Annotation of src/usr.bin/ssh/cipher.c, Revision 1.84
1.84 ! naddy 1: /* $OpenBSD: cipher.c,v 1.83 2012/12/11 22:31:18 markus 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:
1.81 deraadt 38: #include <sys/types.h>
1.1 deraadt 39:
1.80 stevesk 40: #include <openssl/md5.h>
41:
42: #include <string.h>
1.81 deraadt 43: #include <stdarg.h>
1.80 stevesk 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);
1.1 deraadt 52:
1.51 markus 53: struct Cipher {
54: char *name;
55: int number; /* for ssh1 only */
56: u_int block_size;
57: u_int key_len;
1.74 djm 58: u_int discard_len;
1.82 markus 59: u_int cbc_mode;
1.56 markus 60: const EVP_CIPHER *(*evptype)(void);
1.52 markus 61: } ciphers[] = {
1.82 markus 62: { "none", SSH_CIPHER_NONE, 8, 0, 0, 0, EVP_enc_null },
63: { "des", SSH_CIPHER_DES, 8, 8, 0, 1, EVP_des_cbc },
64: { "3des", SSH_CIPHER_3DES, 8, 16, 0, 1, evp_ssh1_3des },
65: { "blowfish", SSH_CIPHER_BLOWFISH, 8, 32, 0, 1, evp_ssh1_bf },
66:
67: { "3des-cbc", SSH_CIPHER_SSH2, 8, 24, 0, 1, EVP_des_ede3_cbc },
68: { "blowfish-cbc", SSH_CIPHER_SSH2, 8, 16, 0, 1, EVP_bf_cbc },
69: { "cast128-cbc", SSH_CIPHER_SSH2, 8, 16, 0, 1, EVP_cast5_cbc },
70: { "arcfour", SSH_CIPHER_SSH2, 8, 16, 0, 0, EVP_rc4 },
71: { "arcfour128", SSH_CIPHER_SSH2, 8, 16, 1536, 0, EVP_rc4 },
72: { "arcfour256", SSH_CIPHER_SSH2, 8, 32, 1536, 0, EVP_rc4 },
73: { "aes128-cbc", SSH_CIPHER_SSH2, 16, 16, 0, 1, EVP_aes_128_cbc },
74: { "aes192-cbc", SSH_CIPHER_SSH2, 16, 24, 0, 1, EVP_aes_192_cbc },
75: { "aes256-cbc", SSH_CIPHER_SSH2, 16, 32, 0, 1, EVP_aes_256_cbc },
1.57 markus 76: { "rijndael-cbc@lysator.liu.se",
1.82 markus 77: SSH_CIPHER_SSH2, 16, 32, 0, 1, EVP_aes_256_cbc },
1.84 ! naddy 78: { "aes128-ctr", SSH_CIPHER_SSH2, 16, 16, 0, 0, EVP_aes_128_ctr },
! 79: { "aes192-ctr", SSH_CIPHER_SSH2, 16, 24, 0, 0, EVP_aes_192_ctr },
! 80: { "aes256-ctr", SSH_CIPHER_SSH2, 16, 32, 0, 0, EVP_aes_256_ctr },
1.82 markus 81: { "acss@openssh.org", SSH_CIPHER_SSH2, 16, 5, 0, 0, EVP_acss },
1.47 markus 82:
1.82 markus 83: { NULL, SSH_CIPHER_INVALID, 0, 0, 0, 0, NULL }
1.32 markus 84: };
85:
86: /*--*/
1.1 deraadt 87:
1.54 markus 88: u_int
1.66 jakob 89: cipher_blocksize(const Cipher *c)
1.51 markus 90: {
91: return (c->block_size);
92: }
1.60 deraadt 93:
1.54 markus 94: u_int
1.66 jakob 95: cipher_keylen(const Cipher *c)
1.51 markus 96: {
97: return (c->key_len);
98: }
1.60 deraadt 99:
1.54 markus 100: u_int
1.66 jakob 101: cipher_get_number(const Cipher *c)
1.53 markus 102: {
103: return (c->number);
1.82 markus 104: }
105:
106: u_int
107: cipher_is_cbc(const Cipher *c)
108: {
109: return (c->cbc_mode);
1.53 markus 110: }
1.51 markus 111:
1.41 markus 112: u_int
1.34 markus 113: cipher_mask_ssh1(int client)
1.1 deraadt 114: {
1.41 markus 115: u_int mask = 0;
1.48 deraadt 116: mask |= 1 << SSH_CIPHER_3DES; /* Mandatory */
1.34 markus 117: mask |= 1 << SSH_CIPHER_BLOWFISH;
118: if (client) {
119: mask |= 1 << SSH_CIPHER_DES;
1.32 markus 120: }
121: return mask;
1.1 deraadt 122: }
123:
1.32 markus 124: Cipher *
125: cipher_by_name(const char *name)
126: {
127: Cipher *c;
128: for (c = ciphers; c->name != NULL; c++)
1.73 djm 129: if (strcmp(c->name, name) == 0)
1.32 markus 130: return c;
131: return NULL;
132: }
133:
134: Cipher *
135: cipher_by_number(int id)
136: {
137: Cipher *c;
138: for (c = ciphers; c->name != NULL; c++)
139: if (c->number == id)
140: return c;
141: return NULL;
142: }
1.24 markus 143:
144: #define CIPHER_SEP ","
145: int
146: ciphers_valid(const char *names)
147: {
1.32 markus 148: Cipher *c;
1.69 avsm 149: char *cipher_list, *cp;
1.24 markus 150: char *p;
151:
1.27 markus 152: if (names == NULL || strcmp(names, "") == 0)
1.24 markus 153: return 0;
1.69 avsm 154: cipher_list = cp = xstrdup(names);
1.32 markus 155: for ((p = strsep(&cp, CIPHER_SEP)); p && *p != '\0';
1.48 deraadt 156: (p = strsep(&cp, CIPHER_SEP))) {
1.32 markus 157: c = cipher_by_name(p);
158: if (c == NULL || c->number != SSH_CIPHER_SSH2) {
159: debug("bad cipher %s [%s]", p, names);
1.69 avsm 160: xfree(cipher_list);
1.24 markus 161: return 0;
1.32 markus 162: } else {
1.36 markus 163: debug3("cipher ok: %s [%s]", p, names);
1.24 markus 164: }
165: }
1.36 markus 166: debug3("ciphers ok: [%s]", names);
1.69 avsm 167: xfree(cipher_list);
1.24 markus 168: return 1;
169: }
170:
1.18 markus 171: /*
172: * Parses the name of the cipher. Returns the number of the corresponding
173: * cipher, or -1 on error.
174: */
1.1 deraadt 175:
1.4 provos 176: int
177: cipher_number(const char *name)
1.1 deraadt 178: {
1.32 markus 179: Cipher *c;
1.27 markus 180: if (name == NULL)
181: return -1;
1.73 djm 182: for (c = ciphers; c->name != NULL; c++)
183: if (strcasecmp(c->name, name) == 0)
184: return c->number;
185: return -1;
1.1 deraadt 186: }
187:
1.32 markus 188: char *
189: cipher_name(int id)
1.1 deraadt 190: {
1.32 markus 191: Cipher *c = cipher_by_number(id);
192: return (c==NULL) ? "<unknown>" : c->name;
1.1 deraadt 193: }
194:
1.26 markus 195: void
1.52 markus 196: cipher_init(CipherContext *cc, Cipher *cipher,
197: const u_char *key, u_int keylen, const u_char *iv, u_int ivlen,
1.69 avsm 198: int do_encrypt)
1.16 markus 199: {
1.52 markus 200: static int dowarn = 1;
201: const EVP_CIPHER *type;
202: int klen;
1.74 djm 203: u_char *junk, *discard;
1.52 markus 204:
205: if (cipher->number == SSH_CIPHER_DES) {
206: if (dowarn) {
207: error("Warning: use of DES is strongly discouraged "
208: "due to cryptographic weaknesses");
209: dowarn = 0;
210: }
211: if (keylen > 8)
212: keylen = 8;
213: }
214: cc->plaintext = (cipher->number == SSH_CIPHER_NONE);
215:
1.32 markus 216: if (keylen < cipher->key_len)
217: fatal("cipher_init: key length %d is insufficient for %s.",
218: keylen, cipher->name);
219: if (iv != NULL && ivlen < cipher->block_size)
220: fatal("cipher_init: iv length %d is insufficient for %s.",
221: ivlen, cipher->name);
222: cc->cipher = cipher;
1.52 markus 223:
224: type = (*cipher->evptype)();
225:
226: EVP_CIPHER_CTX_init(&cc->evp);
227: if (EVP_CipherInit(&cc->evp, type, NULL, (u_char *)iv,
1.69 avsm 228: (do_encrypt == CIPHER_ENCRYPT)) == 0)
1.52 markus 229: fatal("cipher_init: EVP_CipherInit failed for %s",
230: cipher->name);
231: klen = EVP_CIPHER_CTX_key_length(&cc->evp);
1.76 djm 232: if (klen > 0 && keylen != (u_int)klen) {
1.62 markus 233: debug2("cipher_init: set keylen (%d -> %d)", klen, keylen);
1.52 markus 234: if (EVP_CIPHER_CTX_set_key_length(&cc->evp, keylen) == 0)
235: fatal("cipher_init: set keylen failed (%d -> %d)",
236: klen, keylen);
237: }
238: if (EVP_CipherInit(&cc->evp, NULL, (u_char *)key, NULL, -1) == 0)
239: fatal("cipher_init: EVP_CipherInit: set key failed for %s",
240: cipher->name);
1.74 djm 241:
1.77 djm 242: if (cipher->discard_len > 0) {
1.74 djm 243: junk = xmalloc(cipher->discard_len);
244: discard = xmalloc(cipher->discard_len);
245: if (EVP_Cipher(&cc->evp, discard, junk,
246: cipher->discard_len) == 0)
247: fatal("evp_crypt: EVP_Cipher failed during discard");
248: memset(discard, 0, cipher->discard_len);
249: xfree(junk);
250: xfree(discard);
251: }
1.1 deraadt 252: }
1.21 markus 253:
1.83 markus 254: /*
255: * cipher_crypt() operates as following:
256: * Copy 'aadlen' bytes (without en/decryption) from 'src' to 'dest'.
257: * Theses bytes are treated as additional authenticated data for
258: * authenticated encryption modes.
259: * En/Decrypt 'len' bytes at offset 'aadlen' from 'src' to 'dest'.
260: * Both 'aadlen' and 'authlen' can be set to 0.
261: */
1.26 markus 262: void
1.83 markus 263: cipher_crypt(CipherContext *cc, u_char *dest, const u_char *src,
264: u_int len, u_int aadlen)
1.32 markus 265: {
1.83 markus 266: if (aadlen)
267: memcpy(dest, src, aadlen);
1.32 markus 268: if (len % cc->cipher->block_size)
1.83 markus 269: fatal("%s: bad plaintext length %d", __func__, len);
270: if (EVP_Cipher(&cc->evp, dest + aadlen, (u_char *)src + aadlen,
271: len) < 0)
272: fatal("%s: EVP_Cipher failed", __func__);
1.21 markus 273: }
274:
1.26 markus 275: void
1.51 markus 276: cipher_cleanup(CipherContext *cc)
1.16 markus 277: {
1.52 markus 278: if (EVP_CIPHER_CTX_cleanup(&cc->evp) == 0)
279: error("cipher_cleanup: EVP_CIPHER_CTX_cleanup failed");
1.16 markus 280: }
1.1 deraadt 281:
1.32 markus 282: /*
283: * Selects the cipher, and keys if by computing the MD5 checksum of the
284: * passphrase and using the resulting 16 bytes as the key.
285: */
1.1 deraadt 286:
1.26 markus 287: void
1.32 markus 288: cipher_set_key_string(CipherContext *cc, Cipher *cipher,
1.69 avsm 289: const char *passphrase, int do_encrypt)
1.16 markus 290: {
1.32 markus 291: MD5_CTX md;
1.41 markus 292: u_char digest[16];
1.32 markus 293:
294: MD5_Init(&md);
295: MD5_Update(&md, (const u_char *)passphrase, strlen(passphrase));
296: MD5_Final(digest, &md);
1.16 markus 297:
1.69 avsm 298: cipher_init(cc, cipher, digest, 16, NULL, 0, do_encrypt);
1.16 markus 299:
1.32 markus 300: memset(digest, 0, sizeof(digest));
301: memset(&md, 0, sizeof(md));
1.52 markus 302: }
1.53 markus 303:
1.54 markus 304: /*
1.53 markus 305: * Exports an IV from the CipherContext required to export the key
306: * state back from the unprivileged child to the privileged parent
307: * process.
308: */
309:
310: int
1.66 jakob 311: cipher_get_keyiv_len(const CipherContext *cc)
1.53 markus 312: {
313: Cipher *c = cc->cipher;
314: int ivlen;
315:
316: if (c->number == SSH_CIPHER_3DES)
317: ivlen = 24;
318: else
319: ivlen = EVP_CIPHER_CTX_iv_length(&cc->evp);
320: return (ivlen);
321: }
322:
323: void
324: cipher_get_keyiv(CipherContext *cc, u_char *iv, u_int len)
325: {
326: Cipher *c = cc->cipher;
327: int evplen;
328:
329: switch (c->number) {
330: case SSH_CIPHER_SSH2:
331: case SSH_CIPHER_DES:
332: case SSH_CIPHER_BLOWFISH:
333: evplen = EVP_CIPHER_CTX_iv_length(&cc->evp);
1.76 djm 334: if (evplen <= 0)
1.53 markus 335: return;
1.76 djm 336: if ((u_int)evplen != len)
1.58 markus 337: fatal("%s: wrong iv length %d != %d", __func__,
1.53 markus 338: evplen, len);
1.84 ! naddy 339: memcpy(iv, cc->evp.iv, len);
1.63 markus 340: break;
341: case SSH_CIPHER_3DES:
342: ssh1_3des_iv(&cc->evp, 0, iv, 24);
1.53 markus 343: break;
344: default:
1.58 markus 345: fatal("%s: bad cipher %d", __func__, c->number);
1.53 markus 346: }
347: }
348:
349: void
350: cipher_set_keyiv(CipherContext *cc, u_char *iv)
351: {
352: Cipher *c = cc->cipher;
353: int evplen = 0;
354:
355: switch (c->number) {
356: case SSH_CIPHER_SSH2:
357: case SSH_CIPHER_DES:
358: case SSH_CIPHER_BLOWFISH:
359: evplen = EVP_CIPHER_CTX_iv_length(&cc->evp);
360: if (evplen == 0)
361: return;
1.84 ! naddy 362: memcpy(cc->evp.iv, iv, evplen);
1.63 markus 363: break;
364: case SSH_CIPHER_3DES:
365: ssh1_3des_iv(&cc->evp, 1, iv, 24);
1.53 markus 366: break;
367: default:
1.58 markus 368: fatal("%s: bad cipher %d", __func__, c->number);
1.53 markus 369: }
370: }
371:
372: #define EVP_X_STATE(evp) (evp).cipher_data
373: #define EVP_X_STATE_LEN(evp) (evp).cipher->ctx_size
374:
375: int
1.66 jakob 376: cipher_get_keycontext(const CipherContext *cc, u_char *dat)
1.53 markus 377: {
378: Cipher *c = cc->cipher;
1.59 markus 379: int plen = 0;
1.53 markus 380:
1.67 hshoexer 381: if (c->evptype == EVP_rc4 || c->evptype == EVP_acss) {
1.59 markus 382: plen = EVP_X_STATE_LEN(cc->evp);
1.53 markus 383: if (dat == NULL)
1.59 markus 384: return (plen);
385: memcpy(dat, EVP_X_STATE(cc->evp), plen);
1.53 markus 386: }
387: return (plen);
388: }
389:
390: void
391: cipher_set_keycontext(CipherContext *cc, u_char *dat)
392: {
393: Cipher *c = cc->cipher;
394: int plen;
395:
1.67 hshoexer 396: if (c->evptype == EVP_rc4 || c->evptype == EVP_acss) {
1.53 markus 397: plen = EVP_X_STATE_LEN(cc->evp);
398: memcpy(EVP_X_STATE(cc->evp), dat, plen);
399: }
1.1 deraadt 400: }
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