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 1.55 2002/04/03 09:26:11 markus Exp $");
44 #include <openssl/md5.h>
47 #if OPENSSL_VERSION_NUMBER < 0x00906000L
49 #define EVP_CIPHER_CTX_get_app_data(e) ((e)->app_data)
52 static EVP_CIPHER *evp_ssh1_3des(void);
53 static EVP_CIPHER *evp_ssh1_bf(void);
54 static EVP_CIPHER *evp_rijndael(void);
58 int number; /* for ssh1 only */
61 EVP_CIPHER *(*evptype)(void);
63 { "none", SSH_CIPHER_NONE, 8, 0, EVP_enc_null },
64 { "des", SSH_CIPHER_DES, 8, 8, EVP_des_cbc },
65 { "3des", SSH_CIPHER_3DES, 8, 16, evp_ssh1_3des },
66 { "blowfish", SSH_CIPHER_BLOWFISH, 8, 32, evp_ssh1_bf },
68 { "3des-cbc", SSH_CIPHER_SSH2, 8, 24, EVP_des_ede3_cbc },
69 { "blowfish-cbc", SSH_CIPHER_SSH2, 8, 16, EVP_bf_cbc },
70 { "cast128-cbc", SSH_CIPHER_SSH2, 8, 16, EVP_cast5_cbc },
71 { "arcfour", SSH_CIPHER_SSH2, 8, 16, EVP_rc4 },
72 { "aes128-cbc", SSH_CIPHER_SSH2, 16, 16, evp_rijndael },
73 { "aes192-cbc", SSH_CIPHER_SSH2, 16, 24, evp_rijndael },
74 { "aes256-cbc", SSH_CIPHER_SSH2, 16, 32, evp_rijndael },
75 { "rijndael-cbc@lysator.liu.se",
76 SSH_CIPHER_SSH2, 16, 32, evp_rijndael },
78 { NULL, SSH_CIPHER_ILLEGAL, 0, 0, NULL }
84 cipher_blocksize(Cipher *c)
86 return (c->block_size);
89 cipher_keylen(Cipher *c)
94 cipher_get_number(Cipher *c)
100 cipher_mask_ssh1(int client)
103 mask |= 1 << SSH_CIPHER_3DES; /* Mandatory */
104 mask |= 1 << SSH_CIPHER_BLOWFISH;
106 mask |= 1 << SSH_CIPHER_DES;
112 cipher_by_name(const char *name)
115 for (c = ciphers; c->name != NULL; c++)
116 if (strcasecmp(c->name, name) == 0)
122 cipher_by_number(int id)
125 for (c = ciphers; c->name != NULL; c++)
131 #define CIPHER_SEP ","
133 ciphers_valid(const char *names)
139 if (names == NULL || strcmp(names, "") == 0)
141 ciphers = cp = xstrdup(names);
142 for ((p = strsep(&cp, CIPHER_SEP)); p && *p != '\0';
143 (p = strsep(&cp, CIPHER_SEP))) {
144 c = cipher_by_name(p);
145 if (c == NULL || c->number != SSH_CIPHER_SSH2) {
146 debug("bad cipher %s [%s]", p, names);
150 debug3("cipher ok: %s [%s]", p, names);
153 debug3("ciphers ok: [%s]", names);
159 * Parses the name of the cipher. Returns the number of the corresponding
160 * cipher, or -1 on error.
164 cipher_number(const char *name)
169 c = cipher_by_name(name);
170 return (c==NULL) ? -1 : c->number;
176 Cipher *c = cipher_by_number(id);
177 return (c==NULL) ? "<unknown>" : c->name;
181 cipher_init(CipherContext *cc, Cipher *cipher,
182 const u_char *key, u_int keylen, const u_char *iv, u_int ivlen,
185 static int dowarn = 1;
189 const EVP_CIPHER *type;
193 if (cipher->number == SSH_CIPHER_DES) {
195 error("Warning: use of DES is strongly discouraged "
196 "due to cryptographic weaknesses");
202 cc->plaintext = (cipher->number == SSH_CIPHER_NONE);
204 if (keylen < cipher->key_len)
205 fatal("cipher_init: key length %d is insufficient for %s.",
206 keylen, cipher->name);
207 if (iv != NULL && ivlen < cipher->block_size)
208 fatal("cipher_init: iv length %d is insufficient for %s.",
209 ivlen, cipher->name);
212 type = (*cipher->evptype)();
214 EVP_CIPHER_CTX_init(&cc->evp);
216 if (type->key_len > 0 && type->key_len != keylen) {
217 debug("cipher_init: set keylen (%d -> %d)",
218 type->key_len, keylen);
219 type->key_len = keylen;
221 EVP_CipherInit(&cc->evp, type, (u_char *)key, (u_char *)iv,
222 (encrypt == CIPHER_ENCRYPT));
224 if (EVP_CipherInit(&cc->evp, type, NULL, (u_char *)iv,
225 (encrypt == CIPHER_ENCRYPT)) == 0)
226 fatal("cipher_init: EVP_CipherInit failed for %s",
228 klen = EVP_CIPHER_CTX_key_length(&cc->evp);
229 if (klen > 0 && keylen != klen) {
230 debug("cipher_init: set keylen (%d -> %d)", klen, keylen);
231 if (EVP_CIPHER_CTX_set_key_length(&cc->evp, keylen) == 0)
232 fatal("cipher_init: set keylen failed (%d -> %d)",
235 if (EVP_CipherInit(&cc->evp, NULL, (u_char *)key, NULL, -1) == 0)
236 fatal("cipher_init: EVP_CipherInit: set key failed for %s",
242 cipher_crypt(CipherContext *cc, u_char *dest, const u_char *src, u_int len)
244 if (len % cc->cipher->block_size)
245 fatal("cipher_encrypt: bad plaintext length %d", len);
247 EVP_Cipher(&cc->evp, dest, (u_char *)src, len);
249 if (EVP_Cipher(&cc->evp, dest, (u_char *)src, len) == 0)
250 fatal("evp_crypt: EVP_Cipher failed");
255 cipher_cleanup(CipherContext *cc)
258 EVP_CIPHER_CTX_cleanup(&cc->evp);
260 if (EVP_CIPHER_CTX_cleanup(&cc->evp) == 0)
261 error("cipher_cleanup: EVP_CIPHER_CTX_cleanup failed");
266 * Selects the cipher, and keys if by computing the MD5 checksum of the
267 * passphrase and using the resulting 16 bytes as the key.
271 cipher_set_key_string(CipherContext *cc, Cipher *cipher,
272 const char *passphrase, int encrypt)
278 MD5_Update(&md, (const u_char *)passphrase, strlen(passphrase));
279 MD5_Final(digest, &md);
281 cipher_init(cc, cipher, digest, 16, NULL, 0, encrypt);
283 memset(digest, 0, sizeof(digest));
284 memset(&md, 0, sizeof(md));
287 /* Implementations for other non-EVP ciphers */
290 * This is used by SSH1:
292 * What kind of triple DES are these 2 routines?
294 * Why is there a redundant initialization vector?
296 * If only iv3 was used, then, this would till effect have been
297 * outer-cbc. However, there is also a private iv1 == iv2 which
298 * perhaps makes differential analysis easier. On the other hand, the
299 * private iv1 probably makes the CRC-32 attack ineffective. This is a
300 * result of that there is no longer any known iv1 to use when
301 * choosing the X block.
305 EVP_CIPHER_CTX k1, k2, k3;
308 ssh1_3des_init(EVP_CIPHER_CTX *ctx, const u_char *key, const u_char *iv,
311 struct ssh1_3des_ctx *c;
312 u_char *k1, *k2, *k3;
314 if ((c = EVP_CIPHER_CTX_get_app_data(ctx)) == NULL) {
315 c = xmalloc(sizeof(*c));
316 EVP_CIPHER_CTX_set_app_data(ctx, c);
322 k1 = k2 = k3 = (u_char *) key;
324 if (EVP_CIPHER_CTX_key_length(ctx) >= 16+8) {
330 EVP_CIPHER_CTX_init(&c->k1);
331 EVP_CIPHER_CTX_init(&c->k2);
332 EVP_CIPHER_CTX_init(&c->k3);
334 EVP_CipherInit(&c->k1, EVP_des_cbc(), k1, NULL, enc);
335 EVP_CipherInit(&c->k2, EVP_des_cbc(), k2, NULL, !enc);
336 EVP_CipherInit(&c->k3, EVP_des_cbc(), k3, NULL, enc);
338 if (EVP_CipherInit(&c->k1, EVP_des_cbc(), k1, NULL, enc) == 0 ||
339 EVP_CipherInit(&c->k2, EVP_des_cbc(), k2, NULL, !enc) == 0 ||
340 EVP_CipherInit(&c->k3, EVP_des_cbc(), k3, NULL, enc) == 0) {
341 memset(c, 0, sizeof(*c));
343 EVP_CIPHER_CTX_set_app_data(ctx, NULL);
350 ssh1_3des_cbc(EVP_CIPHER_CTX *ctx, u_char *dest, const u_char *src, u_int len)
352 struct ssh1_3des_ctx *c;
354 if ((c = EVP_CIPHER_CTX_get_app_data(ctx)) == NULL) {
355 error("ssh1_3des_cbc: no context");
359 EVP_Cipher(&c->k1, dest, (u_char *)src, len);
360 EVP_Cipher(&c->k2, dest, dest, len);
361 EVP_Cipher(&c->k3, dest, dest, len);
363 if (EVP_Cipher(&c->k1, dest, (u_char *)src, len) == 0 ||
364 EVP_Cipher(&c->k2, dest, dest, len) == 0 ||
365 EVP_Cipher(&c->k3, dest, dest, len) == 0)
371 ssh1_3des_cleanup(EVP_CIPHER_CTX *ctx)
373 struct ssh1_3des_ctx *c;
375 if ((c = EVP_CIPHER_CTX_get_app_data(ctx)) != NULL) {
376 memset(c, 0, sizeof(*c));
378 EVP_CIPHER_CTX_set_app_data(ctx, NULL);
385 static EVP_CIPHER ssh1_3des;
387 memset(&ssh1_3des, 0, sizeof(EVP_CIPHER));
388 ssh1_3des.nid = NID_undef;
389 ssh1_3des.block_size = 8;
390 ssh1_3des.iv_len = 0;
391 ssh1_3des.key_len = 16;
392 ssh1_3des.init = ssh1_3des_init;
393 ssh1_3des.cleanup = ssh1_3des_cleanup;
394 ssh1_3des.do_cipher = ssh1_3des_cbc;
396 ssh1_3des.flags = EVP_CIPH_CBC_MODE | EVP_CIPH_VARIABLE_LENGTH;
402 * SSH1 uses a variation on Blowfish, all bytes must be swapped before
403 * and after encryption/decryption. Thus the swap_bytes stuff (yuk).
406 swap_bytes(const u_char *src, u_char *dst, int n)
410 /* Process 4 bytes every lap. */
411 for (n = n / 4; n > 0; n--) {
423 static int (*orig_bf)(EVP_CIPHER_CTX *, u_char *, const u_char *, u_int) = NULL;
425 bf_ssh1_cipher(EVP_CIPHER_CTX *ctx, u_char *out, const u_char *in, u_int len)
429 swap_bytes(in, out, len);
430 ret = (*orig_bf)(ctx, out, out, len);
431 swap_bytes(out, out, len);
437 static EVP_CIPHER ssh1_bf;
439 memcpy(&ssh1_bf, EVP_bf_cbc(), sizeof(EVP_CIPHER));
440 orig_bf = ssh1_bf.do_cipher;
441 ssh1_bf.nid = NID_undef;
442 ssh1_bf.do_cipher = bf_ssh1_cipher;
443 ssh1_bf.key_len = 32;
448 #define RIJNDAEL_BLOCKSIZE 16
449 struct ssh_rijndael_ctx
452 u_char r_iv[RIJNDAEL_BLOCKSIZE];
456 ssh_rijndael_init(EVP_CIPHER_CTX *ctx, const u_char *key, const u_char *iv,
459 struct ssh_rijndael_ctx *c;
461 if ((c = EVP_CIPHER_CTX_get_app_data(ctx)) == NULL) {
462 c = xmalloc(sizeof(*c));
463 EVP_CIPHER_CTX_set_app_data(ctx, c);
468 rijndael_set_key(&c->r_ctx, (u_char *)key,
469 8*EVP_CIPHER_CTX_key_length(ctx), enc);
472 memcpy(c->r_iv, iv, RIJNDAEL_BLOCKSIZE);
476 ssh_rijndael_cbc(EVP_CIPHER_CTX *ctx, u_char *dest, const u_char *src,
479 struct ssh_rijndael_ctx *c;
480 u_char buf[RIJNDAEL_BLOCKSIZE];
481 u_char *cprev, *cnow, *plain, *ivp;
482 int i, j, blocks = len / RIJNDAEL_BLOCKSIZE;
486 if (len % RIJNDAEL_BLOCKSIZE)
487 fatal("ssh_rijndael_cbc: bad len %d", len);
488 if ((c = EVP_CIPHER_CTX_get_app_data(ctx)) == NULL) {
489 error("ssh_rijndael_cbc: no context");
494 plain = (u_char *)src;
496 for (i = 0; i < blocks; i++, plain+=RIJNDAEL_BLOCKSIZE,
497 cnow+=RIJNDAEL_BLOCKSIZE) {
498 for (j = 0; j < RIJNDAEL_BLOCKSIZE; j++)
499 buf[j] = plain[j] ^ cprev[j];
500 rijndael_encrypt(&c->r_ctx, buf, cnow);
503 memcpy(c->r_iv, cprev, RIJNDAEL_BLOCKSIZE);
505 cnow = (u_char *) (src+len-RIJNDAEL_BLOCKSIZE);
506 plain = dest+len-RIJNDAEL_BLOCKSIZE;
508 memcpy(buf, cnow, RIJNDAEL_BLOCKSIZE);
509 for (i = blocks; i > 0; i--, cnow-=RIJNDAEL_BLOCKSIZE,
510 plain-=RIJNDAEL_BLOCKSIZE) {
511 rijndael_decrypt(&c->r_ctx, cnow, plain);
512 ivp = (i == 1) ? c->r_iv : cnow-RIJNDAEL_BLOCKSIZE;
513 for (j = 0; j < RIJNDAEL_BLOCKSIZE; j++)
516 memcpy(c->r_iv, buf, RIJNDAEL_BLOCKSIZE);
521 ssh_rijndael_cleanup(EVP_CIPHER_CTX *ctx)
523 struct ssh_rijndael_ctx *c;
525 if ((c = EVP_CIPHER_CTX_get_app_data(ctx)) != NULL) {
526 memset(c, 0, sizeof(*c));
528 EVP_CIPHER_CTX_set_app_data(ctx, NULL);
535 static EVP_CIPHER rijndal_cbc;
537 memset(&rijndal_cbc, 0, sizeof(EVP_CIPHER));
538 rijndal_cbc.nid = NID_undef;
539 rijndal_cbc.block_size = RIJNDAEL_BLOCKSIZE;
540 rijndal_cbc.iv_len = RIJNDAEL_BLOCKSIZE;
541 rijndal_cbc.key_len = 16;
542 rijndal_cbc.init = ssh_rijndael_init;
543 rijndal_cbc.cleanup = ssh_rijndael_cleanup;
544 rijndal_cbc.do_cipher = ssh_rijndael_cbc;
546 rijndal_cbc.flags = EVP_CIPH_CBC_MODE | EVP_CIPH_VARIABLE_LENGTH |
547 EVP_CIPH_ALWAYS_CALL_INIT;
549 return (&rijndal_cbc);
553 * Exports an IV from the CipherContext required to export the key
554 * state back from the unprivileged child to the privileged parent
559 cipher_get_keyiv_len(CipherContext *cc)
561 Cipher *c = cc->cipher;
564 if (c->number == SSH_CIPHER_3DES)
567 ivlen = EVP_CIPHER_CTX_iv_length(&cc->evp);
572 cipher_get_keyiv(CipherContext *cc, u_char *iv, u_int len)
574 Cipher *c = cc->cipher;
579 case SSH_CIPHER_SSH2:
581 case SSH_CIPHER_BLOWFISH:
582 evplen = EVP_CIPHER_CTX_iv_length(&cc->evp);
586 fatal("%s: wrong iv length %d != %d", __FUNCTION__,
589 if (c->evptype == evp_rijndael) {
590 struct ssh_rijndael_ctx *aesc;
592 aesc = EVP_CIPHER_CTX_get_app_data(&cc->evp);
594 fatal("%s: no rijndael context", __FUNCTION__);
600 case SSH_CIPHER_3DES: {
601 struct ssh1_3des_ctx *desc;
603 fatal("%s: bad 3des iv length: %d", __FUNCTION__, len);
604 desc = EVP_CIPHER_CTX_get_app_data(&cc->evp);
606 fatal("%s: no 3des context", __FUNCTION__);
607 debug3("%s: Copying 3DES IV", __FUNCTION__);
608 memcpy(iv, desc->k1.iv, 8);
609 memcpy(iv + 8, desc->k2.iv, 8);
610 memcpy(iv + 16, desc->k3.iv, 8);
614 fatal("%s: bad cipher %d", __FUNCTION__, c->number);
616 memcpy(iv, civ, len);
620 cipher_set_keyiv(CipherContext *cc, u_char *iv)
622 Cipher *c = cc->cipher;
627 case SSH_CIPHER_SSH2:
629 case SSH_CIPHER_BLOWFISH:
630 evplen = EVP_CIPHER_CTX_iv_length(&cc->evp);
634 if (c->evptype == evp_rijndael) {
635 struct ssh_rijndael_ctx *aesc;
637 aesc = EVP_CIPHER_CTX_get_app_data(&cc->evp);
639 fatal("%s: no rijndael context", __FUNCTION__);
645 case SSH_CIPHER_3DES: {
646 struct ssh1_3des_ctx *desc;
647 desc = EVP_CIPHER_CTX_get_app_data(&cc->evp);
649 fatal("%s: no 3des context", __FUNCTION__);
650 debug3("%s: Installed 3DES IV", __FUNCTION__);
651 memcpy(desc->k1.iv, iv, 8);
652 memcpy(desc->k2.iv, iv + 8, 8);
653 memcpy(desc->k3.iv, iv + 16, 8);
657 fatal("%s: bad cipher %d", __FUNCTION__, c->number);
659 memcpy(div, iv, evplen);
662 #if OPENSSL_VERSION_NUMBER < 0x00907000L
663 #define EVP_X_STATE(evp) &(evp).c
664 #define EVP_X_STATE_LEN(evp) sizeof((evp).c)
666 #define EVP_X_STATE(evp) (evp).cipher_data
667 #define EVP_X_STATE_LEN(evp) (evp).cipher->ctx_size
671 cipher_get_keycontext(CipherContext *cc, u_char *dat)
673 Cipher *c = cc->cipher;
676 if (c->number == SSH_CIPHER_3DES) {
677 struct ssh1_3des_ctx *desc;
678 desc = EVP_CIPHER_CTX_get_app_data(&cc->evp);
680 fatal("%s: no 3des context", __FUNCTION__);
681 plen = EVP_X_STATE_LEN(desc->k1);
684 memcpy(dat, EVP_X_STATE(desc->k1), plen);
685 memcpy(dat + plen, EVP_X_STATE(desc->k2), plen);
686 memcpy(dat + 2*plen, EVP_X_STATE(desc->k3), plen);
691 plen = EVP_X_STATE_LEN(cc->evp);
695 memcpy(dat, EVP_X_STATE(cc->evp), plen);
700 cipher_set_keycontext(CipherContext *cc, u_char *dat)
702 Cipher *c = cc->cipher;
705 if (c->number == SSH_CIPHER_3DES) {
706 struct ssh1_3des_ctx *desc;
707 desc = EVP_CIPHER_CTX_get_app_data(&cc->evp);
709 fatal("%s: no 3des context", __FUNCTION__);
710 plen = EVP_X_STATE_LEN(desc->k1);
711 memcpy(EVP_X_STATE(desc->k1), dat, plen);
712 memcpy(EVP_X_STATE(desc->k2), dat + plen, plen);
713 memcpy(EVP_X_STATE(desc->k3), dat + 2*plen, plen);
715 plen = EVP_X_STATE_LEN(cc->evp);
716 memcpy(EVP_X_STATE(cc->evp), dat, plen);