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 1.60 2002/06/23 03:26:52 deraadt Exp $");
45 #include <openssl/md5.h>
47 #if OPENSSL_VERSION_NUMBER < 0x00906000L
49 #define EVP_CIPHER_CTX_get_app_data(e) ((e)->app_data)
52 #if OPENSSL_VERSION_NUMBER < 0x00907000L
54 static const EVP_CIPHER *evp_rijndael(void);
56 static const EVP_CIPHER *evp_ssh1_3des(void);
57 static const EVP_CIPHER *evp_ssh1_bf(void);
61 int number; /* for ssh1 only */
64 const EVP_CIPHER *(*evptype)(void);
66 { "none", SSH_CIPHER_NONE, 8, 0, EVP_enc_null },
67 { "des", SSH_CIPHER_DES, 8, 8, EVP_des_cbc },
68 { "3des", SSH_CIPHER_3DES, 8, 16, evp_ssh1_3des },
69 { "blowfish", SSH_CIPHER_BLOWFISH, 8, 32, evp_ssh1_bf },
71 { "3des-cbc", SSH_CIPHER_SSH2, 8, 24, EVP_des_ede3_cbc },
72 { "blowfish-cbc", SSH_CIPHER_SSH2, 8, 16, EVP_bf_cbc },
73 { "cast128-cbc", SSH_CIPHER_SSH2, 8, 16, EVP_cast5_cbc },
74 { "arcfour", SSH_CIPHER_SSH2, 8, 16, EVP_rc4 },
75 #if OPENSSL_VERSION_NUMBER < 0x00907000L
76 { "aes128-cbc", SSH_CIPHER_SSH2, 16, 16, evp_rijndael },
77 { "aes192-cbc", SSH_CIPHER_SSH2, 16, 24, evp_rijndael },
78 { "aes256-cbc", SSH_CIPHER_SSH2, 16, 32, evp_rijndael },
79 { "rijndael-cbc@lysator.liu.se",
80 SSH_CIPHER_SSH2, 16, 32, evp_rijndael },
82 { "aes128-cbc", SSH_CIPHER_SSH2, 16, 16, EVP_aes_128_cbc },
83 { "aes192-cbc", SSH_CIPHER_SSH2, 16, 24, EVP_aes_192_cbc },
84 { "aes256-cbc", SSH_CIPHER_SSH2, 16, 32, EVP_aes_256_cbc },
85 { "rijndael-cbc@lysator.liu.se",
86 SSH_CIPHER_SSH2, 16, 32, EVP_aes_256_cbc },
89 { NULL, SSH_CIPHER_ILLEGAL, 0, 0, NULL }
95 cipher_blocksize(Cipher *c)
97 return (c->block_size);
101 cipher_keylen(Cipher *c)
107 cipher_get_number(Cipher *c)
113 cipher_mask_ssh1(int client)
116 mask |= 1 << SSH_CIPHER_3DES; /* Mandatory */
117 mask |= 1 << SSH_CIPHER_BLOWFISH;
119 mask |= 1 << SSH_CIPHER_DES;
125 cipher_by_name(const char *name)
128 for (c = ciphers; c->name != NULL; c++)
129 if (strcasecmp(c->name, name) == 0)
135 cipher_by_number(int id)
138 for (c = ciphers; c->name != NULL; c++)
144 #define CIPHER_SEP ","
146 ciphers_valid(const char *names)
152 if (names == NULL || strcmp(names, "") == 0)
154 ciphers = cp = xstrdup(names);
155 for ((p = strsep(&cp, CIPHER_SEP)); p && *p != '\0';
156 (p = strsep(&cp, CIPHER_SEP))) {
157 c = cipher_by_name(p);
158 if (c == NULL || c->number != SSH_CIPHER_SSH2) {
159 debug("bad cipher %s [%s]", p, names);
163 debug3("cipher ok: %s [%s]", p, names);
166 debug3("ciphers ok: [%s]", names);
172 * Parses the name of the cipher. Returns the number of the corresponding
173 * cipher, or -1 on error.
177 cipher_number(const char *name)
182 c = cipher_by_name(name);
183 return (c==NULL) ? -1 : c->number;
189 Cipher *c = cipher_by_number(id);
190 return (c==NULL) ? "<unknown>" : c->name;
194 cipher_init(CipherContext *cc, Cipher *cipher,
195 const u_char *key, u_int keylen, const u_char *iv, u_int ivlen,
198 static int dowarn = 1;
202 const EVP_CIPHER *type;
206 if (cipher->number == SSH_CIPHER_DES) {
208 error("Warning: use of DES is strongly discouraged "
209 "due to cryptographic weaknesses");
215 cc->plaintext = (cipher->number == SSH_CIPHER_NONE);
217 if (keylen < cipher->key_len)
218 fatal("cipher_init: key length %d is insufficient for %s.",
219 keylen, cipher->name);
220 if (iv != NULL && ivlen < cipher->block_size)
221 fatal("cipher_init: iv length %d is insufficient for %s.",
222 ivlen, cipher->name);
225 type = (*cipher->evptype)();
227 EVP_CIPHER_CTX_init(&cc->evp);
229 if (type->key_len > 0 && type->key_len != keylen) {
230 debug("cipher_init: set keylen (%d -> %d)",
231 type->key_len, keylen);
232 type->key_len = keylen;
234 EVP_CipherInit(&cc->evp, type, (u_char *)key, (u_char *)iv,
235 (encrypt == CIPHER_ENCRYPT));
237 if (EVP_CipherInit(&cc->evp, type, NULL, (u_char *)iv,
238 (encrypt == CIPHER_ENCRYPT)) == 0)
239 fatal("cipher_init: EVP_CipherInit failed for %s",
241 klen = EVP_CIPHER_CTX_key_length(&cc->evp);
242 if (klen > 0 && keylen != klen) {
243 debug("cipher_init: set keylen (%d -> %d)", klen, keylen);
244 if (EVP_CIPHER_CTX_set_key_length(&cc->evp, keylen) == 0)
245 fatal("cipher_init: set keylen failed (%d -> %d)",
248 if (EVP_CipherInit(&cc->evp, NULL, (u_char *)key, NULL, -1) == 0)
249 fatal("cipher_init: EVP_CipherInit: set key failed for %s",
255 cipher_crypt(CipherContext *cc, u_char *dest, const u_char *src, u_int len)
257 if (len % cc->cipher->block_size)
258 fatal("cipher_encrypt: bad plaintext length %d", len);
260 EVP_Cipher(&cc->evp, dest, (u_char *)src, len);
262 if (EVP_Cipher(&cc->evp, dest, (u_char *)src, len) == 0)
263 fatal("evp_crypt: EVP_Cipher failed");
268 cipher_cleanup(CipherContext *cc)
271 EVP_CIPHER_CTX_cleanup(&cc->evp);
273 if (EVP_CIPHER_CTX_cleanup(&cc->evp) == 0)
274 error("cipher_cleanup: EVP_CIPHER_CTX_cleanup failed");
279 * Selects the cipher, and keys if by computing the MD5 checksum of the
280 * passphrase and using the resulting 16 bytes as the key.
284 cipher_set_key_string(CipherContext *cc, Cipher *cipher,
285 const char *passphrase, int encrypt)
291 MD5_Update(&md, (const u_char *)passphrase, strlen(passphrase));
292 MD5_Final(digest, &md);
294 cipher_init(cc, cipher, digest, 16, NULL, 0, encrypt);
296 memset(digest, 0, sizeof(digest));
297 memset(&md, 0, sizeof(md));
300 /* Implementations for other non-EVP ciphers */
303 * This is used by SSH1:
305 * What kind of triple DES are these 2 routines?
307 * Why is there a redundant initialization vector?
309 * If only iv3 was used, then, this would till effect have been
310 * outer-cbc. However, there is also a private iv1 == iv2 which
311 * perhaps makes differential analysis easier. On the other hand, the
312 * private iv1 probably makes the CRC-32 attack ineffective. This is a
313 * result of that there is no longer any known iv1 to use when
314 * choosing the X block.
318 EVP_CIPHER_CTX k1, k2, k3;
322 ssh1_3des_init(EVP_CIPHER_CTX *ctx, const u_char *key, const u_char *iv,
325 struct ssh1_3des_ctx *c;
326 u_char *k1, *k2, *k3;
328 if ((c = EVP_CIPHER_CTX_get_app_data(ctx)) == NULL) {
329 c = xmalloc(sizeof(*c));
330 EVP_CIPHER_CTX_set_app_data(ctx, c);
336 k1 = k2 = k3 = (u_char *) key;
338 if (EVP_CIPHER_CTX_key_length(ctx) >= 16+8) {
344 EVP_CIPHER_CTX_init(&c->k1);
345 EVP_CIPHER_CTX_init(&c->k2);
346 EVP_CIPHER_CTX_init(&c->k3);
348 EVP_CipherInit(&c->k1, EVP_des_cbc(), k1, NULL, enc);
349 EVP_CipherInit(&c->k2, EVP_des_cbc(), k2, NULL, !enc);
350 EVP_CipherInit(&c->k3, EVP_des_cbc(), k3, NULL, enc);
352 if (EVP_CipherInit(&c->k1, EVP_des_cbc(), k1, NULL, enc) == 0 ||
353 EVP_CipherInit(&c->k2, EVP_des_cbc(), k2, NULL, !enc) == 0 ||
354 EVP_CipherInit(&c->k3, EVP_des_cbc(), k3, NULL, enc) == 0) {
355 memset(c, 0, sizeof(*c));
357 EVP_CIPHER_CTX_set_app_data(ctx, NULL);
365 ssh1_3des_cbc(EVP_CIPHER_CTX *ctx, u_char *dest, const u_char *src, u_int len)
367 struct ssh1_3des_ctx *c;
369 if ((c = EVP_CIPHER_CTX_get_app_data(ctx)) == NULL) {
370 error("ssh1_3des_cbc: no context");
374 EVP_Cipher(&c->k1, dest, (u_char *)src, len);
375 EVP_Cipher(&c->k2, dest, dest, len);
376 EVP_Cipher(&c->k3, dest, dest, len);
378 if (EVP_Cipher(&c->k1, dest, (u_char *)src, len) == 0 ||
379 EVP_Cipher(&c->k2, dest, dest, len) == 0 ||
380 EVP_Cipher(&c->k3, dest, dest, len) == 0)
387 ssh1_3des_cleanup(EVP_CIPHER_CTX *ctx)
389 struct ssh1_3des_ctx *c;
391 if ((c = EVP_CIPHER_CTX_get_app_data(ctx)) != NULL) {
392 memset(c, 0, sizeof(*c));
394 EVP_CIPHER_CTX_set_app_data(ctx, NULL);
399 static const EVP_CIPHER *
402 static EVP_CIPHER ssh1_3des;
404 memset(&ssh1_3des, 0, sizeof(EVP_CIPHER));
405 ssh1_3des.nid = NID_undef;
406 ssh1_3des.block_size = 8;
407 ssh1_3des.iv_len = 0;
408 ssh1_3des.key_len = 16;
409 ssh1_3des.init = ssh1_3des_init;
410 ssh1_3des.cleanup = ssh1_3des_cleanup;
411 ssh1_3des.do_cipher = ssh1_3des_cbc;
413 ssh1_3des.flags = EVP_CIPH_CBC_MODE | EVP_CIPH_VARIABLE_LENGTH;
419 * SSH1 uses a variation on Blowfish, all bytes must be swapped before
420 * and after encryption/decryption. Thus the swap_bytes stuff (yuk).
423 swap_bytes(const u_char *src, u_char *dst, int n)
427 /* Process 4 bytes every lap. */
428 for (n = n / 4; n > 0; n--) {
441 static int (*orig_bf)(EVP_CIPHER_CTX *, u_char *, const u_char *, u_int) = NULL;
444 bf_ssh1_cipher(EVP_CIPHER_CTX *ctx, u_char *out, const u_char *in, u_int len)
448 swap_bytes(in, out, len);
449 ret = (*orig_bf)(ctx, out, out, len);
450 swap_bytes(out, out, len);
454 static const EVP_CIPHER *
457 static EVP_CIPHER ssh1_bf;
459 memcpy(&ssh1_bf, EVP_bf_cbc(), sizeof(EVP_CIPHER));
460 orig_bf = ssh1_bf.do_cipher;
461 ssh1_bf.nid = NID_undef;
462 ssh1_bf.do_cipher = bf_ssh1_cipher;
463 ssh1_bf.key_len = 32;
467 #if OPENSSL_VERSION_NUMBER < 0x00907000L
469 #define RIJNDAEL_BLOCKSIZE 16
470 struct ssh_rijndael_ctx
473 u_char r_iv[RIJNDAEL_BLOCKSIZE];
477 ssh_rijndael_init(EVP_CIPHER_CTX *ctx, const u_char *key, const u_char *iv,
480 struct ssh_rijndael_ctx *c;
482 if ((c = EVP_CIPHER_CTX_get_app_data(ctx)) == NULL) {
483 c = xmalloc(sizeof(*c));
484 EVP_CIPHER_CTX_set_app_data(ctx, c);
489 rijndael_set_key(&c->r_ctx, (u_char *)key,
490 8*EVP_CIPHER_CTX_key_length(ctx), enc);
493 memcpy(c->r_iv, iv, RIJNDAEL_BLOCKSIZE);
498 ssh_rijndael_cbc(EVP_CIPHER_CTX *ctx, u_char *dest, const u_char *src,
501 struct ssh_rijndael_ctx *c;
502 u_char buf[RIJNDAEL_BLOCKSIZE];
503 u_char *cprev, *cnow, *plain, *ivp;
504 int i, j, blocks = len / RIJNDAEL_BLOCKSIZE;
508 if (len % RIJNDAEL_BLOCKSIZE)
509 fatal("ssh_rijndael_cbc: bad len %d", len);
510 if ((c = EVP_CIPHER_CTX_get_app_data(ctx)) == NULL) {
511 error("ssh_rijndael_cbc: no context");
516 plain = (u_char *)src;
518 for (i = 0; i < blocks; i++, plain+=RIJNDAEL_BLOCKSIZE,
519 cnow+=RIJNDAEL_BLOCKSIZE) {
520 for (j = 0; j < RIJNDAEL_BLOCKSIZE; j++)
521 buf[j] = plain[j] ^ cprev[j];
522 rijndael_encrypt(&c->r_ctx, buf, cnow);
525 memcpy(c->r_iv, cprev, RIJNDAEL_BLOCKSIZE);
527 cnow = (u_char *) (src+len-RIJNDAEL_BLOCKSIZE);
528 plain = dest+len-RIJNDAEL_BLOCKSIZE;
530 memcpy(buf, cnow, RIJNDAEL_BLOCKSIZE);
531 for (i = blocks; i > 0; i--, cnow-=RIJNDAEL_BLOCKSIZE,
532 plain-=RIJNDAEL_BLOCKSIZE) {
533 rijndael_decrypt(&c->r_ctx, cnow, plain);
534 ivp = (i == 1) ? c->r_iv : cnow-RIJNDAEL_BLOCKSIZE;
535 for (j = 0; j < RIJNDAEL_BLOCKSIZE; j++)
538 memcpy(c->r_iv, buf, RIJNDAEL_BLOCKSIZE);
544 ssh_rijndael_cleanup(EVP_CIPHER_CTX *ctx)
546 struct ssh_rijndael_ctx *c;
548 if ((c = EVP_CIPHER_CTX_get_app_data(ctx)) != NULL) {
549 memset(c, 0, sizeof(*c));
551 EVP_CIPHER_CTX_set_app_data(ctx, NULL);
556 static const EVP_CIPHER *
559 static EVP_CIPHER rijndal_cbc;
561 memset(&rijndal_cbc, 0, sizeof(EVP_CIPHER));
562 rijndal_cbc.nid = NID_undef;
563 rijndal_cbc.block_size = RIJNDAEL_BLOCKSIZE;
564 rijndal_cbc.iv_len = RIJNDAEL_BLOCKSIZE;
565 rijndal_cbc.key_len = 16;
566 rijndal_cbc.init = ssh_rijndael_init;
567 rijndal_cbc.cleanup = ssh_rijndael_cleanup;
568 rijndal_cbc.do_cipher = ssh_rijndael_cbc;
570 rijndal_cbc.flags = EVP_CIPH_CBC_MODE | EVP_CIPH_VARIABLE_LENGTH |
571 EVP_CIPH_ALWAYS_CALL_INIT;
573 return (&rijndal_cbc);
578 * Exports an IV from the CipherContext required to export the key
579 * state back from the unprivileged child to the privileged parent
584 cipher_get_keyiv_len(CipherContext *cc)
586 Cipher *c = cc->cipher;
589 if (c->number == SSH_CIPHER_3DES)
592 ivlen = EVP_CIPHER_CTX_iv_length(&cc->evp);
597 cipher_get_keyiv(CipherContext *cc, u_char *iv, u_int len)
599 Cipher *c = cc->cipher;
604 case SSH_CIPHER_SSH2:
606 case SSH_CIPHER_BLOWFISH:
607 evplen = EVP_CIPHER_CTX_iv_length(&cc->evp);
611 fatal("%s: wrong iv length %d != %d", __func__,
614 #if OPENSSL_VERSION_NUMBER < 0x00907000L
615 if (c->evptype == evp_rijndael) {
616 struct ssh_rijndael_ctx *aesc;
618 aesc = EVP_CIPHER_CTX_get_app_data(&cc->evp);
620 fatal("%s: no rijndael context", __func__);
628 case SSH_CIPHER_3DES: {
629 struct ssh1_3des_ctx *desc;
631 fatal("%s: bad 3des iv length: %d", __func__, len);
632 desc = EVP_CIPHER_CTX_get_app_data(&cc->evp);
634 fatal("%s: no 3des context", __func__);
635 debug3("%s: Copying 3DES IV", __func__);
636 memcpy(iv, desc->k1.iv, 8);
637 memcpy(iv + 8, desc->k2.iv, 8);
638 memcpy(iv + 16, desc->k3.iv, 8);
642 fatal("%s: bad cipher %d", __func__, c->number);
644 memcpy(iv, civ, len);
648 cipher_set_keyiv(CipherContext *cc, u_char *iv)
650 Cipher *c = cc->cipher;
655 case SSH_CIPHER_SSH2:
657 case SSH_CIPHER_BLOWFISH:
658 evplen = EVP_CIPHER_CTX_iv_length(&cc->evp);
662 #if OPENSSL_VERSION_NUMBER < 0x00907000L
663 if (c->evptype == evp_rijndael) {
664 struct ssh_rijndael_ctx *aesc;
666 aesc = EVP_CIPHER_CTX_get_app_data(&cc->evp);
668 fatal("%s: no rijndael context", __func__);
676 case 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", __func__);
681 debug3("%s: Installed 3DES IV", __func__);
682 memcpy(desc->k1.iv, iv, 8);
683 memcpy(desc->k2.iv, iv + 8, 8);
684 memcpy(desc->k3.iv, iv + 16, 8);
688 fatal("%s: bad cipher %d", __func__, c->number);
690 memcpy(div, iv, evplen);
693 #if OPENSSL_VERSION_NUMBER < 0x00907000L
694 #define EVP_X_STATE(evp) &(evp).c
695 #define EVP_X_STATE_LEN(evp) sizeof((evp).c)
697 #define EVP_X_STATE(evp) (evp).cipher_data
698 #define EVP_X_STATE_LEN(evp) (evp).cipher->ctx_size
702 cipher_get_keycontext(CipherContext *cc, u_char *dat)
704 Cipher *c = cc->cipher;
707 if (c->evptype == EVP_rc4) {
708 plen = EVP_X_STATE_LEN(cc->evp);
711 memcpy(dat, EVP_X_STATE(cc->evp), plen);
717 cipher_set_keycontext(CipherContext *cc, u_char *dat)
719 Cipher *c = cc->cipher;
722 if (c->evptype == EVP_rc4) {
723 plen = EVP_X_STATE_LEN(cc->evp);
724 memcpy(EVP_X_STATE(cc->evp), dat, plen);