1 /* $OpenBSD: cipher.c,v 1.97 2014/02/07 06:55:54 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.
42 #include <sys/types.h>
55 /* compatibility with old or broken OpenSSL versions */
56 #include "openbsd-compat/openssl-compat.h"
58 extern const EVP_CIPHER *evp_ssh1_bf(void);
59 extern const EVP_CIPHER *evp_ssh1_3des(void);
60 extern void ssh1_3des_iv(EVP_CIPHER_CTX *, int, u_char *, int);
64 int number; /* for ssh1 only */
67 u_int iv_len; /* defaults to block_size */
71 #define CFLAG_CBC (1<<0)
72 #define CFLAG_CHACHAPOLY (1<<1)
73 const EVP_CIPHER *(*evptype)(void);
76 static const struct Cipher ciphers[] = {
77 { "none", SSH_CIPHER_NONE, 8, 0, 0, 0, 0, 0, EVP_enc_null },
78 { "des", SSH_CIPHER_DES, 8, 8, 0, 0, 0, 1, EVP_des_cbc },
79 { "3des", SSH_CIPHER_3DES, 8, 16, 0, 0, 0, 1, evp_ssh1_3des },
80 { "blowfish", SSH_CIPHER_BLOWFISH, 8, 32, 0, 0, 0, 1, evp_ssh1_bf },
82 { "3des-cbc", SSH_CIPHER_SSH2, 8, 24, 0, 0, 0, 1, EVP_des_ede3_cbc },
84 SSH_CIPHER_SSH2, 8, 16, 0, 0, 0, 1, EVP_bf_cbc },
86 SSH_CIPHER_SSH2, 8, 16, 0, 0, 0, 1, EVP_cast5_cbc },
87 { "arcfour", SSH_CIPHER_SSH2, 8, 16, 0, 0, 0, 0, EVP_rc4 },
88 { "arcfour128", SSH_CIPHER_SSH2, 8, 16, 0, 0, 1536, 0, EVP_rc4 },
89 { "arcfour256", SSH_CIPHER_SSH2, 8, 32, 0, 0, 1536, 0, EVP_rc4 },
90 { "aes128-cbc", SSH_CIPHER_SSH2, 16, 16, 0, 0, 0, 1, EVP_aes_128_cbc },
91 { "aes192-cbc", SSH_CIPHER_SSH2, 16, 24, 0, 0, 0, 1, EVP_aes_192_cbc },
92 { "aes256-cbc", SSH_CIPHER_SSH2, 16, 32, 0, 0, 0, 1, EVP_aes_256_cbc },
93 { "rijndael-cbc@lysator.liu.se",
94 SSH_CIPHER_SSH2, 16, 32, 0, 0, 0, 1, EVP_aes_256_cbc },
95 { "aes128-ctr", SSH_CIPHER_SSH2, 16, 16, 0, 0, 0, 0, EVP_aes_128_ctr },
96 { "aes192-ctr", SSH_CIPHER_SSH2, 16, 24, 0, 0, 0, 0, EVP_aes_192_ctr },
97 { "aes256-ctr", SSH_CIPHER_SSH2, 16, 32, 0, 0, 0, 0, EVP_aes_256_ctr },
98 #ifdef OPENSSL_HAVE_EVPGCM
99 { "aes128-gcm@openssh.com",
100 SSH_CIPHER_SSH2, 16, 16, 12, 16, 0, 0, EVP_aes_128_gcm },
101 { "aes256-gcm@openssh.com",
102 SSH_CIPHER_SSH2, 16, 32, 12, 16, 0, 0, EVP_aes_256_gcm },
104 { "chacha20-poly1305@openssh.com",
105 SSH_CIPHER_SSH2, 8, 64, 0, 16, 0, CFLAG_CHACHAPOLY, NULL },
106 { NULL, SSH_CIPHER_INVALID, 0, 0, 0, 0, 0, 0, NULL }
111 /* Returns a list of supported ciphers separated by the specified char. */
113 cipher_alg_list(char sep, int auth_only)
116 size_t nlen, rlen = 0;
119 for (c = ciphers; c->name != NULL; c++) {
120 if (c->number != SSH_CIPHER_SSH2)
122 if (auth_only && c->auth_len == 0)
126 nlen = strlen(c->name);
127 ret = xrealloc(ret, 1, rlen + nlen + 2);
128 memcpy(ret + rlen, c->name, nlen + 1);
135 cipher_blocksize(const Cipher *c)
137 return (c->block_size);
141 cipher_keylen(const Cipher *c)
147 cipher_seclen(const Cipher *c)
149 if (strcmp("3des-cbc", c->name) == 0)
151 return cipher_keylen(c);
155 cipher_authlen(const Cipher *c)
157 return (c->auth_len);
161 cipher_ivlen(const Cipher *c)
164 * Default is cipher block size, except for chacha20+poly1305 that
165 * needs no IV. XXX make iv_len == -1 default?
167 return (c->iv_len != 0 || (c->flags & CFLAG_CHACHAPOLY) != 0) ?
168 c->iv_len : c->block_size;
172 cipher_get_number(const Cipher *c)
178 cipher_is_cbc(const Cipher *c)
180 return (c->flags & CFLAG_CBC) != 0;
184 cipher_mask_ssh1(int client)
187 mask |= 1 << SSH_CIPHER_3DES; /* Mandatory */
188 mask |= 1 << SSH_CIPHER_BLOWFISH;
190 mask |= 1 << SSH_CIPHER_DES;
196 cipher_by_name(const char *name)
199 for (c = ciphers; c->name != NULL; c++)
200 if (strcmp(c->name, name) == 0)
206 cipher_by_number(int id)
209 for (c = ciphers; c->name != NULL; c++)
215 #define CIPHER_SEP ","
217 ciphers_valid(const char *names)
220 char *cipher_list, *cp;
223 if (names == NULL || strcmp(names, "") == 0)
225 cipher_list = cp = xstrdup(names);
226 for ((p = strsep(&cp, CIPHER_SEP)); p && *p != '\0';
227 (p = strsep(&cp, CIPHER_SEP))) {
228 c = cipher_by_name(p);
229 #ifdef NONE_CIPHER_ENABLED
230 if (c == NULL || (c->number != SSH_CIPHER_SSH2 &&
231 c->number != SSH_CIPHER_NONE)) {
233 if (c == NULL || (c->number != SSH_CIPHER_SSH2)) {
235 debug("bad cipher %s [%s]", p, names);
240 debug3("ciphers ok: [%s]", names);
246 * Parses the name of the cipher. Returns the number of the corresponding
247 * cipher, or -1 on error.
251 cipher_number(const char *name)
256 for (c = ciphers; c->name != NULL; c++)
257 if (strcasecmp(c->name, name) == 0)
265 const Cipher *c = cipher_by_number(id);
266 return (c==NULL) ? "<unknown>" : c->name;
270 cipher_init(CipherContext *cc, const Cipher *cipher,
271 const u_char *key, u_int keylen, const u_char *iv, u_int ivlen,
274 static int dowarn = 1;
278 const EVP_CIPHER *type;
281 u_char *junk, *discard;
283 if (cipher->number == SSH_CIPHER_DES) {
285 error("Warning: use of DES is strongly discouraged "
286 "due to cryptographic weaknesses");
292 cc->plaintext = (cipher->number == SSH_CIPHER_NONE);
293 cc->encrypt = do_encrypt;
295 if (keylen < cipher->key_len)
296 fatal("cipher_init: key length %d is insufficient for %s.",
297 keylen, cipher->name);
298 if (iv != NULL && ivlen < cipher_ivlen(cipher))
299 fatal("cipher_init: iv length %d is insufficient for %s.",
300 ivlen, cipher->name);
303 if ((cc->cipher->flags & CFLAG_CHACHAPOLY) != 0) {
304 chachapoly_init(&cc->cp_ctx, key, keylen);
307 type = (*cipher->evptype)();
308 EVP_CIPHER_CTX_init(&cc->evp);
310 if (type->key_len > 0 && type->key_len != keylen) {
311 debug("cipher_init: set keylen (%d -> %d)",
312 type->key_len, keylen);
313 type->key_len = keylen;
315 EVP_CipherInit(&cc->evp, type, (u_char *)key, (u_char *)iv,
316 (do_encrypt == CIPHER_ENCRYPT));
318 if (EVP_CipherInit(&cc->evp, type, NULL, (u_char *)iv,
319 (do_encrypt == CIPHER_ENCRYPT)) == 0)
320 fatal("cipher_init: EVP_CipherInit failed for %s",
322 if (cipher_authlen(cipher) &&
323 !EVP_CIPHER_CTX_ctrl(&cc->evp, EVP_CTRL_GCM_SET_IV_FIXED,
325 fatal("cipher_init: EVP_CTRL_GCM_SET_IV_FIXED failed for %s",
327 klen = EVP_CIPHER_CTX_key_length(&cc->evp);
328 if (klen > 0 && keylen != (u_int)klen) {
329 debug2("cipher_init: set keylen (%d -> %d)", klen, keylen);
330 if (EVP_CIPHER_CTX_set_key_length(&cc->evp, keylen) == 0)
331 fatal("cipher_init: set keylen failed (%d -> %d)",
334 if (EVP_CipherInit(&cc->evp, NULL, (u_char *)key, NULL, -1) == 0)
335 fatal("cipher_init: EVP_CipherInit: set key failed for %s",
339 if (cipher->discard_len > 0) {
340 junk = xmalloc(cipher->discard_len);
341 discard = xmalloc(cipher->discard_len);
342 if (EVP_Cipher(&cc->evp, discard, junk,
343 cipher->discard_len) == 0)
344 fatal("evp_crypt: EVP_Cipher failed during discard");
345 explicit_bzero(discard, cipher->discard_len);
352 * cipher_crypt() operates as following:
353 * Copy 'aadlen' bytes (without en/decryption) from 'src' to 'dest'.
354 * Theses bytes are treated as additional authenticated data for
355 * authenticated encryption modes.
356 * En/Decrypt 'len' bytes at offset 'aadlen' from 'src' to 'dest'.
357 * Use 'authlen' bytes at offset 'len'+'aadlen' as the authentication tag.
358 * This tag is written on encryption and verified on decryption.
359 * Both 'aadlen' and 'authlen' can be set to 0.
360 * cipher_crypt() returns 0 on success and -1 if the decryption integrity
364 cipher_crypt(CipherContext *cc, u_int seqnr, u_char *dest, const u_char *src,
365 u_int len, u_int aadlen, u_int authlen)
367 if ((cc->cipher->flags & CFLAG_CHACHAPOLY) != 0)
368 return chachapoly_crypt(&cc->cp_ctx, seqnr, dest, src, len,
369 aadlen, authlen, cc->encrypt);
373 if (authlen != cipher_authlen(cc->cipher))
374 fatal("%s: authlen mismatch %d", __func__, authlen);
376 if (!EVP_CIPHER_CTX_ctrl(&cc->evp, EVP_CTRL_GCM_IV_GEN,
378 fatal("%s: EVP_CTRL_GCM_IV_GEN", __func__);
379 /* set tag on decyption */
381 !EVP_CIPHER_CTX_ctrl(&cc->evp, EVP_CTRL_GCM_SET_TAG,
382 authlen, (u_char *)src + aadlen + len))
383 fatal("%s: EVP_CTRL_GCM_SET_TAG", __func__);
387 EVP_Cipher(&cc->evp, NULL, (u_char *)src, aadlen) < 0)
388 fatal("%s: EVP_Cipher(aad) failed", __func__);
389 memcpy(dest, src, aadlen);
391 if (len % cc->cipher->block_size)
392 fatal("%s: bad plaintext length %d", __func__, len);
393 if (EVP_Cipher(&cc->evp, dest + aadlen, (u_char *)src + aadlen,
395 fatal("%s: EVP_Cipher failed", __func__);
397 /* compute tag (on encrypt) or verify tag (on decrypt) */
398 if (EVP_Cipher(&cc->evp, NULL, NULL, 0) < 0) {
400 fatal("%s: EVP_Cipher(final) failed", __func__);
405 !EVP_CIPHER_CTX_ctrl(&cc->evp, EVP_CTRL_GCM_GET_TAG,
406 authlen, dest + aadlen + len))
407 fatal("%s: EVP_CTRL_GCM_GET_TAG", __func__);
412 /* Extract the packet length, including any decryption necessary beforehand */
414 cipher_get_length(CipherContext *cc, u_int *plenp, u_int seqnr,
415 const u_char *cp, u_int len)
417 if ((cc->cipher->flags & CFLAG_CHACHAPOLY) != 0)
418 return chachapoly_get_length(&cc->cp_ctx, plenp, seqnr,
422 *plenp = get_u32(cp);
427 cipher_cleanup(CipherContext *cc)
429 if ((cc->cipher->flags & CFLAG_CHACHAPOLY) != 0)
430 explicit_bzero(&cc->cp_ctx, sizeof(cc->cp_ctx));
431 else if (EVP_CIPHER_CTX_cleanup(&cc->evp) == 0)
432 error("cipher_cleanup: EVP_CIPHER_CTX_cleanup failed");
436 * Selects the cipher, and keys if by computing the MD5 checksum of the
437 * passphrase and using the resulting 16 bytes as the key.
441 cipher_set_key_string(CipherContext *cc, const Cipher *cipher,
442 const char *passphrase, int do_encrypt)
446 if (ssh_digest_memory(SSH_DIGEST_MD5, passphrase, strlen(passphrase),
447 digest, sizeof(digest)) < 0)
448 fatal("%s: md5 failed", __func__);
450 cipher_init(cc, cipher, digest, 16, NULL, 0, do_encrypt);
452 explicit_bzero(digest, sizeof(digest));
456 * Exports an IV from the CipherContext required to export the key
457 * state back from the unprivileged child to the privileged parent
462 cipher_get_keyiv_len(const CipherContext *cc)
464 const Cipher *c = cc->cipher;
467 if (c->number == SSH_CIPHER_3DES)
469 else if ((cc->cipher->flags & CFLAG_CHACHAPOLY) != 0)
472 ivlen = EVP_CIPHER_CTX_iv_length(&cc->evp);
477 cipher_get_keyiv(CipherContext *cc, u_char *iv, u_int len)
479 const Cipher *c = cc->cipher;
482 if ((cc->cipher->flags & CFLAG_CHACHAPOLY) != 0) {
484 fatal("%s: wrong iv length %d != %d", __func__, len, 0);
489 #ifdef NONE_CIPHER_ENABLED
490 case SSH_CIPHER_NONE:
492 case SSH_CIPHER_SSH2:
494 case SSH_CIPHER_BLOWFISH:
495 evplen = EVP_CIPHER_CTX_iv_length(&cc->evp);
498 if ((u_int)evplen != len)
499 fatal("%s: wrong iv length %d != %d", __func__,
501 #ifdef USE_BUILTIN_RIJNDAEL
502 if (c->evptype == evp_rijndael)
503 ssh_rijndael_iv(&cc->evp, 0, iv, len);
506 #ifndef OPENSSL_HAVE_EVPCTR
507 if (c->evptype == evp_aes_128_ctr)
508 ssh_aes_ctr_iv(&cc->evp, 0, iv, len);
511 memcpy(iv, cc->evp.iv, len);
513 case SSH_CIPHER_3DES:
514 ssh1_3des_iv(&cc->evp, 0, iv, 24);
517 fatal("%s: bad cipher %d", __func__, c->number);
522 cipher_set_keyiv(CipherContext *cc, u_char *iv)
524 const Cipher *c = cc->cipher;
527 if ((cc->cipher->flags & CFLAG_CHACHAPOLY) != 0)
531 #ifdef NONE_CIPHER_ENABLED
532 case SSH_CIPHER_NONE:
534 case SSH_CIPHER_SSH2:
536 case SSH_CIPHER_BLOWFISH:
537 evplen = EVP_CIPHER_CTX_iv_length(&cc->evp);
540 #ifdef USE_BUILTIN_RIJNDAEL
541 if (c->evptype == evp_rijndael)
542 ssh_rijndael_iv(&cc->evp, 1, iv, evplen);
545 #ifndef OPENSSL_HAVE_EVPCTR
546 if (c->evptype == evp_aes_128_ctr)
547 ssh_aes_ctr_iv(&cc->evp, 1, iv, evplen);
550 memcpy(cc->evp.iv, iv, evplen);
552 case SSH_CIPHER_3DES:
553 ssh1_3des_iv(&cc->evp, 1, iv, 24);
556 fatal("%s: bad cipher %d", __func__, c->number);
561 cipher_get_keycontext(const CipherContext *cc, u_char *dat)
563 const Cipher *c = cc->cipher;
566 if (c->evptype == EVP_rc4) {
567 plen = EVP_X_STATE_LEN(cc->evp);
570 memcpy(dat, EVP_X_STATE(cc->evp), plen);
576 cipher_set_keycontext(CipherContext *cc, u_char *dat)
578 const Cipher *c = cc->cipher;
581 if (c->evptype == EVP_rc4) {
582 plen = EVP_X_STATE_LEN(cc->evp);
583 memcpy(EVP_X_STATE(cc->evp), dat, plen);