Annotation of src/usr.bin/ssh/cipher.c, Revision 1.77.4.1
1.77.4.1! brad 1: /* $OpenBSD: cipher.c,v 1.81 2006/08/03 03:34:42 deraadt Exp $ */
1.1 deraadt 2: /*
1.30 deraadt 3: * Author: Tatu Ylonen <ylo@cs.hut.fi>
4: * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
5: * All rights reserved
1.26 markus 6: *
1.30 deraadt 7: * As far as I am concerned, the code I have written for this software
8: * can be used freely for any purpose. Any derived versions of this
9: * software must be clearly marked as such, and if the derived work is
10: * incompatible with the protocol description in the RFC file, it must be
11: * called by a name other than "ssh" or "Secure Shell".
1.26 markus 12: *
13: *
1.30 deraadt 14: * Copyright (c) 1999 Niels Provos. All rights reserved.
1.46 markus 15: * Copyright (c) 1999, 2000 Markus Friedl. All rights reserved.
1.26 markus 16: *
1.30 deraadt 17: * Redistribution and use in source and binary forms, with or without
18: * modification, are permitted provided that the following conditions
19: * are met:
20: * 1. Redistributions of source code must retain the above copyright
21: * notice, this list of conditions and the following disclaimer.
22: * 2. Redistributions in binary form must reproduce the above copyright
23: * notice, this list of conditions and the following disclaimer in the
24: * documentation and/or other materials provided with the distribution.
1.26 markus 25: *
1.30 deraadt 26: * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
27: * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
28: * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
29: * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
30: * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
31: * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
32: * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
33: * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
34: * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
35: * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
1.17 deraadt 36: */
1.1 deraadt 37:
1.77.4.1! brad 38: #include <sys/types.h>
! 39:
! 40: #include <openssl/md5.h>
! 41:
! 42: #include <string.h>
! 43: #include <stdarg.h>
1.1 deraadt 44:
1.24 markus 45: #include "xmalloc.h"
1.42 markus 46: #include "log.h"
47: #include "cipher.h"
1.57 markus 48:
1.64 markus 49: extern const EVP_CIPHER *evp_ssh1_bf(void);
50: extern const EVP_CIPHER *evp_ssh1_3des(void);
51: extern void ssh1_3des_iv(EVP_CIPHER_CTX *, int, u_char *, int);
1.65 markus 52: extern const EVP_CIPHER *evp_aes_128_ctr(void);
53: extern void ssh_aes_ctr_iv(EVP_CIPHER_CTX *, int, u_char *, u_int);
1.1 deraadt 54:
1.51 markus 55: struct Cipher {
56: char *name;
57: int number; /* for ssh1 only */
58: u_int block_size;
59: u_int key_len;
1.74 djm 60: u_int discard_len;
1.56 markus 61: const EVP_CIPHER *(*evptype)(void);
1.52 markus 62: } ciphers[] = {
1.74 djm 63: { "none", SSH_CIPHER_NONE, 8, 0, 0, EVP_enc_null },
64: { "des", SSH_CIPHER_DES, 8, 8, 0, EVP_des_cbc },
65: { "3des", SSH_CIPHER_3DES, 8, 16, 0, evp_ssh1_3des },
66: { "blowfish", SSH_CIPHER_BLOWFISH, 8, 32, 0, evp_ssh1_bf },
67:
68: { "3des-cbc", SSH_CIPHER_SSH2, 8, 24, 0, EVP_des_ede3_cbc },
69: { "blowfish-cbc", SSH_CIPHER_SSH2, 8, 16, 0, EVP_bf_cbc },
70: { "cast128-cbc", SSH_CIPHER_SSH2, 8, 16, 0, EVP_cast5_cbc },
71: { "arcfour", SSH_CIPHER_SSH2, 8, 16, 0, EVP_rc4 },
72: { "arcfour128", SSH_CIPHER_SSH2, 8, 16, 1536, EVP_rc4 },
73: { "arcfour256", SSH_CIPHER_SSH2, 8, 32, 1536, EVP_rc4 },
74: { "aes128-cbc", SSH_CIPHER_SSH2, 16, 16, 0, EVP_aes_128_cbc },
75: { "aes192-cbc", SSH_CIPHER_SSH2, 16, 24, 0, EVP_aes_192_cbc },
76: { "aes256-cbc", SSH_CIPHER_SSH2, 16, 32, 0, EVP_aes_256_cbc },
1.57 markus 77: { "rijndael-cbc@lysator.liu.se",
1.74 djm 78: SSH_CIPHER_SSH2, 16, 32, 0, EVP_aes_256_cbc },
79: { "aes128-ctr", SSH_CIPHER_SSH2, 16, 16, 0, evp_aes_128_ctr },
80: { "aes192-ctr", SSH_CIPHER_SSH2, 16, 24, 0, evp_aes_128_ctr },
81: { "aes256-ctr", SSH_CIPHER_SSH2, 16, 32, 0, evp_aes_128_ctr },
82: { "acss@openssh.org", SSH_CIPHER_SSH2, 16, 5, 0, EVP_acss },
1.47 markus 83:
1.75 dtucker 84: { NULL, SSH_CIPHER_INVALID, 0, 0, 0, NULL }
1.32 markus 85: };
86:
87: /*--*/
1.1 deraadt 88:
1.54 markus 89: u_int
1.66 jakob 90: cipher_blocksize(const Cipher *c)
1.51 markus 91: {
92: return (c->block_size);
93: }
1.60 deraadt 94:
1.54 markus 95: u_int
1.66 jakob 96: cipher_keylen(const Cipher *c)
1.51 markus 97: {
98: return (c->key_len);
99: }
1.60 deraadt 100:
1.54 markus 101: u_int
1.66 jakob 102: cipher_get_number(const Cipher *c)
1.53 markus 103: {
104: return (c->number);
105: }
1.51 markus 106:
1.41 markus 107: u_int
1.34 markus 108: cipher_mask_ssh1(int client)
1.1 deraadt 109: {
1.41 markus 110: u_int mask = 0;
1.48 deraadt 111: mask |= 1 << SSH_CIPHER_3DES; /* Mandatory */
1.34 markus 112: mask |= 1 << SSH_CIPHER_BLOWFISH;
113: if (client) {
114: mask |= 1 << SSH_CIPHER_DES;
1.32 markus 115: }
116: return mask;
1.1 deraadt 117: }
118:
1.32 markus 119: Cipher *
120: cipher_by_name(const char *name)
121: {
122: Cipher *c;
123: for (c = ciphers; c->name != NULL; c++)
1.73 djm 124: if (strcmp(c->name, name) == 0)
1.32 markus 125: return c;
126: return NULL;
127: }
128:
129: Cipher *
130: cipher_by_number(int id)
131: {
132: Cipher *c;
133: for (c = ciphers; c->name != NULL; c++)
134: if (c->number == id)
135: return c;
136: return NULL;
137: }
1.24 markus 138:
139: #define CIPHER_SEP ","
140: int
141: ciphers_valid(const char *names)
142: {
1.32 markus 143: Cipher *c;
1.69 avsm 144: char *cipher_list, *cp;
1.24 markus 145: char *p;
146:
1.27 markus 147: if (names == NULL || strcmp(names, "") == 0)
1.24 markus 148: return 0;
1.69 avsm 149: cipher_list = cp = xstrdup(names);
1.32 markus 150: for ((p = strsep(&cp, CIPHER_SEP)); p && *p != '\0';
1.48 deraadt 151: (p = strsep(&cp, CIPHER_SEP))) {
1.32 markus 152: c = cipher_by_name(p);
153: if (c == NULL || c->number != SSH_CIPHER_SSH2) {
154: debug("bad cipher %s [%s]", p, names);
1.69 avsm 155: xfree(cipher_list);
1.24 markus 156: return 0;
1.32 markus 157: } else {
1.36 markus 158: debug3("cipher ok: %s [%s]", p, names);
1.24 markus 159: }
160: }
1.36 markus 161: debug3("ciphers ok: [%s]", names);
1.69 avsm 162: xfree(cipher_list);
1.24 markus 163: return 1;
164: }
165:
1.18 markus 166: /*
167: * Parses the name of the cipher. Returns the number of the corresponding
168: * cipher, or -1 on error.
169: */
1.1 deraadt 170:
1.4 provos 171: int
172: cipher_number(const char *name)
1.1 deraadt 173: {
1.32 markus 174: Cipher *c;
1.27 markus 175: if (name == NULL)
176: return -1;
1.73 djm 177: for (c = ciphers; c->name != NULL; c++)
178: if (strcasecmp(c->name, name) == 0)
179: return c->number;
180: return -1;
1.1 deraadt 181: }
182:
1.32 markus 183: char *
184: cipher_name(int id)
1.1 deraadt 185: {
1.32 markus 186: Cipher *c = cipher_by_number(id);
187: return (c==NULL) ? "<unknown>" : c->name;
1.1 deraadt 188: }
189:
1.26 markus 190: void
1.52 markus 191: cipher_init(CipherContext *cc, Cipher *cipher,
192: const u_char *key, u_int keylen, const u_char *iv, u_int ivlen,
1.69 avsm 193: int do_encrypt)
1.16 markus 194: {
1.52 markus 195: static int dowarn = 1;
196: const EVP_CIPHER *type;
197: int klen;
1.74 djm 198: u_char *junk, *discard;
1.52 markus 199:
200: if (cipher->number == SSH_CIPHER_DES) {
201: if (dowarn) {
202: error("Warning: use of DES is strongly discouraged "
203: "due to cryptographic weaknesses");
204: dowarn = 0;
205: }
206: if (keylen > 8)
207: keylen = 8;
208: }
209: cc->plaintext = (cipher->number == SSH_CIPHER_NONE);
210:
1.32 markus 211: if (keylen < cipher->key_len)
212: fatal("cipher_init: key length %d is insufficient for %s.",
213: keylen, cipher->name);
214: if (iv != NULL && ivlen < cipher->block_size)
215: fatal("cipher_init: iv length %d is insufficient for %s.",
216: ivlen, cipher->name);
217: cc->cipher = cipher;
1.52 markus 218:
219: type = (*cipher->evptype)();
220:
221: EVP_CIPHER_CTX_init(&cc->evp);
222: if (EVP_CipherInit(&cc->evp, type, NULL, (u_char *)iv,
1.69 avsm 223: (do_encrypt == CIPHER_ENCRYPT)) == 0)
1.52 markus 224: fatal("cipher_init: EVP_CipherInit failed for %s",
225: cipher->name);
226: klen = EVP_CIPHER_CTX_key_length(&cc->evp);
1.76 djm 227: if (klen > 0 && keylen != (u_int)klen) {
1.62 markus 228: debug2("cipher_init: set keylen (%d -> %d)", klen, keylen);
1.52 markus 229: if (EVP_CIPHER_CTX_set_key_length(&cc->evp, keylen) == 0)
230: fatal("cipher_init: set keylen failed (%d -> %d)",
231: klen, keylen);
232: }
233: if (EVP_CipherInit(&cc->evp, NULL, (u_char *)key, NULL, -1) == 0)
234: fatal("cipher_init: EVP_CipherInit: set key failed for %s",
235: cipher->name);
1.74 djm 236:
1.77 djm 237: if (cipher->discard_len > 0) {
1.74 djm 238: junk = xmalloc(cipher->discard_len);
239: discard = xmalloc(cipher->discard_len);
240: if (EVP_Cipher(&cc->evp, discard, junk,
241: cipher->discard_len) == 0)
242: fatal("evp_crypt: EVP_Cipher failed during discard");
243: memset(discard, 0, cipher->discard_len);
244: xfree(junk);
245: xfree(discard);
246: }
1.1 deraadt 247: }
1.21 markus 248:
1.26 markus 249: void
1.51 markus 250: cipher_crypt(CipherContext *cc, u_char *dest, const u_char *src, u_int len)
1.32 markus 251: {
252: if (len % cc->cipher->block_size)
253: fatal("cipher_encrypt: bad plaintext length %d", len);
1.52 markus 254: if (EVP_Cipher(&cc->evp, dest, (u_char *)src, len) == 0)
255: fatal("evp_crypt: EVP_Cipher failed");
1.21 markus 256: }
257:
1.26 markus 258: void
1.51 markus 259: cipher_cleanup(CipherContext *cc)
1.16 markus 260: {
1.52 markus 261: if (EVP_CIPHER_CTX_cleanup(&cc->evp) == 0)
262: error("cipher_cleanup: EVP_CIPHER_CTX_cleanup failed");
1.16 markus 263: }
1.1 deraadt 264:
1.32 markus 265: /*
266: * Selects the cipher, and keys if by computing the MD5 checksum of the
267: * passphrase and using the resulting 16 bytes as the key.
268: */
1.1 deraadt 269:
1.26 markus 270: void
1.32 markus 271: cipher_set_key_string(CipherContext *cc, Cipher *cipher,
1.69 avsm 272: const char *passphrase, int do_encrypt)
1.16 markus 273: {
1.32 markus 274: MD5_CTX md;
1.41 markus 275: u_char digest[16];
1.32 markus 276:
277: MD5_Init(&md);
278: MD5_Update(&md, (const u_char *)passphrase, strlen(passphrase));
279: MD5_Final(digest, &md);
1.16 markus 280:
1.69 avsm 281: cipher_init(cc, cipher, digest, 16, NULL, 0, do_encrypt);
1.16 markus 282:
1.32 markus 283: memset(digest, 0, sizeof(digest));
284: memset(&md, 0, sizeof(md));
1.52 markus 285: }
1.53 markus 286:
1.54 markus 287: /*
1.53 markus 288: * Exports an IV from the CipherContext required to export the key
289: * state back from the unprivileged child to the privileged parent
290: * process.
291: */
292:
293: int
1.66 jakob 294: cipher_get_keyiv_len(const CipherContext *cc)
1.53 markus 295: {
296: Cipher *c = cc->cipher;
297: int ivlen;
298:
299: if (c->number == SSH_CIPHER_3DES)
300: ivlen = 24;
301: else
302: ivlen = EVP_CIPHER_CTX_iv_length(&cc->evp);
303: return (ivlen);
304: }
305:
306: void
307: cipher_get_keyiv(CipherContext *cc, u_char *iv, u_int len)
308: {
309: Cipher *c = cc->cipher;
310: int evplen;
311:
312: switch (c->number) {
313: case SSH_CIPHER_SSH2:
314: case SSH_CIPHER_DES:
315: case SSH_CIPHER_BLOWFISH:
316: evplen = EVP_CIPHER_CTX_iv_length(&cc->evp);
1.76 djm 317: if (evplen <= 0)
1.53 markus 318: return;
1.76 djm 319: if ((u_int)evplen != len)
1.58 markus 320: fatal("%s: wrong iv length %d != %d", __func__,
1.53 markus 321: evplen, len);
1.65 markus 322: if (c->evptype == evp_aes_128_ctr)
323: ssh_aes_ctr_iv(&cc->evp, 0, iv, len);
324: else
1.63 markus 325: memcpy(iv, cc->evp.iv, len);
326: break;
327: case SSH_CIPHER_3DES:
328: ssh1_3des_iv(&cc->evp, 0, iv, 24);
1.53 markus 329: break;
330: default:
1.58 markus 331: fatal("%s: bad cipher %d", __func__, c->number);
1.53 markus 332: }
333: }
334:
335: void
336: cipher_set_keyiv(CipherContext *cc, u_char *iv)
337: {
338: Cipher *c = cc->cipher;
339: int evplen = 0;
340:
341: switch (c->number) {
342: case SSH_CIPHER_SSH2:
343: case SSH_CIPHER_DES:
344: case SSH_CIPHER_BLOWFISH:
345: evplen = EVP_CIPHER_CTX_iv_length(&cc->evp);
346: if (evplen == 0)
347: return;
1.65 markus 348: if (c->evptype == evp_aes_128_ctr)
349: ssh_aes_ctr_iv(&cc->evp, 1, iv, evplen);
350: else
1.63 markus 351: memcpy(cc->evp.iv, iv, evplen);
352: break;
353: case SSH_CIPHER_3DES:
354: ssh1_3des_iv(&cc->evp, 1, iv, 24);
1.53 markus 355: break;
356: default:
1.58 markus 357: fatal("%s: bad cipher %d", __func__, c->number);
1.53 markus 358: }
359: }
360:
361: #define EVP_X_STATE(evp) (evp).cipher_data
362: #define EVP_X_STATE_LEN(evp) (evp).cipher->ctx_size
363:
364: int
1.66 jakob 365: cipher_get_keycontext(const CipherContext *cc, u_char *dat)
1.53 markus 366: {
367: Cipher *c = cc->cipher;
1.59 markus 368: int plen = 0;
1.53 markus 369:
1.67 hshoexer 370: if (c->evptype == EVP_rc4 || c->evptype == EVP_acss) {
1.59 markus 371: plen = EVP_X_STATE_LEN(cc->evp);
1.53 markus 372: if (dat == NULL)
1.59 markus 373: return (plen);
374: memcpy(dat, EVP_X_STATE(cc->evp), plen);
1.53 markus 375: }
376: return (plen);
377: }
378:
379: void
380: cipher_set_keycontext(CipherContext *cc, u_char *dat)
381: {
382: Cipher *c = cc->cipher;
383: int plen;
384:
1.67 hshoexer 385: if (c->evptype == EVP_rc4 || c->evptype == EVP_acss) {
1.53 markus 386: plen = EVP_X_STATE_LEN(cc->evp);
387: memcpy(EVP_X_STATE(cc->evp), dat, plen);
388: }
1.1 deraadt 389: }
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