Annotation of src/usr.bin/ssh/cipher.c, Revision 1.83
1.83 ! markus 1: /* $OpenBSD: cipher.c,v 1.82 2009/01/26 09:58:15 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);
1.65 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;
1.82 markus 61: u_int cbc_mode;
1.56 markus 62: const EVP_CIPHER *(*evptype)(void);
1.52 markus 63: } ciphers[] = {
1.82 markus 64: { "none", SSH_CIPHER_NONE, 8, 0, 0, 0, EVP_enc_null },
65: { "des", SSH_CIPHER_DES, 8, 8, 0, 1, EVP_des_cbc },
66: { "3des", SSH_CIPHER_3DES, 8, 16, 0, 1, evp_ssh1_3des },
67: { "blowfish", SSH_CIPHER_BLOWFISH, 8, 32, 0, 1, evp_ssh1_bf },
68:
69: { "3des-cbc", SSH_CIPHER_SSH2, 8, 24, 0, 1, EVP_des_ede3_cbc },
70: { "blowfish-cbc", SSH_CIPHER_SSH2, 8, 16, 0, 1, EVP_bf_cbc },
71: { "cast128-cbc", SSH_CIPHER_SSH2, 8, 16, 0, 1, EVP_cast5_cbc },
72: { "arcfour", SSH_CIPHER_SSH2, 8, 16, 0, 0, EVP_rc4 },
73: { "arcfour128", SSH_CIPHER_SSH2, 8, 16, 1536, 0, EVP_rc4 },
74: { "arcfour256", SSH_CIPHER_SSH2, 8, 32, 1536, 0, EVP_rc4 },
75: { "aes128-cbc", SSH_CIPHER_SSH2, 16, 16, 0, 1, EVP_aes_128_cbc },
76: { "aes192-cbc", SSH_CIPHER_SSH2, 16, 24, 0, 1, EVP_aes_192_cbc },
77: { "aes256-cbc", SSH_CIPHER_SSH2, 16, 32, 0, 1, EVP_aes_256_cbc },
1.57 markus 78: { "rijndael-cbc@lysator.liu.se",
1.82 markus 79: SSH_CIPHER_SSH2, 16, 32, 0, 1, EVP_aes_256_cbc },
80: { "aes128-ctr", SSH_CIPHER_SSH2, 16, 16, 0, 0, evp_aes_128_ctr },
81: { "aes192-ctr", SSH_CIPHER_SSH2, 16, 24, 0, 0, evp_aes_128_ctr },
82: { "aes256-ctr", SSH_CIPHER_SSH2, 16, 32, 0, 0, evp_aes_128_ctr },
83: { "acss@openssh.org", SSH_CIPHER_SSH2, 16, 5, 0, 0, EVP_acss },
1.47 markus 84:
1.82 markus 85: { NULL, SSH_CIPHER_INVALID, 0, 0, 0, 0, NULL }
1.32 markus 86: };
87:
88: /*--*/
1.1 deraadt 89:
1.54 markus 90: u_int
1.66 jakob 91: cipher_blocksize(const Cipher *c)
1.51 markus 92: {
93: return (c->block_size);
94: }
1.60 deraadt 95:
1.54 markus 96: u_int
1.66 jakob 97: cipher_keylen(const Cipher *c)
1.51 markus 98: {
99: return (c->key_len);
100: }
1.60 deraadt 101:
1.54 markus 102: u_int
1.66 jakob 103: cipher_get_number(const Cipher *c)
1.53 markus 104: {
105: return (c->number);
1.82 markus 106: }
107:
108: u_int
109: cipher_is_cbc(const Cipher *c)
110: {
111: return (c->cbc_mode);
1.53 markus 112: }
1.51 markus 113:
1.41 markus 114: u_int
1.34 markus 115: cipher_mask_ssh1(int client)
1.1 deraadt 116: {
1.41 markus 117: u_int mask = 0;
1.48 deraadt 118: mask |= 1 << SSH_CIPHER_3DES; /* Mandatory */
1.34 markus 119: mask |= 1 << SSH_CIPHER_BLOWFISH;
120: if (client) {
121: mask |= 1 << SSH_CIPHER_DES;
1.32 markus 122: }
123: return mask;
1.1 deraadt 124: }
125:
1.32 markus 126: Cipher *
127: cipher_by_name(const char *name)
128: {
129: Cipher *c;
130: for (c = ciphers; c->name != NULL; c++)
1.73 djm 131: if (strcmp(c->name, name) == 0)
1.32 markus 132: return c;
133: return NULL;
134: }
135:
136: Cipher *
137: cipher_by_number(int id)
138: {
139: Cipher *c;
140: for (c = ciphers; c->name != NULL; c++)
141: if (c->number == id)
142: return c;
143: return NULL;
144: }
1.24 markus 145:
146: #define CIPHER_SEP ","
147: int
148: ciphers_valid(const char *names)
149: {
1.32 markus 150: Cipher *c;
1.69 avsm 151: char *cipher_list, *cp;
1.24 markus 152: char *p;
153:
1.27 markus 154: if (names == NULL || strcmp(names, "") == 0)
1.24 markus 155: return 0;
1.69 avsm 156: cipher_list = cp = xstrdup(names);
1.32 markus 157: for ((p = strsep(&cp, CIPHER_SEP)); p && *p != '\0';
1.48 deraadt 158: (p = strsep(&cp, CIPHER_SEP))) {
1.32 markus 159: c = cipher_by_name(p);
160: if (c == NULL || c->number != SSH_CIPHER_SSH2) {
161: debug("bad cipher %s [%s]", p, names);
1.69 avsm 162: xfree(cipher_list);
1.24 markus 163: return 0;
1.32 markus 164: } else {
1.36 markus 165: debug3("cipher ok: %s [%s]", p, names);
1.24 markus 166: }
167: }
1.36 markus 168: debug3("ciphers ok: [%s]", names);
1.69 avsm 169: xfree(cipher_list);
1.24 markus 170: return 1;
171: }
172:
1.18 markus 173: /*
174: * Parses the name of the cipher. Returns the number of the corresponding
175: * cipher, or -1 on error.
176: */
1.1 deraadt 177:
1.4 provos 178: int
179: cipher_number(const char *name)
1.1 deraadt 180: {
1.32 markus 181: Cipher *c;
1.27 markus 182: if (name == NULL)
183: return -1;
1.73 djm 184: for (c = ciphers; c->name != NULL; c++)
185: if (strcasecmp(c->name, name) == 0)
186: return c->number;
187: return -1;
1.1 deraadt 188: }
189:
1.32 markus 190: char *
191: cipher_name(int id)
1.1 deraadt 192: {
1.32 markus 193: Cipher *c = cipher_by_number(id);
194: return (c==NULL) ? "<unknown>" : c->name;
1.1 deraadt 195: }
196:
1.26 markus 197: void
1.52 markus 198: cipher_init(CipherContext *cc, Cipher *cipher,
199: const u_char *key, u_int keylen, const u_char *iv, u_int ivlen,
1.69 avsm 200: int do_encrypt)
1.16 markus 201: {
1.52 markus 202: static int dowarn = 1;
203: const EVP_CIPHER *type;
204: int klen;
1.74 djm 205: u_char *junk, *discard;
1.52 markus 206:
207: if (cipher->number == SSH_CIPHER_DES) {
208: if (dowarn) {
209: error("Warning: use of DES is strongly discouraged "
210: "due to cryptographic weaknesses");
211: dowarn = 0;
212: }
213: if (keylen > 8)
214: keylen = 8;
215: }
216: cc->plaintext = (cipher->number == SSH_CIPHER_NONE);
217:
1.32 markus 218: if (keylen < cipher->key_len)
219: fatal("cipher_init: key length %d is insufficient for %s.",
220: keylen, cipher->name);
221: if (iv != NULL && ivlen < cipher->block_size)
222: fatal("cipher_init: iv length %d is insufficient for %s.",
223: ivlen, cipher->name);
224: cc->cipher = cipher;
1.52 markus 225:
226: type = (*cipher->evptype)();
227:
228: EVP_CIPHER_CTX_init(&cc->evp);
229: if (EVP_CipherInit(&cc->evp, type, NULL, (u_char *)iv,
1.69 avsm 230: (do_encrypt == CIPHER_ENCRYPT)) == 0)
1.52 markus 231: fatal("cipher_init: EVP_CipherInit failed for %s",
232: cipher->name);
233: klen = EVP_CIPHER_CTX_key_length(&cc->evp);
1.76 djm 234: if (klen > 0 && keylen != (u_int)klen) {
1.62 markus 235: debug2("cipher_init: set keylen (%d -> %d)", klen, keylen);
1.52 markus 236: if (EVP_CIPHER_CTX_set_key_length(&cc->evp, keylen) == 0)
237: fatal("cipher_init: set keylen failed (%d -> %d)",
238: klen, keylen);
239: }
240: if (EVP_CipherInit(&cc->evp, NULL, (u_char *)key, NULL, -1) == 0)
241: fatal("cipher_init: EVP_CipherInit: set key failed for %s",
242: cipher->name);
1.74 djm 243:
1.77 djm 244: if (cipher->discard_len > 0) {
1.74 djm 245: junk = xmalloc(cipher->discard_len);
246: discard = xmalloc(cipher->discard_len);
247: if (EVP_Cipher(&cc->evp, discard, junk,
248: cipher->discard_len) == 0)
249: fatal("evp_crypt: EVP_Cipher failed during discard");
250: memset(discard, 0, cipher->discard_len);
251: xfree(junk);
252: xfree(discard);
253: }
1.1 deraadt 254: }
1.21 markus 255:
1.83 ! markus 256: /*
! 257: * cipher_crypt() operates as following:
! 258: * Copy 'aadlen' bytes (without en/decryption) from 'src' to 'dest'.
! 259: * Theses bytes are treated as additional authenticated data for
! 260: * authenticated encryption modes.
! 261: * En/Decrypt 'len' bytes at offset 'aadlen' from 'src' to 'dest'.
! 262: * Both 'aadlen' and 'authlen' can be set to 0.
! 263: */
1.26 markus 264: void
1.83 ! markus 265: cipher_crypt(CipherContext *cc, u_char *dest, const u_char *src,
! 266: u_int len, u_int aadlen)
1.32 markus 267: {
1.83 ! markus 268: if (aadlen)
! 269: memcpy(dest, src, aadlen);
1.32 markus 270: if (len % cc->cipher->block_size)
1.83 ! markus 271: fatal("%s: bad plaintext length %d", __func__, len);
! 272: if (EVP_Cipher(&cc->evp, dest + aadlen, (u_char *)src + aadlen,
! 273: len) < 0)
! 274: fatal("%s: EVP_Cipher failed", __func__);
1.21 markus 275: }
276:
1.26 markus 277: void
1.51 markus 278: cipher_cleanup(CipherContext *cc)
1.16 markus 279: {
1.52 markus 280: if (EVP_CIPHER_CTX_cleanup(&cc->evp) == 0)
281: error("cipher_cleanup: EVP_CIPHER_CTX_cleanup failed");
1.16 markus 282: }
1.1 deraadt 283:
1.32 markus 284: /*
285: * Selects the cipher, and keys if by computing the MD5 checksum of the
286: * passphrase and using the resulting 16 bytes as the key.
287: */
1.1 deraadt 288:
1.26 markus 289: void
1.32 markus 290: cipher_set_key_string(CipherContext *cc, Cipher *cipher,
1.69 avsm 291: const char *passphrase, int do_encrypt)
1.16 markus 292: {
1.32 markus 293: MD5_CTX md;
1.41 markus 294: u_char digest[16];
1.32 markus 295:
296: MD5_Init(&md);
297: MD5_Update(&md, (const u_char *)passphrase, strlen(passphrase));
298: MD5_Final(digest, &md);
1.16 markus 299:
1.69 avsm 300: cipher_init(cc, cipher, digest, 16, NULL, 0, do_encrypt);
1.16 markus 301:
1.32 markus 302: memset(digest, 0, sizeof(digest));
303: memset(&md, 0, sizeof(md));
1.52 markus 304: }
1.53 markus 305:
1.54 markus 306: /*
1.53 markus 307: * Exports an IV from the CipherContext required to export the key
308: * state back from the unprivileged child to the privileged parent
309: * process.
310: */
311:
312: int
1.66 jakob 313: cipher_get_keyiv_len(const CipherContext *cc)
1.53 markus 314: {
315: Cipher *c = cc->cipher;
316: int ivlen;
317:
318: if (c->number == SSH_CIPHER_3DES)
319: ivlen = 24;
320: else
321: ivlen = EVP_CIPHER_CTX_iv_length(&cc->evp);
322: return (ivlen);
323: }
324:
325: void
326: cipher_get_keyiv(CipherContext *cc, u_char *iv, u_int len)
327: {
328: Cipher *c = cc->cipher;
329: int evplen;
330:
331: switch (c->number) {
332: case SSH_CIPHER_SSH2:
333: case SSH_CIPHER_DES:
334: case SSH_CIPHER_BLOWFISH:
335: evplen = EVP_CIPHER_CTX_iv_length(&cc->evp);
1.76 djm 336: if (evplen <= 0)
1.53 markus 337: return;
1.76 djm 338: if ((u_int)evplen != len)
1.58 markus 339: fatal("%s: wrong iv length %d != %d", __func__,
1.53 markus 340: evplen, len);
1.65 markus 341: if (c->evptype == evp_aes_128_ctr)
342: ssh_aes_ctr_iv(&cc->evp, 0, iv, len);
343: else
1.63 markus 344: memcpy(iv, cc->evp.iv, len);
345: break;
346: case SSH_CIPHER_3DES:
347: ssh1_3des_iv(&cc->evp, 0, iv, 24);
1.53 markus 348: break;
349: default:
1.58 markus 350: fatal("%s: bad cipher %d", __func__, c->number);
1.53 markus 351: }
352: }
353:
354: void
355: cipher_set_keyiv(CipherContext *cc, u_char *iv)
356: {
357: Cipher *c = cc->cipher;
358: int evplen = 0;
359:
360: switch (c->number) {
361: case SSH_CIPHER_SSH2:
362: case SSH_CIPHER_DES:
363: case SSH_CIPHER_BLOWFISH:
364: evplen = EVP_CIPHER_CTX_iv_length(&cc->evp);
365: if (evplen == 0)
366: return;
1.65 markus 367: if (c->evptype == evp_aes_128_ctr)
368: ssh_aes_ctr_iv(&cc->evp, 1, iv, evplen);
369: else
1.63 markus 370: memcpy(cc->evp.iv, iv, evplen);
371: break;
372: case SSH_CIPHER_3DES:
373: ssh1_3des_iv(&cc->evp, 1, iv, 24);
1.53 markus 374: break;
375: default:
1.58 markus 376: fatal("%s: bad cipher %d", __func__, c->number);
1.53 markus 377: }
378: }
379:
380: #define EVP_X_STATE(evp) (evp).cipher_data
381: #define EVP_X_STATE_LEN(evp) (evp).cipher->ctx_size
382:
383: int
1.66 jakob 384: cipher_get_keycontext(const CipherContext *cc, u_char *dat)
1.53 markus 385: {
386: Cipher *c = cc->cipher;
1.59 markus 387: int plen = 0;
1.53 markus 388:
1.67 hshoexer 389: if (c->evptype == EVP_rc4 || c->evptype == EVP_acss) {
1.59 markus 390: plen = EVP_X_STATE_LEN(cc->evp);
1.53 markus 391: if (dat == NULL)
1.59 markus 392: return (plen);
393: memcpy(dat, EVP_X_STATE(cc->evp), plen);
1.53 markus 394: }
395: return (plen);
396: }
397:
398: void
399: cipher_set_keycontext(CipherContext *cc, u_char *dat)
400: {
401: Cipher *c = cc->cipher;
402: int plen;
403:
1.67 hshoexer 404: if (c->evptype == EVP_rc4 || c->evptype == EVP_acss) {
1.53 markus 405: plen = EVP_X_STATE_LEN(cc->evp);
406: memcpy(EVP_X_STATE(cc->evp), dat, plen);
407: }
1.1 deraadt 408: }
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