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 1.35 2000/10/13 18:59:13 markus Exp $");
43 #include <openssl/md5.h>
48 none_setkey(CipherContext *cc, const u_char *key, u_int keylen)
52 none_setiv(CipherContext *cc, const u_char *iv, u_int ivlen)
56 none_crypt(CipherContext *cc, u_char *dest, const u_char *src, u_int len)
58 memcpy(dest, src, len);
63 des_ssh1_setkey(CipherContext *cc, const u_char *key, u_int keylen)
65 static int dowarn = 1;
67 error("Warning: use of DES is strongly discouraged "
68 "due to cryptographic weaknesses");
71 des_set_key((void *)key, cc->u.des.key);
74 des_ssh1_setiv(CipherContext *cc, const u_char *iv, u_int ivlen)
76 memset(cc->u.des.iv, 0, sizeof(cc->u.des.iv));
79 des_ssh1_encrypt(CipherContext *cc, u_char *dest, const u_char *src, u_int len)
81 des_ncbc_encrypt(src, dest, len, cc->u.des.key, &cc->u.des.iv,
85 des_ssh1_decrypt(CipherContext *cc, u_char *dest, const u_char *src, u_int len)
87 des_ncbc_encrypt(src, dest, len, cc->u.des.key, &cc->u.des.iv,
93 des3_setkey(CipherContext *cc, const u_char *key, u_int keylen)
95 des_set_key((void *) key, cc->u.des3.key1);
96 des_set_key((void *) (key+8), cc->u.des3.key2);
97 des_set_key((void *) (key+16), cc->u.des3.key3);
100 des3_setiv(CipherContext *cc, const u_char *iv, u_int ivlen)
102 memset(cc->u.des3.iv2, 0, sizeof(cc->u.des3.iv2));
103 memset(cc->u.des3.iv3, 0, sizeof(cc->u.des3.iv3));
106 memcpy(cc->u.des3.iv3, (char *)iv, 8);
109 des3_cbc_encrypt(CipherContext *cc, u_char *dest, const u_char *src, u_int len)
111 des_ede3_cbc_encrypt(src, dest, len,
112 cc->u.des3.key1, cc->u.des3.key2, cc->u.des3.key3,
113 &cc->u.des3.iv3, DES_ENCRYPT);
116 des3_cbc_decrypt(CipherContext *cc, u_char *dest, const u_char *src, u_int len)
118 des_ede3_cbc_encrypt(src, dest, len,
119 cc->u.des3.key1, cc->u.des3.key2, cc->u.des3.key3,
120 &cc->u.des3.iv3, DES_DECRYPT);
124 * This is used by SSH1:
126 * What kind of triple DES are these 2 routines?
128 * Why is there a redundant initialization vector?
130 * If only iv3 was used, then, this would till effect have been
131 * outer-cbc. However, there is also a private iv1 == iv2 which
132 * perhaps makes differential analysis easier. On the other hand, the
133 * private iv1 probably makes the CRC-32 attack ineffective. This is a
134 * result of that there is no longer any known iv1 to use when
135 * choosing the X block.
138 des3_ssh1_setkey(CipherContext *cc, const u_char *key, u_int keylen)
140 des_set_key((void *) key, cc->u.des3.key1);
141 des_set_key((void *) (key+8), cc->u.des3.key2);
143 des_set_key((void *) key, cc->u.des3.key3);
145 des_set_key((void *) (key+16), cc->u.des3.key3);
148 des3_ssh1_encrypt(CipherContext *cc, u_char *dest, const u_char *src,
152 des_cblock *iv2 = &cc->u.des3.iv2;
153 des_cblock *iv3 = &cc->u.des3.iv3;
155 memcpy(&iv1, iv2, 8);
157 des_cbc_encrypt(src, dest, len, cc->u.des3.key1, &iv1, DES_ENCRYPT);
158 memcpy(&iv1, dest + len - 8, 8);
160 des_cbc_encrypt(dest, dest, len, cc->u.des3.key2, iv2, DES_DECRYPT);
161 memcpy(iv2, &iv1, 8); /* Note how iv1 == iv2 on entry and exit. */
163 des_cbc_encrypt(dest, dest, len, cc->u.des3.key3, iv3, DES_ENCRYPT);
164 memcpy(iv3, dest + len - 8, 8);
167 des3_ssh1_decrypt(CipherContext *cc, u_char *dest, const u_char *src,
171 des_cblock *iv2 = &cc->u.des3.iv2;
172 des_cblock *iv3 = &cc->u.des3.iv3;
174 memcpy(&iv1, iv2, 8);
176 des_cbc_encrypt(src, dest, len, cc->u.des3.key3, iv3, DES_DECRYPT);
177 memcpy(iv3, src + len - 8, 8);
179 des_cbc_encrypt(dest, dest, len, cc->u.des3.key2, iv2, DES_ENCRYPT);
180 memcpy(iv2, dest + len - 8, 8);
182 des_cbc_encrypt(dest, dest, len, cc->u.des3.key1, &iv1, DES_DECRYPT);
183 /* memcpy(&iv1, iv2, 8); */
184 /* Note how iv1 == iv2 on entry and exit. */
189 blowfish_setkey(CipherContext *cc, const u_char *key, u_int keylen)
191 BF_set_key(&cc->u.bf.key, keylen, (unsigned char *)key);
194 blowfish_setiv(CipherContext *cc, const u_char *iv, u_int ivlen)
197 memset(cc->u.bf.iv, 0, 8);
199 memcpy(cc->u.bf.iv, (char *)iv, 8);
202 blowfish_cbc_encrypt(CipherContext *cc, u_char *dest, const u_char *src,
205 BF_cbc_encrypt((void *)src, dest, len, &cc->u.bf.key, cc->u.bf.iv,
209 blowfish_cbc_decrypt(CipherContext *cc, u_char *dest, const u_char *src,
212 BF_cbc_encrypt((void *)src, dest, len, &cc->u.bf.key, cc->u.bf.iv,
217 * SSH1 uses a variation on Blowfish, all bytes must be swapped before
218 * and after encryption/decryption. Thus the swap_bytes stuff (yuk).
221 swap_bytes(const unsigned char *src, unsigned char *dst_, int n)
223 /* dst must be properly aligned. */
224 u_int32_t *dst = (u_int32_t *) dst_;
230 /* Process 8 bytes every lap. */
231 for (n = n / 8; n > 0; n--) {
247 blowfish_ssh1_encrypt(CipherContext *cc, u_char *dest, const u_char *src,
250 swap_bytes(src, dest, len);
251 BF_cbc_encrypt((void *)dest, dest, len, &cc->u.bf.key, cc->u.bf.iv,
253 swap_bytes(dest, dest, len);
256 blowfish_ssh1_decrypt(CipherContext *cc, u_char *dest, const u_char *src,
259 swap_bytes(src, dest, len);
260 BF_cbc_encrypt((void *)dest, dest, len, &cc->u.bf.key, cc->u.bf.iv,
262 swap_bytes(dest, dest, len);
267 arcfour_setkey(CipherContext *cc, const u_char *key, u_int keylen)
269 RC4_set_key(&cc->u.rc4, keylen, (u_char *)key);
272 arcfour_crypt(CipherContext *cc, u_char *dest, const u_char *src, u_int len)
274 RC4(&cc->u.rc4, len, (u_char *)src, dest);
279 cast_setkey(CipherContext *cc, const u_char *key, u_int keylen)
281 CAST_set_key(&cc->u.cast.key, keylen, (unsigned char *) key);
284 cast_setiv(CipherContext *cc, const u_char *iv, u_int ivlen)
287 fatal("no IV for %s.", cc->cipher->name);
288 memcpy(cc->u.cast.iv, (char *)iv, 8);
291 cast_cbc_encrypt(CipherContext *cc, u_char *dest, const u_char *src, u_int len)
293 CAST_cbc_encrypt(src, dest, len, &cc->u.cast.key, cc->u.cast.iv,
297 cast_cbc_decrypt(CipherContext *cc, u_char *dest, const u_char *src, u_int len)
299 CAST_cbc_encrypt(src, dest, len, &cc->u.cast.key, cc->u.cast.iv,
305 #define RIJNDAEL_BLOCKSIZE 16
307 rijndael_setkey(CipherContext *cc, const u_char *key, u_int keylen)
309 rijndael_set_key(&cc->u.rijndael.enc, (u4byte *)key, 8*keylen, 1);
310 rijndael_set_key(&cc->u.rijndael.dec, (u4byte *)key, 8*keylen, 0);
313 rijndael_setiv(CipherContext *cc, const u_char *iv, u_int ivlen)
316 fatal("no IV for %s.", cc->cipher->name);
317 memcpy((u_char *)cc->u.rijndael.iv, iv, RIJNDAEL_BLOCKSIZE);
320 rijndael_cbc_encrypt(CipherContext *cc, u_char *dest, const u_char *src,
323 rijndael_ctx *ctx = &cc->u.rijndael.enc;
324 u4byte *iv = cc->u.rijndael.iv;
326 u4byte *cprev, *cnow, *plain;
327 int i, blocks = len / RIJNDAEL_BLOCKSIZE;
330 if (len % RIJNDAEL_BLOCKSIZE)
331 fatal("rijndael_cbc_encrypt: bad len %d", len);
332 cnow = (u4byte*) dest;
333 plain = (u4byte*) src;
335 for(i = 0; i < blocks; i++, plain+=4, cnow+=4) {
336 in[0] = plain[0] ^ cprev[0];
337 in[1] = plain[1] ^ cprev[1];
338 in[2] = plain[2] ^ cprev[2];
339 in[3] = plain[3] ^ cprev[3];
340 rijndael_encrypt(ctx, in, cnow);
343 memcpy(iv, cprev, RIJNDAEL_BLOCKSIZE);
347 rijndael_cbc_decrypt(CipherContext *cc, u_char *dest, const u_char *src,
350 rijndael_ctx *ctx = &cc->u.rijndael.dec;
351 u4byte *iv = cc->u.rijndael.iv;
353 u4byte *cnow = (u4byte*) (src+len-RIJNDAEL_BLOCKSIZE);
354 u4byte *plain = (u4byte*) (dest+len-RIJNDAEL_BLOCKSIZE);
356 int i, blocks = len / RIJNDAEL_BLOCKSIZE;
359 if (len % RIJNDAEL_BLOCKSIZE)
360 fatal("rijndael_cbc_decrypt: bad len %d", len);
361 memcpy(ivsaved, cnow, RIJNDAEL_BLOCKSIZE);
362 for(i = blocks; i > 0; i--, cnow-=4, plain-=4) {
363 rijndael_decrypt(ctx, cnow, plain);
364 ivp = (i == 1) ? iv : cnow-4;
370 memcpy(iv, ivsaved, RIJNDAEL_BLOCKSIZE);
375 SSH_CIPHER_NONE, 8, 0,
376 none_setkey, none_setiv,
377 none_crypt, none_crypt },
379 SSH_CIPHER_DES, 8, 8,
380 des_ssh1_setkey, des_ssh1_setiv,
381 des_ssh1_encrypt, des_ssh1_decrypt },
383 SSH_CIPHER_3DES, 8, 16,
384 des3_ssh1_setkey, des3_setiv,
385 des3_ssh1_encrypt, des3_ssh1_decrypt },
387 SSH_CIPHER_BLOWFISH, 8, 16,
388 blowfish_setkey, blowfish_setiv,
389 blowfish_ssh1_encrypt, blowfish_ssh1_decrypt },
392 SSH_CIPHER_SSH2, 8, 24,
393 des3_setkey, des3_setiv,
394 des3_cbc_encrypt, des3_cbc_decrypt },
396 SSH_CIPHER_SSH2, 8, 16,
397 blowfish_setkey, blowfish_setiv,
398 blowfish_cbc_encrypt, blowfish_cbc_decrypt },
400 SSH_CIPHER_SSH2, 8, 16,
401 cast_setkey, cast_setiv,
402 cast_cbc_encrypt, cast_cbc_decrypt },
404 SSH_CIPHER_SSH2, 8, 16,
405 arcfour_setkey, none_setiv,
406 arcfour_crypt, arcfour_crypt },
408 SSH_CIPHER_SSH2, 16, 16,
409 rijndael_setkey, rijndael_setiv,
410 rijndael_cbc_encrypt, rijndael_cbc_decrypt },
412 SSH_CIPHER_SSH2, 16, 24,
413 rijndael_setkey, rijndael_setiv,
414 rijndael_cbc_encrypt, rijndael_cbc_decrypt },
416 SSH_CIPHER_SSH2, 16, 32,
417 rijndael_setkey, rijndael_setiv,
418 rijndael_cbc_encrypt, rijndael_cbc_decrypt },
420 SSH_CIPHER_SSH2, 16, 16,
421 rijndael_setkey, rijndael_setiv,
422 rijndael_cbc_encrypt, rijndael_cbc_decrypt },
424 SSH_CIPHER_SSH2, 16, 24,
425 rijndael_setkey, rijndael_setiv,
426 rijndael_cbc_encrypt, rijndael_cbc_decrypt },
428 SSH_CIPHER_SSH2, 16, 32,
429 rijndael_setkey, rijndael_setiv,
430 rijndael_cbc_encrypt, rijndael_cbc_decrypt },
431 { "rijndael-cbc@lysator.liu.se",
432 SSH_CIPHER_SSH2, 16, 32,
433 rijndael_setkey, rijndael_setiv,
434 rijndael_cbc_encrypt, rijndael_cbc_decrypt },
435 { NULL, SSH_CIPHER_ILLEGAL, 0, 0, NULL, NULL, NULL, NULL }
441 cipher_mask_ssh1(int client)
443 unsigned int mask = 0;
444 mask |= 1 << SSH_CIPHER_3DES; /* Mandatory */
445 mask |= 1 << SSH_CIPHER_BLOWFISH;
447 mask |= 1 << SSH_CIPHER_DES;
453 cipher_by_name(const char *name)
456 for (c = ciphers; c->name != NULL; c++)
457 if (strcasecmp(c->name, name) == 0)
463 cipher_by_number(int id)
466 for (c = ciphers; c->name != NULL; c++)
472 #define CIPHER_SEP ","
474 ciphers_valid(const char *names)
480 if (names == NULL || strcmp(names, "") == 0)
482 ciphers = cp = xstrdup(names);
483 for ((p = strsep(&cp, CIPHER_SEP)); p && *p != '\0';
484 (p = strsep(&cp, CIPHER_SEP))) {
485 c = cipher_by_name(p);
486 if (c == NULL || c->number != SSH_CIPHER_SSH2) {
487 debug("bad cipher %s [%s]", p, names);
491 debug("cipher ok: %s [%s]", p, names);
494 debug("ciphers ok: [%s]", names);
500 * Parses the name of the cipher. Returns the number of the corresponding
501 * cipher, or -1 on error.
505 cipher_number(const char *name)
510 c = cipher_by_name(name);
511 return (c==NULL) ? -1 : c->number;
517 Cipher *c = cipher_by_number(id);
518 return (c==NULL) ? "<unknown>" : c->name;
522 cipher_init(CipherContext *cc, Cipher *cipher,
523 const u_char *key, u_int keylen, const u_char *iv, u_int ivlen)
525 if (keylen < cipher->key_len)
526 fatal("cipher_init: key length %d is insufficient for %s.",
527 keylen, cipher->name);
528 if (iv != NULL && ivlen < cipher->block_size)
529 fatal("cipher_init: iv length %d is insufficient for %s.",
530 ivlen, cipher->name);
532 cipher->setkey(cc, key, keylen);
533 cipher->setiv(cc, iv, ivlen);
537 cipher_encrypt(CipherContext *cc, u_char *dest, const u_char *src, u_int len)
539 if (len % cc->cipher->block_size)
540 fatal("cipher_encrypt: bad plaintext length %d", len);
541 cc->cipher->encrypt(cc, dest, src, len);
545 cipher_decrypt(CipherContext *cc, u_char *dest, const u_char *src, u_int len)
547 if (len % cc->cipher->block_size)
548 fatal("cipher_decrypt: bad ciphertext length %d", len);
549 cc->cipher->decrypt(cc, dest, src, len);
553 * Selects the cipher, and keys if by computing the MD5 checksum of the
554 * passphrase and using the resulting 16 bytes as the key.
558 cipher_set_key_string(CipherContext *cc, Cipher *cipher,
559 const char *passphrase)
562 unsigned char digest[16];
565 MD5_Update(&md, (const u_char *)passphrase, strlen(passphrase));
566 MD5_Final(digest, &md);
568 cipher_init(cc, cipher, digest, 16, NULL, 0);
570 memset(digest, 0, sizeof(digest));
571 memset(&md, 0, sizeof(md));