1 /* $OpenBSD: cipher.c,v 1.87 2013/01/26 06:11:05 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);
70 { "none", SSH_CIPHER_NONE, 8, 0, 0, 0, 0, 0, EVP_enc_null },
71 { "des", SSH_CIPHER_DES, 8, 8, 0, 0, 0, 1, EVP_des_cbc },
72 { "3des", SSH_CIPHER_3DES, 8, 16, 0, 0, 0, 1, evp_ssh1_3des },
73 { "blowfish", SSH_CIPHER_BLOWFISH, 8, 32, 0, 0, 0, 1, evp_ssh1_bf },
75 { "3des-cbc", SSH_CIPHER_SSH2, 8, 24, 0, 0, 0, 1, EVP_des_ede3_cbc },
77 SSH_CIPHER_SSH2, 8, 16, 0, 0, 0, 1, EVP_bf_cbc },
79 SSH_CIPHER_SSH2, 8, 16, 0, 0, 0, 1, EVP_cast5_cbc },
80 { "arcfour", SSH_CIPHER_SSH2, 8, 16, 0, 0, 0, 0, EVP_rc4 },
81 { "arcfour128", SSH_CIPHER_SSH2, 8, 16, 0, 0, 1536, 0, EVP_rc4 },
82 { "arcfour256", SSH_CIPHER_SSH2, 8, 32, 0, 0, 1536, 0, EVP_rc4 },
83 { "aes128-cbc", SSH_CIPHER_SSH2, 16, 16, 0, 0, 0, 1, EVP_aes_128_cbc },
84 { "aes192-cbc", SSH_CIPHER_SSH2, 16, 24, 0, 0, 0, 1, EVP_aes_192_cbc },
85 { "aes256-cbc", SSH_CIPHER_SSH2, 16, 32, 0, 0, 0, 1, EVP_aes_256_cbc },
86 { "rijndael-cbc@lysator.liu.se",
87 SSH_CIPHER_SSH2, 16, 32, 0, 0, 0, 1, EVP_aes_256_cbc },
88 { "aes128-ctr", SSH_CIPHER_SSH2, 16, 16, 0, 0, 0, 0, EVP_aes_128_ctr },
89 { "aes192-ctr", SSH_CIPHER_SSH2, 16, 24, 0, 0, 0, 0, EVP_aes_192_ctr },
90 { "aes256-ctr", SSH_CIPHER_SSH2, 16, 32, 0, 0, 0, 0, EVP_aes_256_ctr },
91 #ifdef OPENSSL_HAVE_EVPGCM
92 { "aes128-gcm@openssh.com",
93 SSH_CIPHER_SSH2, 16, 16, 12, 16, 0, 0, EVP_aes_128_gcm },
94 { "aes256-gcm@openssh.com",
95 SSH_CIPHER_SSH2, 16, 32, 12, 16, 0, 0, EVP_aes_256_gcm },
97 { NULL, SSH_CIPHER_INVALID, 0, 0, 0, 0, 0, 0, NULL }
103 cipher_blocksize(const Cipher *c)
105 return (c->block_size);
109 cipher_keylen(const Cipher *c)
115 cipher_authlen(const Cipher *c)
117 return (c->auth_len);
121 cipher_ivlen(const Cipher *c)
123 return (c->iv_len ? c->iv_len : c->block_size);
127 cipher_get_number(const Cipher *c)
133 cipher_is_cbc(const Cipher *c)
135 return (c->cbc_mode);
139 cipher_mask_ssh1(int client)
142 mask |= 1 << SSH_CIPHER_3DES; /* Mandatory */
143 mask |= 1 << SSH_CIPHER_BLOWFISH;
145 mask |= 1 << SSH_CIPHER_DES;
151 cipher_by_name(const char *name)
154 for (c = ciphers; c->name != NULL; c++)
155 if (strcmp(c->name, name) == 0)
161 cipher_by_number(int id)
164 for (c = ciphers; c->name != NULL; c++)
170 #define CIPHER_SEP ","
172 ciphers_valid(const char *names)
175 char *cipher_list, *cp;
178 if (names == NULL || strcmp(names, "") == 0)
180 cipher_list = cp = xstrdup(names);
181 for ((p = strsep(&cp, CIPHER_SEP)); p && *p != '\0';
182 (p = strsep(&cp, CIPHER_SEP))) {
183 c = cipher_by_name(p);
184 #ifdef NONE_CIPHER_ENABLED
185 if (c == NULL || (c->number != SSH_CIPHER_SSH2 &&
186 c->number != SSH_CIPHER_NONE)) {
188 if (c == NULL || (c->number != SSH_CIPHER_SSH2)) {
190 debug("bad cipher %s [%s]", p, names);
194 debug3("cipher ok: %s [%s]", p, names);
197 debug3("ciphers ok: [%s]", names);
203 * Parses the name of the cipher. Returns the number of the corresponding
204 * cipher, or -1 on error.
208 cipher_number(const char *name)
213 for (c = ciphers; c->name != NULL; c++)
214 if (strcasecmp(c->name, name) == 0)
222 Cipher *c = cipher_by_number(id);
223 return (c==NULL) ? "<unknown>" : c->name;
227 cipher_init(CipherContext *cc, Cipher *cipher,
228 const u_char *key, u_int keylen, const u_char *iv, u_int ivlen,
231 static int dowarn = 1;
235 const EVP_CIPHER *type;
238 u_char *junk, *discard;
240 if (cipher->number == SSH_CIPHER_DES) {
242 error("Warning: use of DES is strongly discouraged "
243 "due to cryptographic weaknesses");
249 cc->plaintext = (cipher->number == SSH_CIPHER_NONE);
250 cc->encrypt = do_encrypt;
252 if (keylen < cipher->key_len)
253 fatal("cipher_init: key length %d is insufficient for %s.",
254 keylen, cipher->name);
255 if (iv != NULL && ivlen < cipher_ivlen(cipher))
256 fatal("cipher_init: iv length %d is insufficient for %s.",
257 ivlen, cipher->name);
260 type = (*cipher->evptype)();
262 EVP_CIPHER_CTX_init(&cc->evp);
264 if (type->key_len > 0 && type->key_len != keylen) {
265 debug("cipher_init: set keylen (%d -> %d)",
266 type->key_len, keylen);
267 type->key_len = keylen;
269 EVP_CipherInit(&cc->evp, type, (u_char *)key, (u_char *)iv,
270 (do_encrypt == CIPHER_ENCRYPT));
272 if (EVP_CipherInit(&cc->evp, type, NULL, (u_char *)iv,
273 (do_encrypt == CIPHER_ENCRYPT)) == 0)
274 fatal("cipher_init: EVP_CipherInit failed for %s",
276 if (cipher_authlen(cipher) &&
277 !EVP_CIPHER_CTX_ctrl(&cc->evp, EVP_CTRL_GCM_SET_IV_FIXED,
279 fatal("cipher_init: EVP_CTRL_GCM_SET_IV_FIXED failed for %s",
281 klen = EVP_CIPHER_CTX_key_length(&cc->evp);
282 if (klen > 0 && keylen != (u_int)klen) {
283 debug2("cipher_init: set keylen (%d -> %d)", klen, keylen);
284 if (EVP_CIPHER_CTX_set_key_length(&cc->evp, keylen) == 0)
285 fatal("cipher_init: set keylen failed (%d -> %d)",
288 if (EVP_CipherInit(&cc->evp, NULL, (u_char *)key, NULL, -1) == 0)
289 fatal("cipher_init: EVP_CipherInit: set key failed for %s",
293 if (cipher->discard_len > 0) {
294 junk = xmalloc(cipher->discard_len);
295 discard = xmalloc(cipher->discard_len);
296 if (EVP_Cipher(&cc->evp, discard, junk,
297 cipher->discard_len) == 0)
298 fatal("evp_crypt: EVP_Cipher failed during discard");
299 memset(discard, 0, cipher->discard_len);
306 * cipher_crypt() operates as following:
307 * Copy 'aadlen' bytes (without en/decryption) from 'src' to 'dest'.
308 * Theses bytes are treated as additional authenticated data for
309 * authenticated encryption modes.
310 * En/Decrypt 'len' bytes at offset 'aadlen' from 'src' to 'dest'.
311 * Use 'authlen' bytes at offset 'len'+'aadlen' as the authentication tag.
312 * This tag is written on encryption and verified on decryption.
313 * Both 'aadlen' and 'authlen' can be set to 0.
316 cipher_crypt(CipherContext *cc, u_char *dest, const u_char *src,
317 u_int len, u_int aadlen, u_int authlen)
322 if (authlen != cipher_authlen(cc->cipher))
323 fatal("%s: authlen mismatch %d", __func__, authlen);
325 if (!EVP_CIPHER_CTX_ctrl(&cc->evp, EVP_CTRL_GCM_IV_GEN,
327 fatal("%s: EVP_CTRL_GCM_IV_GEN", __func__);
328 /* set tag on decyption */
330 !EVP_CIPHER_CTX_ctrl(&cc->evp, EVP_CTRL_GCM_SET_TAG,
331 authlen, (u_char *)src + aadlen + len))
332 fatal("%s: EVP_CTRL_GCM_SET_TAG", __func__);
336 EVP_Cipher(&cc->evp, NULL, (u_char *)src, aadlen) < 0)
337 fatal("%s: EVP_Cipher(aad) failed", __func__);
338 memcpy(dest, src, aadlen);
340 if (len % cc->cipher->block_size)
341 fatal("%s: bad plaintext length %d", __func__, len);
342 if (EVP_Cipher(&cc->evp, dest + aadlen, (u_char *)src + aadlen,
344 fatal("%s: EVP_Cipher failed", __func__);
346 /* compute tag (on encrypt) or verify tag (on decrypt) */
347 if (EVP_Cipher(&cc->evp, NULL, NULL, 0) < 0) {
349 fatal("%s: EVP_Cipher(final) failed", __func__);
351 fatal("Decryption integrity check failed");
354 !EVP_CIPHER_CTX_ctrl(&cc->evp, EVP_CTRL_GCM_GET_TAG,
355 authlen, dest + aadlen + len))
356 fatal("%s: EVP_CTRL_GCM_GET_TAG", __func__);
361 cipher_cleanup(CipherContext *cc)
363 if (EVP_CIPHER_CTX_cleanup(&cc->evp) == 0)
364 error("cipher_cleanup: EVP_CIPHER_CTX_cleanup failed");
368 * Selects the cipher, and keys if by computing the MD5 checksum of the
369 * passphrase and using the resulting 16 bytes as the key.
373 cipher_set_key_string(CipherContext *cc, Cipher *cipher,
374 const char *passphrase, int do_encrypt)
380 MD5_Update(&md, (const u_char *)passphrase, strlen(passphrase));
381 MD5_Final(digest, &md);
383 cipher_init(cc, cipher, digest, 16, NULL, 0, do_encrypt);
385 memset(digest, 0, sizeof(digest));
386 memset(&md, 0, sizeof(md));
390 * Exports an IV from the CipherContext required to export the key
391 * state back from the unprivileged child to the privileged parent
396 cipher_get_keyiv_len(const CipherContext *cc)
398 Cipher *c = cc->cipher;
401 if (c->number == SSH_CIPHER_3DES)
404 ivlen = EVP_CIPHER_CTX_iv_length(&cc->evp);
409 cipher_get_keyiv(CipherContext *cc, u_char *iv, u_int len)
411 Cipher *c = cc->cipher;
415 #ifdef NONE_CIPHER_ENABLED
416 case SSH_CIPHER_NONE:
418 case SSH_CIPHER_SSH2:
420 case SSH_CIPHER_BLOWFISH:
421 evplen = EVP_CIPHER_CTX_iv_length(&cc->evp);
424 if ((u_int)evplen != len)
425 fatal("%s: wrong iv length %d != %d", __func__,
427 #ifdef USE_BUILTIN_RIJNDAEL
428 if (c->evptype == evp_rijndael)
429 ssh_rijndael_iv(&cc->evp, 0, iv, len);
432 #ifndef OPENSSL_HAVE_EVPCTR
433 if (c->evptype == evp_aes_128_ctr)
434 ssh_aes_ctr_iv(&cc->evp, 0, iv, len);
437 memcpy(iv, cc->evp.iv, len);
439 case SSH_CIPHER_3DES:
440 ssh1_3des_iv(&cc->evp, 0, iv, 24);
443 fatal("%s: bad cipher %d", __func__, c->number);
448 cipher_set_keyiv(CipherContext *cc, u_char *iv)
450 Cipher *c = cc->cipher;
454 #ifdef NONE_CIPHER_ENABLED
455 case SSH_CIPHER_NONE:
457 case SSH_CIPHER_SSH2:
459 case SSH_CIPHER_BLOWFISH:
460 evplen = EVP_CIPHER_CTX_iv_length(&cc->evp);
463 #ifdef USE_BUILTIN_RIJNDAEL
464 if (c->evptype == evp_rijndael)
465 ssh_rijndael_iv(&cc->evp, 1, iv, evplen);
468 #ifndef OPENSSL_HAVE_EVPCTR
469 if (c->evptype == evp_aes_128_ctr)
470 ssh_aes_ctr_iv(&cc->evp, 1, iv, evplen);
473 memcpy(cc->evp.iv, iv, evplen);
475 case SSH_CIPHER_3DES:
476 ssh1_3des_iv(&cc->evp, 1, iv, 24);
479 fatal("%s: bad cipher %d", __func__, c->number);
484 cipher_get_keycontext(const CipherContext *cc, u_char *dat)
486 Cipher *c = cc->cipher;
489 if (c->evptype == EVP_rc4) {
490 plen = EVP_X_STATE_LEN(cc->evp);
493 memcpy(dat, EVP_X_STATE(cc->evp), plen);
499 cipher_set_keycontext(CipherContext *cc, u_char *dat)
501 Cipher *c = cc->cipher;
504 if (c->evptype == EVP_rc4) {
505 plen = EVP_X_STATE_LEN(cc->evp);
506 memcpy(EVP_X_STATE(cc->evp), dat, plen);