHER *evp_rijndael(void);
55 static const EVP_CIPHER *evp_ssh1_3des(void);
56 static const EVP_CIPHER *evp_ssh1_bf(void);
60 int number; /* for ssh1 only */
63 const EVP_CIPHER *(*evptype)(void);
65 { "none", SSH_CIPHER_NONE, 8, 0, EVP_enc_null },
66 { "des", SSH_CIPHER_DES, 8, 8, EVP_des_cbc },
67 { "3des", SSH_CIPHER_3DES, 8, 16, evp_ssh1_3des },
68 { "blowfish", SSH_CIPHER_BLOWFISH, 8, 32, evp_ssh1_bf },
70 { "3des-cbc", SSH_CIPHER_SSH2, 8, 24, EVP_des_ede3_cbc },
71 { "blowfish-cbc", SSH_CIPHER_SSH2, 8, 16, EVP_bf_cbc },
72 { "cast128-cbc", SSH_CIPHER_SSH2, 8, 16, EVP_cast5_cbc },
73 { "arcfour", SSH_CIPHER_SSH2, 8, 16, EVP_rc4 },
74 #if OPENSSL_VERSION_NUMBER < 0x00907000L
75 { "aes128-cbc", SSH_CIPHER_SSH2, 16, 16, evp_rijndael },
76 { "aes192-cbc", SSH_CIPHER_SSH2, 16, 24, evp_rijndael },
77 { "aes256-cbc", SSH_CIPHER_SSH2, 16, 32, evp_rijndael },
78 { "rijndael-cbc@lysator.liu.se",
79 SSH_CIPHER_SSH2, 16, 32, evp_rijndael },
81 { "aes128-cbc", SSH_CIPHER_SSH2, 16, 16, EVP_aes_128_cbc },
82 { "aes192-cbc", SSH_CIPHER_SSH2, 16, 24, EVP_aes_192_cbc },
83 { "aes256-cbc", SSH_CIPHER_SSH2, 16, 32, EVP_aes_256_cbc },
84 { "rijndael-cbc@lysator.liu.se",
85 SSH_CIPHER_SSH2, 16, 32, EVP_aes_256_cbc },
88 { NULL, SSH_CIPHER_ILLEGAL, 0, 0, NULL }
94 cipher_blocksize(Cipher *c)
96 return (c->block_size);
100 cipher_keylen(Cipher *c)
106 cipher_get_number(Cipher *c)
112 cipher_mask_ssh1(int client)
115 mask |= 1 << SSH_CIPHER_3DES; /* Mandatory */
116 mask |= 1 << SSH_CIPHER_BLOWFISH;
118 mask |= 1 << SSH_CIPHER_DES;
124 cipher_by_name(const char *name)
127 for (c = ciphers; c->name != NULL; c++)
128 if (strcasecmp(c->name, name) == 0)
134 cipher_by_number(int id)
137 for (c = ciphers; c->name != NULL; c++)
143 #define CIPHER_SEP ","
145 ciphers_valid(const char *names)
151 if (names == NULL || strcmp(names, "") == 0)
153 ciphers = cp = xstrdup(names);
154 for ((p = strsep(&cp, CIPHER_SEP)); p && *p != '\0';
155 (p = strsep(&cp, CIPHER_SEP))) {
156 c = cipher_by_name(p);
157 if (c == NULL || c->number != SSH_CIPHER_SSH2) {
158 debug("bad cipher %s [%s]", p, names);
162 debug3("cipher ok: %s [%s]", p, names);
165 debug3("ciphers ok: [%s]", names);
171 * Parses the name of the cipher. Returns the number of the corresponding
172 * cipher, or -1 on error.
176 cipher_number(const char *name)
181 c = cipher_by_name(name);
182 return (c==NULL) ? -1 : c->number;
188 Cipher *c = cipher_by_number(id);
189 return (c==NULL) ? "<unknown>" : c->name;
193 cipher_init(CipherContext *cc, Cipher *cipher,
194 const u_char *key, u_int keylen, const u_char *iv, u_int ivlen,
197 static int dowarn = 1;
201 const EVP_CIPHER *type;
205 if (cipher->number == SSH_CIPHER_DES) {
207 error("Warning: use of DES is strongly discouraged "
208 "due to cryptographic weaknesses");
214 cc->plaintext = (cipher->number == SSH_CIPHER_NONE);
216 if (keylen < cipher->key_len)
217 fatal("cipher_init: key length %d is insufficient for %s.",
218 keylen, cipher->name);
219 if (iv != NULL && ivlen < cipher->block_size)
220 fatal("cipher_init: iv length %d is insufficient for %s.",
221 ivlen, cipher->name);
224 type = (*cipher->evptype)();
226 EVP_CIPHER_CTX_init(&cc->evp);
228 if (type->key_len > 0 && type->key_len != keylen) {
229 debug("cipher_init: set keylen (%d -> %d)",
230 type->key_len, keylen);
231 type->key_len = keylen;
233 EVP_CipherInit(&cc->evp, type, (u_char *)key, (u_char *)iv,
234 (encrypt == CIPHER_ENCRYPT));
236 if (EVP_CipherInit(&cc->evp, type, NULL, (u_char *)iv,
237 (encrypt == CIPHER_ENCRYPT)) == 0)
238 fatal("cipher_init: EVP_CipherInit failed for %s",
240 klen = EVP_CIPHER_CTX_key_length(&cc->evp);
241 if (klen > 0 && keylen != klen) {
242 debug("cipher_init: set keylen (%d -> %d)", klen, keylen);
243 if (EVP_CIPHER_CTX_set_key_length(&cc->evp, keylen) == 0)
244 fatal("cipher_init: set keylen failed (%d -> %d)",
247 if (EVP_CipherInit(&cc->evp, NULL, (u_char *)key, NULL, -1) == 0)
248 fatal("cipher_init: EVP_CipherInit: set key failed for %s",
254 cipher_crypt(CipherContext *cc, u_char *dest, const u_char *src, u_int len)
256 if (len % cc->cipher->block_size)
257 fatal("cipher_encrypt: bad plaintext length %d", len);
259 EVP_Cipher(&cc->evp, dest, (u_char *)src, len);
261 if (EVP_Cipher(&cc->evp, dest, (u_char *)src, len) == 0)
262 fatal("evp_crypt: EVP_Cipher failed");
267 cipher_cleanup(CipherContext *cc)
270 EVP_CIPHER_CTX_cleanup(&cc->evp);
272 if (EVP_CIPHER_CTX_cleanup(&cc->evp) == 0)
273 error("cipher_cleanup: EVP_CIPHER_CTX_cleanup failed");
278 * Selects the cipher, and keys if by computing the MD5 checksum of the
279 * passphrase and using the resulting 16 bytes as the key.
283 cipher_set_key_string(CipherContext *cc, Cipher *cipher,
284 const char *passphrase, int encrypt)
290 MD5_Update(&md, (const u_char *)passphrase, strlen(passphrase));
291 MD5_Final(digest, &md);
293 cipher_init(cc, cipher, digest, 16, NULL, 0, encrypt);
295 memset(digest, 0, sizeof(digest));
296 memset(&md, 0, sizeof(md));
299 /* Implementations for other non-EVP ciphers */
302 * This is used by SSH1:
304 * What kind of triple DES are these 2 routines?
306 * Why is there a redundant initialization vector?
308 * If only iv3 was used, then, this would till effect have been
309 * outer-cbc. However, there is also a private iv1 == iv2 which
310 * perhaps makes differential analysis easier. On the other hand, the
311 * private iv1 probably makes the CRC-32 attack ineffective. This is a
312 * result of that there is no longer any known iv1 to use when
313 * choosing the X block.
317 EVP_CIPHER_CTX k1, k2, k3;
321 ssh1_3des_init(EVP_CIPHER_CTX *ctx, const u_char *key, const u_char *iv,
324 struct ssh1_3des_ctx *c;
325 u_char *k1, *k2, *k3;
327 if ((c = EVP_CIPHER_CTX_get_app_data(ctx)) == NULL) {
328 c = xmalloc(sizeof(*c));
329 EVP_CIPHER_CTX_set_app_data(ctx, c);
335 k1 = k2 = k3 = (u_char *) key;
337 if (EVP_CIPHER_CTX_key_length(ctx) >= 16+8) {
343 EVP_CIPHER_CTX_init(&c->k1);
344 EVP_CIPHER_CTX_init(&c->k2);
345 EVP_CIPHER_CTX_init(&c->k3);
347 EVP_CipherInit(&c->k1, EVP_des_cbc(), k1, NULL, enc);
348 EVP_CipherInit(&c->k2, EVP_des_cbc(), k2, NULL, !enc);
349 EVP_CipherInit(&c->k3, EVP_des_cbc(), k3, NULL, enc);
351 if (EVP_CipherInit(&c->k1, EVP_des_cbc(), k1, NULL, enc) == 0 ||
352 EVP_CipherInit(&c->k2, EVP_des_cbc(), k2, NULL, !enc) == 0 ||
353 EVP_CipherInit(&c->k3, EVP_des_cbc(), k3, NULL, enc) == 0) {
354 memset(c, 0, sizeof(*c));
356 EVP_CIPHER_CTX_set_app_data(ctx, NULL);
364 ssh1_3des_cbc(EVP_CIPHER_CTX *ctx, u_char *dest, const u_char *src, u_int len)
366 struct ssh1_3des_ctx *c;
368 if ((c = EVP_CIPHER_CTX_get_app_data(ctx)) == NULL) {
369 error("ssh1_3des_cbc: no context");
373 EVP_Cipher(&c->k1, dest, (u_char *)src, len);
374 EVP_Cipher(&c->k2, dest, dest, len);
375 EVP_Cipher(&c->k3, dest, dest, len);
377 if (EVP_Cipher(&c->k1, dest, (u_char *)src, len) == 0 ||
378 EVP_Cipher(&c->k2, dest, dest, len) == 0 ||
379 EVP_Cipher(&c->k3, dest, dest, len) == 0)
386 ssh1_3des_cleanup(EVP_CIPHER_CTX *ctx)
388 struct ssh1_3des_ctx *c;
390 if ((c = EVP_CIPHER_CTX_get_app_data(ctx)) != NULL) {
391 memset(c, 0, sizeof(*c));
393 EVP_CIPHER_CTX_set_app_data(ctx, NULL);
398 static const EVP_CIPHER *
401 static EVP_CIPHER ssh1_3des;
403 memset(&ssh1_3des, 0, sizeof(EVP_CIPHER));
404 ssh1_3des.nid = NID_undef;
405 ssh1_3des.block_size = 8;
406 ssh1_3des.iv_len = 0;
407 ssh1_3des.key_len = 16;
408 ssh1_3des.init = ssh1_3des_init;
409 ssh1_3des.cleanup = ssh1_3des_cleanup;
410 ssh1_3des.do_cipher = ssh1_3des_cbc;
412 ssh1_3des.flags = EVP_CIPH_CBC_MODE | EVP_CIPH_VARIABLE_LENGTH;
418 * SSH1 uses a variation on Blowfish, all bytes must be swapped before
419 * and after encryption/decryption. Thus the swap_bytes stuff (yuk).
422 swap_bytes(const u_char *src, u_char *dst, int n)
426 /* Process 4 bytes every lap. */
427 for (n = n / 4; n > 0; n--) {
441 static void bf_ssh1_init (EVP_CIPHER_CTX * ctx, const unsigned char *key,
442 const unsigned char *iv, int enc)
445 memcpy (&(ctx->oiv[0]), iv, 8);
446 memcpy (&(ctx->iv[0]), &(ctx->oiv[0]), 8);
448 BF_set_key (&(ctx->c.bf_ks), EVP_CIPHER_CTX_key_length (ctx),
452 static int (*orig_bf)(EVP_CIPHER_CTX *, u_char *, const u_char *, u_int) = NULL;
455 bf_ssh1_cipher(EVP_CIPHER_CTX *ctx, u_char *out, const u_char *in, u_int len)
459 swap_bytes(in, out, len);
460 ret = (*orig_bf)(ctx, out, out, len);
461 swap_bytes(out, out, len);
465 static const EVP_CIPHER *
468 static EVP_CIPHER ssh1_bf;
470 memcpy(&ssh1_bf, EVP_bf_cbc(), sizeof(EVP_CIPHER));
471 orig_bf = ssh1_bf.do_cipher;
472 ssh1_bf.nid = NID_undef;
474 ssh1_bf.init = bf_ssh1_init;
476 ssh1_bf.do_cipher = bf_ssh1_cipher;
477 ssh1_bf.key_len = 32;
481 #if OPENSSL_VERSION_NUMBER < 0x00907000L
483 #define RIJNDAEL_BLOCKSIZE 16
484 struct ssh_rijndael_ctx
487 u_char r_iv[RIJNDAEL_BLOCKSIZE];
491 ssh_rijndael_init(EVP_CIPHER_CTX *ctx, const u_char *key, const u_char *iv,
494 struct ssh_rijndael_ctx *c;
496 if ((c = EVP_CIPHER_CTX_get_app_data(ctx)) == NULL) {
497 c = xmalloc(sizeof(*c));
498 EVP_CIPHER_CTX_set_app_data(ctx, c);
503 rijndael_set_key(&c->r_ctx, (u_char *)key,
504 8*EVP_CIPHER_CTX_key_length(ctx), enc);
507 memcpy(c->r_iv, iv, RIJNDAEL_BLOCKSIZE);
512 ssh_rijndael_cbc(EVP_CIPHER_CTX *ctx, u_char *dest, const u_char *src,
515 struct ssh_rijndael_ctx *c;
516 u_char buf[RIJNDAEL_BLOCKSIZE];
517 u_char *cprev, *cnow, *plain, *ivp;
518 int i, j, blocks = len / RIJNDAEL_BLOCKSIZE;
522 if (len % RIJNDAEL_BLOCKSIZE)
523 fatal("ssh_rijndael_cbc: bad len %d", len);
524 if ((c = EVP_CIPHER_CTX_get_app_data(ctx)) == NULL) {
525 error("ssh_rijndael_cbc: no context");
530 plain = (u_char *)src;
532 for (i = 0; i < blocks; i++, plain+=RIJNDAEL_BLOCKSIZE,
533 cnow+=RIJNDAEL_BLOCKSIZE) {
534 for (j = 0; j < RIJNDAEL_BLOCKSIZE; j++)
535 buf[j] = plain[j] ^ cprev[j];
536 rijndael_encrypt(&c->r_ctx, buf, cnow);
539 memcpy(c->r_iv, cprev, RIJNDAEL_BLOCKSIZE);
541 cnow = (u_char *) (src+len-RIJNDAEL_BLOCKSIZE);
542 plain = dest+len-RIJNDAEL_BLOCKSIZE;
544 memcpy(buf, cnow, RIJNDAEL_BLOCKSIZE);
545 for (i = blocks; i > 0; i--, cnow-=RIJNDAEL_BLOCKSIZE,
546 plain-=RIJNDAEL_BLOCKSIZE) {
547 rijndael_decrypt(&c->r_ctx, cnow, plain);
548 ivp = (i == 1) ? c->r_iv : cnow-RIJNDAEL_BLOCKSIZE;
549 for (j = 0; j < RIJNDAEL_BLOCKSIZE; j++)
552 memcpy(c->r_iv, buf, RIJNDAEL_BLOCKSIZE);
558 ssh_rijndael_cleanup(EVP_CIPHER_CTX *ctx)
560 struct ssh_rijndael_ctx *c;
562 if ((c = EVP_CIPHER_CTX_get_app_data(ctx)) != NULL) {
563 memset(c, 0, sizeof(*c));
565 EVP_CIPHER_CTX_set_app_data(ctx, NULL);
570 static const EVP_CIPHER *
573 static EVP_CIPHER rijndal_cbc;
575 memset(&rijndal_cbc, 0, sizeof(EVP_CIPHER));
576 rijndal_cbc.nid = NID_undef;
577 rijndal_cbc.block_size = RIJNDAEL_BLOCKSIZE;
578 rijndal_cbc.iv_len = RIJNDAEL_BLOCKSIZE;
579 rijndal_cbc.key_len = 16;
580 rijndal_cbc.init = ssh_rijndael_init;
581 rijndal_cbc.cleanup = ssh_rijndael_cleanup;
582 rijndal_cbc.do_cipher = ssh_rijndael_cbc;
584 rijndal_cbc.flags = EVP_CIPH_CBC_MODE | EVP_CIPH_VARIABLE_LENGTH |
585 EVP_CIPH_ALWAYS_CALL_INIT | EVP_CIPH_CUSTOM_IV;
587 return (&rijndal_cbc);
592 * Exports an IV from the CipherContext required to export the key
593 * state back from the unprivileged child to the privileged parent
598 cipher_get_keyiv_len(CipherContext *cc)
600 Cipher *c = cc->cipher;
603 if (c->number == SSH_CIPHER_3DES)
606 ivlen = EVP_CIPHER_CTX_iv_length(&cc->evp);
611 cipher_get_keyiv(CipherContext *cc, u_char *iv, u_int len)
613 Cipher *c = cc->cipher;
618 case SSH_CIPHER_SSH2:
620 case SSH_CIPHER_BLOWFISH:
621 evplen = EVP_CIPHER_CTX_iv_length(&cc->evp);
625 fatal("%s: wrong iv length %d != %d", __func__,
628 #if OPENSSL_VERSION_NUMBER < 0x00907000L
629 if (c->evptype == evp_rijndael) {
630 struct ssh_rijndael_ctx *aesc;
632 aesc = EVP_CIPHER_CTX_get_app_data(&cc->evp);
634 fatal("%s: no rijndael context", __func__);
642 case SSH_CIPHER_3DES: {
643 struct ssh1_3des_ctx *desc;
645 fatal("%s: bad 3des iv length: %d", __func__, len);
646 desc = EVP_CIPHER_CTX_get_app_data(&cc->evp);
648 fatal("%s: no 3des context", __func__);
649 debug3("%s: Copying 3DES IV", __func__);
650 memcpy(iv, desc->k1.iv, 8);
651 memcpy(iv + 8, desc->k2.iv, 8);
652 memcpy(iv + 16, desc->k3.iv, 8);
656 fatal("%s: bad cipher %d", __func__, c->number);
658 memcpy(iv, civ, len);
662 cipher_set_keyiv(CipherContext *cc, u_char *iv)
664 Cipher *c = cc->cipher;
669 case SSH_CIPHER_SSH2:
671 case SSH_CIPHER_BLOWFISH:
672 evplen = EVP_CIPHER_CTX_iv_length(&cc->evp);
676 #if OPENSSL_VERSION_NUMBER < 0x00907000L
677 if (c->evptype == evp_rijndael) {
678 struct ssh_rijndael_ctx *aesc;
680 aesc = EVP_CIPHER_CTX_get_app_data(&cc->evp);
682 fatal("%s: no rijndael context", __func__);
690 case SSH_CIPHER_3DES: {
691 struct ssh1_3des_ctx *desc;
692 desc = EVP_CIPHER_CTX_get_app_data(&cc->evp);
694 fatal("%s: no 3des context", __func__);
695 debug3("%s: Installed 3DES IV", __func__);
696 memcpy(desc->k1.iv, iv, 8);
697 memcpy(desc->k2.iv, iv + 8, 8);
698 memcpy(desc->k3.iv, iv + 16, 8);
702 fatal("%s: bad cipher %d", __func__, c->number);
704 memcpy(div, iv, evplen);
707 #if OPENSSL_VERSION_NUMBER < 0x00907000L
708 #define EVP_X_STATE(evp) &(evp).c
709 #define EVP_X_STATE_LEN(evp) sizeof((evp).c)
711 #define EVP_X_STATE(evp) (evp).cipher_data
712 #define EVP_X_STATE_LEN(evp) (evp).cipher->ctx_size
716 cipher_get_keycontext(CipherContext *cc, u_char *dat)
718 Cipher *c = cc->cipher;
721 if (c->evptype == EVP_rc4) {
722 plen = EVP_X_STATE_LEN(cc->evp);
725 memcpy(dat, EVP_X_STATE(cc->evp), plen);
731 cipher_set_keycontext(CipherContext *cc, u_char *dat)
733 Cipher *c = cc->cipher;
736 if (c->evptype == EVP_rc4) {
737 plen = EVP_X_STATE_LEN(cc->evp);
738 memcpy(EVP_X_STATE(cc->evp), dat, plen);