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