1 /* $NetBSD: cipher.c,v 1.2 2009/06/07 22:38:46 christos Exp $ */ 2 /* $OpenBSD: cipher.c,v 1.82 2009/01/26 09:58:15 markus Exp $ */ 3 /* 4 * Author: Tatu Ylonen <ylo@cs.hut.fi> 5 * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland 6 * All rights reserved 7 * 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". 13 * 14 * 15 * Copyright (c) 1999 Niels Provos. All rights reserved. 16 * Copyright (c) 1999, 2000 Markus Friedl. All rights reserved. 17 * 18 * Redistribution and use in source and binary forms, with or without 19 * modification, are permitted provided that the following conditions 20 * are met: 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. 26 * 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. 37 */ 38 39 #include "includes.h" 40 __RCSID("$NetBSD: cipher.c,v 1.2 2009/06/07 22:38:46 christos Exp $"); 41 #include <sys/types.h> 42 43 #include <openssl/md5.h> 44 45 #include <string.h> 46 #include <stdarg.h> 47 48 #include "xmalloc.h" 49 #include "log.h" 50 #include "cipher.h" 51 52 extern const EVP_CIPHER *evp_ssh1_bf(void); 53 extern const EVP_CIPHER *evp_ssh1_3des(void); 54 extern void ssh1_3des_iv(EVP_CIPHER_CTX *, int, u_char *, int); 55 extern const EVP_CIPHER *evp_aes_128_ctr(void); 56 extern const EVP_CIPHER *evp_aes_ctr_mt(void); 57 extern void ssh_aes_ctr_iv(EVP_CIPHER_CTX *, int, u_char *, u_int); 58 59 struct Cipher { 60 char *name; 61 int number; /* for ssh1 only */ 62 u_int block_size; 63 u_int key_len; 64 u_int discard_len; 65 u_int cbc_mode; 66 const EVP_CIPHER *(*evptype)(void); 67 } ciphers[] = { 68 { "none", SSH_CIPHER_NONE, 8, 0, 0, 0, EVP_enc_null }, 69 { "des", SSH_CIPHER_DES, 8, 8, 0, 1, EVP_des_cbc }, 70 { "3des", SSH_CIPHER_3DES, 8, 16, 0, 1, evp_ssh1_3des }, 71 { "blowfish", SSH_CIPHER_BLOWFISH, 8, 32, 0, 1, evp_ssh1_bf }, 72 73 { "3des-cbc", SSH_CIPHER_SSH2, 8, 24, 0, 1, EVP_des_ede3_cbc }, 74 { "blowfish-cbc", SSH_CIPHER_SSH2, 8, 16, 0, 1, EVP_bf_cbc }, 75 { "cast128-cbc", SSH_CIPHER_SSH2, 8, 16, 0, 1, EVP_cast5_cbc }, 76 { "arcfour", SSH_CIPHER_SSH2, 8, 16, 0, 0, EVP_rc4 }, 77 { "arcfour128", SSH_CIPHER_SSH2, 8, 16, 1536, 0, EVP_rc4 }, 78 { "arcfour256", SSH_CIPHER_SSH2, 8, 32, 1536, 0, EVP_rc4 }, 79 { "aes128-cbc", SSH_CIPHER_SSH2, 16, 16, 0, 1, EVP_aes_128_cbc }, 80 { "aes192-cbc", SSH_CIPHER_SSH2, 16, 24, 0, 1, EVP_aes_192_cbc }, 81 { "aes256-cbc", SSH_CIPHER_SSH2, 16, 32, 0, 1, EVP_aes_256_cbc }, 82 { "rijndael-cbc@lysator.liu.se", 83 SSH_CIPHER_SSH2, 16, 32, 0, 1, EVP_aes_256_cbc }, 84 #ifdef AES_CTR_MT 85 { "aes128-ctr", SSH_CIPHER_SSH2, 16, 16, 0, 0, evp_aes_ctr_mt }, 86 { "aes192-ctr", SSH_CIPHER_SSH2, 16, 24, 0, 0, evp_aes_ctr_mt }, 87 { "aes256-ctr", SSH_CIPHER_SSH2, 16, 32, 0, 0, evp_aes_ctr_mt }, 88 #else 89 { "aes128-ctr", SSH_CIPHER_SSH2, 16, 16, 0, 0, evp_aes_128_ctr }, 90 { "aes192-ctr", SSH_CIPHER_SSH2, 16, 24, 0, 0, evp_aes_128_ctr }, 91 { "aes256-ctr", SSH_CIPHER_SSH2, 16, 32, 0, 0, evp_aes_128_ctr }, 92 #endif 93 #ifdef ACSS 94 { "acss@openssh.org", SSH_CIPHER_SSH2, 16, 5, 0, 0, EVP_acss }, 95 #endif 96 97 { NULL, SSH_CIPHER_INVALID, 0, 0, 0, 0, NULL } 98 }; 99 100 #ifndef ACSS 101 static const EVP_CIPHER *EVP_acss(void) { return NULL; } 102 #endif 103 104 /*--*/ 105 106 u_int 107 cipher_blocksize(const Cipher *c) 108 { 109 return (c->block_size); 110 } 111 112 u_int 113 cipher_keylen(const Cipher *c) 114 { 115 return (c->key_len); 116 } 117 118 u_int 119 cipher_get_number(const Cipher *c) 120 { 121 return (c->number); 122 } 123 124 u_int 125 cipher_is_cbc(const Cipher *c) 126 { 127 return (c->cbc_mode); 128 } 129 130 u_int 131 cipher_mask_ssh1(int client) 132 { 133 u_int mask = 0; 134 mask |= 1 << SSH_CIPHER_3DES; /* Mandatory */ 135 mask |= 1 << SSH_CIPHER_BLOWFISH; 136 if (client) { 137 mask |= 1 << SSH_CIPHER_DES; 138 } 139 return mask; 140 } 141 142 Cipher * 143 cipher_by_name(const char *name) 144 { 145 Cipher *c; 146 for (c = ciphers; c->name != NULL; c++) 147 if (strcmp(c->name, name) == 0) 148 return c; 149 return NULL; 150 } 151 152 Cipher * 153 cipher_by_number(int id) 154 { 155 Cipher *c; 156 for (c = ciphers; c->name != NULL; c++) 157 if (c->number == id) 158 return c; 159 return NULL; 160 } 161 162 #define CIPHER_SEP "," 163 int 164 ciphers_valid(const char *names) 165 { 166 Cipher *c; 167 char *cipher_list, *cp; 168 char *p; 169 170 if (names == NULL || strcmp(names, "") == 0) 171 return 0; 172 cipher_list = cp = xstrdup(names); 173 for ((p = strsep(&cp, CIPHER_SEP)); p && *p != '\0'; 174 (p = strsep(&cp, CIPHER_SEP))) { 175 c = cipher_by_name(p); 176 if (c == NULL || (c->number != SSH_CIPHER_SSH2 && 177 c->number != SSH_CIPHER_NONE)) { 178 debug("bad cipher %s [%s]", p, names); 179 xfree(cipher_list); 180 return 0; 181 } else { 182 debug3("cipher ok: %s [%s]", p, names); 183 } 184 } 185 debug3("ciphers ok: [%s]", names); 186 xfree(cipher_list); 187 return 1; 188 } 189 190 /* 191 * Parses the name of the cipher. Returns the number of the corresponding 192 * cipher, or -1 on error. 193 */ 194 195 int 196 cipher_number(const char *name) 197 { 198 Cipher *c; 199 if (name == NULL) 200 return -1; 201 for (c = ciphers; c->name != NULL; c++) 202 if (strcasecmp(c->name, name) == 0) 203 return c->number; 204 return -1; 205 } 206 207 char * 208 cipher_name(int id) 209 { 210 Cipher *c = cipher_by_number(id); 211 return (c==NULL) ? "<unknown>" : c->name; 212 } 213 214 void 215 cipher_init(CipherContext *cc, Cipher *cipher, 216 const u_char *key, u_int keylen, const u_char *iv, u_int ivlen, 217 int do_encrypt) 218 { 219 static int dowarn = 1; 220 const EVP_CIPHER *type; 221 int klen; 222 u_char *junk, *discard; 223 224 if (cipher->number == SSH_CIPHER_DES) { 225 if (dowarn) { 226 error("Warning: use of DES is strongly discouraged " 227 "due to cryptographic weaknesses"); 228 dowarn = 0; 229 } 230 if (keylen > 8) 231 keylen = 8; 232 } 233 cc->plaintext = (cipher->number == SSH_CIPHER_NONE); 234 235 if (keylen < cipher->key_len) 236 fatal("cipher_init: key length %d is insufficient for %s.", 237 keylen, cipher->name); 238 if (iv != NULL && ivlen < cipher->block_size) 239 fatal("cipher_init: iv length %d is insufficient for %s.", 240 ivlen, cipher->name); 241 cc->cipher = cipher; 242 243 type = (*cipher->evptype)(); 244 245 EVP_CIPHER_CTX_init(&cc->evp); 246 if (EVP_CipherInit(&cc->evp, type, NULL, (u_char *)iv, 247 (do_encrypt == CIPHER_ENCRYPT)) == 0) 248 fatal("cipher_init: EVP_CipherInit failed for %s", 249 cipher->name); 250 klen = EVP_CIPHER_CTX_key_length(&cc->evp); 251 if (klen > 0 && keylen != (u_int)klen) { 252 debug2("cipher_init: set keylen (%d -> %d)", klen, keylen); 253 if (EVP_CIPHER_CTX_set_key_length(&cc->evp, keylen) == 0) 254 fatal("cipher_init: set keylen failed (%d -> %d)", 255 klen, keylen); 256 } 257 if (EVP_CipherInit(&cc->evp, NULL, (u_char *)key, NULL, -1) == 0) 258 fatal("cipher_init: EVP_CipherInit: set key failed for %s", 259 cipher->name); 260 261 if (cipher->discard_len > 0) { 262 junk = xmalloc(cipher->discard_len); 263 discard = xmalloc(cipher->discard_len); 264 if (EVP_Cipher(&cc->evp, discard, junk, 265 cipher->discard_len) == 0) 266 fatal("evp_crypt: EVP_Cipher failed during discard"); 267 memset(discard, 0, cipher->discard_len); 268 xfree(junk); 269 xfree(discard); 270 } 271 } 272 273 void 274 cipher_crypt(CipherContext *cc, u_char *dest, const u_char *src, u_int len) 275 { 276 if (len % cc->cipher->block_size) 277 fatal("cipher_encrypt: bad plaintext length %d", len); 278 if (EVP_Cipher(&cc->evp, dest, (u_char *)src, len) == 0) 279 fatal("evp_crypt: EVP_Cipher failed"); 280 } 281 282 void 283 cipher_cleanup(CipherContext *cc) 284 { 285 if (EVP_CIPHER_CTX_cleanup(&cc->evp) == 0) 286 error("cipher_cleanup: EVP_CIPHER_CTX_cleanup failed"); 287 } 288 289 /* 290 * Selects the cipher, and keys if by computing the MD5 checksum of the 291 * passphrase and using the resulting 16 bytes as the key. 292 */ 293 294 void 295 cipher_set_key_string(CipherContext *cc, Cipher *cipher, 296 const char *passphrase, int do_encrypt) 297 { 298 MD5_CTX md; 299 u_char digest[16]; 300 301 MD5_Init(&md); 302 MD5_Update(&md, (const u_char *)passphrase, strlen(passphrase)); 303 MD5_Final(digest, &md); 304 305 cipher_init(cc, cipher, digest, 16, NULL, 0, do_encrypt); 306 307 memset(digest, 0, sizeof(digest)); 308 memset(&md, 0, sizeof(md)); 309 } 310 311 /* 312 * Exports an IV from the CipherContext required to export the key 313 * state back from the unprivileged child to the privileged parent 314 * process. 315 */ 316 317 int 318 cipher_get_keyiv_len(const CipherContext *cc) 319 { 320 Cipher *c = cc->cipher; 321 int ivlen; 322 323 if (c->number == SSH_CIPHER_3DES) 324 ivlen = 24; 325 else 326 ivlen = EVP_CIPHER_CTX_iv_length(&cc->evp); 327 return (ivlen); 328 } 329 330 void 331 cipher_get_keyiv(CipherContext *cc, u_char *iv, u_int len) 332 { 333 Cipher *c = cc->cipher; 334 int evplen; 335 336 switch (c->number) { 337 case SSH_CIPHER_NONE: 338 case SSH_CIPHER_SSH2: 339 case SSH_CIPHER_DES: 340 case SSH_CIPHER_BLOWFISH: 341 evplen = EVP_CIPHER_CTX_iv_length(&cc->evp); 342 if (evplen <= 0) 343 return; 344 if ((u_int)evplen != len) 345 fatal("%s: wrong iv length %d != %d", __func__, 346 evplen, len); 347 if (c->evptype == evp_aes_128_ctr) 348 ssh_aes_ctr_iv(&cc->evp, 0, iv, len); 349 else 350 memcpy(iv, cc->evp.iv, len); 351 break; 352 case SSH_CIPHER_3DES: 353 ssh1_3des_iv(&cc->evp, 0, iv, 24); 354 break; 355 default: 356 fatal("%s: bad cipher %d", __func__, c->number); 357 } 358 } 359 360 void 361 cipher_set_keyiv(CipherContext *cc, u_char *iv) 362 { 363 Cipher *c = cc->cipher; 364 int evplen = 0; 365 366 switch (c->number) { 367 case SSH_CIPHER_NONE: 368 case SSH_CIPHER_SSH2: 369 case SSH_CIPHER_DES: 370 case SSH_CIPHER_BLOWFISH: 371 evplen = EVP_CIPHER_CTX_iv_length(&cc->evp); 372 if (evplen == 0) 373 return; 374 if (c->evptype == evp_aes_128_ctr) 375 ssh_aes_ctr_iv(&cc->evp, 1, iv, evplen); 376 else 377 memcpy(cc->evp.iv, iv, evplen); 378 break; 379 case SSH_CIPHER_3DES: 380 ssh1_3des_iv(&cc->evp, 1, iv, 24); 381 break; 382 default: 383 fatal("%s: bad cipher %d", __func__, c->number); 384 } 385 } 386 387 #define EVP_X_STATE(evp) (evp).cipher_data 388 #define EVP_X_STATE_LEN(evp) (evp).cipher->ctx_size 389 390 int 391 cipher_get_keycontext(const CipherContext *cc, u_char *dat) 392 { 393 Cipher *c = cc->cipher; 394 int plen = 0; 395 396 if (c->evptype == EVP_rc4 || c->evptype == EVP_acss) { 397 plen = EVP_X_STATE_LEN(cc->evp); 398 if (dat == NULL) 399 return (plen); 400 memcpy(dat, EVP_X_STATE(cc->evp), plen); 401 } 402 return (plen); 403 } 404 405 void 406 cipher_set_keycontext(CipherContext *cc, u_char *dat) 407 { 408 Cipher *c = cc->cipher; 409 int plen; 410 411 if (c->evptype == EVP_rc4 || c->evptype == EVP_acss) { 412 plen = EVP_X_STATE_LEN(cc->evp); 413 memcpy(EVP_X_STATE(cc->evp), dat, plen); 414 } 415 } 416