Annotation of src/usr.bin/ssh/cipher.c, Revision 1.71.2.1
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"
1.71.2.1! brad 38: RCSID("$OpenBSD: cipher.c,v 1.73 2005/01/23 10:18:12 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;
1.56 markus 57: const EVP_CIPHER *(*evptype)(void);
1.52 markus 58: } ciphers[] = {
1.70 deraadt 59: { "none", SSH_CIPHER_NONE, 8, 0, EVP_enc_null },
60: { "des", SSH_CIPHER_DES, 8, 8, EVP_des_cbc },
61: { "3des", SSH_CIPHER_3DES, 8, 16, evp_ssh1_3des },
62: { "blowfish", SSH_CIPHER_BLOWFISH, 8, 32, evp_ssh1_bf },
1.52 markus 63:
1.70 deraadt 64: { "3des-cbc", SSH_CIPHER_SSH2, 8, 24, EVP_des_ede3_cbc },
65: { "blowfish-cbc", SSH_CIPHER_SSH2, 8, 16, EVP_bf_cbc },
66: { "cast128-cbc", SSH_CIPHER_SSH2, 8, 16, EVP_cast5_cbc },
67: { "arcfour", SSH_CIPHER_SSH2, 8, 16, EVP_rc4 },
1.57 markus 68: { "aes128-cbc", SSH_CIPHER_SSH2, 16, 16, EVP_aes_128_cbc },
69: { "aes192-cbc", SSH_CIPHER_SSH2, 16, 24, EVP_aes_192_cbc },
70: { "aes256-cbc", SSH_CIPHER_SSH2, 16, 32, EVP_aes_256_cbc },
71: { "rijndael-cbc@lysator.liu.se",
72: SSH_CIPHER_SSH2, 16, 32, EVP_aes_256_cbc },
1.70 deraadt 73: { "aes128-ctr", SSH_CIPHER_SSH2, 16, 16, evp_aes_128_ctr },
74: { "aes192-ctr", SSH_CIPHER_SSH2, 16, 24, evp_aes_128_ctr },
75: { "aes256-ctr", SSH_CIPHER_SSH2, 16, 32, evp_aes_128_ctr },
1.68 hshoexer 76: { "acss@openssh.org", SSH_CIPHER_SSH2, 16, 5, EVP_acss },
1.47 markus 77:
1.71 markus 78: { NULL, SSH_CIPHER_INVALID, 0, 0, NULL }
1.32 markus 79: };
80:
81: /*--*/
1.1 deraadt 82:
1.54 markus 83: u_int
1.66 jakob 84: cipher_blocksize(const Cipher *c)
1.51 markus 85: {
86: return (c->block_size);
87: }
1.60 deraadt 88:
1.54 markus 89: u_int
1.66 jakob 90: cipher_keylen(const Cipher *c)
1.51 markus 91: {
92: return (c->key_len);
93: }
1.60 deraadt 94:
1.54 markus 95: u_int
1.66 jakob 96: cipher_get_number(const Cipher *c)
1.53 markus 97: {
98: return (c->number);
99: }
1.51 markus 100:
1.41 markus 101: u_int
1.34 markus 102: cipher_mask_ssh1(int client)
1.1 deraadt 103: {
1.41 markus 104: u_int mask = 0;
1.48 deraadt 105: mask |= 1 << SSH_CIPHER_3DES; /* Mandatory */
1.34 markus 106: mask |= 1 << SSH_CIPHER_BLOWFISH;
107: if (client) {
108: mask |= 1 << SSH_CIPHER_DES;
1.32 markus 109: }
110: return mask;
1.1 deraadt 111: }
112:
1.32 markus 113: Cipher *
114: cipher_by_name(const char *name)
115: {
116: Cipher *c;
117: for (c = ciphers; c->name != NULL; c++)
1.71.2.1! brad 118: if (strcmp(c->name, name) == 0)
1.32 markus 119: return c;
120: return NULL;
121: }
122:
123: Cipher *
124: cipher_by_number(int id)
125: {
126: Cipher *c;
127: for (c = ciphers; c->name != NULL; c++)
128: if (c->number == id)
129: return c;
130: return NULL;
131: }
1.24 markus 132:
133: #define CIPHER_SEP ","
134: int
135: ciphers_valid(const char *names)
136: {
1.32 markus 137: Cipher *c;
1.69 avsm 138: char *cipher_list, *cp;
1.24 markus 139: char *p;
140:
1.27 markus 141: if (names == NULL || strcmp(names, "") == 0)
1.24 markus 142: return 0;
1.69 avsm 143: cipher_list = cp = xstrdup(names);
1.32 markus 144: for ((p = strsep(&cp, CIPHER_SEP)); p && *p != '\0';
1.48 deraadt 145: (p = strsep(&cp, CIPHER_SEP))) {
1.32 markus 146: c = cipher_by_name(p);
147: if (c == NULL || c->number != SSH_CIPHER_SSH2) {
148: debug("bad cipher %s [%s]", p, names);
1.69 avsm 149: xfree(cipher_list);
1.24 markus 150: return 0;
1.32 markus 151: } else {
1.36 markus 152: debug3("cipher ok: %s [%s]", p, names);
1.24 markus 153: }
154: }
1.36 markus 155: debug3("ciphers ok: [%s]", names);
1.69 avsm 156: xfree(cipher_list);
1.24 markus 157: return 1;
158: }
159:
1.18 markus 160: /*
161: * Parses the name of the cipher. Returns the number of the corresponding
162: * cipher, or -1 on error.
163: */
1.1 deraadt 164:
1.4 provos 165: int
166: cipher_number(const char *name)
1.1 deraadt 167: {
1.32 markus 168: Cipher *c;
1.27 markus 169: if (name == NULL)
170: return -1;
1.71.2.1! brad 171: for (c = ciphers; c->name != NULL; c++)
! 172: if (strcasecmp(c->name, name) == 0)
! 173: return c->number;
! 174: return -1;
1.1 deraadt 175: }
176:
1.32 markus 177: char *
178: cipher_name(int id)
1.1 deraadt 179: {
1.32 markus 180: Cipher *c = cipher_by_number(id);
181: return (c==NULL) ? "<unknown>" : c->name;
1.1 deraadt 182: }
183:
1.26 markus 184: void
1.52 markus 185: cipher_init(CipherContext *cc, Cipher *cipher,
186: const u_char *key, u_int keylen, const u_char *iv, u_int ivlen,
1.69 avsm 187: int do_encrypt)
1.16 markus 188: {
1.52 markus 189: static int dowarn = 1;
190: const EVP_CIPHER *type;
191: int klen;
192:
193: if (cipher->number == SSH_CIPHER_DES) {
194: if (dowarn) {
195: error("Warning: use of DES is strongly discouraged "
196: "due to cryptographic weaknesses");
197: dowarn = 0;
198: }
199: if (keylen > 8)
200: keylen = 8;
201: }
202: cc->plaintext = (cipher->number == SSH_CIPHER_NONE);
203:
1.32 markus 204: if (keylen < cipher->key_len)
205: fatal("cipher_init: key length %d is insufficient for %s.",
206: keylen, cipher->name);
207: if (iv != NULL && ivlen < cipher->block_size)
208: fatal("cipher_init: iv length %d is insufficient for %s.",
209: ivlen, cipher->name);
210: cc->cipher = cipher;
1.52 markus 211:
212: type = (*cipher->evptype)();
213:
214: EVP_CIPHER_CTX_init(&cc->evp);
215: if (EVP_CipherInit(&cc->evp, type, NULL, (u_char *)iv,
1.69 avsm 216: (do_encrypt == CIPHER_ENCRYPT)) == 0)
1.52 markus 217: fatal("cipher_init: EVP_CipherInit failed for %s",
218: cipher->name);
219: klen = EVP_CIPHER_CTX_key_length(&cc->evp);
220: if (klen > 0 && keylen != klen) {
1.62 markus 221: debug2("cipher_init: set keylen (%d -> %d)", klen, keylen);
1.52 markus 222: if (EVP_CIPHER_CTX_set_key_length(&cc->evp, keylen) == 0)
223: fatal("cipher_init: set keylen failed (%d -> %d)",
224: klen, keylen);
225: }
226: if (EVP_CipherInit(&cc->evp, NULL, (u_char *)key, NULL, -1) == 0)
227: fatal("cipher_init: EVP_CipherInit: set key failed for %s",
228: cipher->name);
1.1 deraadt 229: }
1.21 markus 230:
1.26 markus 231: void
1.51 markus 232: cipher_crypt(CipherContext *cc, u_char *dest, const u_char *src, u_int len)
1.32 markus 233: {
234: if (len % cc->cipher->block_size)
235: fatal("cipher_encrypt: bad plaintext length %d", len);
1.52 markus 236: if (EVP_Cipher(&cc->evp, dest, (u_char *)src, len) == 0)
237: fatal("evp_crypt: EVP_Cipher failed");
1.21 markus 238: }
239:
1.26 markus 240: void
1.51 markus 241: cipher_cleanup(CipherContext *cc)
1.16 markus 242: {
1.52 markus 243: if (EVP_CIPHER_CTX_cleanup(&cc->evp) == 0)
244: error("cipher_cleanup: EVP_CIPHER_CTX_cleanup failed");
1.16 markus 245: }
1.1 deraadt 246:
1.32 markus 247: /*
248: * Selects the cipher, and keys if by computing the MD5 checksum of the
249: * passphrase and using the resulting 16 bytes as the key.
250: */
1.1 deraadt 251:
1.26 markus 252: void
1.32 markus 253: cipher_set_key_string(CipherContext *cc, Cipher *cipher,
1.69 avsm 254: const char *passphrase, int do_encrypt)
1.16 markus 255: {
1.32 markus 256: MD5_CTX md;
1.41 markus 257: u_char digest[16];
1.32 markus 258:
259: MD5_Init(&md);
260: MD5_Update(&md, (const u_char *)passphrase, strlen(passphrase));
261: MD5_Final(digest, &md);
1.16 markus 262:
1.69 avsm 263: cipher_init(cc, cipher, digest, 16, NULL, 0, do_encrypt);
1.16 markus 264:
1.32 markus 265: memset(digest, 0, sizeof(digest));
266: memset(&md, 0, sizeof(md));
1.52 markus 267: }
1.53 markus 268:
1.54 markus 269: /*
1.53 markus 270: * Exports an IV from the CipherContext required to export the key
271: * state back from the unprivileged child to the privileged parent
272: * process.
273: */
274:
275: int
1.66 jakob 276: cipher_get_keyiv_len(const CipherContext *cc)
1.53 markus 277: {
278: Cipher *c = cc->cipher;
279: int ivlen;
280:
281: if (c->number == SSH_CIPHER_3DES)
282: ivlen = 24;
283: else
284: ivlen = EVP_CIPHER_CTX_iv_length(&cc->evp);
285: return (ivlen);
286: }
287:
288: void
289: cipher_get_keyiv(CipherContext *cc, u_char *iv, u_int len)
290: {
291: Cipher *c = cc->cipher;
292: int evplen;
293:
294: switch (c->number) {
295: case SSH_CIPHER_SSH2:
296: case SSH_CIPHER_DES:
297: case SSH_CIPHER_BLOWFISH:
298: evplen = EVP_CIPHER_CTX_iv_length(&cc->evp);
299: if (evplen == 0)
300: return;
301: if (evplen != len)
1.58 markus 302: fatal("%s: wrong iv length %d != %d", __func__,
1.53 markus 303: evplen, len);
1.65 markus 304: if (c->evptype == evp_aes_128_ctr)
305: ssh_aes_ctr_iv(&cc->evp, 0, iv, len);
306: else
1.63 markus 307: memcpy(iv, cc->evp.iv, len);
308: break;
309: case SSH_CIPHER_3DES:
310: ssh1_3des_iv(&cc->evp, 0, iv, 24);
1.53 markus 311: break;
312: default:
1.58 markus 313: fatal("%s: bad cipher %d", __func__, c->number);
1.53 markus 314: }
315: }
316:
317: void
318: cipher_set_keyiv(CipherContext *cc, u_char *iv)
319: {
320: Cipher *c = cc->cipher;
321: int evplen = 0;
322:
323: switch (c->number) {
324: case SSH_CIPHER_SSH2:
325: case SSH_CIPHER_DES:
326: case SSH_CIPHER_BLOWFISH:
327: evplen = EVP_CIPHER_CTX_iv_length(&cc->evp);
328: if (evplen == 0)
329: return;
1.65 markus 330: if (c->evptype == evp_aes_128_ctr)
331: ssh_aes_ctr_iv(&cc->evp, 1, iv, evplen);
332: else
1.63 markus 333: memcpy(cc->evp.iv, iv, evplen);
334: break;
335: case SSH_CIPHER_3DES:
336: ssh1_3des_iv(&cc->evp, 1, iv, 24);
1.53 markus 337: break;
338: default:
1.58 markus 339: fatal("%s: bad cipher %d", __func__, c->number);
1.53 markus 340: }
341: }
342:
343: #define EVP_X_STATE(evp) (evp).cipher_data
344: #define EVP_X_STATE_LEN(evp) (evp).cipher->ctx_size
345:
346: int
1.66 jakob 347: cipher_get_keycontext(const CipherContext *cc, u_char *dat)
1.53 markus 348: {
349: Cipher *c = cc->cipher;
1.59 markus 350: int plen = 0;
1.53 markus 351:
1.67 hshoexer 352: if (c->evptype == EVP_rc4 || c->evptype == EVP_acss) {
1.59 markus 353: plen = EVP_X_STATE_LEN(cc->evp);
1.53 markus 354: if (dat == NULL)
1.59 markus 355: return (plen);
356: memcpy(dat, EVP_X_STATE(cc->evp), plen);
1.53 markus 357: }
358: return (plen);
359: }
360:
361: void
362: cipher_set_keycontext(CipherContext *cc, u_char *dat)
363: {
364: Cipher *c = cc->cipher;
365: int plen;
366:
1.67 hshoexer 367: if (c->evptype == EVP_rc4 || c->evptype == EVP_acss) {
1.53 markus 368: plen = EVP_X_STATE_LEN(cc->evp);
369: memcpy(EVP_X_STATE(cc->evp), dat, plen);
370: }
1.1 deraadt 371: }
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