Annotation of src/usr.bin/ssh/cipher.c, Revision 1.80
1.80 ! stevesk 1: /* $OpenBSD: cipher.c,v 1.79 2006/03/25 13:17:01 djm 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:
38: #include "includes.h"
39:
1.80 ! stevesk 40: #include <openssl/md5.h>
! 41:
! 42: #include <string.h>
! 43:
1.24 markus 44: #include "xmalloc.h"
1.42 markus 45: #include "log.h"
46: #include "cipher.h"
1.57 markus 47:
1.64 markus 48: extern const EVP_CIPHER *evp_ssh1_bf(void);
49: extern const EVP_CIPHER *evp_ssh1_3des(void);
50: extern void ssh1_3des_iv(EVP_CIPHER_CTX *, int, u_char *, int);
1.65 markus 51: extern const EVP_CIPHER *evp_aes_128_ctr(void);
52: extern void ssh_aes_ctr_iv(EVP_CIPHER_CTX *, int, u_char *, u_int);
1.1 deraadt 53:
1.51 markus 54: struct Cipher {
55: char *name;
56: int number; /* for ssh1 only */
57: u_int block_size;
58: u_int key_len;
1.74 djm 59: u_int discard_len;
1.56 markus 60: const EVP_CIPHER *(*evptype)(void);
1.52 markus 61: } ciphers[] = {
1.74 djm 62: { "none", SSH_CIPHER_NONE, 8, 0, 0, EVP_enc_null },
63: { "des", SSH_CIPHER_DES, 8, 8, 0, EVP_des_cbc },
64: { "3des", SSH_CIPHER_3DES, 8, 16, 0, evp_ssh1_3des },
65: { "blowfish", SSH_CIPHER_BLOWFISH, 8, 32, 0, evp_ssh1_bf },
66:
67: { "3des-cbc", SSH_CIPHER_SSH2, 8, 24, 0, EVP_des_ede3_cbc },
68: { "blowfish-cbc", SSH_CIPHER_SSH2, 8, 16, 0, EVP_bf_cbc },
69: { "cast128-cbc", SSH_CIPHER_SSH2, 8, 16, 0, EVP_cast5_cbc },
70: { "arcfour", SSH_CIPHER_SSH2, 8, 16, 0, EVP_rc4 },
71: { "arcfour128", SSH_CIPHER_SSH2, 8, 16, 1536, EVP_rc4 },
72: { "arcfour256", SSH_CIPHER_SSH2, 8, 32, 1536, EVP_rc4 },
73: { "aes128-cbc", SSH_CIPHER_SSH2, 16, 16, 0, EVP_aes_128_cbc },
74: { "aes192-cbc", SSH_CIPHER_SSH2, 16, 24, 0, EVP_aes_192_cbc },
75: { "aes256-cbc", SSH_CIPHER_SSH2, 16, 32, 0, EVP_aes_256_cbc },
1.57 markus 76: { "rijndael-cbc@lysator.liu.se",
1.74 djm 77: SSH_CIPHER_SSH2, 16, 32, 0, EVP_aes_256_cbc },
78: { "aes128-ctr", SSH_CIPHER_SSH2, 16, 16, 0, evp_aes_128_ctr },
79: { "aes192-ctr", SSH_CIPHER_SSH2, 16, 24, 0, evp_aes_128_ctr },
80: { "aes256-ctr", SSH_CIPHER_SSH2, 16, 32, 0, evp_aes_128_ctr },
81: { "acss@openssh.org", SSH_CIPHER_SSH2, 16, 5, 0, EVP_acss },
1.47 markus 82:
1.75 dtucker 83: { NULL, SSH_CIPHER_INVALID, 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);
104: }
1.51 markus 105:
1.41 markus 106: u_int
1.34 markus 107: cipher_mask_ssh1(int client)
1.1 deraadt 108: {
1.41 markus 109: u_int mask = 0;
1.48 deraadt 110: mask |= 1 << SSH_CIPHER_3DES; /* Mandatory */
1.34 markus 111: mask |= 1 << SSH_CIPHER_BLOWFISH;
112: if (client) {
113: mask |= 1 << SSH_CIPHER_DES;
1.32 markus 114: }
115: return mask;
1.1 deraadt 116: }
117:
1.32 markus 118: Cipher *
119: cipher_by_name(const char *name)
120: {
121: Cipher *c;
122: for (c = ciphers; c->name != NULL; c++)
1.73 djm 123: if (strcmp(c->name, name) == 0)
1.32 markus 124: return c;
125: return NULL;
126: }
127:
128: Cipher *
129: cipher_by_number(int id)
130: {
131: Cipher *c;
132: for (c = ciphers; c->name != NULL; c++)
133: if (c->number == id)
134: return c;
135: return NULL;
136: }
1.24 markus 137:
138: #define CIPHER_SEP ","
139: int
140: ciphers_valid(const char *names)
141: {
1.32 markus 142: Cipher *c;
1.69 avsm 143: char *cipher_list, *cp;
1.24 markus 144: char *p;
145:
1.27 markus 146: if (names == NULL || strcmp(names, "") == 0)
1.24 markus 147: return 0;
1.69 avsm 148: cipher_list = cp = xstrdup(names);
1.32 markus 149: for ((p = strsep(&cp, CIPHER_SEP)); p && *p != '\0';
1.48 deraadt 150: (p = strsep(&cp, CIPHER_SEP))) {
1.32 markus 151: c = cipher_by_name(p);
152: if (c == NULL || c->number != SSH_CIPHER_SSH2) {
153: debug("bad cipher %s [%s]", p, names);
1.69 avsm 154: xfree(cipher_list);
1.24 markus 155: return 0;
1.32 markus 156: } else {
1.36 markus 157: debug3("cipher ok: %s [%s]", p, names);
1.24 markus 158: }
159: }
1.36 markus 160: debug3("ciphers ok: [%s]", names);
1.69 avsm 161: xfree(cipher_list);
1.24 markus 162: return 1;
163: }
164:
1.18 markus 165: /*
166: * Parses the name of the cipher. Returns the number of the corresponding
167: * cipher, or -1 on error.
168: */
1.1 deraadt 169:
1.4 provos 170: int
171: cipher_number(const char *name)
1.1 deraadt 172: {
1.32 markus 173: Cipher *c;
1.27 markus 174: if (name == NULL)
175: return -1;
1.73 djm 176: for (c = ciphers; c->name != NULL; c++)
177: if (strcasecmp(c->name, name) == 0)
178: return c->number;
179: return -1;
1.1 deraadt 180: }
181:
1.32 markus 182: char *
183: cipher_name(int id)
1.1 deraadt 184: {
1.32 markus 185: Cipher *c = cipher_by_number(id);
186: return (c==NULL) ? "<unknown>" : c->name;
1.1 deraadt 187: }
188:
1.26 markus 189: void
1.52 markus 190: cipher_init(CipherContext *cc, Cipher *cipher,
191: const u_char *key, u_int keylen, const u_char *iv, u_int ivlen,
1.69 avsm 192: int do_encrypt)
1.16 markus 193: {
1.52 markus 194: static int dowarn = 1;
195: const EVP_CIPHER *type;
196: int klen;
1.74 djm 197: u_char *junk, *discard;
1.52 markus 198:
199: if (cipher->number == SSH_CIPHER_DES) {
200: if (dowarn) {
201: error("Warning: use of DES is strongly discouraged "
202: "due to cryptographic weaknesses");
203: dowarn = 0;
204: }
205: if (keylen > 8)
206: keylen = 8;
207: }
208: cc->plaintext = (cipher->number == SSH_CIPHER_NONE);
209:
1.32 markus 210: if (keylen < cipher->key_len)
211: fatal("cipher_init: key length %d is insufficient for %s.",
212: keylen, cipher->name);
213: if (iv != NULL && ivlen < cipher->block_size)
214: fatal("cipher_init: iv length %d is insufficient for %s.",
215: ivlen, cipher->name);
216: cc->cipher = cipher;
1.52 markus 217:
218: type = (*cipher->evptype)();
219:
220: EVP_CIPHER_CTX_init(&cc->evp);
221: if (EVP_CipherInit(&cc->evp, type, NULL, (u_char *)iv,
1.69 avsm 222: (do_encrypt == CIPHER_ENCRYPT)) == 0)
1.52 markus 223: fatal("cipher_init: EVP_CipherInit failed for %s",
224: cipher->name);
225: klen = EVP_CIPHER_CTX_key_length(&cc->evp);
1.76 djm 226: if (klen > 0 && keylen != (u_int)klen) {
1.62 markus 227: debug2("cipher_init: set keylen (%d -> %d)", klen, keylen);
1.52 markus 228: if (EVP_CIPHER_CTX_set_key_length(&cc->evp, keylen) == 0)
229: fatal("cipher_init: set keylen failed (%d -> %d)",
230: klen, keylen);
231: }
232: if (EVP_CipherInit(&cc->evp, NULL, (u_char *)key, NULL, -1) == 0)
233: fatal("cipher_init: EVP_CipherInit: set key failed for %s",
234: cipher->name);
1.74 djm 235:
1.77 djm 236: if (cipher->discard_len > 0) {
1.74 djm 237: junk = xmalloc(cipher->discard_len);
238: discard = xmalloc(cipher->discard_len);
239: if (EVP_Cipher(&cc->evp, discard, junk,
240: cipher->discard_len) == 0)
241: fatal("evp_crypt: EVP_Cipher failed during discard");
242: memset(discard, 0, cipher->discard_len);
243: xfree(junk);
244: xfree(discard);
245: }
1.1 deraadt 246: }
1.21 markus 247:
1.26 markus 248: void
1.51 markus 249: cipher_crypt(CipherContext *cc, u_char *dest, const u_char *src, u_int len)
1.32 markus 250: {
251: if (len % cc->cipher->block_size)
252: fatal("cipher_encrypt: bad plaintext length %d", len);
1.52 markus 253: if (EVP_Cipher(&cc->evp, dest, (u_char *)src, len) == 0)
254: fatal("evp_crypt: EVP_Cipher failed");
1.21 markus 255: }
256:
1.26 markus 257: void
1.51 markus 258: cipher_cleanup(CipherContext *cc)
1.16 markus 259: {
1.52 markus 260: if (EVP_CIPHER_CTX_cleanup(&cc->evp) == 0)
261: error("cipher_cleanup: EVP_CIPHER_CTX_cleanup failed");
1.16 markus 262: }
1.1 deraadt 263:
1.32 markus 264: /*
265: * Selects the cipher, and keys if by computing the MD5 checksum of the
266: * passphrase and using the resulting 16 bytes as the key.
267: */
1.1 deraadt 268:
1.26 markus 269: void
1.32 markus 270: cipher_set_key_string(CipherContext *cc, Cipher *cipher,
1.69 avsm 271: const char *passphrase, int do_encrypt)
1.16 markus 272: {
1.32 markus 273: MD5_CTX md;
1.41 markus 274: u_char digest[16];
1.32 markus 275:
276: MD5_Init(&md);
277: MD5_Update(&md, (const u_char *)passphrase, strlen(passphrase));
278: MD5_Final(digest, &md);
1.16 markus 279:
1.69 avsm 280: cipher_init(cc, cipher, digest, 16, NULL, 0, do_encrypt);
1.16 markus 281:
1.32 markus 282: memset(digest, 0, sizeof(digest));
283: memset(&md, 0, sizeof(md));
1.52 markus 284: }
1.53 markus 285:
1.54 markus 286: /*
1.53 markus 287: * Exports an IV from the CipherContext required to export the key
288: * state back from the unprivileged child to the privileged parent
289: * process.
290: */
291:
292: int
1.66 jakob 293: cipher_get_keyiv_len(const CipherContext *cc)
1.53 markus 294: {
295: Cipher *c = cc->cipher;
296: int ivlen;
297:
298: if (c->number == SSH_CIPHER_3DES)
299: ivlen = 24;
300: else
301: ivlen = EVP_CIPHER_CTX_iv_length(&cc->evp);
302: return (ivlen);
303: }
304:
305: void
306: cipher_get_keyiv(CipherContext *cc, u_char *iv, u_int len)
307: {
308: Cipher *c = cc->cipher;
309: int evplen;
310:
311: switch (c->number) {
312: case SSH_CIPHER_SSH2:
313: case SSH_CIPHER_DES:
314: case SSH_CIPHER_BLOWFISH:
315: evplen = EVP_CIPHER_CTX_iv_length(&cc->evp);
1.76 djm 316: if (evplen <= 0)
1.53 markus 317: return;
1.76 djm 318: if ((u_int)evplen != len)
1.58 markus 319: fatal("%s: wrong iv length %d != %d", __func__,
1.53 markus 320: evplen, len);
1.65 markus 321: if (c->evptype == evp_aes_128_ctr)
322: ssh_aes_ctr_iv(&cc->evp, 0, iv, len);
323: else
1.63 markus 324: memcpy(iv, cc->evp.iv, len);
325: break;
326: case SSH_CIPHER_3DES:
327: ssh1_3des_iv(&cc->evp, 0, iv, 24);
1.53 markus 328: break;
329: default:
1.58 markus 330: fatal("%s: bad cipher %d", __func__, c->number);
1.53 markus 331: }
332: }
333:
334: void
335: cipher_set_keyiv(CipherContext *cc, u_char *iv)
336: {
337: Cipher *c = cc->cipher;
338: int evplen = 0;
339:
340: switch (c->number) {
341: case SSH_CIPHER_SSH2:
342: case SSH_CIPHER_DES:
343: case SSH_CIPHER_BLOWFISH:
344: evplen = EVP_CIPHER_CTX_iv_length(&cc->evp);
345: if (evplen == 0)
346: return;
1.65 markus 347: if (c->evptype == evp_aes_128_ctr)
348: ssh_aes_ctr_iv(&cc->evp, 1, iv, evplen);
349: else
1.63 markus 350: memcpy(cc->evp.iv, iv, evplen);
351: break;
352: case SSH_CIPHER_3DES:
353: ssh1_3des_iv(&cc->evp, 1, iv, 24);
1.53 markus 354: break;
355: default:
1.58 markus 356: fatal("%s: bad cipher %d", __func__, c->number);
1.53 markus 357: }
358: }
359:
360: #define EVP_X_STATE(evp) (evp).cipher_data
361: #define EVP_X_STATE_LEN(evp) (evp).cipher->ctx_size
362:
363: int
1.66 jakob 364: cipher_get_keycontext(const CipherContext *cc, u_char *dat)
1.53 markus 365: {
366: Cipher *c = cc->cipher;
1.59 markus 367: int plen = 0;
1.53 markus 368:
1.67 hshoexer 369: if (c->evptype == EVP_rc4 || c->evptype == EVP_acss) {
1.59 markus 370: plen = EVP_X_STATE_LEN(cc->evp);
1.53 markus 371: if (dat == NULL)
1.59 markus 372: return (plen);
373: memcpy(dat, EVP_X_STATE(cc->evp), plen);
1.53 markus 374: }
375: return (plen);
376: }
377:
378: void
379: cipher_set_keycontext(CipherContext *cc, u_char *dat)
380: {
381: Cipher *c = cc->cipher;
382: int plen;
383:
1.67 hshoexer 384: if (c->evptype == EVP_rc4 || c->evptype == EVP_acss) {
1.53 markus 385: plen = EVP_X_STATE_LEN(cc->evp);
386: memcpy(EVP_X_STATE(cc->evp), dat, plen);
387: }
1.1 deraadt 388: }
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