Annotation of src/usr.bin/ssh/cipher.c, Revision 1.32
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.
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"
1.32 ! markus 38: RCSID("$OpenBSD: cipher.c,v 1.31 2000/09/12 00:38:32 deraadt Exp $");
1.1 deraadt 39:
40: #include "ssh.h"
1.24 markus 41: #include "xmalloc.h"
1.8 deraadt 42:
1.25 markus 43: #include <openssl/md5.h>
1.1 deraadt 44:
1.32 ! markus 45:
! 46: /* no encryption */
! 47: void
! 48: none_setkey(CipherContext *cc, const u_char *key, u_int keylen)
! 49: {
! 50: }
! 51: void
! 52: none_setiv(CipherContext *cc, const u_char *iv, u_int ivlen)
! 53: {
! 54: }
! 55: void
! 56: none_crypt(CipherContext *cc, u_char *dest, const u_char *src, u_int len)
! 57: {
! 58: memcpy(dest, src, len);
! 59: }
! 60:
! 61: /* DES */
! 62: void
! 63: des_ssh1_setkey(CipherContext *cc, const u_char *key, u_int keylen)
! 64: {
! 65: des_set_key((void *)key, cc->u.des.key);
! 66: }
! 67: void
! 68: des_ssh1_setiv(CipherContext *cc, const u_char *iv, u_int ivlen)
! 69: {
! 70: memset(cc->u.des.iv, 0, sizeof(cc->u.des.iv));
! 71: }
! 72: void
! 73: des_ssh1_encrypt(CipherContext *cc, u_char *dest, const u_char *src, u_int len)
! 74: {
! 75: des_ncbc_encrypt(src, dest, len, cc->u.des.key, &cc->u.des.iv,
! 76: DES_ENCRYPT);
! 77: }
! 78: void
! 79: des_ssh1_decrypt(CipherContext *cc, u_char *dest, const u_char *src, u_int len)
! 80: {
! 81: des_ncbc_encrypt(src, dest, len, cc->u.des.key, &cc->u.des.iv,
! 82: DES_DECRYPT);
! 83: }
! 84:
! 85: /* 3DES */
! 86: void
! 87: des3_setkey(CipherContext *cc, const u_char *key, u_int keylen)
! 88: {
! 89: des_set_key((void *) key, cc->u.des3.key1);
! 90: des_set_key((void *) (key+8), cc->u.des3.key2);
! 91: des_set_key((void *) (key+16), cc->u.des3.key3);
! 92: }
! 93: void
! 94: des3_setiv(CipherContext *cc, const u_char *iv, u_int ivlen)
! 95: {
! 96: memset(cc->u.des3.iv2, 0, sizeof(cc->u.des3.iv2));
! 97: memset(cc->u.des3.iv3, 0, sizeof(cc->u.des3.iv3));
! 98: if (iv == NULL)
! 99: return;
! 100: memcpy(cc->u.des3.iv3, (char *)iv, 8);
! 101: }
! 102: void
! 103: des3_cbc_encrypt(CipherContext *cc, u_char *dest, const u_char *src, u_int len)
! 104: {
! 105: des_ede3_cbc_encrypt(src, dest, len,
! 106: cc->u.des3.key1, cc->u.des3.key2, cc->u.des3.key3,
! 107: &cc->u.des3.iv3, DES_ENCRYPT);
! 108: }
! 109: void
! 110: des3_cbc_decrypt(CipherContext *cc, u_char *dest, const u_char *src, u_int len)
! 111: {
! 112: des_ede3_cbc_encrypt(src, dest, len,
! 113: cc->u.des3.key1, cc->u.des3.key2, cc->u.des3.key3,
! 114: &cc->u.des3.iv3, DES_DECRYPT);
! 115: }
! 116:
1.1 deraadt 117: /*
1.24 markus 118: * This is used by SSH1:
119: *
1.23 deraadt 120: * What kind of triple DES are these 2 routines?
1.1 deraadt 121: *
122: * Why is there a redundant initialization vector?
123: *
124: * If only iv3 was used, then, this would till effect have been
125: * outer-cbc. However, there is also a private iv1 == iv2 which
126: * perhaps makes differential analysis easier. On the other hand, the
127: * private iv1 probably makes the CRC-32 attack ineffective. This is a
128: * result of that there is no longer any known iv1 to use when
129: * choosing the X block.
130: */
131: void
1.32 ! markus 132: des3_ssh1_setkey(CipherContext *cc, const u_char *key, u_int keylen)
! 133: {
! 134: des_set_key((void *) key, cc->u.des3.key1);
! 135: des_set_key((void *) (key+8), cc->u.des3.key2);
! 136: if (keylen <= 16)
! 137: des_set_key((void *) key, cc->u.des3.key3);
! 138: else
! 139: des_set_key((void *) (key+16), cc->u.des3.key3);
! 140: }
! 141: void
! 142: des3_ssh1_encrypt(CipherContext *cc, u_char *dest, const u_char *src,
! 143: u_int len)
1.1 deraadt 144: {
1.16 markus 145: des_cblock iv1;
1.32 ! markus 146: des_cblock *iv2 = &cc->u.des3.iv2;
! 147: des_cblock *iv3 = &cc->u.des3.iv3;
1.1 deraadt 148:
1.16 markus 149: memcpy(&iv1, iv2, 8);
1.1 deraadt 150:
1.32 ! markus 151: des_cbc_encrypt(src, dest, len, cc->u.des3.key1, &iv1, DES_ENCRYPT);
1.16 markus 152: memcpy(&iv1, dest + len - 8, 8);
1.1 deraadt 153:
1.32 ! markus 154: des_cbc_encrypt(dest, dest, len, cc->u.des3.key2, iv2, DES_DECRYPT);
1.16 markus 155: memcpy(iv2, &iv1, 8); /* Note how iv1 == iv2 on entry and exit. */
1.1 deraadt 156:
1.32 ! markus 157: des_cbc_encrypt(dest, dest, len, cc->u.des3.key3, iv3, DES_ENCRYPT);
1.16 markus 158: memcpy(iv3, dest + len - 8, 8);
1.1 deraadt 159: }
160: void
1.32 ! markus 161: des3_ssh1_decrypt(CipherContext *cc, u_char *dest, const u_char *src,
! 162: u_int len)
1.1 deraadt 163: {
1.16 markus 164: des_cblock iv1;
1.32 ! markus 165: des_cblock *iv2 = &cc->u.des3.iv2;
! 166: des_cblock *iv3 = &cc->u.des3.iv3;
1.1 deraadt 167:
1.16 markus 168: memcpy(&iv1, iv2, 8);
1.1 deraadt 169:
1.32 ! markus 170: des_cbc_encrypt(src, dest, len, cc->u.des3.key3, iv3, DES_DECRYPT);
1.16 markus 171: memcpy(iv3, src + len - 8, 8);
1.1 deraadt 172:
1.32 ! markus 173: des_cbc_encrypt(dest, dest, len, cc->u.des3.key2, iv2, DES_ENCRYPT);
1.16 markus 174: memcpy(iv2, dest + len - 8, 8);
1.1 deraadt 175:
1.32 ! markus 176: des_cbc_encrypt(dest, dest, len, cc->u.des3.key1, &iv1, DES_DECRYPT);
1.16 markus 177: /* memcpy(&iv1, iv2, 8); */
178: /* Note how iv1 == iv2 on entry and exit. */
1.1 deraadt 179: }
180:
1.32 ! markus 181: /* Blowfish */
! 182: void
! 183: blowfish_setkey(CipherContext *cc, const u_char *key, u_int keylen)
! 184: {
! 185: BF_set_key(&cc->u.bf.key, keylen, (unsigned char *)key);
! 186: }
! 187: void
! 188: blowfish_setiv(CipherContext *cc, const u_char *iv, u_int ivlen)
! 189: {
! 190: if (iv == NULL)
! 191: memset(cc->u.bf.iv, 0, 8);
! 192: else
! 193: memcpy(cc->u.bf.iv, (char *)iv, 8);
! 194: }
! 195: void
! 196: blowfish_cbc_encrypt(CipherContext *cc, u_char *dest, const u_char *src,
! 197: u_int len)
! 198: {
! 199: BF_cbc_encrypt((void *)src, dest, len, &cc->u.bf.key, cc->u.bf.iv,
! 200: BF_ENCRYPT);
! 201: }
! 202: void
! 203: blowfish_cbc_decrypt(CipherContext *cc, u_char *dest, const u_char *src,
! 204: u_int len)
! 205: {
! 206: BF_cbc_encrypt((void *)src, dest, len, &cc->u.bf.key, cc->u.bf.iv,
! 207: BF_DECRYPT);
! 208: }
! 209:
1.1 deraadt 210: /*
1.24 markus 211: * SSH1 uses a variation on Blowfish, all bytes must be swapped before
1.1 deraadt 212: * and after encryption/decryption. Thus the swap_bytes stuff (yuk).
213: */
1.16 markus 214: static void
1.1 deraadt 215: swap_bytes(const unsigned char *src, unsigned char *dst_, int n)
216: {
1.16 markus 217: /* dst must be properly aligned. */
218: u_int32_t *dst = (u_int32_t *) dst_;
219: union {
220: u_int32_t i;
221: char c[4];
222: } t;
223:
224: /* Process 8 bytes every lap. */
225: for (n = n / 8; n > 0; n--) {
226: t.c[3] = *src++;
227: t.c[2] = *src++;
228: t.c[1] = *src++;
229: t.c[0] = *src++;
230: *dst++ = t.i;
231:
232: t.c[3] = *src++;
233: t.c[2] = *src++;
234: t.c[1] = *src++;
235: t.c[0] = *src++;
236: *dst++ = t.i;
237: }
1.1 deraadt 238: }
239:
1.32 ! markus 240: void
! 241: blowfish_ssh1_encrypt(CipherContext *cc, u_char *dest, const u_char *src,
! 242: u_int len)
! 243: {
! 244: swap_bytes(src, dest, len);
! 245: BF_cbc_encrypt((void *)dest, dest, len, &cc->u.bf.key, cc->u.bf.iv,
! 246: BF_ENCRYPT);
! 247: swap_bytes(dest, dest, len);
! 248: }
! 249: void
! 250: blowfish_ssh1_decrypt(CipherContext *cc, u_char *dest, const u_char *src,
! 251: u_int len)
1.4 provos 252: {
1.32 ! markus 253: swap_bytes(src, dest, len);
! 254: BF_cbc_encrypt((void *)dest, dest, len, &cc->u.bf.key, cc->u.bf.iv,
! 255: BF_DECRYPT);
! 256: swap_bytes(dest, dest, len);
! 257: }
1.1 deraadt 258:
1.32 ! markus 259: /* alleged rc4 */
! 260: void
! 261: arcfour_setkey(CipherContext *cc, const u_char *key, u_int keylen)
! 262: {
! 263: RC4_set_key(&cc->u.rc4, keylen, (u_char *)key);
! 264: }
! 265: void
! 266: arcfour_crypt(CipherContext *cc, u_char *dest, const u_char *src, u_int len)
! 267: {
! 268: RC4(&cc->u.rc4, len, (u_char *)src, dest);
! 269: }
1.1 deraadt 270:
1.32 ! markus 271: /* CAST */
! 272: void
! 273: cast_setkey(CipherContext *cc, const u_char *key, u_int keylen)
! 274: {
! 275: CAST_set_key(&cc->u.cast.key, keylen, (unsigned char *) key);
! 276: }
! 277: void
! 278: cast_setiv(CipherContext *cc, const u_char *iv, u_int ivlen)
1.1 deraadt 279: {
1.32 ! markus 280: if (iv == NULL)
! 281: fatal("no IV for %s.", cc->cipher->name);
! 282: memcpy(cc->u.cast.iv, (char *)iv, 8);
1.22 markus 283: }
1.32 ! markus 284: void
! 285: cast_cbc_encrypt(CipherContext *cc, u_char *dest, const u_char *src, u_int len)
1.22 markus 286: {
1.32 ! markus 287: CAST_cbc_encrypt(src, dest, len, &cc->u.cast.key, cc->u.cast.iv,
! 288: CAST_ENCRYPT);
1.1 deraadt 289: }
1.32 ! markus 290: void
! 291: cast_cbc_decrypt(CipherContext *cc, u_char *dest, const u_char *src, u_int len)
1.22 markus 292: {
1.32 ! markus 293: CAST_cbc_encrypt(src, dest, len, &cc->u.cast.key, cc->u.cast.iv,
! 294: CAST_DECRYPT);
1.22 markus 295: }
1.1 deraadt 296:
1.32 ! markus 297: /*--*/
! 298:
! 299: Cipher ciphers[] = {
! 300: { "none",
! 301: SSH_CIPHER_NONE, 8, 0,
! 302: none_setkey, none_setiv,
! 303: none_crypt, none_crypt },
! 304: { "des",
! 305: SSH_CIPHER_DES, 8, 8,
! 306: des_ssh1_setkey, des_ssh1_setiv,
! 307: des_ssh1_encrypt, des_ssh1_decrypt },
! 308: { "3des",
! 309: SSH_CIPHER_3DES, 8, 16,
! 310: des3_ssh1_setkey, des3_setiv,
! 311: des3_ssh1_encrypt, des3_ssh1_decrypt },
! 312: { "blowfish",
! 313: SSH_CIPHER_BLOWFISH, 8, 16,
! 314: blowfish_setkey, blowfish_setiv,
! 315: blowfish_ssh1_encrypt, blowfish_ssh1_decrypt },
! 316:
! 317: { "3des-cbc",
! 318: SSH_CIPHER_SSH2, 8, 24,
! 319: des3_setkey, des3_setiv,
! 320: des3_cbc_encrypt, des3_cbc_decrypt },
! 321: { "blowfish-cbc",
! 322: SSH_CIPHER_SSH2, 8, 16,
! 323: blowfish_setkey, blowfish_setiv,
! 324: blowfish_cbc_encrypt, blowfish_cbc_decrypt },
! 325: { "cast128-cbc",
! 326: SSH_CIPHER_SSH2, 8, 16,
! 327: cast_setkey, cast_setiv,
! 328: cast_cbc_encrypt, cast_cbc_decrypt },
! 329: { "arcfour",
! 330: SSH_CIPHER_SSH2, 8, 16,
! 331: arcfour_setkey, none_setiv,
! 332: arcfour_crypt, arcfour_crypt },
! 333: { NULL, SSH_CIPHER_ILLEGAL, 0, 0, NULL, NULL, NULL, NULL }
! 334: };
! 335:
! 336: /*--*/
1.1 deraadt 337:
1.32 ! markus 338: unsigned int
! 339: cipher_mask1()
1.1 deraadt 340: {
1.32 ! markus 341: unsigned int mask = 0;
! 342: Cipher *c;
! 343: for (c = ciphers; c->name != NULL; c++) {
! 344: if (c->number > SSH_CIPHER_NONE)
! 345: mask |= 1 << c->number;
! 346: }
! 347: return mask;
1.1 deraadt 348: }
349:
1.32 ! markus 350: Cipher *
! 351: cipher_by_name(const char *name)
! 352: {
! 353: Cipher *c;
! 354: if (strcmp(name, "des") == 0)
! 355: error("Warning: use of DES is strongly discouraged "
! 356: "due to cryptographic weaknesses");
! 357: for (c = ciphers; c->name != NULL; c++)
! 358: if (strcasecmp(c->name, name) == 0)
! 359: return c;
! 360: return NULL;
! 361: }
! 362:
! 363: Cipher *
! 364: cipher_by_number(int id)
! 365: {
! 366: Cipher *c;
! 367: for (c = ciphers; c->name != NULL; c++)
! 368: if (c->number == id)
! 369: return c;
! 370: return NULL;
! 371: }
1.24 markus 372:
373: #define CIPHER_SEP ","
374: int
375: ciphers_valid(const char *names)
376: {
1.32 ! markus 377: Cipher *c;
1.29 ho 378: char *ciphers, *cp;
1.24 markus 379: char *p;
380:
1.27 markus 381: if (names == NULL || strcmp(names, "") == 0)
1.24 markus 382: return 0;
1.29 ho 383: ciphers = cp = xstrdup(names);
1.32 ! markus 384: for ((p = strsep(&cp, CIPHER_SEP)); p && *p != '\0';
1.29 ho 385: (p = strsep(&cp, CIPHER_SEP))) {
1.32 ! markus 386: c = cipher_by_name(p);
! 387: if (c == NULL || c->number != SSH_CIPHER_SSH2) {
! 388: debug("bad cipher %s [%s]", p, names);
1.24 markus 389: xfree(ciphers);
390: return 0;
1.32 ! markus 391: } else {
! 392: debug("cipher ok: %s [%s]", p, names);
1.24 markus 393: }
394: }
1.32 ! markus 395: debug("ciphers ok: [%s]", names);
1.24 markus 396: xfree(ciphers);
397: return 1;
398: }
399:
1.18 markus 400: /*
401: * Parses the name of the cipher. Returns the number of the corresponding
402: * cipher, or -1 on error.
403: */
1.1 deraadt 404:
1.4 provos 405: int
406: cipher_number(const char *name)
1.1 deraadt 407: {
1.32 ! markus 408: Cipher *c;
1.27 markus 409: if (name == NULL)
410: return -1;
1.32 ! markus 411: c = cipher_by_name(name);
! 412: return (c==NULL) ? -1 : c->number;
1.1 deraadt 413: }
414:
1.32 ! markus 415: char *
! 416: cipher_name(int id)
1.1 deraadt 417: {
1.32 ! markus 418: Cipher *c = cipher_by_number(id);
! 419: return (c==NULL) ? "<unknown>" : c->name;
1.1 deraadt 420: }
421:
1.26 markus 422: void
1.32 ! markus 423: cipher_init(CipherContext *cc, Cipher *cipher,
! 424: const u_char *key, u_int keylen, const u_char *iv, u_int ivlen)
1.16 markus 425: {
1.32 ! markus 426: if (keylen < cipher->key_len)
! 427: fatal("cipher_init: key length %d is insufficient for %s.",
! 428: keylen, cipher->name);
! 429: if (iv != NULL && ivlen < cipher->block_size)
! 430: fatal("cipher_init: iv length %d is insufficient for %s.",
! 431: ivlen, cipher->name);
! 432: cc->cipher = cipher;
! 433: cipher->setkey(cc, key, keylen);
! 434: cipher->setiv(cc, iv, ivlen);
1.1 deraadt 435: }
1.21 markus 436:
1.26 markus 437: void
1.32 ! markus 438: cipher_encrypt(CipherContext *cc, u_char *dest, const u_char *src, u_int len)
! 439: {
! 440: if (len % cc->cipher->block_size)
! 441: fatal("cipher_encrypt: bad plaintext length %d", len);
! 442: cc->cipher->encrypt(cc, dest, src, len);
1.21 markus 443: }
444:
1.26 markus 445: void
1.32 ! markus 446: cipher_decrypt(CipherContext *cc, u_char *dest, const u_char *src, u_int len)
1.16 markus 447: {
1.32 ! markus 448: if (len % cc->cipher->block_size)
! 449: fatal("cipher_decrypt: bad ciphertext length %d", len);
! 450: cc->cipher->decrypt(cc, dest, src, len);
1.16 markus 451: }
1.1 deraadt 452:
1.32 ! markus 453: /*
! 454: * Selects the cipher, and keys if by computing the MD5 checksum of the
! 455: * passphrase and using the resulting 16 bytes as the key.
! 456: */
1.1 deraadt 457:
1.26 markus 458: void
1.32 ! markus 459: cipher_set_key_string(CipherContext *cc, Cipher *cipher,
! 460: const char *passphrase)
1.16 markus 461: {
1.32 ! markus 462: MD5_CTX md;
! 463: unsigned char digest[16];
! 464:
! 465: MD5_Init(&md);
! 466: MD5_Update(&md, (const u_char *)passphrase, strlen(passphrase));
! 467: MD5_Final(digest, &md);
1.16 markus 468:
1.32 ! markus 469: cipher_init(cc, cipher, digest, 16, NULL, 0);
1.16 markus 470:
1.32 ! markus 471: memset(digest, 0, sizeof(digest));
! 472: memset(&md, 0, sizeof(md));
1.1 deraadt 473: }
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