| 1 | /* |
| 2 | * Code for PuTTY to import and export private key files in other |
| 3 | * SSH clients' formats. |
| 4 | */ |
| 5 | |
| 6 | #include <stdio.h> |
| 7 | #include <stdlib.h> |
| 8 | #include <assert.h> |
| 9 | #include <ctype.h> |
| 10 | |
| 11 | #include "ssh.h" |
| 12 | #include "misc.h" |
| 13 | |
| 14 | #define PUT_32BIT(cp, value) do { \ |
| 15 | (cp)[3] = (unsigned char)(value); \ |
| 16 | (cp)[2] = (unsigned char)((value) >> 8); \ |
| 17 | (cp)[1] = (unsigned char)((value) >> 16); \ |
| 18 | (cp)[0] = (unsigned char)((value) >> 24); } while (0) |
| 19 | |
| 20 | #define GET_32BIT(cp) \ |
| 21 | (((unsigned long)(unsigned char)(cp)[0] << 24) | \ |
| 22 | ((unsigned long)(unsigned char)(cp)[1] << 16) | \ |
| 23 | ((unsigned long)(unsigned char)(cp)[2] << 8) | \ |
| 24 | ((unsigned long)(unsigned char)(cp)[3])) |
| 25 | |
| 26 | int openssh_encrypted(char *filename); |
| 27 | struct ssh2_userkey *openssh_read(char *filename, char *passphrase); |
| 28 | int openssh_write(char *filename, struct ssh2_userkey *key, char *passphrase); |
| 29 | |
| 30 | int sshcom_encrypted(char *filename, char **comment); |
| 31 | struct ssh2_userkey *sshcom_read(char *filename, char *passphrase); |
| 32 | int sshcom_write(char *filename, struct ssh2_userkey *key, char *passphrase); |
| 33 | |
| 34 | /* |
| 35 | * Given a key type, determine whether we know how to import it. |
| 36 | */ |
| 37 | int import_possible(int type) |
| 38 | { |
| 39 | if (type == SSH_KEYTYPE_OPENSSH) |
| 40 | return 1; |
| 41 | if (type == SSH_KEYTYPE_SSHCOM) |
| 42 | return 1; |
| 43 | return 0; |
| 44 | } |
| 45 | |
| 46 | /* |
| 47 | * Given a key type, determine what native key type |
| 48 | * (SSH_KEYTYPE_SSH1 or SSH_KEYTYPE_SSH2) it will come out as once |
| 49 | * we've imported it. |
| 50 | */ |
| 51 | int import_target_type(int type) |
| 52 | { |
| 53 | /* |
| 54 | * There are no known foreign SSH1 key formats. |
| 55 | */ |
| 56 | return SSH_KEYTYPE_SSH2; |
| 57 | } |
| 58 | |
| 59 | /* |
| 60 | * Determine whether a foreign key is encrypted. |
| 61 | */ |
| 62 | int import_encrypted(char *filename, int type, char **comment) |
| 63 | { |
| 64 | if (type == SSH_KEYTYPE_OPENSSH) { |
| 65 | *comment = dupstr(filename); /* OpenSSH doesn't do key comments */ |
| 66 | return openssh_encrypted(filename); |
| 67 | } |
| 68 | if (type == SSH_KEYTYPE_SSHCOM) { |
| 69 | return sshcom_encrypted(filename, comment); |
| 70 | } |
| 71 | return 0; |
| 72 | } |
| 73 | |
| 74 | /* |
| 75 | * Import an SSH1 key. |
| 76 | */ |
| 77 | int import_ssh1(char *filename, int type, struct RSAKey *key, char *passphrase) |
| 78 | { |
| 79 | return 0; |
| 80 | } |
| 81 | |
| 82 | /* |
| 83 | * Import an SSH2 key. |
| 84 | */ |
| 85 | struct ssh2_userkey *import_ssh2(char *filename, int type, char *passphrase) |
| 86 | { |
| 87 | if (type == SSH_KEYTYPE_OPENSSH) |
| 88 | return openssh_read(filename, passphrase); |
| 89 | if (type == SSH_KEYTYPE_SSHCOM) |
| 90 | return sshcom_read(filename, passphrase); |
| 91 | return NULL; |
| 92 | } |
| 93 | |
| 94 | /* |
| 95 | * Export an SSH1 key. |
| 96 | */ |
| 97 | int export_ssh1(char *filename, int type, struct RSAKey *key, char *passphrase) |
| 98 | { |
| 99 | return 0; |
| 100 | } |
| 101 | |
| 102 | /* |
| 103 | * Export an SSH2 key. |
| 104 | */ |
| 105 | int export_ssh2(char *filename, int type, |
| 106 | struct ssh2_userkey *key, char *passphrase) |
| 107 | { |
| 108 | if (type == SSH_KEYTYPE_OPENSSH) |
| 109 | return openssh_write(filename, key, passphrase); |
| 110 | if (type == SSH_KEYTYPE_SSHCOM) |
| 111 | return sshcom_write(filename, key, passphrase); |
| 112 | return 0; |
| 113 | } |
| 114 | |
| 115 | /* ---------------------------------------------------------------------- |
| 116 | * Helper routines. (The base64 ones are defined in sshpubk.c.) |
| 117 | */ |
| 118 | |
| 119 | #define isbase64(c) ( ((c) >= 'A' && (c) <= 'Z') || \ |
| 120 | ((c) >= 'a' && (c) <= 'z') || \ |
| 121 | ((c) >= '0' && (c) <= '9') || \ |
| 122 | (c) == '+' || (c) == '/' || (c) == '=' \ |
| 123 | ) |
| 124 | |
| 125 | extern int base64_decode_atom(char *atom, unsigned char *out); |
| 126 | extern int base64_lines(int datalen); |
| 127 | extern void base64_encode_atom(unsigned char *data, int n, char *out); |
| 128 | extern void base64_encode(FILE *fp, unsigned char *data, int datalen, int cpl); |
| 129 | |
| 130 | /* |
| 131 | * Read an ASN.1/BER identifier and length pair. |
| 132 | * |
| 133 | * Flags are a combination of the #defines listed below. |
| 134 | * |
| 135 | * Returns -1 if unsuccessful; otherwise returns the number of |
| 136 | * bytes used out of the source data. |
| 137 | */ |
| 138 | |
| 139 | /* ASN.1 tag classes. */ |
| 140 | #define ASN1_CLASS_UNIVERSAL (0 << 6) |
| 141 | #define ASN1_CLASS_APPLICATION (1 << 6) |
| 142 | #define ASN1_CLASS_CONTEXT_SPECIFIC (2 << 6) |
| 143 | #define ASN1_CLASS_PRIVATE (3 << 6) |
| 144 | #define ASN1_CLASS_MASK (3 << 6) |
| 145 | |
| 146 | /* Primitive versus constructed bit. */ |
| 147 | #define ASN1_CONSTRUCTED (1 << 5) |
| 148 | |
| 149 | int ber_read_id_len(void *source, int sourcelen, |
| 150 | int *id, int *length, int *flags) |
| 151 | { |
| 152 | unsigned char *p = (unsigned char *) source; |
| 153 | |
| 154 | if (sourcelen == 0) |
| 155 | return -1; |
| 156 | |
| 157 | *flags = (*p & 0xE0); |
| 158 | if ((*p & 0x1F) == 0x1F) { |
| 159 | *id = 0; |
| 160 | while (*p & 0x80) { |
| 161 | *id = (*id << 7) | (*p & 0x7F); |
| 162 | p++, sourcelen--; |
| 163 | if (sourcelen == 0) |
| 164 | return -1; |
| 165 | } |
| 166 | *id = (*id << 7) | (*p & 0x7F); |
| 167 | p++, sourcelen--; |
| 168 | } else { |
| 169 | *id = *p & 0x1F; |
| 170 | p++, sourcelen--; |
| 171 | } |
| 172 | |
| 173 | if (sourcelen == 0) |
| 174 | return -1; |
| 175 | |
| 176 | if (*p & 0x80) { |
| 177 | int n = *p & 0x7F; |
| 178 | p++, sourcelen--; |
| 179 | if (sourcelen < n) |
| 180 | return -1; |
| 181 | *length = 0; |
| 182 | while (n--) |
| 183 | *length = (*length << 8) | (*p++); |
| 184 | sourcelen -= n; |
| 185 | } else { |
| 186 | *length = *p; |
| 187 | p++, sourcelen--; |
| 188 | } |
| 189 | |
| 190 | return p - (unsigned char *) source; |
| 191 | } |
| 192 | |
| 193 | /* |
| 194 | * Write an ASN.1/BER identifier and length pair. Returns the |
| 195 | * number of bytes consumed. Assumes dest contains enough space. |
| 196 | * Will avoid writing anything if dest is NULL, but still return |
| 197 | * amount of space required. |
| 198 | */ |
| 199 | int ber_write_id_len(void *dest, int id, int length, int flags) |
| 200 | { |
| 201 | unsigned char *d = (unsigned char *)dest; |
| 202 | int len = 0; |
| 203 | |
| 204 | if (id <= 30) { |
| 205 | /* |
| 206 | * Identifier is one byte. |
| 207 | */ |
| 208 | len++; |
| 209 | if (d) *d++ = id | flags; |
| 210 | } else { |
| 211 | int n; |
| 212 | /* |
| 213 | * Identifier is multiple bytes: the first byte is 11111 |
| 214 | * plus the flags, and subsequent bytes encode the value of |
| 215 | * the identifier, 7 bits at a time, with the top bit of |
| 216 | * each byte 1 except the last one which is 0. |
| 217 | */ |
| 218 | len++; |
| 219 | if (d) *d++ = 0x1F | flags; |
| 220 | for (n = 1; (id >> (7*n)) > 0; n++) |
| 221 | continue; /* count the bytes */ |
| 222 | while (n--) { |
| 223 | len++; |
| 224 | if (d) *d++ = (n ? 0x80 : 0) | ((id >> (7*n)) & 0x7F); |
| 225 | } |
| 226 | } |
| 227 | |
| 228 | if (length < 128) { |
| 229 | /* |
| 230 | * Length is one byte. |
| 231 | */ |
| 232 | len++; |
| 233 | if (d) *d++ = length; |
| 234 | } else { |
| 235 | int n; |
| 236 | /* |
| 237 | * Length is multiple bytes. The first is 0x80 plus the |
| 238 | * number of subsequent bytes, and the subsequent bytes |
| 239 | * encode the actual length. |
| 240 | */ |
| 241 | for (n = 1; (length >> (8*n)) > 0; n++) |
| 242 | continue; /* count the bytes */ |
| 243 | len++; |
| 244 | if (d) *d++ = 0x80 | n; |
| 245 | while (n--) { |
| 246 | len++; |
| 247 | if (d) *d++ = (length >> (8*n)) & 0xFF; |
| 248 | } |
| 249 | } |
| 250 | |
| 251 | return len; |
| 252 | } |
| 253 | |
| 254 | static int put_string(void *target, void *data, int len) |
| 255 | { |
| 256 | unsigned char *d = (unsigned char *)target; |
| 257 | |
| 258 | PUT_32BIT(d, len); |
| 259 | memcpy(d+4, data, len); |
| 260 | return len+4; |
| 261 | } |
| 262 | |
| 263 | static int put_mp(void *target, void *data, int len) |
| 264 | { |
| 265 | unsigned char *d = (unsigned char *)target; |
| 266 | unsigned char *i = (unsigned char *)data; |
| 267 | |
| 268 | if (*i & 0x80) { |
| 269 | PUT_32BIT(d, len+1); |
| 270 | d[4] = 0; |
| 271 | memcpy(d+5, data, len); |
| 272 | return len+5; |
| 273 | } else { |
| 274 | PUT_32BIT(d, len); |
| 275 | memcpy(d+4, data, len); |
| 276 | return len+4; |
| 277 | } |
| 278 | } |
| 279 | |
| 280 | /* Simple structure to point to an mp-int within a blob. */ |
| 281 | struct mpint_pos { void *start; int bytes; }; |
| 282 | |
| 283 | int ssh2_read_mpint(void *data, int len, struct mpint_pos *ret) |
| 284 | { |
| 285 | int bytes; |
| 286 | unsigned char *d = (unsigned char *) data; |
| 287 | |
| 288 | if (len < 4) |
| 289 | goto error; |
| 290 | bytes = GET_32BIT(d); |
| 291 | if (len < 4+bytes) |
| 292 | goto error; |
| 293 | |
| 294 | ret->start = d + 4; |
| 295 | ret->bytes = bytes; |
| 296 | return bytes+4; |
| 297 | |
| 298 | error: |
| 299 | ret->start = NULL; |
| 300 | ret->bytes = -1; |
| 301 | return len; /* ensure further calls fail as well */ |
| 302 | } |
| 303 | |
| 304 | /* ---------------------------------------------------------------------- |
| 305 | * Code to read and write OpenSSH private keys. |
| 306 | */ |
| 307 | |
| 308 | enum { OSSH_DSA, OSSH_RSA }; |
| 309 | struct openssh_key { |
| 310 | int type; |
| 311 | int encrypted; |
| 312 | char iv[32]; |
| 313 | unsigned char *keyblob; |
| 314 | int keyblob_len, keyblob_size; |
| 315 | }; |
| 316 | |
| 317 | struct openssh_key *load_openssh_key(char *filename) |
| 318 | { |
| 319 | struct openssh_key *ret; |
| 320 | FILE *fp; |
| 321 | char buffer[256]; |
| 322 | char *errmsg, *p; |
| 323 | int headers_done; |
| 324 | char base64_bit[4]; |
| 325 | int base64_chars = 0; |
| 326 | |
| 327 | ret = smalloc(sizeof(*ret)); |
| 328 | ret->keyblob = NULL; |
| 329 | ret->keyblob_len = ret->keyblob_size = 0; |
| 330 | ret->encrypted = 0; |
| 331 | memset(ret->iv, 0, sizeof(ret->iv)); |
| 332 | |
| 333 | fp = fopen(filename, "r"); |
| 334 | if (!fp) { |
| 335 | errmsg = "Unable to open key file"; |
| 336 | goto error; |
| 337 | } |
| 338 | if (!fgets(buffer, sizeof(buffer), fp) || |
| 339 | 0 != strncmp(buffer, "-----BEGIN ", 11) || |
| 340 | 0 != strcmp(buffer+strlen(buffer)-17, "PRIVATE KEY-----\n")) { |
| 341 | errmsg = "File does not begin with OpenSSH key header"; |
| 342 | goto error; |
| 343 | } |
| 344 | if (!strcmp(buffer, "-----BEGIN RSA PRIVATE KEY-----\n")) |
| 345 | ret->type = OSSH_RSA; |
| 346 | else if (!strcmp(buffer, "-----BEGIN DSA PRIVATE KEY-----\n")) |
| 347 | ret->type = OSSH_DSA; |
| 348 | else { |
| 349 | errmsg = "Unrecognised key type"; |
| 350 | goto error; |
| 351 | } |
| 352 | |
| 353 | headers_done = 0; |
| 354 | while (1) { |
| 355 | if (!fgets(buffer, sizeof(buffer), fp)) { |
| 356 | errmsg = "Unexpected end of file"; |
| 357 | goto error; |
| 358 | } |
| 359 | if (0 == strncmp(buffer, "-----END ", 9) && |
| 360 | 0 == strcmp(buffer+strlen(buffer)-17, "PRIVATE KEY-----\n")) |
| 361 | break; /* done */ |
| 362 | if ((p = strchr(buffer, ':')) != NULL) { |
| 363 | if (headers_done) { |
| 364 | errmsg = "Header found in body of key data"; |
| 365 | goto error; |
| 366 | } |
| 367 | *p++ = '\0'; |
| 368 | while (*p && isspace((unsigned char)*p)) p++; |
| 369 | if (!strcmp(buffer, "Proc-Type")) { |
| 370 | if (p[0] != '4' || p[1] != ',') { |
| 371 | errmsg = "Proc-Type is not 4 (only 4 is supported)"; |
| 372 | goto error; |
| 373 | } |
| 374 | p += 2; |
| 375 | if (!strcmp(p, "ENCRYPTED\n")) |
| 376 | ret->encrypted = 1; |
| 377 | } else if (!strcmp(buffer, "DEK-Info")) { |
| 378 | int i, j; |
| 379 | |
| 380 | if (strncmp(p, "DES-EDE3-CBC,", 13)) { |
| 381 | errmsg = "Ciphers other than DES-EDE3-CBC not supported"; |
| 382 | goto error; |
| 383 | } |
| 384 | p += 13; |
| 385 | for (i = 0; i < 8; i++) { |
| 386 | if (1 != sscanf(p, "%2x", &j)) |
| 387 | break; |
| 388 | ret->iv[i] = j; |
| 389 | p += 2; |
| 390 | } |
| 391 | if (i < 8) { |
| 392 | errmsg = "Expected 16-digit iv in DEK-Info"; |
| 393 | goto error; |
| 394 | } |
| 395 | } |
| 396 | } else { |
| 397 | headers_done = 1; |
| 398 | |
| 399 | p = buffer; |
| 400 | while (isbase64(*p)) { |
| 401 | base64_bit[base64_chars++] = *p; |
| 402 | if (base64_chars == 4) { |
| 403 | unsigned char out[3]; |
| 404 | int len; |
| 405 | |
| 406 | base64_chars = 0; |
| 407 | |
| 408 | len = base64_decode_atom(base64_bit, out); |
| 409 | |
| 410 | if (len <= 0) { |
| 411 | errmsg = "Invalid base64 encoding"; |
| 412 | goto error; |
| 413 | } |
| 414 | |
| 415 | if (ret->keyblob_len + len > ret->keyblob_size) { |
| 416 | ret->keyblob_size = ret->keyblob_len + len + 256; |
| 417 | ret->keyblob = srealloc(ret->keyblob, ret->keyblob_size); |
| 418 | } |
| 419 | |
| 420 | memcpy(ret->keyblob + ret->keyblob_len, out, len); |
| 421 | ret->keyblob_len += len; |
| 422 | |
| 423 | memset(out, 0, sizeof(out)); |
| 424 | } |
| 425 | |
| 426 | p++; |
| 427 | } |
| 428 | } |
| 429 | } |
| 430 | |
| 431 | if (ret->keyblob_len == 0 || !ret->keyblob) { |
| 432 | errmsg = "Key body not present"; |
| 433 | goto error; |
| 434 | } |
| 435 | |
| 436 | if (ret->encrypted && ret->keyblob_len % 8 != 0) { |
| 437 | errmsg = "Encrypted key blob is not a multiple of cipher block size"; |
| 438 | goto error; |
| 439 | } |
| 440 | |
| 441 | memset(buffer, 0, sizeof(buffer)); |
| 442 | memset(base64_bit, 0, sizeof(base64_bit)); |
| 443 | return ret; |
| 444 | |
| 445 | error: |
| 446 | memset(buffer, 0, sizeof(buffer)); |
| 447 | memset(base64_bit, 0, sizeof(base64_bit)); |
| 448 | if (ret) { |
| 449 | if (ret->keyblob) { |
| 450 | memset(ret->keyblob, 0, ret->keyblob_size); |
| 451 | sfree(ret->keyblob); |
| 452 | } |
| 453 | memset(&ret, 0, sizeof(ret)); |
| 454 | sfree(ret); |
| 455 | } |
| 456 | return NULL; |
| 457 | } |
| 458 | |
| 459 | int openssh_encrypted(char *filename) |
| 460 | { |
| 461 | struct openssh_key *key = load_openssh_key(filename); |
| 462 | int ret; |
| 463 | |
| 464 | if (!key) |
| 465 | return 0; |
| 466 | ret = key->encrypted; |
| 467 | memset(key->keyblob, 0, key->keyblob_size); |
| 468 | sfree(key->keyblob); |
| 469 | memset(&key, 0, sizeof(key)); |
| 470 | sfree(key); |
| 471 | return ret; |
| 472 | } |
| 473 | |
| 474 | struct ssh2_userkey *openssh_read(char *filename, char *passphrase) |
| 475 | { |
| 476 | struct openssh_key *key = load_openssh_key(filename); |
| 477 | struct ssh2_userkey *retkey; |
| 478 | unsigned char *p; |
| 479 | int ret, id, len, flags; |
| 480 | int i, num_integers; |
| 481 | struct ssh2_userkey *retval = NULL; |
| 482 | char *errmsg; |
| 483 | unsigned char *blob; |
| 484 | int blobsize, blobptr, privptr; |
| 485 | char *modptr; |
| 486 | int modlen; |
| 487 | |
| 488 | blob = NULL; |
| 489 | |
| 490 | if (!key) |
| 491 | return NULL; |
| 492 | |
| 493 | if (key->encrypted) { |
| 494 | /* |
| 495 | * Derive encryption key from passphrase and iv/salt: |
| 496 | * |
| 497 | * - let block A equal MD5(passphrase || iv) |
| 498 | * - let block B equal MD5(A || passphrase || iv) |
| 499 | * - block C would be MD5(B || passphrase || iv) and so on |
| 500 | * - encryption key is the first N bytes of A || B |
| 501 | */ |
| 502 | struct MD5Context md5c; |
| 503 | unsigned char keybuf[32]; |
| 504 | |
| 505 | MD5Init(&md5c); |
| 506 | MD5Update(&md5c, passphrase, strlen(passphrase)); |
| 507 | MD5Update(&md5c, key->iv, 8); |
| 508 | MD5Final(keybuf, &md5c); |
| 509 | |
| 510 | MD5Init(&md5c); |
| 511 | MD5Update(&md5c, keybuf, 16); |
| 512 | MD5Update(&md5c, passphrase, strlen(passphrase)); |
| 513 | MD5Update(&md5c, key->iv, 8); |
| 514 | MD5Final(keybuf+16, &md5c); |
| 515 | |
| 516 | /* |
| 517 | * Now decrypt the key blob. |
| 518 | */ |
| 519 | des3_decrypt_pubkey_ossh(keybuf, key->iv, |
| 520 | key->keyblob, key->keyblob_len); |
| 521 | |
| 522 | memset(&md5c, 0, sizeof(md5c)); |
| 523 | memset(keybuf, 0, sizeof(keybuf)); |
| 524 | } |
| 525 | |
| 526 | /* |
| 527 | * Now we have a decrypted key blob, which contains an ASN.1 |
| 528 | * encoded private key. We must now untangle the ASN.1. |
| 529 | * |
| 530 | * We expect the whole key blob to be formatted as a SEQUENCE |
| 531 | * (0x30 followed by a length code indicating that the rest of |
| 532 | * the blob is part of the sequence). Within that SEQUENCE we |
| 533 | * expect to see a bunch of INTEGERs. What those integers mean |
| 534 | * depends on the key type: |
| 535 | * |
| 536 | * - For RSA, we expect the integers to be 0, n, e, d, p, q, |
| 537 | * dmp1, dmq1, iqmp in that order. (The last three are d mod |
| 538 | * (p-1), d mod (q-1), inverse of q mod p respectively.) |
| 539 | * |
| 540 | * - For DSA, we expect them to be 0, p, q, g, y, x in that |
| 541 | * order. |
| 542 | */ |
| 543 | |
| 544 | p = key->keyblob; |
| 545 | |
| 546 | /* Expect the SEQUENCE header. Take its absence as a failure to decrypt. */ |
| 547 | ret = ber_read_id_len(p, key->keyblob_len, &id, &len, &flags); |
| 548 | p += ret; |
| 549 | if (ret < 0 || id != 16) { |
| 550 | errmsg = "ASN.1 decoding failure"; |
| 551 | retval = SSH2_WRONG_PASSPHRASE; |
| 552 | goto error; |
| 553 | } |
| 554 | |
| 555 | /* Expect a load of INTEGERs. */ |
| 556 | if (key->type == OSSH_RSA) |
| 557 | num_integers = 9; |
| 558 | else if (key->type == OSSH_DSA) |
| 559 | num_integers = 6; |
| 560 | |
| 561 | /* |
| 562 | * Space to create key blob in. |
| 563 | */ |
| 564 | blobsize = 256+key->keyblob_len; |
| 565 | blob = smalloc(blobsize); |
| 566 | PUT_32BIT(blob, 7); |
| 567 | if (key->type == OSSH_DSA) |
| 568 | memcpy(blob+4, "ssh-dss", 7); |
| 569 | else if (key->type == OSSH_RSA) |
| 570 | memcpy(blob+4, "ssh-rsa", 7); |
| 571 | blobptr = 4+7; |
| 572 | privptr = -1; |
| 573 | |
| 574 | for (i = 0; i < num_integers; i++) { |
| 575 | ret = ber_read_id_len(p, key->keyblob+key->keyblob_len-p, |
| 576 | &id, &len, &flags); |
| 577 | p += ret; |
| 578 | if (ret < 0 || id != 2 || |
| 579 | key->keyblob+key->keyblob_len-p < len) { |
| 580 | errmsg = "ASN.1 decoding failure"; |
| 581 | goto error; |
| 582 | } |
| 583 | |
| 584 | if (i == 0) { |
| 585 | /* |
| 586 | * The first integer should be zero always (I think |
| 587 | * this is some sort of version indication). |
| 588 | */ |
| 589 | if (len != 1 || p[0] != 0) { |
| 590 | errmsg = "Version number mismatch"; |
| 591 | goto error; |
| 592 | } |
| 593 | } else if (key->type == OSSH_RSA) { |
| 594 | /* |
| 595 | * Integers 1 and 2 go into the public blob but in the |
| 596 | * opposite order; integers 3, 4, 5 and 8 go into the |
| 597 | * private blob. The other two (6 and 7) are ignored. |
| 598 | */ |
| 599 | if (i == 1) { |
| 600 | /* Save the details for after we deal with number 2. */ |
| 601 | modptr = p; |
| 602 | modlen = len; |
| 603 | } else if (i != 6 && i != 7) { |
| 604 | PUT_32BIT(blob+blobptr, len); |
| 605 | memcpy(blob+blobptr+4, p, len); |
| 606 | blobptr += 4+len; |
| 607 | if (i == 2) { |
| 608 | PUT_32BIT(blob+blobptr, modlen); |
| 609 | memcpy(blob+blobptr+4, modptr, modlen); |
| 610 | blobptr += 4+modlen; |
| 611 | privptr = blobptr; |
| 612 | } |
| 613 | } |
| 614 | } else if (key->type == OSSH_DSA) { |
| 615 | /* |
| 616 | * Integers 1-4 go into the public blob; integer 5 goes |
| 617 | * into the private blob. |
| 618 | */ |
| 619 | PUT_32BIT(blob+blobptr, len); |
| 620 | memcpy(blob+blobptr+4, p, len); |
| 621 | blobptr += 4+len; |
| 622 | if (i == 4) |
| 623 | privptr = blobptr; |
| 624 | } |
| 625 | |
| 626 | /* Skip past the number. */ |
| 627 | p += len; |
| 628 | } |
| 629 | |
| 630 | /* |
| 631 | * Now put together the actual key. Simplest way to do this is |
| 632 | * to assemble our own key blobs and feed them to the createkey |
| 633 | * functions; this is a bit faffy but it does mean we get all |
| 634 | * the sanity checks for free. |
| 635 | */ |
| 636 | assert(privptr > 0); /* should have bombed by now if not */ |
| 637 | retkey = smalloc(sizeof(struct ssh2_userkey)); |
| 638 | retkey->alg = (key->type == OSSH_RSA ? &ssh_rsa : &ssh_dss); |
| 639 | retkey->data = retkey->alg->createkey(blob, privptr, |
| 640 | blob+privptr, blobptr-privptr); |
| 641 | if (!retkey->data) { |
| 642 | sfree(retkey); |
| 643 | errmsg = "unable to create key data structure"; |
| 644 | goto error; |
| 645 | } |
| 646 | |
| 647 | retkey->comment = dupstr("imported-openssh-key"); |
| 648 | errmsg = NULL; /* no error */ |
| 649 | retval = retkey; |
| 650 | |
| 651 | error: |
| 652 | if (blob) { |
| 653 | memset(blob, 0, blobsize); |
| 654 | sfree(blob); |
| 655 | } |
| 656 | memset(key->keyblob, 0, key->keyblob_size); |
| 657 | sfree(key->keyblob); |
| 658 | memset(&key, 0, sizeof(key)); |
| 659 | sfree(key); |
| 660 | return retval; |
| 661 | } |
| 662 | |
| 663 | int openssh_write(char *filename, struct ssh2_userkey *key, char *passphrase) |
| 664 | { |
| 665 | unsigned char *pubblob, *privblob, *spareblob; |
| 666 | int publen, privlen, sparelen; |
| 667 | unsigned char *outblob; |
| 668 | int outlen; |
| 669 | struct mpint_pos numbers[9]; |
| 670 | int nnumbers, pos, len, seqlen, i; |
| 671 | char *header, *footer; |
| 672 | char zero[1]; |
| 673 | unsigned char iv[8]; |
| 674 | int ret = 0; |
| 675 | FILE *fp; |
| 676 | |
| 677 | /* |
| 678 | * Fetch the key blobs. |
| 679 | */ |
| 680 | pubblob = key->alg->public_blob(key->data, &publen); |
| 681 | privblob = key->alg->private_blob(key->data, &privlen); |
| 682 | spareblob = outblob = NULL; |
| 683 | |
| 684 | /* |
| 685 | * Find the sequence of integers to be encoded into the OpenSSH |
| 686 | * key blob, and also decide on the header line. |
| 687 | */ |
| 688 | if (key->alg == &ssh_rsa) { |
| 689 | int pos; |
| 690 | struct mpint_pos n, e, d, p, q, iqmp, dmp1, dmq1; |
| 691 | Bignum bd, bp, bq, bdmp1, bdmq1; |
| 692 | |
| 693 | pos = 4 + GET_32BIT(pubblob); |
| 694 | pos += ssh2_read_mpint(pubblob+pos, publen-pos, &e); |
| 695 | pos += ssh2_read_mpint(pubblob+pos, publen-pos, &n); |
| 696 | pos = 0; |
| 697 | pos += ssh2_read_mpint(privblob+pos, privlen-pos, &d); |
| 698 | pos += ssh2_read_mpint(privblob+pos, privlen-pos, &p); |
| 699 | pos += ssh2_read_mpint(privblob+pos, privlen-pos, &q); |
| 700 | pos += ssh2_read_mpint(privblob+pos, privlen-pos, &iqmp); |
| 701 | |
| 702 | assert(e.start && iqmp.start); /* can't go wrong */ |
| 703 | |
| 704 | /* We also need d mod (p-1) and d mod (q-1). */ |
| 705 | bd = bignum_from_bytes(d.start, d.bytes); |
| 706 | bp = bignum_from_bytes(p.start, p.bytes); |
| 707 | bq = bignum_from_bytes(q.start, q.bytes); |
| 708 | decbn(bp); |
| 709 | decbn(bq); |
| 710 | bdmp1 = bigmod(bd, bp); |
| 711 | bdmq1 = bigmod(bd, bq); |
| 712 | freebn(bd); |
| 713 | freebn(bp); |
| 714 | freebn(bq); |
| 715 | |
| 716 | dmp1.bytes = (bignum_bitcount(bdmp1)+8)/8; |
| 717 | dmq1.bytes = (bignum_bitcount(bdmq1)+8)/8; |
| 718 | sparelen = dmp1.bytes + dmq1.bytes; |
| 719 | spareblob = smalloc(sparelen); |
| 720 | dmp1.start = spareblob; |
| 721 | dmq1.start = spareblob + dmp1.bytes; |
| 722 | for (i = 0; i < dmp1.bytes; i++) |
| 723 | spareblob[i] = bignum_byte(bdmp1, dmp1.bytes-1 - i); |
| 724 | for (i = 0; i < dmq1.bytes; i++) |
| 725 | spareblob[i+dmp1.bytes] = bignum_byte(bdmq1, dmq1.bytes-1 - i); |
| 726 | freebn(bdmp1); |
| 727 | freebn(bdmq1); |
| 728 | |
| 729 | numbers[0].start = zero; numbers[0].bytes = 1; zero[0] = '\0'; |
| 730 | numbers[1] = n; |
| 731 | numbers[2] = e; |
| 732 | numbers[3] = d; |
| 733 | numbers[4] = p; |
| 734 | numbers[5] = q; |
| 735 | numbers[6] = dmp1; |
| 736 | numbers[7] = dmq1; |
| 737 | numbers[8] = iqmp; |
| 738 | |
| 739 | nnumbers = 9; |
| 740 | header = "-----BEGIN RSA PRIVATE KEY-----\n"; |
| 741 | footer = "-----END RSA PRIVATE KEY-----\n"; |
| 742 | } else if (key->alg == &ssh_dss) { |
| 743 | int pos; |
| 744 | struct mpint_pos p, q, g, y, x; |
| 745 | |
| 746 | pos = 4 + GET_32BIT(pubblob); |
| 747 | pos += ssh2_read_mpint(pubblob+pos, publen-pos, &p); |
| 748 | pos += ssh2_read_mpint(pubblob+pos, publen-pos, &q); |
| 749 | pos += ssh2_read_mpint(pubblob+pos, publen-pos, &g); |
| 750 | pos += ssh2_read_mpint(pubblob+pos, publen-pos, &y); |
| 751 | pos = 0; |
| 752 | pos += ssh2_read_mpint(privblob+pos, privlen-pos, &x); |
| 753 | |
| 754 | assert(y.start && x.start); /* can't go wrong */ |
| 755 | |
| 756 | numbers[0].start = zero; numbers[0].bytes = 1; zero[0] = '\0'; |
| 757 | numbers[1] = p; |
| 758 | numbers[2] = q; |
| 759 | numbers[3] = g; |
| 760 | numbers[4] = y; |
| 761 | numbers[5] = x; |
| 762 | |
| 763 | nnumbers = 6; |
| 764 | header = "-----BEGIN DSA PRIVATE KEY-----\n"; |
| 765 | footer = "-----END DSA PRIVATE KEY-----\n"; |
| 766 | } else { |
| 767 | assert(0); /* zoinks! */ |
| 768 | } |
| 769 | |
| 770 | /* |
| 771 | * Now count up the total size of the ASN.1 encoded integers, |
| 772 | * so as to determine the length of the containing SEQUENCE. |
| 773 | */ |
| 774 | len = 0; |
| 775 | for (i = 0; i < nnumbers; i++) { |
| 776 | len += ber_write_id_len(NULL, 2, numbers[i].bytes, 0); |
| 777 | len += numbers[i].bytes; |
| 778 | } |
| 779 | seqlen = len; |
| 780 | /* Now add on the SEQUENCE header. */ |
| 781 | len += ber_write_id_len(NULL, 16, seqlen, ASN1_CONSTRUCTED); |
| 782 | /* Round up to the cipher block size, ensuring we have at least one |
| 783 | * byte of padding (see below). */ |
| 784 | outlen = len; |
| 785 | if (passphrase) |
| 786 | outlen = (outlen+8) &~ 7; |
| 787 | |
| 788 | /* |
| 789 | * Now we know how big outblob needs to be. Allocate it. |
| 790 | */ |
| 791 | outblob = smalloc(outlen); |
| 792 | |
| 793 | /* |
| 794 | * And write the data into it. |
| 795 | */ |
| 796 | pos = 0; |
| 797 | pos += ber_write_id_len(outblob+pos, 16, seqlen, ASN1_CONSTRUCTED); |
| 798 | for (i = 0; i < nnumbers; i++) { |
| 799 | pos += ber_write_id_len(outblob+pos, 2, numbers[i].bytes, 0); |
| 800 | memcpy(outblob+pos, numbers[i].start, numbers[i].bytes); |
| 801 | pos += numbers[i].bytes; |
| 802 | } |
| 803 | |
| 804 | /* |
| 805 | * Padding on OpenSSH keys is deterministic. The number of |
| 806 | * padding bytes is always more than zero, and always at most |
| 807 | * the cipher block length. The value of each padding byte is |
| 808 | * equal to the number of padding bytes. So a plaintext that's |
| 809 | * an exact multiple of the block size will be padded with 08 |
| 810 | * 08 08 08 08 08 08 08 (assuming a 64-bit block cipher); a |
| 811 | * plaintext one byte less than a multiple of the block size |
| 812 | * will be padded with just 01. |
| 813 | * |
| 814 | * This enables the OpenSSL key decryption function to strip |
| 815 | * off the padding algorithmically and return the unpadded |
| 816 | * plaintext to the next layer: it looks at the final byte, and |
| 817 | * then expects to find that many bytes at the end of the data |
| 818 | * with the same value. Those are all removed and the rest is |
| 819 | * returned. |
| 820 | */ |
| 821 | assert(pos == len); |
| 822 | while (pos < outlen) { |
| 823 | outblob[pos++] = outlen - len; |
| 824 | } |
| 825 | |
| 826 | /* |
| 827 | * Encrypt the key. |
| 828 | */ |
| 829 | if (passphrase) { |
| 830 | /* |
| 831 | * Invent an iv. Then derive encryption key from passphrase |
| 832 | * and iv/salt: |
| 833 | * |
| 834 | * - let block A equal MD5(passphrase || iv) |
| 835 | * - let block B equal MD5(A || passphrase || iv) |
| 836 | * - block C would be MD5(B || passphrase || iv) and so on |
| 837 | * - encryption key is the first N bytes of A || B |
| 838 | */ |
| 839 | struct MD5Context md5c; |
| 840 | unsigned char keybuf[32]; |
| 841 | |
| 842 | for (i = 0; i < 8; i++) iv[i] = random_byte(); |
| 843 | |
| 844 | MD5Init(&md5c); |
| 845 | MD5Update(&md5c, passphrase, strlen(passphrase)); |
| 846 | MD5Update(&md5c, iv, 8); |
| 847 | MD5Final(keybuf, &md5c); |
| 848 | |
| 849 | MD5Init(&md5c); |
| 850 | MD5Update(&md5c, keybuf, 16); |
| 851 | MD5Update(&md5c, passphrase, strlen(passphrase)); |
| 852 | MD5Update(&md5c, iv, 8); |
| 853 | MD5Final(keybuf+16, &md5c); |
| 854 | |
| 855 | /* |
| 856 | * Now encrypt the key blob. |
| 857 | */ |
| 858 | des3_encrypt_pubkey_ossh(keybuf, iv, outblob, outlen); |
| 859 | |
| 860 | memset(&md5c, 0, sizeof(md5c)); |
| 861 | memset(keybuf, 0, sizeof(keybuf)); |
| 862 | } |
| 863 | |
| 864 | /* |
| 865 | * And save it. We'll use Unix line endings just in case it's |
| 866 | * subsequently transferred in binary mode. |
| 867 | */ |
| 868 | fp = fopen(filename, "wb"); /* ensure Unix line endings */ |
| 869 | if (!fp) |
| 870 | goto error; |
| 871 | fputs(header, fp); |
| 872 | if (passphrase) { |
| 873 | fprintf(fp, "Proc-Type: 4,ENCRYPTED\nDEK-Info: DES-EDE3-CBC,"); |
| 874 | for (i = 0; i < 8; i++) |
| 875 | fprintf(fp, "%02X", iv[i]); |
| 876 | fprintf(fp, "\n\n"); |
| 877 | } |
| 878 | base64_encode(fp, outblob, outlen, 64); |
| 879 | fputs(footer, fp); |
| 880 | fclose(fp); |
| 881 | ret = 1; |
| 882 | |
| 883 | error: |
| 884 | if (outblob) { |
| 885 | memset(outblob, 0, outlen); |
| 886 | sfree(outblob); |
| 887 | } |
| 888 | if (spareblob) { |
| 889 | memset(spareblob, 0, sparelen); |
| 890 | sfree(spareblob); |
| 891 | } |
| 892 | if (privblob) { |
| 893 | memset(privblob, 0, privlen); |
| 894 | sfree(privblob); |
| 895 | } |
| 896 | if (pubblob) { |
| 897 | memset(pubblob, 0, publen); |
| 898 | sfree(pubblob); |
| 899 | } |
| 900 | return ret; |
| 901 | } |
| 902 | |
| 903 | /* ---------------------------------------------------------------------- |
| 904 | * Code to read ssh.com private keys. |
| 905 | */ |
| 906 | |
| 907 | /* |
| 908 | * The format of the base64 blob is largely ssh2-packet-formatted, |
| 909 | * except that mpints are a bit different: they're more like the |
| 910 | * old ssh1 mpint. You have a 32-bit bit count N, followed by |
| 911 | * (N+7)/8 bytes of data. |
| 912 | * |
| 913 | * So. The blob contains: |
| 914 | * |
| 915 | * - uint32 0x3f6ff9eb (magic number) |
| 916 | * - uint32 size (total blob size) |
| 917 | * - string key-type (see below) |
| 918 | * - string cipher-type (tells you if key is encrypted) |
| 919 | * - string encrypted-blob |
| 920 | * |
| 921 | * (The first size field includes the size field itself and the |
| 922 | * magic number before it. All other size fields are ordinary ssh2 |
| 923 | * strings, so the size field indicates how much data is to |
| 924 | * _follow_.) |
| 925 | * |
| 926 | * The encrypted blob, once decrypted, contains a single string |
| 927 | * which in turn contains the payload. (This allows padding to be |
| 928 | * added after that string while still making it clear where the |
| 929 | * real payload ends. Also it probably makes for a reasonable |
| 930 | * decryption check.) |
| 931 | * |
| 932 | * The payload blob, for an RSA key, contains: |
| 933 | * - mpint e |
| 934 | * - mpint d |
| 935 | * - mpint n (yes, the public and private stuff is intermixed) |
| 936 | * - mpint u (presumably inverse of p mod q) |
| 937 | * - mpint p (p is the smaller prime) |
| 938 | * - mpint q (q is the larger) |
| 939 | * |
| 940 | * For a DSA key, the payload blob contains: |
| 941 | * - uint32 0 |
| 942 | * - mpint p |
| 943 | * - mpint g |
| 944 | * - mpint q |
| 945 | * - mpint y |
| 946 | * - mpint x |
| 947 | * |
| 948 | * Alternatively, if the parameters are `predefined', that |
| 949 | * (0,p,g,q) sequence can be replaced by a uint32 1 and a string |
| 950 | * containing some predefined parameter specification. *shudder*, |
| 951 | * but I doubt we'll encounter this in real life. |
| 952 | * |
| 953 | * The key type strings are ghastly. The RSA key I looked at had a |
| 954 | * type string of |
| 955 | * |
| 956 | * `if-modn{sign{rsa-pkcs1-sha1},encrypt{rsa-pkcs1v2-oaep}}' |
| 957 | * |
| 958 | * and the DSA key wasn't much better: |
| 959 | * |
| 960 | * `dl-modp{sign{dsa-nist-sha1},dh{plain}}' |
| 961 | * |
| 962 | * It isn't clear that these will always be the same. I think it |
| 963 | * might be wise just to look at the `if-modn{sign{rsa' and |
| 964 | * `dl-modp{sign{dsa' prefixes. |
| 965 | * |
| 966 | * Finally, the encryption. The cipher-type string appears to be |
| 967 | * either `none' or `3des-cbc'. Looks as if this is SSH2-style |
| 968 | * 3des-cbc (i.e. outer cbc rather than inner). The key is created |
| 969 | * from the passphrase by means of yet another hashing faff: |
| 970 | * |
| 971 | * - first 16 bytes are MD5(passphrase) |
| 972 | * - next 16 bytes are MD5(passphrase || first 16 bytes) |
| 973 | * - if there were more, they'd be MD5(passphrase || first 32), |
| 974 | * and so on. |
| 975 | */ |
| 976 | |
| 977 | #define SSHCOM_MAGIC_NUMBER 0x3f6ff9eb |
| 978 | |
| 979 | struct sshcom_key { |
| 980 | char comment[256]; /* allowing any length is overkill */ |
| 981 | unsigned char *keyblob; |
| 982 | int keyblob_len, keyblob_size; |
| 983 | }; |
| 984 | |
| 985 | struct sshcom_key *load_sshcom_key(char *filename) |
| 986 | { |
| 987 | struct sshcom_key *ret; |
| 988 | FILE *fp; |
| 989 | char buffer[256]; |
| 990 | int len; |
| 991 | char *errmsg, *p; |
| 992 | int headers_done; |
| 993 | char base64_bit[4]; |
| 994 | int base64_chars = 0; |
| 995 | |
| 996 | ret = smalloc(sizeof(*ret)); |
| 997 | ret->comment[0] = '\0'; |
| 998 | ret->keyblob = NULL; |
| 999 | ret->keyblob_len = ret->keyblob_size = 0; |
| 1000 | |
| 1001 | fp = fopen(filename, "r"); |
| 1002 | if (!fp) { |
| 1003 | errmsg = "Unable to open key file"; |
| 1004 | goto error; |
| 1005 | } |
| 1006 | if (!fgets(buffer, sizeof(buffer), fp) || |
| 1007 | 0 != strcmp(buffer, "---- BEGIN SSH2 ENCRYPTED PRIVATE KEY ----\n")) { |
| 1008 | errmsg = "File does not begin with ssh.com key header"; |
| 1009 | goto error; |
| 1010 | } |
| 1011 | |
| 1012 | headers_done = 0; |
| 1013 | while (1) { |
| 1014 | if (!fgets(buffer, sizeof(buffer), fp)) { |
| 1015 | errmsg = "Unexpected end of file"; |
| 1016 | goto error; |
| 1017 | } |
| 1018 | if (!strcmp(buffer, "---- END SSH2 ENCRYPTED PRIVATE KEY ----\n")) |
| 1019 | break; /* done */ |
| 1020 | if ((p = strchr(buffer, ':')) != NULL) { |
| 1021 | if (headers_done) { |
| 1022 | errmsg = "Header found in body of key data"; |
| 1023 | goto error; |
| 1024 | } |
| 1025 | *p++ = '\0'; |
| 1026 | while (*p && isspace((unsigned char)*p)) p++; |
| 1027 | /* |
| 1028 | * Header lines can end in a trailing backslash for |
| 1029 | * continuation. |
| 1030 | */ |
| 1031 | while ((len = strlen(p)) > (int)(sizeof(buffer) - (p-buffer) -1) || |
| 1032 | p[len-1] != '\n' || p[len-2] == '\\') { |
| 1033 | if (len > (int)((p-buffer) + sizeof(buffer)-2)) { |
| 1034 | errmsg = "Header line too long to deal with"; |
| 1035 | goto error; |
| 1036 | } |
| 1037 | if (!fgets(p+len-2, sizeof(buffer)-(p-buffer)-(len-2), fp)) { |
| 1038 | errmsg = "Unexpected end of file"; |
| 1039 | goto error; |
| 1040 | } |
| 1041 | } |
| 1042 | p[strcspn(p, "\n")] = '\0'; |
| 1043 | if (!strcmp(buffer, "Comment")) { |
| 1044 | /* Strip quotes in comment if present. */ |
| 1045 | if (p[0] == '"' && p[strlen(p)-1] == '"') { |
| 1046 | p++; |
| 1047 | p[strlen(p)-1] = '\0'; |
| 1048 | } |
| 1049 | strncpy(ret->comment, p, sizeof(ret->comment)); |
| 1050 | ret->comment[sizeof(ret->comment)-1] = '\0'; |
| 1051 | } |
| 1052 | } else { |
| 1053 | headers_done = 1; |
| 1054 | |
| 1055 | p = buffer; |
| 1056 | while (isbase64(*p)) { |
| 1057 | base64_bit[base64_chars++] = *p; |
| 1058 | if (base64_chars == 4) { |
| 1059 | unsigned char out[3]; |
| 1060 | |
| 1061 | base64_chars = 0; |
| 1062 | |
| 1063 | len = base64_decode_atom(base64_bit, out); |
| 1064 | |
| 1065 | if (len <= 0) { |
| 1066 | errmsg = "Invalid base64 encoding"; |
| 1067 | goto error; |
| 1068 | } |
| 1069 | |
| 1070 | if (ret->keyblob_len + len > ret->keyblob_size) { |
| 1071 | ret->keyblob_size = ret->keyblob_len + len + 256; |
| 1072 | ret->keyblob = srealloc(ret->keyblob, ret->keyblob_size); |
| 1073 | } |
| 1074 | |
| 1075 | memcpy(ret->keyblob + ret->keyblob_len, out, len); |
| 1076 | ret->keyblob_len += len; |
| 1077 | } |
| 1078 | |
| 1079 | p++; |
| 1080 | } |
| 1081 | } |
| 1082 | } |
| 1083 | |
| 1084 | if (ret->keyblob_len == 0 || !ret->keyblob) { |
| 1085 | errmsg = "Key body not present"; |
| 1086 | goto error; |
| 1087 | } |
| 1088 | |
| 1089 | return ret; |
| 1090 | |
| 1091 | error: |
| 1092 | if (ret) { |
| 1093 | if (ret->keyblob) { |
| 1094 | memset(ret->keyblob, 0, ret->keyblob_size); |
| 1095 | sfree(ret->keyblob); |
| 1096 | } |
| 1097 | memset(&ret, 0, sizeof(ret)); |
| 1098 | sfree(ret); |
| 1099 | } |
| 1100 | return NULL; |
| 1101 | } |
| 1102 | |
| 1103 | int sshcom_encrypted(char *filename, char **comment) |
| 1104 | { |
| 1105 | struct sshcom_key *key = load_sshcom_key(filename); |
| 1106 | int pos, len, answer; |
| 1107 | |
| 1108 | *comment = NULL; |
| 1109 | if (!key) |
| 1110 | return 0; |
| 1111 | |
| 1112 | /* |
| 1113 | * Check magic number. |
| 1114 | */ |
| 1115 | if (GET_32BIT(key->keyblob) != 0x3f6ff9eb) |
| 1116 | return 0; /* key is invalid */ |
| 1117 | |
| 1118 | /* |
| 1119 | * Find the cipher-type string. |
| 1120 | */ |
| 1121 | answer = 0; |
| 1122 | pos = 8; |
| 1123 | if (key->keyblob_len < pos+4) |
| 1124 | goto done; /* key is far too short */ |
| 1125 | pos += 4 + GET_32BIT(key->keyblob + pos); /* skip key type */ |
| 1126 | if (key->keyblob_len < pos+4) |
| 1127 | goto done; /* key is far too short */ |
| 1128 | len = GET_32BIT(key->keyblob + pos); /* find cipher-type length */ |
| 1129 | if (key->keyblob_len < pos+4+len) |
| 1130 | goto done; /* cipher type string is incomplete */ |
| 1131 | if (len != 4 || 0 != memcmp(key->keyblob + pos + 4, "none", 4)) |
| 1132 | answer = 1; |
| 1133 | |
| 1134 | done: |
| 1135 | *comment = dupstr(key->comment); |
| 1136 | memset(key->keyblob, 0, key->keyblob_size); |
| 1137 | sfree(key->keyblob); |
| 1138 | memset(&key, 0, sizeof(key)); |
| 1139 | sfree(key); |
| 1140 | return answer; |
| 1141 | } |
| 1142 | |
| 1143 | int sshcom_read_mpint(void *data, int len, struct mpint_pos *ret) |
| 1144 | { |
| 1145 | int bits; |
| 1146 | int bytes; |
| 1147 | unsigned char *d = (unsigned char *) data; |
| 1148 | |
| 1149 | if (len < 4) |
| 1150 | goto error; |
| 1151 | bits = GET_32BIT(d); |
| 1152 | |
| 1153 | bytes = (bits + 7) / 8; |
| 1154 | if (len < 4+bytes) |
| 1155 | goto error; |
| 1156 | |
| 1157 | ret->start = d + 4; |
| 1158 | ret->bytes = bytes; |
| 1159 | return bytes+4; |
| 1160 | |
| 1161 | error: |
| 1162 | ret->start = NULL; |
| 1163 | ret->bytes = -1; |
| 1164 | return len; /* ensure further calls fail as well */ |
| 1165 | } |
| 1166 | |
| 1167 | static int sshcom_put_mpint(void *target, void *data, int len) |
| 1168 | { |
| 1169 | unsigned char *d = (unsigned char *)target; |
| 1170 | unsigned char *i = (unsigned char *)data; |
| 1171 | int bits = len * 8 - 1; |
| 1172 | |
| 1173 | while (bits > 0) { |
| 1174 | if (*i & (1 << (bits & 7))) |
| 1175 | break; |
| 1176 | if (!(bits-- & 7)) |
| 1177 | i++, len--; |
| 1178 | } |
| 1179 | |
| 1180 | PUT_32BIT(d, bits+1); |
| 1181 | memcpy(d+4, i, len); |
| 1182 | return len+4; |
| 1183 | } |
| 1184 | |
| 1185 | struct ssh2_userkey *sshcom_read(char *filename, char *passphrase) |
| 1186 | { |
| 1187 | struct sshcom_key *key = load_sshcom_key(filename); |
| 1188 | char *errmsg; |
| 1189 | int pos, len; |
| 1190 | const char prefix_rsa[] = "if-modn{sign{rsa"; |
| 1191 | const char prefix_dsa[] = "dl-modp{sign{dsa"; |
| 1192 | enum { RSA, DSA } type; |
| 1193 | int encrypted; |
| 1194 | char *ciphertext; |
| 1195 | int cipherlen; |
| 1196 | struct ssh2_userkey *ret = NULL, *retkey; |
| 1197 | const struct ssh_signkey *alg; |
| 1198 | unsigned char *blob = NULL; |
| 1199 | int blobsize, publen, privlen; |
| 1200 | |
| 1201 | if (!key) |
| 1202 | return NULL; |
| 1203 | |
| 1204 | /* |
| 1205 | * Check magic number. |
| 1206 | */ |
| 1207 | if (GET_32BIT(key->keyblob) != SSHCOM_MAGIC_NUMBER) { |
| 1208 | errmsg = "Key does not begin with magic number"; |
| 1209 | goto error; |
| 1210 | } |
| 1211 | |
| 1212 | /* |
| 1213 | * Determine the key type. |
| 1214 | */ |
| 1215 | pos = 8; |
| 1216 | if (key->keyblob_len < pos+4 || |
| 1217 | (len = GET_32BIT(key->keyblob + pos)) > key->keyblob_len - pos - 4) { |
| 1218 | errmsg = "Key blob does not contain a key type string"; |
| 1219 | goto error; |
| 1220 | } |
| 1221 | if (len > sizeof(prefix_rsa) - 1 && |
| 1222 | !memcmp(key->keyblob+pos+4, prefix_rsa, sizeof(prefix_rsa) - 1)) { |
| 1223 | type = RSA; |
| 1224 | } else if (len > sizeof(prefix_dsa) - 1 && |
| 1225 | !memcmp(key->keyblob+pos+4, prefix_dsa, sizeof(prefix_dsa) - 1)) { |
| 1226 | type = DSA; |
| 1227 | } else { |
| 1228 | errmsg = "Key is of unknown type"; |
| 1229 | goto error; |
| 1230 | } |
| 1231 | pos += 4+len; |
| 1232 | |
| 1233 | /* |
| 1234 | * Determine the cipher type. |
| 1235 | */ |
| 1236 | if (key->keyblob_len < pos+4 || |
| 1237 | (len = GET_32BIT(key->keyblob + pos)) > key->keyblob_len - pos - 4) { |
| 1238 | errmsg = "Key blob does not contain a cipher type string"; |
| 1239 | goto error; |
| 1240 | } |
| 1241 | if (len == 4 && !memcmp(key->keyblob+pos+4, "none", 4)) |
| 1242 | encrypted = 0; |
| 1243 | else if (len == 8 && !memcmp(key->keyblob+pos+4, "3des-cbc", 8)) |
| 1244 | encrypted = 1; |
| 1245 | else { |
| 1246 | errmsg = "Key encryption is of unknown type"; |
| 1247 | goto error; |
| 1248 | } |
| 1249 | pos += 4+len; |
| 1250 | |
| 1251 | /* |
| 1252 | * Get hold of the encrypted part of the key. |
| 1253 | */ |
| 1254 | if (key->keyblob_len < pos+4 || |
| 1255 | (len = GET_32BIT(key->keyblob + pos)) > key->keyblob_len - pos - 4) { |
| 1256 | errmsg = "Key blob does not contain actual key data"; |
| 1257 | goto error; |
| 1258 | } |
| 1259 | ciphertext = key->keyblob + pos + 4; |
| 1260 | cipherlen = len; |
| 1261 | if (cipherlen == 0) { |
| 1262 | errmsg = "Length of key data is zero"; |
| 1263 | goto error; |
| 1264 | } |
| 1265 | |
| 1266 | /* |
| 1267 | * Decrypt it if necessary. |
| 1268 | */ |
| 1269 | if (encrypted) { |
| 1270 | /* |
| 1271 | * Derive encryption key from passphrase and iv/salt: |
| 1272 | * |
| 1273 | * - let block A equal MD5(passphrase) |
| 1274 | * - let block B equal MD5(passphrase || A) |
| 1275 | * - block C would be MD5(passphrase || A || B) and so on |
| 1276 | * - encryption key is the first N bytes of A || B |
| 1277 | */ |
| 1278 | struct MD5Context md5c; |
| 1279 | unsigned char keybuf[32], iv[8]; |
| 1280 | |
| 1281 | if (cipherlen % 8 != 0) { |
| 1282 | errmsg = "Encrypted part of key is not a multiple of cipher block" |
| 1283 | " size"; |
| 1284 | goto error; |
| 1285 | } |
| 1286 | |
| 1287 | MD5Init(&md5c); |
| 1288 | MD5Update(&md5c, passphrase, strlen(passphrase)); |
| 1289 | MD5Final(keybuf, &md5c); |
| 1290 | |
| 1291 | MD5Init(&md5c); |
| 1292 | MD5Update(&md5c, passphrase, strlen(passphrase)); |
| 1293 | MD5Update(&md5c, keybuf, 16); |
| 1294 | MD5Final(keybuf+16, &md5c); |
| 1295 | |
| 1296 | /* |
| 1297 | * Now decrypt the key blob. |
| 1298 | */ |
| 1299 | memset(iv, 0, sizeof(iv)); |
| 1300 | des3_decrypt_pubkey_ossh(keybuf, iv, ciphertext, cipherlen); |
| 1301 | |
| 1302 | memset(&md5c, 0, sizeof(md5c)); |
| 1303 | memset(keybuf, 0, sizeof(keybuf)); |
| 1304 | |
| 1305 | /* |
| 1306 | * Hereafter we return WRONG_PASSPHRASE for any parsing |
| 1307 | * error. (But only if we've just tried to decrypt it! |
| 1308 | * Returning WRONG_PASSPHRASE for an unencrypted key is |
| 1309 | * automatic doom.) |
| 1310 | */ |
| 1311 | if (encrypted) |
| 1312 | ret = SSH2_WRONG_PASSPHRASE; |
| 1313 | } |
| 1314 | |
| 1315 | /* |
| 1316 | * Strip away the containing string to get to the real meat. |
| 1317 | */ |
| 1318 | len = GET_32BIT(ciphertext); |
| 1319 | if (len > cipherlen-4) { |
| 1320 | errmsg = "containing string was ill-formed"; |
| 1321 | goto error; |
| 1322 | } |
| 1323 | ciphertext += 4; |
| 1324 | cipherlen = len; |
| 1325 | |
| 1326 | /* |
| 1327 | * Now we break down into RSA versus DSA. In either case we'll |
| 1328 | * construct public and private blobs in our own format, and |
| 1329 | * end up feeding them to alg->createkey(). |
| 1330 | */ |
| 1331 | blobsize = cipherlen + 256; |
| 1332 | blob = smalloc(blobsize); |
| 1333 | privlen = 0; |
| 1334 | if (type == RSA) { |
| 1335 | struct mpint_pos n, e, d, u, p, q; |
| 1336 | int pos = 0; |
| 1337 | pos += sshcom_read_mpint(ciphertext+pos, cipherlen-pos, &e); |
| 1338 | pos += sshcom_read_mpint(ciphertext+pos, cipherlen-pos, &d); |
| 1339 | pos += sshcom_read_mpint(ciphertext+pos, cipherlen-pos, &n); |
| 1340 | pos += sshcom_read_mpint(ciphertext+pos, cipherlen-pos, &u); |
| 1341 | pos += sshcom_read_mpint(ciphertext+pos, cipherlen-pos, &p); |
| 1342 | pos += sshcom_read_mpint(ciphertext+pos, cipherlen-pos, &q); |
| 1343 | if (!q.start) { |
| 1344 | errmsg = "key data did not contain six integers"; |
| 1345 | goto error; |
| 1346 | } |
| 1347 | |
| 1348 | alg = &ssh_rsa; |
| 1349 | pos = 0; |
| 1350 | pos += put_string(blob+pos, "ssh-rsa", 7); |
| 1351 | pos += put_mp(blob+pos, e.start, e.bytes); |
| 1352 | pos += put_mp(blob+pos, n.start, n.bytes); |
| 1353 | publen = pos; |
| 1354 | pos += put_string(blob+pos, d.start, d.bytes); |
| 1355 | pos += put_mp(blob+pos, q.start, q.bytes); |
| 1356 | pos += put_mp(blob+pos, p.start, p.bytes); |
| 1357 | pos += put_mp(blob+pos, u.start, u.bytes); |
| 1358 | privlen = pos - publen; |
| 1359 | } else if (type == DSA) { |
| 1360 | struct mpint_pos p, q, g, x, y; |
| 1361 | int pos = 4; |
| 1362 | if (GET_32BIT(ciphertext) != 0) { |
| 1363 | errmsg = "predefined DSA parameters not supported"; |
| 1364 | goto error; |
| 1365 | } |
| 1366 | pos += sshcom_read_mpint(ciphertext+pos, cipherlen-pos, &p); |
| 1367 | pos += sshcom_read_mpint(ciphertext+pos, cipherlen-pos, &g); |
| 1368 | pos += sshcom_read_mpint(ciphertext+pos, cipherlen-pos, &q); |
| 1369 | pos += sshcom_read_mpint(ciphertext+pos, cipherlen-pos, &y); |
| 1370 | pos += sshcom_read_mpint(ciphertext+pos, cipherlen-pos, &x); |
| 1371 | if (!x.start) { |
| 1372 | errmsg = "key data did not contain five integers"; |
| 1373 | goto error; |
| 1374 | } |
| 1375 | |
| 1376 | alg = &ssh_dss; |
| 1377 | pos = 0; |
| 1378 | pos += put_string(blob+pos, "ssh-dss", 7); |
| 1379 | pos += put_mp(blob+pos, p.start, p.bytes); |
| 1380 | pos += put_mp(blob+pos, q.start, q.bytes); |
| 1381 | pos += put_mp(blob+pos, g.start, g.bytes); |
| 1382 | pos += put_mp(blob+pos, y.start, y.bytes); |
| 1383 | publen = pos; |
| 1384 | pos += put_mp(blob+pos, x.start, x.bytes); |
| 1385 | privlen = pos - publen; |
| 1386 | } |
| 1387 | |
| 1388 | assert(privlen > 0); /* should have bombed by now if not */ |
| 1389 | |
| 1390 | retkey = smalloc(sizeof(struct ssh2_userkey)); |
| 1391 | retkey->alg = alg; |
| 1392 | retkey->data = alg->createkey(blob, publen, blob+publen, privlen); |
| 1393 | if (!retkey->data) { |
| 1394 | sfree(retkey); |
| 1395 | errmsg = "unable to create key data structure"; |
| 1396 | goto error; |
| 1397 | } |
| 1398 | retkey->comment = dupstr(key->comment); |
| 1399 | |
| 1400 | errmsg = NULL; /* no error */ |
| 1401 | ret = retkey; |
| 1402 | |
| 1403 | error: |
| 1404 | if (blob) { |
| 1405 | memset(blob, 0, blobsize); |
| 1406 | sfree(blob); |
| 1407 | } |
| 1408 | memset(key->keyblob, 0, key->keyblob_size); |
| 1409 | sfree(key->keyblob); |
| 1410 | memset(&key, 0, sizeof(key)); |
| 1411 | sfree(key); |
| 1412 | return ret; |
| 1413 | } |
| 1414 | |
| 1415 | int sshcom_write(char *filename, struct ssh2_userkey *key, char *passphrase) |
| 1416 | { |
| 1417 | unsigned char *pubblob, *privblob; |
| 1418 | int publen, privlen; |
| 1419 | unsigned char *outblob; |
| 1420 | int outlen; |
| 1421 | struct mpint_pos numbers[6]; |
| 1422 | int nnumbers, initial_zero, pos, lenpos, i; |
| 1423 | char *type; |
| 1424 | char *ciphertext; |
| 1425 | int cipherlen; |
| 1426 | int ret = 0; |
| 1427 | FILE *fp; |
| 1428 | |
| 1429 | /* |
| 1430 | * Fetch the key blobs. |
| 1431 | */ |
| 1432 | pubblob = key->alg->public_blob(key->data, &publen); |
| 1433 | privblob = key->alg->private_blob(key->data, &privlen); |
| 1434 | outblob = NULL; |
| 1435 | |
| 1436 | /* |
| 1437 | * Find the sequence of integers to be encoded into the OpenSSH |
| 1438 | * key blob, and also decide on the header line. |
| 1439 | */ |
| 1440 | if (key->alg == &ssh_rsa) { |
| 1441 | int pos; |
| 1442 | struct mpint_pos n, e, d, p, q, iqmp; |
| 1443 | |
| 1444 | pos = 4 + GET_32BIT(pubblob); |
| 1445 | pos += ssh2_read_mpint(pubblob+pos, publen-pos, &e); |
| 1446 | pos += ssh2_read_mpint(pubblob+pos, publen-pos, &n); |
| 1447 | pos = 0; |
| 1448 | pos += ssh2_read_mpint(privblob+pos, privlen-pos, &d); |
| 1449 | pos += ssh2_read_mpint(privblob+pos, privlen-pos, &p); |
| 1450 | pos += ssh2_read_mpint(privblob+pos, privlen-pos, &q); |
| 1451 | pos += ssh2_read_mpint(privblob+pos, privlen-pos, &iqmp); |
| 1452 | |
| 1453 | assert(e.start && iqmp.start); /* can't go wrong */ |
| 1454 | |
| 1455 | numbers[0] = e; |
| 1456 | numbers[1] = d; |
| 1457 | numbers[2] = n; |
| 1458 | numbers[3] = iqmp; |
| 1459 | numbers[4] = q; |
| 1460 | numbers[5] = p; |
| 1461 | |
| 1462 | nnumbers = 6; |
| 1463 | initial_zero = 0; |
| 1464 | type = "if-modn{sign{rsa-pkcs1-sha1},encrypt{rsa-pkcs1v2-oaep}}"; |
| 1465 | } else if (key->alg == &ssh_dss) { |
| 1466 | int pos; |
| 1467 | struct mpint_pos p, q, g, y, x; |
| 1468 | |
| 1469 | pos = 4 + GET_32BIT(pubblob); |
| 1470 | pos += ssh2_read_mpint(pubblob+pos, publen-pos, &p); |
| 1471 | pos += ssh2_read_mpint(pubblob+pos, publen-pos, &q); |
| 1472 | pos += ssh2_read_mpint(pubblob+pos, publen-pos, &g); |
| 1473 | pos += ssh2_read_mpint(pubblob+pos, publen-pos, &y); |
| 1474 | pos = 0; |
| 1475 | pos += ssh2_read_mpint(privblob+pos, privlen-pos, &x); |
| 1476 | |
| 1477 | assert(y.start && x.start); /* can't go wrong */ |
| 1478 | |
| 1479 | numbers[0] = p; |
| 1480 | numbers[1] = g; |
| 1481 | numbers[2] = q; |
| 1482 | numbers[3] = y; |
| 1483 | numbers[4] = x; |
| 1484 | |
| 1485 | nnumbers = 5; |
| 1486 | initial_zero = 1; |
| 1487 | type = "dl-modp{sign{dsa-nist-sha1},dh{plain}}"; |
| 1488 | } else { |
| 1489 | assert(0); /* zoinks! */ |
| 1490 | } |
| 1491 | |
| 1492 | /* |
| 1493 | * Total size of key blob will be somewhere under 512 plus |
| 1494 | * combined length of integers. We'll calculate the more |
| 1495 | * precise size as we construct the blob. |
| 1496 | */ |
| 1497 | outlen = 512; |
| 1498 | for (i = 0; i < nnumbers; i++) |
| 1499 | outlen += 4 + numbers[i].bytes; |
| 1500 | outblob = smalloc(outlen); |
| 1501 | |
| 1502 | /* |
| 1503 | * Create the unencrypted key blob. |
| 1504 | */ |
| 1505 | pos = 0; |
| 1506 | PUT_32BIT(outblob+pos, SSHCOM_MAGIC_NUMBER); pos += 4; |
| 1507 | pos += 4; /* length field, fill in later */ |
| 1508 | pos += put_string(outblob+pos, type, strlen(type)); |
| 1509 | { |
| 1510 | char *ciphertype = passphrase ? "3des-cbc" : "none"; |
| 1511 | pos += put_string(outblob+pos, ciphertype, strlen(ciphertype)); |
| 1512 | } |
| 1513 | lenpos = pos; /* remember this position */ |
| 1514 | pos += 4; /* encrypted-blob size */ |
| 1515 | pos += 4; /* encrypted-payload size */ |
| 1516 | if (initial_zero) { |
| 1517 | PUT_32BIT(outblob+pos, 0); |
| 1518 | pos += 4; |
| 1519 | } |
| 1520 | for (i = 0; i < nnumbers; i++) |
| 1521 | pos += sshcom_put_mpint(outblob+pos, |
| 1522 | numbers[i].start, numbers[i].bytes); |
| 1523 | /* Now wrap up the encrypted payload. */ |
| 1524 | PUT_32BIT(outblob+lenpos+4, pos - (lenpos+8)); |
| 1525 | /* Pad encrypted blob to a multiple of cipher block size. */ |
| 1526 | if (passphrase) { |
| 1527 | int padding = -(pos - (lenpos+4)) & 7; |
| 1528 | while (padding--) |
| 1529 | outblob[pos++] = random_byte(); |
| 1530 | } |
| 1531 | ciphertext = outblob+lenpos+4; |
| 1532 | cipherlen = pos - (lenpos+4); |
| 1533 | assert(!passphrase || cipherlen % 8 == 0); |
| 1534 | /* Wrap up the encrypted blob string. */ |
| 1535 | PUT_32BIT(outblob+lenpos, cipherlen); |
| 1536 | /* And finally fill in the total length field. */ |
| 1537 | PUT_32BIT(outblob+4, pos); |
| 1538 | |
| 1539 | assert(pos < outlen); |
| 1540 | |
| 1541 | /* |
| 1542 | * Encrypt the key. |
| 1543 | */ |
| 1544 | if (passphrase) { |
| 1545 | /* |
| 1546 | * Derive encryption key from passphrase and iv/salt: |
| 1547 | * |
| 1548 | * - let block A equal MD5(passphrase) |
| 1549 | * - let block B equal MD5(passphrase || A) |
| 1550 | * - block C would be MD5(passphrase || A || B) and so on |
| 1551 | * - encryption key is the first N bytes of A || B |
| 1552 | */ |
| 1553 | struct MD5Context md5c; |
| 1554 | unsigned char keybuf[32], iv[8]; |
| 1555 | |
| 1556 | MD5Init(&md5c); |
| 1557 | MD5Update(&md5c, passphrase, strlen(passphrase)); |
| 1558 | MD5Final(keybuf, &md5c); |
| 1559 | |
| 1560 | MD5Init(&md5c); |
| 1561 | MD5Update(&md5c, passphrase, strlen(passphrase)); |
| 1562 | MD5Update(&md5c, keybuf, 16); |
| 1563 | MD5Final(keybuf+16, &md5c); |
| 1564 | |
| 1565 | /* |
| 1566 | * Now decrypt the key blob. |
| 1567 | */ |
| 1568 | memset(iv, 0, sizeof(iv)); |
| 1569 | des3_encrypt_pubkey_ossh(keybuf, iv, ciphertext, cipherlen); |
| 1570 | |
| 1571 | memset(&md5c, 0, sizeof(md5c)); |
| 1572 | memset(keybuf, 0, sizeof(keybuf)); |
| 1573 | } |
| 1574 | |
| 1575 | /* |
| 1576 | * And save it. We'll use Unix line endings just in case it's |
| 1577 | * subsequently transferred in binary mode. |
| 1578 | */ |
| 1579 | fp = fopen(filename, "wb"); /* ensure Unix line endings */ |
| 1580 | if (!fp) |
| 1581 | goto error; |
| 1582 | fputs("---- BEGIN SSH2 ENCRYPTED PRIVATE KEY ----\n", fp); |
| 1583 | fprintf(fp, "Comment: \""); |
| 1584 | /* |
| 1585 | * Comment header is broken with backslash-newline if it goes |
| 1586 | * over 70 chars. Although it's surrounded by quotes, it |
| 1587 | * _doesn't_ escape backslashes or quotes within the string. |
| 1588 | * Don't ask me, I didn't design it. |
| 1589 | */ |
| 1590 | { |
| 1591 | int slen = 60; /* starts at 60 due to "Comment: " */ |
| 1592 | char *c = key->comment; |
| 1593 | while ((int)strlen(c) > slen) { |
| 1594 | fprintf(fp, "%.*s\\\n", slen, c); |
| 1595 | c += slen; |
| 1596 | slen = 70; /* allow 70 chars on subsequent lines */ |
| 1597 | } |
| 1598 | fprintf(fp, "%s\"\n", c); |
| 1599 | } |
| 1600 | base64_encode(fp, outblob, pos, 70); |
| 1601 | fputs("---- END SSH2 ENCRYPTED PRIVATE KEY ----\n", fp); |
| 1602 | fclose(fp); |
| 1603 | ret = 1; |
| 1604 | |
| 1605 | error: |
| 1606 | if (outblob) { |
| 1607 | memset(outblob, 0, outlen); |
| 1608 | sfree(outblob); |
| 1609 | } |
| 1610 | if (privblob) { |
| 1611 | memset(privblob, 0, privlen); |
| 1612 | sfree(privblob); |
| 1613 | } |
| 1614 | if (pubblob) { |
| 1615 | memset(pubblob, 0, publen); |
| 1616 | sfree(pubblob); |
| 1617 | } |
| 1618 | return ret; |
| 1619 | } |