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 1.54 2002/03/19 10:49:35 markus Exp $");
44 #include <openssl/md5.h>
47 static EVP_CIPHER *evp_ssh1_3des(void);
48 static EVP_CIPHER *evp_ssh1_bf(void);
49 static EVP_CIPHER *evp_rijndael(void);
53 int number; /* for ssh1 only */
56 EVP_CIPHER *(*evptype)(void);
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 },
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 },
71 { NULL, SSH_CIPHER_ILLEGAL, 0, 0, NULL }
77 cipher_blocksize(Cipher *c)
79 return (c->block_size);
82 cipher_keylen(Cipher *c)
87 cipher_get_number(Cipher *c)
93 cipher_mask_ssh1(int client)
96 mask |= 1 << SSH_CIPHER_3DES; /* Mandatory */
97 mask |= 1 << SSH_CIPHER_BLOWFISH;
99 mask |= 1 << SSH_CIPHER_DES;
105 cipher_by_name(const char *name)
108 for (c = ciphers; c->name != NULL; c++)
109 if (strcasecmp(c->name, name) == 0)
115 cipher_by_number(int id)
118 for (c = ciphers; c->name != NULL; c++)
124 #define CIPHER_SEP ","
126 ciphers_valid(const char *names)
132 if (names == NULL || strcmp(names, "") == 0)
134 ciphers = cp = xstrdup(names);
135 for ((p = strsep(&cp, CIPHER_SEP)); p && *p != '\0';
136 (p = strsep(&cp, CIPHER_SEP))) {
137 c = cipher_by_name(p);
138 if (c == NULL || c->number != SSH_CIPHER_SSH2) {
139 debug("bad cipher %s [%s]", p, names);
143 debug3("cipher ok: %s [%s]", p, names);
146 debug3("ciphers ok: [%s]", names);
152 * Parses the name of the cipher. Returns the number of the corresponding
153 * cipher, or -1 on error.
157 cipher_number(const char *name)
162 c = cipher_by_name(name);
163 return (c==NULL) ? -1 : c->number;
169 Cipher *c = cipher_by_number(id);
170 return (c==NULL) ? "<unknown>" : c->name;
174 cipher_init(CipherContext *cc, Cipher *cipher,
175 const u_char *key, u_int keylen, const u_char *iv, u_int ivlen,
178 static int dowarn = 1;
179 const EVP_CIPHER *type;
182 if (cipher->number == SSH_CIPHER_DES) {
184 error("Warning: use of DES is strongly discouraged "
185 "due to cryptographic weaknesses");
191 cc->plaintext = (cipher->number == SSH_CIPHER_NONE);
193 if (keylen < cipher->key_len)
194 fatal("cipher_init: key length %d is insufficient for %s.",
195 keylen, cipher->name);
196 if (iv != NULL && ivlen < cipher->block_size)
197 fatal("cipher_init: iv length %d is insufficient for %s.",
198 ivlen, cipher->name);
201 type = (*cipher->evptype)();
203 EVP_CIPHER_CTX_init(&cc->evp);
204 if (EVP_CipherInit(&cc->evp, type, NULL, (u_char *)iv,
205 (encrypt == CIPHER_ENCRYPT)) == 0)
206 fatal("cipher_init: EVP_CipherInit failed for %s",
208 klen = EVP_CIPHER_CTX_key_length(&cc->evp);
209 if (klen > 0 && keylen != klen) {
210 debug("cipher_init: set keylen (%d -> %d)", klen, keylen);
211 if (EVP_CIPHER_CTX_set_key_length(&cc->evp, keylen) == 0)
212 fatal("cipher_init: set keylen failed (%d -> %d)",
215 if (EVP_CipherInit(&cc->evp, NULL, (u_char *)key, NULL, -1) == 0)
216 fatal("cipher_init: EVP_CipherInit: set key failed for %s",
221 cipher_crypt(CipherContext *cc, u_char *dest, const u_char *src, u_int len)
223 if (len % cc->cipher->block_size)
224 fatal("cipher_encrypt: bad plaintext length %d", len);
225 if (EVP_Cipher(&cc->evp, dest, (u_char *)src, len) == 0)
226 fatal("evp_crypt: EVP_Cipher failed");
230 cipher_cleanup(CipherContext *cc)
232 if (EVP_CIPHER_CTX_cleanup(&cc->evp) == 0)
233 error("cipher_cleanup: EVP_CIPHER_CTX_cleanup failed");
237 * Selects the cipher, and keys if by computing the MD5 checksum of the
238 * passphrase and using the resulting 16 bytes as the key.
242 cipher_set_key_string(CipherContext *cc, Cipher *cipher,
243 const char *passphrase, int encrypt)
249 MD5_Update(&md, (const u_char *)passphrase, strlen(passphrase));
250 MD5_Final(digest, &md);
252 cipher_init(cc, cipher, digest, 16, NULL, 0, encrypt);
254 memset(digest, 0, sizeof(digest));
255 memset(&md, 0, sizeof(md));
258 /* Implementations for other non-EVP ciphers */
261 * This is used by SSH1:
263 * What kind of triple DES are these 2 routines?
265 * Why is there a redundant initialization vector?
267 * If only iv3 was used, then, this would till effect have been
268 * outer-cbc. However, there is also a private iv1 == iv2 which
269 * perhaps makes differential analysis easier. On the other hand, the
270 * private iv1 probably makes the CRC-32 attack ineffective. This is a
271 * result of that there is no longer any known iv1 to use when
272 * choosing the X block.
276 EVP_CIPHER_CTX k1, k2, k3;
279 ssh1_3des_init(EVP_CIPHER_CTX *ctx, const u_char *key, const u_char *iv,
282 struct ssh1_3des_ctx *c;
283 u_char *k1, *k2, *k3;
285 if ((c = EVP_CIPHER_CTX_get_app_data(ctx)) == NULL) {
286 c = xmalloc(sizeof(*c));
287 EVP_CIPHER_CTX_set_app_data(ctx, c);
293 k1 = k2 = k3 = (u_char *) key;
295 if (EVP_CIPHER_CTX_key_length(ctx) >= 16+8) {
301 EVP_CIPHER_CTX_init(&c->k1);
302 EVP_CIPHER_CTX_init(&c->k2);
303 EVP_CIPHER_CTX_init(&c->k3);
304 if (EVP_CipherInit(&c->k1, EVP_des_cbc(), k1, NULL, enc) == 0 ||
305 EVP_CipherInit(&c->k2, EVP_des_cbc(), k2, NULL, !enc) == 0 ||
306 EVP_CipherInit(&c->k3, EVP_des_cbc(), k3, NULL, enc) == 0) {
307 memset(c, 0, sizeof(*c));
309 EVP_CIPHER_CTX_set_app_data(ctx, NULL);
315 ssh1_3des_cbc(EVP_CIPHER_CTX *ctx, u_char *dest, const u_char *src, u_int len)
317 struct ssh1_3des_ctx *c;
319 if ((c = EVP_CIPHER_CTX_get_app_data(ctx)) == NULL) {
320 error("ssh1_3des_cbc: no context");
323 if (EVP_Cipher(&c->k1, dest, (u_char *)src, len) == 0 ||
324 EVP_Cipher(&c->k2, dest, dest, len) == 0 ||
325 EVP_Cipher(&c->k3, dest, dest, len) == 0)
330 ssh1_3des_cleanup(EVP_CIPHER_CTX *ctx)
332 struct ssh1_3des_ctx *c;
334 if ((c = EVP_CIPHER_CTX_get_app_data(ctx)) != NULL) {
335 memset(c, 0, sizeof(*c));
337 EVP_CIPHER_CTX_set_app_data(ctx, NULL);
344 static EVP_CIPHER ssh1_3des;
346 memset(&ssh1_3des, 0, sizeof(EVP_CIPHER));
347 ssh1_3des.nid = NID_undef;
348 ssh1_3des.block_size = 8;
349 ssh1_3des.iv_len = 0;
350 ssh1_3des.key_len = 16;
351 ssh1_3des.init = ssh1_3des_init;
352 ssh1_3des.cleanup = ssh1_3des_cleanup;
353 ssh1_3des.do_cipher = ssh1_3des_cbc;
354 ssh1_3des.flags = EVP_CIPH_CBC_MODE | EVP_CIPH_VARIABLE_LENGTH;
359 * SSH1 uses a variation on Blowfish, all bytes must be swapped before
360 * and after encryption/decryption. Thus the swap_bytes stuff (yuk).
363 swap_bytes(const u_char *src, u_char *dst, int n)
367 /* Process 4 bytes every lap. */
368 for (n = n / 4; n > 0; n--) {
380 static int (*orig_bf)(EVP_CIPHER_CTX *, u_char *, const u_char *, u_int) = NULL;
382 bf_ssh1_cipher(EVP_CIPHER_CTX *ctx, u_char *out, const u_char *in, u_int len)
386 swap_bytes(in, out, len);
387 ret = (*orig_bf)(ctx, out, out, len);
388 swap_bytes(out, out, len);
394 static EVP_CIPHER ssh1_bf;
396 memcpy(&ssh1_bf, EVP_bf_cbc(), sizeof(EVP_CIPHER));
397 orig_bf = ssh1_bf.do_cipher;
398 ssh1_bf.nid = NID_undef;
399 ssh1_bf.do_cipher = bf_ssh1_cipher;
400 ssh1_bf.key_len = 32;
405 #define RIJNDAEL_BLOCKSIZE 16
406 struct ssh_rijndael_ctx
409 u_char r_iv[RIJNDAEL_BLOCKSIZE];
413 ssh_rijndael_init(EVP_CIPHER_CTX *ctx, const u_char *key, const u_char *iv,
416 struct ssh_rijndael_ctx *c;
418 if ((c = EVP_CIPHER_CTX_get_app_data(ctx)) == NULL) {
419 c = xmalloc(sizeof(*c));
420 EVP_CIPHER_CTX_set_app_data(ctx, c);
425 rijndael_set_key(&c->r_ctx, (u_char *)key,
426 8*EVP_CIPHER_CTX_key_length(ctx), enc);
429 memcpy(c->r_iv, iv, RIJNDAEL_BLOCKSIZE);
433 ssh_rijndael_cbc(EVP_CIPHER_CTX *ctx, u_char *dest, const u_char *src,
436 struct ssh_rijndael_ctx *c;
437 u_char buf[RIJNDAEL_BLOCKSIZE];
438 u_char *cprev, *cnow, *plain, *ivp;
439 int i, j, blocks = len / RIJNDAEL_BLOCKSIZE;
443 if (len % RIJNDAEL_BLOCKSIZE)
444 fatal("ssh_rijndael_cbc: bad len %d", len);
445 if ((c = EVP_CIPHER_CTX_get_app_data(ctx)) == NULL) {
446 error("ssh_rijndael_cbc: no context");
451 plain = (u_char *)src;
453 for (i = 0; i < blocks; i++, plain+=RIJNDAEL_BLOCKSIZE,
454 cnow+=RIJNDAEL_BLOCKSIZE) {
455 for (j = 0; j < RIJNDAEL_BLOCKSIZE; j++)
456 buf[j] = plain[j] ^ cprev[j];
457 rijndael_encrypt(&c->r_ctx, buf, cnow);
460 memcpy(c->r_iv, cprev, RIJNDAEL_BLOCKSIZE);
462 cnow = (u_char *) (src+len-RIJNDAEL_BLOCKSIZE);
463 plain = dest+len-RIJNDAEL_BLOCKSIZE;
465 memcpy(buf, cnow, RIJNDAEL_BLOCKSIZE);
466 for (i = blocks; i > 0; i--, cnow-=RIJNDAEL_BLOCKSIZE,
467 plain-=RIJNDAEL_BLOCKSIZE) {
468 rijndael_decrypt(&c->r_ctx, cnow, plain);
469 ivp = (i == 1) ? c->r_iv : cnow-RIJNDAEL_BLOCKSIZE;
470 for (j = 0; j < RIJNDAEL_BLOCKSIZE; j++)
473 memcpy(c->r_iv, buf, RIJNDAEL_BLOCKSIZE);
478 ssh_rijndael_cleanup(EVP_CIPHER_CTX *ctx)
480 struct ssh_rijndael_ctx *c;
482 if ((c = EVP_CIPHER_CTX_get_app_data(ctx)) != NULL) {
483 memset(c, 0, sizeof(*c));
485 EVP_CIPHER_CTX_set_app_data(ctx, NULL);
492 static EVP_CIPHER rijndal_cbc;
494 memset(&rijndal_cbc, 0, sizeof(EVP_CIPHER));
495 rijndal_cbc.nid = NID_undef;
496 rijndal_cbc.block_size = RIJNDAEL_BLOCKSIZE;
497 rijndal_cbc.iv_len = RIJNDAEL_BLOCKSIZE;
498 rijndal_cbc.key_len = 16;
499 rijndal_cbc.init = ssh_rijndael_init;
500 rijndal_cbc.cleanup = ssh_rijndael_cleanup;
501 rijndal_cbc.do_cipher = ssh_rijndael_cbc;
502 rijndal_cbc.flags = EVP_CIPH_CBC_MODE | EVP_CIPH_VARIABLE_LENGTH |
503 EVP_CIPH_ALWAYS_CALL_INIT;
504 return (&rijndal_cbc);
508 * Exports an IV from the CipherContext required to export the key
509 * state back from the unprivileged child to the privileged parent
514 cipher_get_keyiv_len(CipherContext *cc)
516 Cipher *c = cc->cipher;
519 if (c->number == SSH_CIPHER_3DES)
522 ivlen = EVP_CIPHER_CTX_iv_length(&cc->evp);
527 cipher_get_keyiv(CipherContext *cc, u_char *iv, u_int len)
529 Cipher *c = cc->cipher;
534 case SSH_CIPHER_SSH2:
536 case SSH_CIPHER_BLOWFISH:
537 evplen = EVP_CIPHER_CTX_iv_length(&cc->evp);
541 fatal("%s: wrong iv length %d != %d", __FUNCTION__,
544 if (strncmp(c->name, "aes", 3) == 0) {
545 struct ssh_rijndael_ctx *aesc;
547 aesc = EVP_CIPHER_CTX_get_app_data(&cc->evp);
549 fatal("%s: no rijndael context", __FUNCTION__);
555 case SSH_CIPHER_3DES: {
556 struct ssh1_3des_ctx *desc;
558 fatal("%s: bad 3des iv length: %d", __FUNCTION__, len);
559 desc = EVP_CIPHER_CTX_get_app_data(&cc->evp);
561 fatal("%s: no 3des context", __FUNCTION__);
562 debug3("%s: Copying 3DES IV", __FUNCTION__);
563 memcpy(iv, desc->k1.iv, 8);
564 memcpy(iv + 8, desc->k2.iv, 8);
565 memcpy(iv + 16, desc->k3.iv, 8);
569 fatal("%s: bad cipher %d", __FUNCTION__, c->number);
571 memcpy(iv, civ, len);
575 cipher_set_keyiv(CipherContext *cc, u_char *iv)
577 Cipher *c = cc->cipher;
582 case SSH_CIPHER_SSH2:
584 case SSH_CIPHER_BLOWFISH:
585 evplen = EVP_CIPHER_CTX_iv_length(&cc->evp);
589 if (strncmp(c->name, "aes", 3) == 0) {
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;
602 desc = EVP_CIPHER_CTX_get_app_data(&cc->evp);
604 fatal("%s: no 3des context", __FUNCTION__);
605 debug3("%s: Installed 3DES IV", __FUNCTION__);
606 memcpy(desc->k1.iv, iv, 8);
607 memcpy(desc->k2.iv, iv + 8, 8);
608 memcpy(desc->k3.iv, iv + 16, 8);
612 fatal("%s: bad cipher %d", __FUNCTION__, c->number);
614 memcpy(div, iv, evplen);
617 #if OPENSSL_VERSION_NUMBER < 0x00907000L
618 #define EVP_X_STATE(evp) &(evp).c
619 #define EVP_X_STATE_LEN(evp) sizeof((evp).c)
621 #define EVP_X_STATE(evp) (evp).cipher_data
622 #define EVP_X_STATE_LEN(evp) (evp).cipher->ctx_size
626 cipher_get_keycontext(CipherContext *cc, u_char *dat)
628 Cipher *c = cc->cipher;
631 if (c->number == SSH_CIPHER_3DES) {
632 struct ssh1_3des_ctx *desc;
633 desc = EVP_CIPHER_CTX_get_app_data(&cc->evp);
635 fatal("%s: no 3des context", __FUNCTION__);
636 plen = EVP_X_STATE_LEN(desc->k1);
639 memcpy(dat, EVP_X_STATE(desc->k1), plen);
640 memcpy(dat + plen, EVP_X_STATE(desc->k2), plen);
641 memcpy(dat + 2*plen, EVP_X_STATE(desc->k3), plen);
646 plen = EVP_X_STATE_LEN(cc->evp);
650 memcpy(dat, EVP_X_STATE(cc->evp), plen);
655 cipher_set_keycontext(CipherContext *cc, u_char *dat)
657 Cipher *c = cc->cipher;
660 if (c->number == SSH_CIPHER_3DES) {
661 struct ssh1_3des_ctx *desc;
662 desc = EVP_CIPHER_CTX_get_app_data(&cc->evp);
664 fatal("%s: no 3des context", __FUNCTION__);
665 plen = EVP_X_STATE_LEN(desc->k1);
666 memcpy(EVP_X_STATE(desc->k1), dat, plen);
667 memcpy(EVP_X_STATE(desc->k2), dat + plen, plen);
668 memcpy(EVP_X_STATE(desc->k3), dat + 2*plen, plen);
670 plen = EVP_X_STATE_LEN(cc->evp);
671 memcpy(EVP_X_STATE(cc->evp), dat, plen);