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 1.52 2002/02/18 13:05:32 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)
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;
182 const EVP_CIPHER *type;
186 if (cipher->number == SSH_CIPHER_DES) {
188 error("Warning: use of DES is strongly discouraged "
189 "due to cryptographic weaknesses");
195 cc->plaintext = (cipher->number == SSH_CIPHER_NONE);
197 if (keylen < cipher->key_len)
198 fatal("cipher_init: key length %d is insufficient for %s.",
199 keylen, cipher->name);
200 if (iv != NULL && ivlen < cipher->block_size)
201 fatal("cipher_init: iv length %d is insufficient for %s.",
202 ivlen, cipher->name);
205 type = (*cipher->evptype)();
207 EVP_CIPHER_CTX_init(&cc->evp);
209 if (type->key_len > 0 && type->key_len != keylen) {
210 debug("cipher_init: set keylen (%d -> %d)",
211 type->key_len, keylen);
212 type->key_len = keylen;
214 EVP_CipherInit(&cc->evp, type, (u_char *)key, (u_char *)iv,
215 (encrypt == CIPHER_ENCRYPT));
217 if (EVP_CipherInit(&cc->evp, type, NULL, (u_char *)iv,
218 (encrypt == CIPHER_ENCRYPT)) == 0)
219 fatal("cipher_init: EVP_CipherInit failed for %s",
221 klen = EVP_CIPHER_CTX_key_length(&cc->evp);
222 if (klen > 0 && keylen != klen) {
223 debug("cipher_init: set keylen (%d -> %d)", klen, keylen);
224 if (EVP_CIPHER_CTX_set_key_length(&cc->evp, keylen) == 0)
225 fatal("cipher_init: set keylen failed (%d -> %d)",
228 if (EVP_CipherInit(&cc->evp, NULL, (u_char *)key, NULL, -1) == 0)
229 fatal("cipher_init: EVP_CipherInit: set key failed for %s",
235 cipher_crypt(CipherContext *cc, u_char *dest, const u_char *src, u_int len)
237 if (len % cc->cipher->block_size)
238 fatal("cipher_encrypt: bad plaintext length %d", len);
240 EVP_Cipher(&cc->evp, dest, (u_char *)src, len);
242 if (EVP_Cipher(&cc->evp, dest, (u_char *)src, len) == 0)
243 fatal("evp_crypt: EVP_Cipher failed");
248 cipher_cleanup(CipherContext *cc)
251 EVP_CIPHER_CTX_cleanup(&cc->evp);
253 if (EVP_CIPHER_CTX_cleanup(&cc->evp) == 0)
254 error("cipher_cleanup: EVP_CIPHER_CTX_cleanup failed");
259 * Selects the cipher, and keys if by computing the MD5 checksum of the
260 * passphrase and using the resulting 16 bytes as the key.
264 cipher_set_key_string(CipherContext *cc, Cipher *cipher,
265 const char *passphrase, int encrypt)
271 MD5_Update(&md, (const u_char *)passphrase, strlen(passphrase));
272 MD5_Final(digest, &md);
274 cipher_init(cc, cipher, digest, 16, NULL, 0, encrypt);
276 memset(digest, 0, sizeof(digest));
277 memset(&md, 0, sizeof(md));
280 /* Implementations for other non-EVP ciphers */
283 * This is used by SSH1:
285 * What kind of triple DES are these 2 routines?
287 * Why is there a redundant initialization vector?
289 * If only iv3 was used, then, this would till effect have been
290 * outer-cbc. However, there is also a private iv1 == iv2 which
291 * perhaps makes differential analysis easier. On the other hand, the
292 * private iv1 probably makes the CRC-32 attack ineffective. This is a
293 * result of that there is no longer any known iv1 to use when
294 * choosing the X block.
298 EVP_CIPHER_CTX k1, k2, k3;
301 ssh1_3des_init(EVP_CIPHER_CTX *ctx, const u_char *key, const u_char *iv,
304 struct ssh1_3des_ctx *c;
305 u_char *k1, *k2, *k3;
307 if ((c = EVP_CIPHER_CTX_get_app_data(ctx)) == NULL) {
308 c = xmalloc(sizeof(*c));
309 EVP_CIPHER_CTX_set_app_data(ctx, c);
315 k1 = k2 = k3 = (u_char *) key;
317 if (EVP_CIPHER_CTX_key_length(ctx) >= 16+8) {
323 EVP_CIPHER_CTX_init(&c->k1);
324 EVP_CIPHER_CTX_init(&c->k2);
325 EVP_CIPHER_CTX_init(&c->k3);
327 EVP_CipherInit(&c->k1, EVP_des_cbc(), k1, NULL, enc);
328 EVP_CipherInit(&c->k2, EVP_des_cbc(), k2, NULL, !enc);
329 EVP_CipherInit(&c->k3, EVP_des_cbc(), k3, NULL, enc);
331 if (EVP_CipherInit(&c->k1, EVP_des_cbc(), k1, NULL, enc) == 0 ||
332 EVP_CipherInit(&c->k2, EVP_des_cbc(), k2, NULL, !enc) == 0 ||
333 EVP_CipherInit(&c->k3, EVP_des_cbc(), k3, NULL, enc) == 0) {
334 memset(c, 0, sizeof(*c));
336 EVP_CIPHER_CTX_set_app_data(ctx, NULL);
343 ssh1_3des_cbc(EVP_CIPHER_CTX *ctx, u_char *dest, const u_char *src, u_int len)
345 struct ssh1_3des_ctx *c;
347 if ((c = EVP_CIPHER_CTX_get_app_data(ctx)) == NULL) {
348 error("ssh1_3des_cbc: no context");
352 EVP_Cipher(&c->k1, dest, (u_char *)src, len);
353 EVP_Cipher(&c->k2, dest, dest, len);
354 EVP_Cipher(&c->k3, dest, dest, len);
356 if (EVP_Cipher(&c->k1, dest, (u_char *)src, len) == 0 ||
357 EVP_Cipher(&c->k2, dest, dest, len) == 0 ||
358 EVP_Cipher(&c->k3, dest, dest, len) == 0)
364 ssh1_3des_cleanup(EVP_CIPHER_CTX *ctx)
366 struct ssh1_3des_ctx *c;
368 if ((c = EVP_CIPHER_CTX_get_app_data(ctx)) != NULL) {
369 memset(c, 0, sizeof(*c));
371 EVP_CIPHER_CTX_set_app_data(ctx, NULL);
378 static EVP_CIPHER ssh1_3des;
380 memset(&ssh1_3des, 0, sizeof(EVP_CIPHER));
381 ssh1_3des.nid = NID_undef;
382 ssh1_3des.block_size = 8;
383 ssh1_3des.iv_len = 0;
384 ssh1_3des.key_len = 16;
385 ssh1_3des.init = ssh1_3des_init;
386 ssh1_3des.cleanup = ssh1_3des_cleanup;
387 ssh1_3des.do_cipher = ssh1_3des_cbc;
389 ssh1_3des.flags = EVP_CIPH_CBC_MODE | EVP_CIPH_VARIABLE_LENGTH;
395 * SSH1 uses a variation on Blowfish, all bytes must be swapped before
396 * and after encryption/decryption. Thus the swap_bytes stuff (yuk).
399 swap_bytes(const u_char *src, u_char *dst, int n)
403 /* Process 4 bytes every lap. */
404 for (n = n / 4; n > 0; n--) {
416 static int (*orig_bf)(EVP_CIPHER_CTX *, u_char *, const u_char *, u_int) = NULL;
418 bf_ssh1_cipher(EVP_CIPHER_CTX *ctx, u_char *out, const u_char *in, u_int len)
422 swap_bytes(in, out, len);
423 ret = (*orig_bf)(ctx, out, out, len);
424 swap_bytes(out, out, len);
430 static EVP_CIPHER ssh1_bf;
432 memcpy(&ssh1_bf, EVP_bf_cbc(), sizeof(EVP_CIPHER));
433 orig_bf = ssh1_bf.do_cipher;
434 ssh1_bf.nid = NID_undef;
435 ssh1_bf.do_cipher = bf_ssh1_cipher;
436 ssh1_bf.key_len = 32;
441 #define RIJNDAEL_BLOCKSIZE 16
442 struct ssh_rijndael_ctx
445 u_char r_iv[RIJNDAEL_BLOCKSIZE];
449 ssh_rijndael_init(EVP_CIPHER_CTX *ctx, const u_char *key, const u_char *iv,
452 struct ssh_rijndael_ctx *c;
454 if ((c = EVP_CIPHER_CTX_get_app_data(ctx)) == NULL) {
455 c = xmalloc(sizeof(*c));
456 EVP_CIPHER_CTX_set_app_data(ctx, c);
461 rijndael_set_key(&c->r_ctx, (u_char *)key,
462 8*EVP_CIPHER_CTX_key_length(ctx), enc);
465 memcpy(c->r_iv, iv, RIJNDAEL_BLOCKSIZE);
469 ssh_rijndael_cbc(EVP_CIPHER_CTX *ctx, u_char *dest, const u_char *src,
472 struct ssh_rijndael_ctx *c;
473 u_char buf[RIJNDAEL_BLOCKSIZE];
474 u_char *cprev, *cnow, *plain, *ivp;
475 int i, j, blocks = len / RIJNDAEL_BLOCKSIZE;
479 if (len % RIJNDAEL_BLOCKSIZE)
480 fatal("ssh_rijndael_cbc: bad len %d", len);
481 if ((c = EVP_CIPHER_CTX_get_app_data(ctx)) == NULL) {
482 error("ssh_rijndael_cbc: no context");
487 plain = (u_char *)src;
489 for (i = 0; i < blocks; i++, plain+=RIJNDAEL_BLOCKSIZE,
490 cnow+=RIJNDAEL_BLOCKSIZE) {
491 for (j = 0; j < RIJNDAEL_BLOCKSIZE; j++)
492 buf[j] = plain[j] ^ cprev[j];
493 rijndael_encrypt(&c->r_ctx, buf, cnow);
496 memcpy(c->r_iv, cprev, RIJNDAEL_BLOCKSIZE);
498 cnow = (u_char *) (src+len-RIJNDAEL_BLOCKSIZE);
499 plain = dest+len-RIJNDAEL_BLOCKSIZE;
501 memcpy(buf, cnow, RIJNDAEL_BLOCKSIZE);
502 for (i = blocks; i > 0; i--, cnow-=RIJNDAEL_BLOCKSIZE,
503 plain-=RIJNDAEL_BLOCKSIZE) {
504 rijndael_decrypt(&c->r_ctx, cnow, plain);
505 ivp = (i == 1) ? c->r_iv : cnow-RIJNDAEL_BLOCKSIZE;
506 for (j = 0; j < RIJNDAEL_BLOCKSIZE; j++)
509 memcpy(c->r_iv, buf, RIJNDAEL_BLOCKSIZE);
514 ssh_rijndael_cleanup(EVP_CIPHER_CTX *ctx)
516 struct ssh_rijndael_ctx *c;
518 if ((c = EVP_CIPHER_CTX_get_app_data(ctx)) != NULL) {
519 memset(c, 0, sizeof(*c));
521 EVP_CIPHER_CTX_set_app_data(ctx, NULL);
528 static EVP_CIPHER rijndal_cbc;
530 memset(&rijndal_cbc, 0, sizeof(EVP_CIPHER));
531 rijndal_cbc.nid = NID_undef;
532 rijndal_cbc.block_size = RIJNDAEL_BLOCKSIZE;
533 rijndal_cbc.iv_len = RIJNDAEL_BLOCKSIZE;
534 rijndal_cbc.key_len = 16;
535 rijndal_cbc.init = ssh_rijndael_init;
536 rijndal_cbc.cleanup = ssh_rijndael_cleanup;
537 rijndal_cbc.do_cipher = ssh_rijndael_cbc;
539 rijndal_cbc.flags = EVP_CIPH_CBC_MODE | EVP_CIPH_VARIABLE_LENGTH |
540 EVP_CIPH_ALWAYS_CALL_INIT;
542 return (&rijndal_cbc);
546 * Exports an IV from the CipherContext required to export the key
547 * state back from the unprivileged child to the privileged parent
552 cipher_get_keyiv(CipherContext *cc, u_char *iv, u_int len)
554 Cipher *c = cc->cipher;
559 case SSH_CIPHER_SSH2:
560 evplen = EVP_CIPHER_CTX_iv_length(&cc->evp);
564 fatal("%s: wrong iv length %d != %d", __FUNCTION__,
567 if (strncmp(c->name, "aes", 3) == 0) {
568 struct ssh_rijndael_ctx *aesc;
570 aesc = EVP_CIPHER_CTX_get_app_data(&cc->evp);
572 fatal("ssh_rijndael_cbc: no context");
579 fatal("%s: bad cipher %d", __FUNCTION__, c->number);
581 memcpy(iv, civ, len);