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 1.31 2000/09/12 00:38:32 deraadt Exp $");
44 #include <openssl/md5.h>
47 * This is used by SSH1:
49 * What kind of triple DES are these 2 routines?
51 * Why is there a redundant initialization vector?
53 * If only iv3 was used, then, this would till effect have been
54 * outer-cbc. However, there is also a private iv1 == iv2 which
55 * perhaps makes differential analysis easier. On the other hand, the
56 * private iv1 probably makes the CRC-32 attack ineffective. This is a
57 * result of that there is no longer any known iv1 to use when
58 * choosing the X block.
61 SSH_3CBC_ENCRYPT(des_key_schedule ks1,
62 des_key_schedule ks2, des_cblock * iv2,
63 des_key_schedule ks3, des_cblock * iv3,
64 unsigned char *dest, unsigned char *src,
71 des_cbc_encrypt(src, dest, len, ks1, &iv1, DES_ENCRYPT);
72 memcpy(&iv1, dest + len - 8, 8);
74 des_cbc_encrypt(dest, dest, len, ks2, iv2, DES_DECRYPT);
75 memcpy(iv2, &iv1, 8); /* Note how iv1 == iv2 on entry and exit. */
77 des_cbc_encrypt(dest, dest, len, ks3, iv3, DES_ENCRYPT);
78 memcpy(iv3, dest + len - 8, 8);
82 SSH_3CBC_DECRYPT(des_key_schedule ks1,
83 des_key_schedule ks2, des_cblock * iv2,
84 des_key_schedule ks3, des_cblock * iv3,
85 unsigned char *dest, unsigned char *src,
92 des_cbc_encrypt(src, dest, len, ks3, iv3, DES_DECRYPT);
93 memcpy(iv3, src + len - 8, 8);
95 des_cbc_encrypt(dest, dest, len, ks2, iv2, DES_ENCRYPT);
96 memcpy(iv2, dest + len - 8, 8);
98 des_cbc_encrypt(dest, dest, len, ks1, &iv1, DES_DECRYPT);
99 /* memcpy(&iv1, iv2, 8); */
100 /* Note how iv1 == iv2 on entry and exit. */
104 * SSH1 uses a variation on Blowfish, all bytes must be swapped before
105 * and after encryption/decryption. Thus the swap_bytes stuff (yuk).
108 swap_bytes(const unsigned char *src, unsigned char *dst_, int n)
110 /* dst must be properly aligned. */
111 u_int32_t *dst = (u_int32_t *) dst_;
117 /* Process 8 bytes every lap. */
118 for (n = n / 8; n > 0; n--) {
134 * Names of all encryption algorithms.
135 * These must match the numbers defined in cipher.h.
137 static char *cipher_names[] =
144 "rc4", /* Alleged RC4 */
154 * Returns a bit mask indicating which ciphers are supported by this
155 * implementation. The bit mask has the corresponding bit set of each
162 unsigned int mask = 0;
163 mask |= 1 << SSH_CIPHER_3DES; /* Mandatory */
164 mask |= 1 << SSH_CIPHER_BLOWFISH;
170 unsigned int mask = 0;
171 mask |= 1 << SSH_CIPHER_BLOWFISH_CBC;
172 mask |= 1 << SSH_CIPHER_3DES_CBC;
173 mask |= 1 << SSH_CIPHER_ARCFOUR;
174 mask |= 1 << SSH_CIPHER_CAST128_CBC;
180 return cipher_mask1() | cipher_mask2();
183 /* Returns the name of the cipher. */
186 cipher_name(int cipher)
188 if (cipher < 0 || cipher >= sizeof(cipher_names) / sizeof(cipher_names[0]) ||
189 cipher_names[cipher] == NULL)
190 fatal("cipher_name: bad cipher name: %d", cipher);
191 return cipher_names[cipher];
194 /* Returns 1 if the name of the ciphers are valid. */
196 #define CIPHER_SEP ","
198 ciphers_valid(const char *names)
204 if (names == NULL || strcmp(names, "") == 0)
206 ciphers = cp = xstrdup(names);
207 for ((p = strsep(&cp, CIPHER_SEP)); p && *p != '\0';
208 (p = strsep(&cp, CIPHER_SEP))) {
209 i = cipher_number(p);
210 if (i == -1 || !(cipher_mask2() & (1 << i))) {
220 * Parses the name of the cipher. Returns the number of the corresponding
221 * cipher, or -1 on error.
225 cipher_number(const char *name)
230 for (i = 0; i < sizeof(cipher_names) / sizeof(cipher_names[0]); i++)
231 if (strcmp(cipher_names[i], name) == 0 &&
232 (cipher_mask() & (1 << i)))
238 * Selects the cipher, and keys if by computing the MD5 checksum of the
239 * passphrase and using the resulting 16 bytes as the key.
243 cipher_set_key_string(CipherContext *context, int cipher, const char *passphrase)
246 unsigned char digest[16];
249 MD5_Update(&md, (const unsigned char *) passphrase, strlen(passphrase));
250 MD5_Final(digest, &md);
252 cipher_set_key(context, cipher, digest, 16);
254 memset(digest, 0, sizeof(digest));
255 memset(&md, 0, sizeof(md));
258 /* Selects the cipher to use and sets the key. */
261 cipher_set_key(CipherContext *context, int cipher, const unsigned char *key,
264 unsigned char padded[32];
266 /* Set cipher type. */
267 context->type = cipher;
269 /* Get 32 bytes of key data. Pad if necessary. (So that code
270 below does not need to worry about key size). */
271 memset(padded, 0, sizeof(padded));
272 memcpy(padded, key, keylen < sizeof(padded) ? keylen : sizeof(padded));
274 /* Initialize the initialization vector. */
276 case SSH_CIPHER_NONE:
278 * Has to stay for authfile saving of private key with no
283 case SSH_CIPHER_3DES:
285 * Note: the least significant bit of each byte of key is
286 * parity, and must be ignored by the implementation. 16
287 * bytes of key are used (first and last keys are the same).
290 error("Key length %d is insufficient for 3DES.", keylen);
291 des_set_key((void *) padded, context->u.des3.key1);
292 des_set_key((void *) (padded + 8), context->u.des3.key2);
294 des_set_key((void *) padded, context->u.des3.key3);
296 des_set_key((void *) (padded + 16), context->u.des3.key3);
297 memset(context->u.des3.iv2, 0, sizeof(context->u.des3.iv2));
298 memset(context->u.des3.iv3, 0, sizeof(context->u.des3.iv3));
301 case SSH_CIPHER_BLOWFISH:
303 error("Key length %d is insufficient for blowfish.", keylen);
304 BF_set_key(&context->u.bf.key, keylen, padded);
305 memset(context->u.bf.iv, 0, 8);
308 case SSH_CIPHER_3DES_CBC:
309 case SSH_CIPHER_BLOWFISH_CBC:
310 case SSH_CIPHER_ARCFOUR:
311 case SSH_CIPHER_CAST128_CBC:
312 fatal("cipher_set_key: illegal cipher: %s", cipher_name(cipher));
316 fatal("cipher_set_key: unknown cipher: %s", cipher_name(cipher));
318 memset(padded, 0, sizeof(padded));
322 cipher_set_key_iv(CipherContext * context, int cipher,
323 const unsigned char *key, int keylen,
324 const unsigned char *iv, int ivlen)
326 /* Set cipher type. */
327 context->type = cipher;
329 /* Initialize the initialization vector. */
331 case SSH_CIPHER_NONE:
334 case SSH_CIPHER_3DES:
335 case SSH_CIPHER_BLOWFISH:
336 fatal("cipher_set_key_iv: illegal cipher: %s", cipher_name(cipher));
339 case SSH_CIPHER_3DES_CBC:
341 error("Key length %d is insufficient for 3des-cbc.", keylen);
342 des_set_key((void *) key, context->u.des3.key1);
343 des_set_key((void *) (key+8), context->u.des3.key2);
344 des_set_key((void *) (key+16), context->u.des3.key3);
346 error("IV length %d is insufficient for 3des-cbc.", ivlen);
347 memcpy(context->u.des3.iv3, (char *)iv, 8);
350 case SSH_CIPHER_BLOWFISH_CBC:
352 error("Key length %d is insufficient for blowfish.", keylen);
354 error("IV length %d is insufficient for blowfish.", ivlen);
355 BF_set_key(&context->u.bf.key, keylen, (unsigned char *)key);
356 memcpy(context->u.bf.iv, (char *)iv, 8);
359 case SSH_CIPHER_ARCFOUR:
361 error("Key length %d is insufficient for arcfour.", keylen);
362 RC4_set_key(&context->u.rc4, keylen, (unsigned char *)key);
365 case SSH_CIPHER_CAST128_CBC:
367 error("Key length %d is insufficient for cast128.", keylen);
369 error("IV length %d is insufficient for cast128.", ivlen);
370 CAST_set_key(&context->u.cast.key, keylen, (unsigned char *) key);
371 memcpy(context->u.cast.iv, (char *)iv, 8);
375 fatal("cipher_set_key: unknown cipher: %s", cipher_name(cipher));
379 /* Encrypts data using the cipher. */
382 cipher_encrypt(CipherContext *context, unsigned char *dest,
383 const unsigned char *src, unsigned int len)
386 fatal("cipher_encrypt: bad plaintext length %d", len);
388 switch (context->type) {
389 case SSH_CIPHER_NONE:
390 memcpy(dest, src, len);
393 case SSH_CIPHER_3DES:
394 SSH_3CBC_ENCRYPT(context->u.des3.key1,
395 context->u.des3.key2, &context->u.des3.iv2,
396 context->u.des3.key3, &context->u.des3.iv3,
397 dest, (unsigned char *) src, len);
400 case SSH_CIPHER_BLOWFISH:
401 swap_bytes(src, dest, len);
402 BF_cbc_encrypt(dest, dest, len,
403 &context->u.bf.key, context->u.bf.iv,
405 swap_bytes(dest, dest, len);
408 case SSH_CIPHER_BLOWFISH_CBC:
409 BF_cbc_encrypt((void *)src, dest, len,
410 &context->u.bf.key, context->u.bf.iv,
414 case SSH_CIPHER_3DES_CBC:
415 des_ede3_cbc_encrypt(src, dest, len,
416 context->u.des3.key1, context->u.des3.key2,
417 context->u.des3.key3, &context->u.des3.iv3, DES_ENCRYPT);
420 case SSH_CIPHER_ARCFOUR:
421 RC4(&context->u.rc4, len, (unsigned char *)src, dest);
424 case SSH_CIPHER_CAST128_CBC:
425 CAST_cbc_encrypt(src, dest, len,
426 &context->u.cast.key, context->u.cast.iv, CAST_ENCRYPT);
430 fatal("cipher_encrypt: unknown cipher: %s", cipher_name(context->type));
434 /* Decrypts data using the cipher. */
437 cipher_decrypt(CipherContext *context, unsigned char *dest,
438 const unsigned char *src, unsigned int len)
441 fatal("cipher_decrypt: bad ciphertext length %d", len);
443 switch (context->type) {
444 case SSH_CIPHER_NONE:
445 memcpy(dest, src, len);
448 case SSH_CIPHER_3DES:
449 SSH_3CBC_DECRYPT(context->u.des3.key1,
450 context->u.des3.key2, &context->u.des3.iv2,
451 context->u.des3.key3, &context->u.des3.iv3,
452 dest, (unsigned char *) src, len);
455 case SSH_CIPHER_BLOWFISH:
456 swap_bytes(src, dest, len);
457 BF_cbc_encrypt((void *) dest, dest, len,
458 &context->u.bf.key, context->u.bf.iv,
460 swap_bytes(dest, dest, len);
463 case SSH_CIPHER_BLOWFISH_CBC:
464 BF_cbc_encrypt((void *) src, dest, len,
465 &context->u.bf.key, context->u.bf.iv,
469 case SSH_CIPHER_3DES_CBC:
470 des_ede3_cbc_encrypt(src, dest, len,
471 context->u.des3.key1, context->u.des3.key2,
472 context->u.des3.key3, &context->u.des3.iv3, DES_DECRYPT);
475 case SSH_CIPHER_ARCFOUR:
476 RC4(&context->u.rc4, len, (unsigned char *)src, dest);
479 case SSH_CIPHER_CAST128_CBC:
480 CAST_cbc_encrypt(src, dest, len,
481 &context->u.cast.key, context->u.cast.iv, CAST_DECRYPT);
485 fatal("cipher_decrypt: unknown cipher: %s", cipher_name(context->type));