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 1.53 2002/03/18 17:13:15 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 },
76 { NULL, SSH_CIPHER_ILLEGAL, 0, 0, NULL }
82 cipher_blocksize(Cipher *c)
84 return (c->block_size);
87 cipher_keylen(Cipher *c)
92 cipher_get_number(Cipher *c)
98 cipher_mask_ssh1(int client)
101 mask |= 1 << SSH_CIPHER_3DES; /* Mandatory */
102 mask |= 1 << SSH_CIPHER_BLOWFISH;
104 mask |= 1 << SSH_CIPHER_DES;
110 cipher_by_name(const char *name)
113 for (c = ciphers; c->name != NULL; c++)
114 if (strcasecmp(c->name, name) == 0)
120 cipher_by_number(int id)
123 for (c = ciphers; c->name != NULL; c++)
129 #define CIPHER_SEP ","
131 ciphers_valid(const char *names)
137 if (names == NULL || strcmp(names, "") == 0)
139 ciphers = cp = xstrdup(names);
140 for ((p = strsep(&cp, CIPHER_SEP)); p && *p != '\0';
141 (p = strsep(&cp, CIPHER_SEP))) {
142 c = cipher_by_name(p);
143 if (c == NULL || c->number != SSH_CIPHER_SSH2) {
144 debug("bad cipher %s [%s]", p, names);
148 debug3("cipher ok: %s [%s]", p, names);
151 debug3("ciphers ok: [%s]", names);
157 * Parses the name of the cipher. Returns the number of the corresponding
158 * cipher, or -1 on error.
162 cipher_number(const char *name)
167 c = cipher_by_name(name);
168 return (c==NULL) ? -1 : c->number;
174 Cipher *c = cipher_by_number(id);
175 return (c==NULL) ? "<unknown>" : c->name;
179 cipher_init(CipherContext *cc, Cipher *cipher,
180 const u_char *key, u_int keylen, const u_char *iv, u_int ivlen,
183 static int dowarn = 1;
187 const EVP_CIPHER *type;
191 if (cipher->number == SSH_CIPHER_DES) {
193 error("Warning: use of DES is strongly discouraged "
194 "due to cryptographic weaknesses");
200 cc->plaintext = (cipher->number == SSH_CIPHER_NONE);
202 if (keylen < cipher->key_len)
203 fatal("cipher_init: key length %d is insufficient for %s.",
204 keylen, cipher->name);
205 if (iv != NULL && ivlen < cipher->block_size)
206 fatal("cipher_init: iv length %d is insufficient for %s.",
207 ivlen, cipher->name);
210 type = (*cipher->evptype)();
212 EVP_CIPHER_CTX_init(&cc->evp);
214 if (type->key_len > 0 && type->key_len != keylen) {
215 debug("cipher_init: set keylen (%d -> %d)",
216 type->key_len, keylen);
217 type->key_len = keylen;
219 EVP_CipherInit(&cc->evp, type, (u_char *)key, (u_char *)iv,
220 (encrypt == CIPHER_ENCRYPT));
222 if (EVP_CipherInit(&cc->evp, type, NULL, (u_char *)iv,
223 (encrypt == CIPHER_ENCRYPT)) == 0)
224 fatal("cipher_init: EVP_CipherInit failed for %s",
226 klen = EVP_CIPHER_CTX_key_length(&cc->evp);
227 if (klen > 0 && keylen != klen) {
228 debug("cipher_init: set keylen (%d -> %d)", klen, keylen);
229 if (EVP_CIPHER_CTX_set_key_length(&cc->evp, keylen) == 0)
230 fatal("cipher_init: set keylen failed (%d -> %d)",
233 if (EVP_CipherInit(&cc->evp, NULL, (u_char *)key, NULL, -1) == 0)
234 fatal("cipher_init: EVP_CipherInit: set key failed for %s",
240 cipher_crypt(CipherContext *cc, u_char *dest, const u_char *src, u_int len)
242 if (len % cc->cipher->block_size)
243 fatal("cipher_encrypt: bad plaintext length %d", len);
245 EVP_Cipher(&cc->evp, dest, (u_char *)src, len);
247 if (EVP_Cipher(&cc->evp, dest, (u_char *)src, len) == 0)
248 fatal("evp_crypt: EVP_Cipher failed");
253 cipher_cleanup(CipherContext *cc)
256 EVP_CIPHER_CTX_cleanup(&cc->evp);
258 if (EVP_CIPHER_CTX_cleanup(&cc->evp) == 0)
259 error("cipher_cleanup: EVP_CIPHER_CTX_cleanup failed");
264 * Selects the cipher, and keys if by computing the MD5 checksum of the
265 * passphrase and using the resulting 16 bytes as the key.
269 cipher_set_key_string(CipherContext *cc, Cipher *cipher,
270 const char *passphrase, int encrypt)
276 MD5_Update(&md, (const u_char *)passphrase, strlen(passphrase));
277 MD5_Final(digest, &md);
279 cipher_init(cc, cipher, digest, 16, NULL, 0, encrypt);
281 memset(digest, 0, sizeof(digest));
282 memset(&md, 0, sizeof(md));
285 /* Implementations for other non-EVP ciphers */
288 * This is used by SSH1:
290 * What kind of triple DES are these 2 routines?
292 * Why is there a redundant initialization vector?
294 * If only iv3 was used, then, this would till effect have been
295 * outer-cbc. However, there is also a private iv1 == iv2 which
296 * perhaps makes differential analysis easier. On the other hand, the
297 * private iv1 probably makes the CRC-32 attack ineffective. This is a
298 * result of that there is no longer any known iv1 to use when
299 * choosing the X block.
303 EVP_CIPHER_CTX k1, k2, k3;
306 ssh1_3des_init(EVP_CIPHER_CTX *ctx, const u_char *key, const u_char *iv,
309 struct ssh1_3des_ctx *c;
310 u_char *k1, *k2, *k3;
312 if ((c = EVP_CIPHER_CTX_get_app_data(ctx)) == NULL) {
313 c = xmalloc(sizeof(*c));
314 EVP_CIPHER_CTX_set_app_data(ctx, c);
320 k1 = k2 = k3 = (u_char *) key;
322 if (EVP_CIPHER_CTX_key_length(ctx) >= 16+8) {
328 EVP_CIPHER_CTX_init(&c->k1);
329 EVP_CIPHER_CTX_init(&c->k2);
330 EVP_CIPHER_CTX_init(&c->k3);
332 EVP_CipherInit(&c->k1, EVP_des_cbc(), k1, NULL, enc);
333 EVP_CipherInit(&c->k2, EVP_des_cbc(), k2, NULL, !enc);
334 EVP_CipherInit(&c->k3, EVP_des_cbc(), k3, NULL, enc);
336 if (EVP_CipherInit(&c->k1, EVP_des_cbc(), k1, NULL, enc) == 0 ||
337 EVP_CipherInit(&c->k2, EVP_des_cbc(), k2, NULL, !enc) == 0 ||
338 EVP_CipherInit(&c->k3, EVP_des_cbc(), k3, NULL, enc) == 0) {
339 memset(c, 0, sizeof(*c));
341 EVP_CIPHER_CTX_set_app_data(ctx, NULL);
348 ssh1_3des_cbc(EVP_CIPHER_CTX *ctx, u_char *dest, const u_char *src, u_int len)
350 struct ssh1_3des_ctx *c;
352 if ((c = EVP_CIPHER_CTX_get_app_data(ctx)) == NULL) {
353 error("ssh1_3des_cbc: no context");
357 EVP_Cipher(&c->k1, dest, (u_char *)src, len);
358 EVP_Cipher(&c->k2, dest, dest, len);
359 EVP_Cipher(&c->k3, dest, dest, len);
361 if (EVP_Cipher(&c->k1, dest, (u_char *)src, len) == 0 ||
362 EVP_Cipher(&c->k2, dest, dest, len) == 0 ||
363 EVP_Cipher(&c->k3, dest, dest, len) == 0)
369 ssh1_3des_cleanup(EVP_CIPHER_CTX *ctx)
371 struct ssh1_3des_ctx *c;
373 if ((c = EVP_CIPHER_CTX_get_app_data(ctx)) != NULL) {
374 memset(c, 0, sizeof(*c));
376 EVP_CIPHER_CTX_set_app_data(ctx, NULL);
383 static EVP_CIPHER ssh1_3des;
385 memset(&ssh1_3des, 0, sizeof(EVP_CIPHER));
386 ssh1_3des.nid = NID_undef;
387 ssh1_3des.block_size = 8;
388 ssh1_3des.iv_len = 0;
389 ssh1_3des.key_len = 16;
390 ssh1_3des.init = ssh1_3des_init;
391 ssh1_3des.cleanup = ssh1_3des_cleanup;
392 ssh1_3des.do_cipher = ssh1_3des_cbc;
394 ssh1_3des.flags = EVP_CIPH_CBC_MODE | EVP_CIPH_VARIABLE_LENGTH;
400 * SSH1 uses a variation on Blowfish, all bytes must be swapped before
401 * and after encryption/decryption. Thus the swap_bytes stuff (yuk).
404 swap_bytes(const u_char *src, u_char *dst, int n)
408 /* Process 4 bytes every lap. */
409 for (n = n / 4; n > 0; n--) {
421 static int (*orig_bf)(EVP_CIPHER_CTX *, u_char *, const u_char *, u_int) = NULL;
423 bf_ssh1_cipher(EVP_CIPHER_CTX *ctx, u_char *out, const u_char *in, u_int len)
427 swap_bytes(in, out, len);
428 ret = (*orig_bf)(ctx, out, out, len);
429 swap_bytes(out, out, len);
435 static EVP_CIPHER ssh1_bf;
437 memcpy(&ssh1_bf, EVP_bf_cbc(), sizeof(EVP_CIPHER));
438 orig_bf = ssh1_bf.do_cipher;
439 ssh1_bf.nid = NID_undef;
440 ssh1_bf.do_cipher = bf_ssh1_cipher;
441 ssh1_bf.key_len = 32;
446 #define RIJNDAEL_BLOCKSIZE 16
447 struct ssh_rijndael_ctx
450 u_char r_iv[RIJNDAEL_BLOCKSIZE];
454 ssh_rijndael_init(EVP_CIPHER_CTX *ctx, const u_char *key, const u_char *iv,
457 struct ssh_rijndael_ctx *c;
459 if ((c = EVP_CIPHER_CTX_get_app_data(ctx)) == NULL) {
460 c = xmalloc(sizeof(*c));
461 EVP_CIPHER_CTX_set_app_data(ctx, c);
466 rijndael_set_key(&c->r_ctx, (u_char *)key,
467 8*EVP_CIPHER_CTX_key_length(ctx), enc);
470 memcpy(c->r_iv, iv, RIJNDAEL_BLOCKSIZE);
474 ssh_rijndael_cbc(EVP_CIPHER_CTX *ctx, u_char *dest, const u_char *src,
477 struct ssh_rijndael_ctx *c;
478 u_char buf[RIJNDAEL_BLOCKSIZE];
479 u_char *cprev, *cnow, *plain, *ivp;
480 int i, j, blocks = len / RIJNDAEL_BLOCKSIZE;
484 if (len % RIJNDAEL_BLOCKSIZE)
485 fatal("ssh_rijndael_cbc: bad len %d", len);
486 if ((c = EVP_CIPHER_CTX_get_app_data(ctx)) == NULL) {
487 error("ssh_rijndael_cbc: no context");
492 plain = (u_char *)src;
494 for (i = 0; i < blocks; i++, plain+=RIJNDAEL_BLOCKSIZE,
495 cnow+=RIJNDAEL_BLOCKSIZE) {
496 for (j = 0; j < RIJNDAEL_BLOCKSIZE; j++)
497 buf[j] = plain[j] ^ cprev[j];
498 rijndael_encrypt(&c->r_ctx, buf, cnow);
501 memcpy(c->r_iv, cprev, RIJNDAEL_BLOCKSIZE);
503 cnow = (u_char *) (src+len-RIJNDAEL_BLOCKSIZE);
504 plain = dest+len-RIJNDAEL_BLOCKSIZE;
506 memcpy(buf, cnow, RIJNDAEL_BLOCKSIZE);
507 for (i = blocks; i > 0; i--, cnow-=RIJNDAEL_BLOCKSIZE,
508 plain-=RIJNDAEL_BLOCKSIZE) {
509 rijndael_decrypt(&c->r_ctx, cnow, plain);
513 * Exports an IV from the CipherContext required to export the key
514 * state back from the unprivileged child to the privileged parent
519 cipher_get_keyiv_len(CipherContext *cc)
521 Cipher *c = cc->cipher;
524 if (c->number == SSH_CIPHER_3DES)
527 ivlen = EVP_CIPHER_CTX_iv_length(&cc->evp);
532 cipher_get_keyiv(CipherContext *cc, u_char *iv, u_int len)
534 Cipher *c = cc->cipher;
539 case SSH_CIPHER_SSH2:
541 case SSH_CIPHER_BLOWFISH:
542 evplen = EVP_CIPHER_CTX_iv_length(&cc->evp);
546 fatal("%s: wrong iv length %d != %d", __FUNCTION__,
549 if (strncmp(c->name, "aes", 3) == 0) {
550 struct ssh_rijndael_ctx *aesc;
552 aesc = EVP_CIPHER_CTX_get_app_data(&cc->evp);
554 fatal("%s: no rijndael context", __FUNCTION__);
560 case SSH_CIPHER_3DES: {
561 struct ssh1_3des_ctx *desc;
563 fatal("%s: bad 3des iv length: %d", __FUNCTION__, len);
564 desc = EVP_CIPHER_CTX_get_app_data(&cc->evp);
566 fatal("%s: no 3des context", __FUNCTION__);
567 debug3("%s: Copying 3DES IV", __FUNCTION__);
568 memcpy(iv, desc->k1.iv, 8);
569 memcpy(iv + 8, desc->k2.iv, 8);
570 memcpy(iv + 16, desc->k3.iv, 8);
574 fatal("%s: bad cipher %d", __FUNCTION__, c->number);
576 memcpy(iv, civ, len);
580 cipher_set_keyiv(CipherContext *cc, u_char *iv)
582 Cipher *c = cc->cipher;
587 case SSH_CIPHER_SSH2:
589 case SSH_CIPHER_BLOWFISH:
590 evplen = EVP_CIPHER_CTX_iv_length(&cc->evp);
594 if (strncmp(c->name, "aes", 3) == 0) {
595 struct ssh_rijndael_ctx *aesc;
597 aesc = EVP_CIPHER_CTX_get_app_data(&cc->evp);
599 fatal("%s: no rijndael context", __FUNCTION__);
605 case SSH_CIPHER_3DES: {
606 struct ssh1_3des_ctx *desc;
607 desc = EVP_CIPHER_CTX_get_app_data(&cc->evp);
609 fatal("%s: no 3des context", __FUNCTION__);
610 debug3("%s: Installed 3DES IV", __FUNCTION__);
611 memcpy(desc->k1.iv, iv, 8);
612 memcpy(desc->k2.iv, iv + 8, 8);
613 memcpy(desc->k3.iv, iv + 16, 8);
617 fatal("%s: bad cipher %d", __FUNCTION__, c->number);
619 memcpy(div, iv, evplen);
622 #if OPENSSL_VERSION_NUMBER < 0x00907000L
623 #define EVP_X_STATE(evp) &(evp).c
624 #define EVP_X_STATE_LEN(evp) sizeof((evp).c)
626 #define EVP_X_STATE(evp) (evp).cipher_data
627 #define EVP_X_STATE_LEN(evp) (evp).cipher->ctx_size
631 cipher_get_keycontext(CipherContext *cc, u_char *dat)
633 Cipher *c = cc->cipher;
636 if (c->number == SSH_CIPHER_3DES) {
637 struct ssh1_3des_ctx *desc;
638 desc = EVP_CIPHER_CTX_get_app_data(&cc->evp);
640 fatal("%s: no 3des context", __FUNCTION__);
641 plen = EVP_X_STATE_LEN(desc->k1);
644 memcpy(dat, EVP_X_STATE(desc->k1), plen);
645 memcpy(dat + plen, EVP_X_STATE(desc->k2), plen);
646 memcpy(dat + 2*plen, EVP_X_STATE(desc->k3), plen);
651 plen = EVP_X_STATE_LEN(cc->evp);
655 memcpy(dat, EVP_X_STATE(cc->evp), plen);
660 cipher_set_keycontext(CipherContext *cc, u_char *dat)
662 Cipher *c = cc->cipher;
665 if (c->number == SSH_CIPHER_3DES) {
666 struct ssh1_3des_ctx *desc;
667 desc = EVP_CIPHER_CTX_get_app_data(&cc->evp);
669 fatal("%s: no 3des context", __FUNCTION__);
670 plen = EVP_X_STATE_LEN(desc->k1);
671 memcpy(EVP_X_STATE(desc->k1), dat, plen);
672 memcpy(EVP_X_STATE(desc->k2), dat + plen, plen);
673 memcpy(EVP_X_STATE(desc->k3), dat + 2*plen, plen);
675 plen = EVP_X_STATE_LEN(cc->evp);
676 memcpy(EVP_X_STATE(cc->evp), dat, plen);
678 ivp = (i == 1) ? c->r_iv : cnow-RIJNDAEL_BLOCKSIZE;
679 for (j = 0; j < RIJNDAEL_BLOCKSIZE; j++)
682 memcpy(c->r_iv, buf, RIJNDAEL_BLOCKSIZE);
687 ssh_rijndael_cleanup(EVP_CIPHER_CTX *ctx)
689 struct ssh_rijndael_ctx *c;
691 if ((c = EVP_CIPHER_CTX_get_app_data(ctx)) != NULL) {
692 memset(c, 0, sizeof(*c));
694 EVP_CIPHER_CTX_set_app_data(ctx, NULL);
701 static EVP_CIPHER rijndal_cbc;
703 memset(&rijndal_cbc, 0, sizeof(EVP_CIPHER));
704 rijndal_cbc.nid = NID_undef;
705 rijndal_cbc.block_size = RIJNDAEL_BLOCKSIZE;
706 rijndal_cbc.iv_len = RIJNDAEL_BLOCKSIZE;
707 rijndal_cbc.key_len = 16;
708 rijndal_cbc.init = ssh_rijndael_init;
709 rijndal_cbc.cleanup = ssh_rijndael_cleanup;
710 rijndal_cbc.do_cipher = ssh_rijndael_cbc;
712 rijndal_cbc.flags = EVP_CIPH_CBC_MODE | EVP_CIPH_VARIABLE_LENGTH |
713 EVP_CIPH_ALWAYS_CALL_INIT;
715 return (&rijndal_cbc);