1 /* $OpenBSD: cipher.c,v 1.89 2013/05/17 00:13:13 djm Exp $ */
4 * Author: Tatu Ylonen <ylo@cs.hut.fi>
5 * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
8 * As far as I am concerned, the code I have written for this software
9 * can be used freely for any purpose. Any derived versions of this
10 * software must be clearly marked as such, and if the derived work is
11 * incompatible with the protocol description in the RFC file, it must be
12 * called by a name other than "ssh" or "Secure Shell".
15 * Copyright (c) 1999 Niels Provos. All rights reserved.
16 * Copyright (c) 1999, 2000 Markus Friedl. All rights reserved.
18 * Redistribution and use in source and binary forms, with or without
19 * modification, are permitted provided that the following conditions
21 * 1. Redistributions of source code must retain the above copyright
22 * notice, this list of conditions and the following disclaimer.
23 * 2. Redistributions in binary form must reproduce the above copyright
24 * notice, this list of conditions and the following disclaimer in the
25 * documentation and/or other materials provided with the distribution.
27 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
28 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
29 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
30 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
31 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
32 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
33 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
34 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
35 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
36 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
41 #include <sys/types.h>
43 #include <openssl/md5.h>
52 /* compatibility with old or broken OpenSSL versions */
53 #include "openbsd-compat/openssl-compat.h"
55 extern const EVP_CIPHER *evp_ssh1_bf(void);
56 extern const EVP_CIPHER *evp_ssh1_3des(void);
57 extern void ssh1_3des_iv(EVP_CIPHER_CTX *, int, u_char *, int);
61 int number; /* for ssh1 only */
64 u_int iv_len; /* defaults to block_size */
68 const EVP_CIPHER *(*evptype)(void);
71 static const struct Cipher ciphers[] = {
72 { "none", SSH_CIPHER_NONE, 8, 0, 0, 0, 0, 0, EVP_enc_null },
73 { "des", SSH_CIPHER_DES, 8, 8, 0, 0, 0, 1, EVP_des_cbc },
74 { "3des", SSH_CIPHER_3DES, 8, 16, 0, 0, 0, 1, evp_ssh1_3des },
75 { "blowfish", SSH_CIPHER_BLOWFISH, 8, 32, 0, 0, 0, 1, evp_ssh1_bf },
77 { "3des-cbc", SSH_CIPHER_SSH2, 8, 24, 0, 0, 0, 1, EVP_des_ede3_cbc },
79 SSH_CIPHER_SSH2, 8, 16, 0, 0, 0, 1, EVP_bf_cbc },
81 SSH_CIPHER_SSH2, 8, 16, 0, 0, 0, 1, EVP_cast5_cbc },
82 { "arcfour", SSH_CIPHER_SSH2, 8, 16, 0, 0, 0, 0, EVP_rc4 },
83 { "arcfour128", SSH_CIPHER_SSH2, 8, 16, 0, 0, 1536, 0, EVP_rc4 },
84 { "arcfour256", SSH_CIPHER_SSH2, 8, 32, 0, 0, 1536, 0, EVP_rc4 },
85 { "aes128-cbc", SSH_CIPHER_SSH2, 16, 16, 0, 0, 0, 1, EVP_aes_128_cbc },
86 { "aes192-cbc", SSH_CIPHER_SSH2, 16, 24, 0, 0, 0, 1, EVP_aes_192_cbc },
87 { "aes256-cbc", SSH_CIPHER_SSH2, 16, 32, 0, 0, 0, 1, EVP_aes_256_cbc },
88 { "rijndael-cbc@lysator.liu.se",
89 SSH_CIPHER_SSH2, 16, 32, 0, 0, 0, 1, EVP_aes_256_cbc },
90 { "aes128-ctr", SSH_CIPHER_SSH2, 16, 16, 0, 0, 0, 0, EVP_aes_128_ctr },
91 { "aes192-ctr", SSH_CIPHER_SSH2, 16, 24, 0, 0, 0, 0, EVP_aes_192_ctr },
92 { "aes256-ctr", SSH_CIPHER_SSH2, 16, 32, 0, 0, 0, 0, EVP_aes_256_ctr },
93 #ifdef OPENSSL_HAVE_EVPGCM
94 { "aes128-gcm@openssh.com",
95 SSH_CIPHER_SSH2, 16, 16, 12, 16, 0, 0, EVP_aes_128_gcm },
96 { "aes256-gcm@openssh.com",
97 SSH_CIPHER_SSH2, 16, 32, 12, 16, 0, 0, EVP_aes_256_gcm },
99 { NULL, SSH_CIPHER_INVALID, 0, 0, 0, 0, 0, 0, NULL }
104 /* Returns a comma-separated list of supported ciphers. */
106 cipher_alg_list(void)
109 size_t nlen, rlen = 0;
112 for (c = ciphers; c->name != NULL; c++) {
113 if (c->number != SSH_CIPHER_SSH2)
117 nlen = strlen(c->name);
118 ret = xrealloc(ret, 1, rlen + nlen + 2);
119 memcpy(ret + rlen, c->name, nlen + 1);
126 cipher_blocksize(const Cipher *c)
128 return (c->block_size);
132 cipher_keylen(const Cipher *c)
138 cipher_authlen(const Cipher *c)
140 return (c->auth_len);
144 cipher_ivlen(const Cipher *c)
146 return (c->iv_len ? c->iv_len : c->block_size);
150 cipher_get_number(const Cipher *c)
156 cipher_is_cbc(const Cipher *c)
158 return (c->cbc_mode);
162 cipher_mask_ssh1(int client)
165 mask |= 1 << SSH_CIPHER_3DES; /* Mandatory */
166 mask |= 1 << SSH_CIPHER_BLOWFISH;
168 mask |= 1 << SSH_CIPHER_DES;
174 cipher_by_name(const char *name)
177 for (c = ciphers; c->name != NULL; c++)
178 if (strcmp(c->name, name) == 0)
184 cipher_by_number(int id)
187 for (c = ciphers; c->name != NULL; c++)
193 #define CIPHER_SEP ","
195 ciphers_valid(const char *names)
198 char *cipher_list, *cp;
201 if (names == NULL || strcmp(names, "") == 0)
203 cipher_list = cp = xstrdup(names);
204 for ((p = strsep(&cp, CIPHER_SEP)); p && *p != '\0';
205 (p = strsep(&cp, CIPHER_SEP))) {
206 c = cipher_by_name(p);
207 #ifdef NONE_CIPHER_ENABLED
208 if (c == NULL || (c->number != SSH_CIPHER_SSH2 &&
209 c->number != SSH_CIPHER_NONE)) {
211 if (c == NULL || (c->number != SSH_CIPHER_SSH2)) {
213 debug("bad cipher %s [%s]", p, names);
217 debug3("cipher ok: %s [%s]", p, names);
220 debug3("ciphers ok: [%s]", names);
226 * Parses the name of the cipher. Returns the number of the corresponding
227 * cipher, or -1 on error.
231 cipher_number(const char *name)
236 for (c = ciphers; c->name != NULL; c++)
237 if (strcasecmp(c->name, name) == 0)
245 const Cipher *c = cipher_by_number(id);
246 return (c==NULL) ? "<unknown>" : c->name;
250 cipher_init(CipherContext *cc, const Cipher *cipher,
251 const u_char *key, u_int keylen, const u_char *iv, u_int ivlen,
254 static int dowarn = 1;
258 const EVP_CIPHER *type;
261 u_char *junk, *discard;
263 if (cipher->number == SSH_CIPHER_DES) {
265 error("Warning: use of DES is strongly discouraged "
266 "due to cryptographic weaknesses");
272 cc->plaintext = (cipher->number == SSH_CIPHER_NONE);
273 cc->encrypt = do_encrypt;
275 if (keylen < cipher->key_len)
276 fatal("cipher_init: key length %d is insufficient for %s.",
277 keylen, cipher->name);
278 if (iv != NULL && ivlen < cipher_ivlen(cipher))
279 fatal("cipher_init: iv length %d is insufficient for %s.",
280 ivlen, cipher->name);
283 type = (*cipher->evptype)();
285 EVP_CIPHER_CTX_init(&cc->evp);
287 if (type->key_len > 0 && type->key_len != keylen) {
288 debug("cipher_init: set keylen (%d -> %d)",
289 type->key_len, keylen);
290 type->key_len = keylen;
292 EVP_CipherInit(&cc->evp, type, (u_char *)key, (u_char *)iv,
293 (do_encrypt == CIPHER_ENCRYPT));
295 if (EVP_CipherInit(&cc->evp, type, NULL, (u_char *)iv,
296 (do_encrypt == CIPHER_ENCRYPT)) == 0)
297 fatal("cipher_init: EVP_CipherInit failed for %s",
299 if (cipher_authlen(cipher) &&
300 !EVP_CIPHER_CTX_ctrl(&cc->evp, EVP_CTRL_GCM_SET_IV_FIXED,
302 fatal("cipher_init: EVP_CTRL_GCM_SET_IV_FIXED failed for %s",
304 klen = EVP_CIPHER_CTX_key_length(&cc->evp);
305 if (klen > 0 && keylen != (u_int)klen) {
306 debug2("cipher_init: set keylen (%d -> %d)", klen, keylen);
307 if (EVP_CIPHER_CTX_set_key_length(&cc->evp, keylen) == 0)
308 fatal("cipher_init: set keylen failed (%d -> %d)",
311 if (EVP_CipherInit(&cc->evp, NULL, (u_char *)key, NULL, -1) == 0)
312 fatal("cipher_init: EVP_CipherInit: set key failed for %s",
316 if (cipher->discard_len > 0) {
317 junk = xmalloc(cipher->discard_len);
318 discard = xmalloc(cipher->discard_len);
319 if (EVP_Cipher(&cc->evp, discard, junk,
320 cipher->discard_len) == 0)
321 fatal("evp_crypt: EVP_Cipher failed during discard");
322 memset(discard, 0, cipher->discard_len);
329 * cipher_crypt() operates as following:
330 * Copy 'aadlen' bytes (without en/decryption) from 'src' to 'dest'.
331 * Theses bytes are treated as additional authenticated data for
332 * authenticated encryption modes.
333 * En/Decrypt 'len' bytes at offset 'aadlen' from 'src' to 'dest'.
334 * Use 'authlen' bytes at offset 'len'+'aadlen' as the authentication tag.
335 * This tag is written on encryption and verified on decryption.
336 * Both 'aadlen' and 'authlen' can be set to 0.
339 cipher_crypt(CipherContext *cc, u_char *dest, const u_char *src,
340 u_int len, u_int aadlen, u_int authlen)
345 if (authlen != cipher_authlen(cc->cipher))
346 fatal("%s: authlen mismatch %d", __func__, authlen);
348 if (!EVP_CIPHER_CTX_ctrl(&cc->evp, EVP_CTRL_GCM_IV_GEN,
350 fatal("%s: EVP_CTRL_GCM_IV_GEN", __func__);
351 /* set tag on decyption */
353 !EVP_CIPHER_CTX_ctrl(&cc->evp, EVP_CTRL_GCM_SET_TAG,
354 authlen, (u_char *)src + aadlen + len))
355 fatal("%s: EVP_CTRL_GCM_SET_TAG", __func__);
359 EVP_Cipher(&cc->evp, NULL, (u_char *)src, aadlen) < 0)
360 fatal("%s: EVP_Cipher(aad) failed", __func__);
361 memcpy(dest, src, aadlen);
363 if (len % cc->cipher->block_size)
364 fatal("%s: bad plaintext length %d", __func__, len);
365 if (EVP_Cipher(&cc->evp, dest + aadlen, (u_char *)src + aadlen,
367 fatal("%s: EVP_Cipher failed", __func__);
369 /* compute tag (on encrypt) or verify tag (on decrypt) */
370 if (EVP_Cipher(&cc->evp, NULL, NULL, 0) < 0) {
372 fatal("%s: EVP_Cipher(final) failed", __func__);
374 fatal("Decryption integrity check failed");
377 !EVP_CIPHER_CTX_ctrl(&cc->evp, EVP_CTRL_GCM_GET_TAG,
378 authlen, dest + aadlen + len))
379 fatal("%s: EVP_CTRL_GCM_GET_TAG", __func__);
384 cipher_cleanup(CipherContext *cc)
386 if (EVP_CIPHER_CTX_cleanup(&cc->evp) == 0)
387 error("cipher_cleanup: EVP_CIPHER_CTX_cleanup failed");
391 * Selects the cipher, and keys if by computing the MD5 checksum of the
392 * passphrase and using the resulting 16 bytes as the key.
396 cipher_set_key_string(CipherContext *cc, const Cipher *cipher,
397 const char *passphrase, int do_encrypt)
403 MD5_Update(&md, (const u_char *)passphrase, strlen(passphrase));
404 MD5_Final(digest, &md);
406 cipher_init(cc, cipher, digest, 16, NULL, 0, do_encrypt);
408 memset(digest, 0, sizeof(digest));
409 memset(&md, 0, sizeof(md));
413 * Exports an IV from the CipherContext required to export the key
414 * state back from the unprivileged child to the privileged parent
419 cipher_get_keyiv_len(const CipherContext *cc)
421 const Cipher *c = cc->cipher;
424 if (c->number == SSH_CIPHER_3DES)
427 ivlen = EVP_CIPHER_CTX_iv_length(&cc->evp);
432 cipher_get_keyiv(CipherContext *cc, u_char *iv, u_int len)
434 const Cipher *c = cc->cipher;
438 #ifdef NONE_CIPHER_ENABLED
439 case SSH_CIPHER_NONE:
441 case SSH_CIPHER_SSH2:
443 case SSH_CIPHER_BLOWFISH:
444 evplen = EVP_CIPHER_CTX_iv_length(&cc->evp);
447 if ((u_int)evplen != len)
448 fatal("%s: wrong iv length %d != %d", __func__,
450 #ifdef USE_BUILTIN_RIJNDAEL
451 if (c->evptype == evp_rijndael)
452 ssh_rijndael_iv(&cc->evp, 0, iv, len);
455 #ifndef OPENSSL_HAVE_EVPCTR
456 if (c->evptype == evp_aes_128_ctr)
457 ssh_aes_ctr_iv(&cc->evp, 0, iv, len);
460 memcpy(iv, cc->evp.iv, len);
462 case SSH_CIPHER_3DES:
463 ssh1_3des_iv(&cc->evp, 0, iv, 24);
466 fatal("%s: bad cipher %d", __func__, c->number);
471 cipher_set_keyiv(CipherContext *cc, u_char *iv)
473 const Cipher *c = cc->cipher;
477 #ifdef NONE_CIPHER_ENABLED
478 case SSH_CIPHER_NONE:
480 case SSH_CIPHER_SSH2:
482 case SSH_CIPHER_BLOWFISH:
483 evplen = EVP_CIPHER_CTX_iv_length(&cc->evp);
486 #ifdef USE_BUILTIN_RIJNDAEL
487 if (c->evptype == evp_rijndael)
488 ssh_rijndael_iv(&cc->evp, 1, iv, evplen);
491 #ifndef OPENSSL_HAVE_EVPCTR
492 if (c->evptype == evp_aes_128_ctr)
493 ssh_aes_ctr_iv(&cc->evp, 1, iv, evplen);
496 memcpy(cc->evp.iv, iv, evplen);
498 case SSH_CIPHER_3DES:
499 ssh1_3des_iv(&cc->evp, 1, iv, 24);
502 fatal("%s: bad cipher %d", __func__, c->number);
507 cipher_get_keycontext(const CipherContext *cc, u_char *dat)
509 const Cipher *c = cc->cipher;
512 if (c->evptype == EVP_rc4) {
513 plen = EVP_X_STATE_LEN(cc->evp);
516 memcpy(dat, EVP_X_STATE(cc->evp), plen);
522 cipher_set_keycontext(CipherContext *cc, u_char *dat)
524 const Cipher *c = cc->cipher;
527 if (c->evptype == EVP_rc4) {
528 plen = EVP_X_STATE_LEN(cc->evp);
529 memcpy(EVP_X_STATE(cc->evp), dat, plen);