Annotation of src/usr.bin/ssh/cipher.c, Revision 1.71.2.2
1.1 deraadt 1: /*
1.30 deraadt 2: * Author: Tatu Ylonen <ylo@cs.hut.fi>
3: * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
4: * All rights reserved
1.26 markus 5: *
1.30 deraadt 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".
1.26 markus 11: *
12: *
1.30 deraadt 13: * Copyright (c) 1999 Niels Provos. All rights reserved.
1.46 markus 14: * Copyright (c) 1999, 2000 Markus Friedl. All rights reserved.
1.26 markus 15: *
1.30 deraadt 16: * Redistribution and use in source and binary forms, with or without
17: * modification, are permitted provided that the following conditions
18: * are met:
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.
1.26 markus 24: *
1.30 deraadt 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.
1.17 deraadt 35: */
1.1 deraadt 36:
37: #include "includes.h"
1.71.2.2! brad 38: RCSID("$OpenBSD: cipher.c,v 1.77 2005/07/16 01:35:24 djm Exp $");
1.1 deraadt 39:
1.24 markus 40: #include "xmalloc.h"
1.42 markus 41: #include "log.h"
42: #include "cipher.h"
1.8 deraadt 43:
1.25 markus 44: #include <openssl/md5.h>
1.57 markus 45:
1.64 markus 46: extern const EVP_CIPHER *evp_ssh1_bf(void);
47: extern const EVP_CIPHER *evp_ssh1_3des(void);
48: extern void ssh1_3des_iv(EVP_CIPHER_CTX *, int, u_char *, int);
1.65 markus 49: extern const EVP_CIPHER *evp_aes_128_ctr(void);
50: extern void ssh_aes_ctr_iv(EVP_CIPHER_CTX *, int, u_char *, u_int);
1.1 deraadt 51:
1.51 markus 52: struct Cipher {
53: char *name;
54: int number; /* for ssh1 only */
55: u_int block_size;
56: u_int key_len;
1.71.2.2! brad 57: u_int discard_len;
1.56 markus 58: const EVP_CIPHER *(*evptype)(void);
1.52 markus 59: } ciphers[] = {
1.71.2.2! brad 60: { "none", SSH_CIPHER_NONE, 8, 0, 0, EVP_enc_null },
! 61: { "des", SSH_CIPHER_DES, 8, 8, 0, EVP_des_cbc },
! 62: { "3des", SSH_CIPHER_3DES, 8, 16, 0, evp_ssh1_3des },
! 63: { "blowfish", SSH_CIPHER_BLOWFISH, 8, 32, 0, evp_ssh1_bf },
! 64:
! 65: { "3des-cbc", SSH_CIPHER_SSH2, 8, 24, 0, EVP_des_ede3_cbc },
! 66: { "blowfish-cbc", SSH_CIPHER_SSH2, 8, 16, 0, EVP_bf_cbc },
! 67: { "cast128-cbc", SSH_CIPHER_SSH2, 8, 16, 0, EVP_cast5_cbc },
! 68: { "arcfour", SSH_CIPHER_SSH2, 8, 16, 0, EVP_rc4 },
! 69: { "arcfour128", SSH_CIPHER_SSH2, 8, 16, 1536, EVP_rc4 },
! 70: { "arcfour256", SSH_CIPHER_SSH2, 8, 32, 1536, EVP_rc4 },
! 71: { "aes128-cbc", SSH_CIPHER_SSH2, 16, 16, 0, EVP_aes_128_cbc },
! 72: { "aes192-cbc", SSH_CIPHER_SSH2, 16, 24, 0, EVP_aes_192_cbc },
! 73: { "aes256-cbc", SSH_CIPHER_SSH2, 16, 32, 0, EVP_aes_256_cbc },
1.57 markus 74: { "rijndael-cbc@lysator.liu.se",
1.71.2.2! brad 75: SSH_CIPHER_SSH2, 16, 32, 0, EVP_aes_256_cbc },
! 76: { "aes128-ctr", SSH_CIPHER_SSH2, 16, 16, 0, evp_aes_128_ctr },
! 77: { "aes192-ctr", SSH_CIPHER_SSH2, 16, 24, 0, evp_aes_128_ctr },
! 78: { "aes256-ctr", SSH_CIPHER_SSH2, 16, 32, 0, evp_aes_128_ctr },
! 79: { "acss@openssh.org", SSH_CIPHER_SSH2, 16, 5, 0, EVP_acss },
1.47 markus 80:
1.71.2.2! brad 81: { NULL, SSH_CIPHER_INVALID, 0, 0, 0, NULL }
1.32 markus 82: };
83:
84: /*--*/
1.1 deraadt 85:
1.54 markus 86: u_int
1.66 jakob 87: cipher_blocksize(const Cipher *c)
1.51 markus 88: {
89: return (c->block_size);
90: }
1.60 deraadt 91:
1.54 markus 92: u_int
1.66 jakob 93: cipher_keylen(const Cipher *c)
1.51 markus 94: {
95: return (c->key_len);
96: }
1.60 deraadt 97:
1.54 markus 98: u_int
1.66 jakob 99: cipher_get_number(const Cipher *c)
1.53 markus 100: {
101: return (c->number);
102: }
1.51 markus 103:
1.41 markus 104: u_int
1.34 markus 105: cipher_mask_ssh1(int client)
1.1 deraadt 106: {
1.41 markus 107: u_int mask = 0;
1.48 deraadt 108: mask |= 1 << SSH_CIPHER_3DES; /* Mandatory */
1.34 markus 109: mask |= 1 << SSH_CIPHER_BLOWFISH;
110: if (client) {
111: mask |= 1 << SSH_CIPHER_DES;
1.32 markus 112: }
113: return mask;
1.1 deraadt 114: }
115:
1.32 markus 116: Cipher *
117: cipher_by_name(const char *name)
118: {
119: Cipher *c;
120: for (c = ciphers; c->name != NULL; c++)
1.71.2.1 brad 121: if (strcmp(c->name, name) == 0)
1.32 markus 122: return c;
123: return NULL;
124: }
125:
126: Cipher *
127: cipher_by_number(int id)
128: {
129: Cipher *c;
130: for (c = ciphers; c->name != NULL; c++)
131: if (c->number == id)
132: return c;
133: return NULL;
134: }
1.24 markus 135:
136: #define CIPHER_SEP ","
137: int
138: ciphers_valid(const char *names)
139: {
1.32 markus 140: Cipher *c;
1.69 avsm 141: char *cipher_list, *cp;
1.24 markus 142: char *p;
143:
1.27 markus 144: if (names == NULL || strcmp(names, "") == 0)
1.24 markus 145: return 0;
1.69 avsm 146: cipher_list = cp = xstrdup(names);
1.32 markus 147: for ((p = strsep(&cp, CIPHER_SEP)); p && *p != '\0';
1.48 deraadt 148: (p = strsep(&cp, CIPHER_SEP))) {
1.32 markus 149: c = cipher_by_name(p);
150: if (c == NULL || c->number != SSH_CIPHER_SSH2) {
151: debug("bad cipher %s [%s]", p, names);
1.69 avsm 152: xfree(cipher_list);
1.24 markus 153: return 0;
1.32 markus 154: } else {
1.36 markus 155: debug3("cipher ok: %s [%s]", p, names);
1.24 markus 156: }
157: }
1.36 markus 158: debug3("ciphers ok: [%s]", names);
1.69 avsm 159: xfree(cipher_list);
1.24 markus 160: return 1;
161: }
162:
1.18 markus 163: /*
164: * Parses the name of the cipher. Returns the number of the corresponding
165: * cipher, or -1 on error.
166: */
1.1 deraadt 167:
1.4 provos 168: int
169: cipher_number(const char *name)
1.1 deraadt 170: {
1.32 markus 171: Cipher *c;
1.27 markus 172: if (name == NULL)
173: return -1;
1.71.2.1 brad 174: for (c = ciphers; c->name != NULL; c++)
175: if (strcasecmp(c->name, name) == 0)
176: return c->number;
177: return -1;
1.1 deraadt 178: }
179:
1.32 markus 180: char *
181: cipher_name(int id)
1.1 deraadt 182: {
1.32 markus 183: Cipher *c = cipher_by_number(id);
184: return (c==NULL) ? "<unknown>" : c->name;
1.1 deraadt 185: }
186:
1.26 markus 187: void
1.52 markus 188: cipher_init(CipherContext *cc, Cipher *cipher,
189: const u_char *key, u_int keylen, const u_char *iv, u_int ivlen,
1.69 avsm 190: int do_encrypt)
1.16 markus 191: {
1.52 markus 192: static int dowarn = 1;
193: const EVP_CIPHER *type;
194: int klen;
1.71.2.2! brad 195: u_char *junk, *discard;
1.52 markus 196:
197: if (cipher->number == SSH_CIPHER_DES) {
198: if (dowarn) {
199: error("Warning: use of DES is strongly discouraged "
200: "due to cryptographic weaknesses");
201: dowarn = 0;
202: }
203: if (keylen > 8)
204: keylen = 8;
205: }
206: cc->plaintext = (cipher->number == SSH_CIPHER_NONE);
207:
1.32 markus 208: if (keylen < cipher->key_len)
209: fatal("cipher_init: key length %d is insufficient for %s.",
210: keylen, cipher->name);
211: if (iv != NULL && ivlen < cipher->block_size)
212: fatal("cipher_init: iv length %d is insufficient for %s.",
213: ivlen, cipher->name);
214: cc->cipher = cipher;
1.52 markus 215:
216: type = (*cipher->evptype)();
217:
218: EVP_CIPHER_CTX_init(&cc->evp);
219: if (EVP_CipherInit(&cc->evp, type, NULL, (u_char *)iv,
1.69 avsm 220: (do_encrypt == CIPHER_ENCRYPT)) == 0)
1.52 markus 221: fatal("cipher_init: EVP_CipherInit failed for %s",
222: cipher->name);
223: klen = EVP_CIPHER_CTX_key_length(&cc->evp);
1.71.2.2! brad 224: if (klen > 0 && keylen != (u_int)klen) {
1.62 markus 225: debug2("cipher_init: set keylen (%d -> %d)", klen, keylen);
1.52 markus 226: if (EVP_CIPHER_CTX_set_key_length(&cc->evp, keylen) == 0)
227: fatal("cipher_init: set keylen failed (%d -> %d)",
228: klen, keylen);
229: }
230: if (EVP_CipherInit(&cc->evp, NULL, (u_char *)key, NULL, -1) == 0)
231: fatal("cipher_init: EVP_CipherInit: set key failed for %s",
232: cipher->name);
1.71.2.2! brad 233:
! 234: if (cipher->discard_len > 0) {
! 235: junk = xmalloc(cipher->discard_len);
! 236: discard = xmalloc(cipher->discard_len);
! 237: if (EVP_Cipher(&cc->evp, discard, junk,
! 238: cipher->discard_len) == 0)
! 239: fatal("evp_crypt: EVP_Cipher failed during discard");
! 240: memset(discard, 0, cipher->discard_len);
! 241: xfree(junk);
! 242: xfree(discard);
! 243: }
1.1 deraadt 244: }
1.21 markus 245:
1.26 markus 246: void
1.51 markus 247: cipher_crypt(CipherContext *cc, u_char *dest, const u_char *src, u_int len)
1.32 markus 248: {
249: if (len % cc->cipher->block_size)
250: fatal("cipher_encrypt: bad plaintext length %d", len);
1.52 markus 251: if (EVP_Cipher(&cc->evp, dest, (u_char *)src, len) == 0)
252: fatal("evp_crypt: EVP_Cipher failed");
1.21 markus 253: }
254:
1.26 markus 255: void
1.51 markus 256: cipher_cleanup(CipherContext *cc)
1.16 markus 257: {
1.52 markus 258: if (EVP_CIPHER_CTX_cleanup(&cc->evp) == 0)
259: error("cipher_cleanup: EVP_CIPHER_CTX_cleanup failed");
1.16 markus 260: }
1.1 deraadt 261:
1.32 markus 262: /*
263: * Selects the cipher, and keys if by computing the MD5 checksum of the
264: * passphrase and using the resulting 16 bytes as the key.
265: */
1.1 deraadt 266:
1.26 markus 267: void
1.32 markus 268: cipher_set_key_string(CipherContext *cc, Cipher *cipher,
1.69 avsm 269: const char *passphrase, int do_encrypt)
1.16 markus 270: {
1.32 markus 271: MD5_CTX md;
1.41 markus 272: u_char digest[16];
1.32 markus 273:
274: MD5_Init(&md);
275: MD5_Update(&md, (const u_char *)passphrase, strlen(passphrase));
276: MD5_Final(digest, &md);
1.16 markus 277:
1.69 avsm 278: cipher_init(cc, cipher, digest, 16, NULL, 0, do_encrypt);
1.16 markus 279:
1.32 markus 280: memset(digest, 0, sizeof(digest));
281: memset(&md, 0, sizeof(md));
1.52 markus 282: }
1.53 markus 283:
1.54 markus 284: /*
1.53 markus 285: * Exports an IV from the CipherContext required to export the key
286: * state back from the unprivileged child to the privileged parent
287: * process.
288: */
289:
290: int
1.66 jakob 291: cipher_get_keyiv_len(const CipherContext *cc)
1.53 markus 292: {
293: Cipher *c = cc->cipher;
294: int ivlen;
295:
296: if (c->number == SSH_CIPHER_3DES)
297: ivlen = 24;
298: else
299: ivlen = EVP_CIPHER_CTX_iv_length(&cc->evp);
300: return (ivlen);
301: }
302:
303: void
304: cipher_get_keyiv(CipherContext *cc, u_char *iv, u_int len)
305: {
306: Cipher *c = cc->cipher;
307: int evplen;
308:
309: switch (c->number) {
310: case SSH_CIPHER_SSH2:
311: case SSH_CIPHER_DES:
312: case SSH_CIPHER_BLOWFISH:
313: evplen = EVP_CIPHER_CTX_iv_length(&cc->evp);
1.71.2.2! brad 314: if (evplen <= 0)
1.53 markus 315: return;
1.71.2.2! brad 316: if ((u_int)evplen != len)
1.58 markus 317: fatal("%s: wrong iv length %d != %d", __func__,
1.53 markus 318: evplen, len);
1.65 markus 319: if (c->evptype == evp_aes_128_ctr)
320: ssh_aes_ctr_iv(&cc->evp, 0, iv, len);
321: else
1.63 markus 322: memcpy(iv, cc->evp.iv, len);
323: break;
324: case SSH_CIPHER_3DES:
325: ssh1_3des_iv(&cc->evp, 0, iv, 24);
1.53 markus 326: break;
327: default:
1.58 markus 328: fatal("%s: bad cipher %d", __func__, c->number);
1.53 markus 329: }
330: }
331:
332: void
333: cipher_set_keyiv(CipherContext *cc, u_char *iv)
334: {
335: Cipher *c = cc->cipher;
336: int evplen = 0;
337:
338: switch (c->number) {
339: case SSH_CIPHER_SSH2:
340: case SSH_CIPHER_DES:
341: case SSH_CIPHER_BLOWFISH:
342: evplen = EVP_CIPHER_CTX_iv_length(&cc->evp);
343: if (evplen == 0)
344: return;
1.65 markus 345: if (c->evptype == evp_aes_128_ctr)
346: ssh_aes_ctr_iv(&cc->evp, 1, iv, evplen);
347: else
1.63 markus 348: memcpy(cc->evp.iv, iv, evplen);
349: break;
350: case SSH_CIPHER_3DES:
351: ssh1_3des_iv(&cc->evp, 1, iv, 24);
1.53 markus 352: break;
353: default:
1.58 markus 354: fatal("%s: bad cipher %d", __func__, c->number);
1.53 markus 355: }
356: }
357:
358: #define EVP_X_STATE(evp) (evp).cipher_data
359: #define EVP_X_STATE_LEN(evp) (evp).cipher->ctx_size
360:
361: int
1.66 jakob 362: cipher_get_keycontext(const CipherContext *cc, u_char *dat)
1.53 markus 363: {
364: Cipher *c = cc->cipher;
1.59 markus 365: int plen = 0;
1.53 markus 366:
1.67 hshoexer 367: if (c->evptype == EVP_rc4 || c->evptype == EVP_acss) {
1.59 markus 368: plen = EVP_X_STATE_LEN(cc->evp);
1.53 markus 369: if (dat == NULL)
1.59 markus 370: return (plen);
371: memcpy(dat, EVP_X_STATE(cc->evp), plen);
1.53 markus 372: }
373: return (plen);
374: }
375:
376: void
377: cipher_set_keycontext(CipherContext *cc, u_char *dat)
378: {
379: Cipher *c = cc->cipher;
380: int plen;
381:
1.67 hshoexer 382: if (c->evptype == EVP_rc4 || c->evptype == EVP_acss) {
1.53 markus 383: plen = EVP_X_STATE_LEN(cc->evp);
384: memcpy(EVP_X_STATE(cc->evp), dat, plen);
385: }
1.1 deraadt 386: }
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