| 1 | /* |
| 2 | * Generic SSH public-key handling operations. In particular, |
| 3 | * reading of SSH public-key files, and also the generic `sign' |
| 4 | * operation for ssh2 (which checks the type of the key and |
| 5 | * dispatches to the appropriate key-type specific function). |
| 6 | */ |
| 7 | |
| 8 | #include <stdio.h> |
| 9 | #include <stdlib.h> |
| 10 | #include <assert.h> |
| 11 | |
| 12 | #include "ssh.h" |
| 13 | |
| 14 | #define PUT_32BIT(cp, value) do { \ |
| 15 | (cp)[3] = (value); \ |
| 16 | (cp)[2] = (value) >> 8; \ |
| 17 | (cp)[1] = (value) >> 16; \ |
| 18 | (cp)[0] = (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 | #define rsa_signature "SSH PRIVATE KEY FILE FORMAT 1.1\n" |
| 27 | |
| 28 | #define BASE64_TOINT(x) ( (x)-'A'<26 ? (x)-'A'+0 :\ |
| 29 | (x)-'a'<26 ? (x)-'a'+26 :\ |
| 30 | (x)-'0'<10 ? (x)-'0'+52 :\ |
| 31 | (x)=='+' ? 62 : \ |
| 32 | (x)=='/' ? 63 : 0 ) |
| 33 | |
| 34 | static int loadrsakey_main(FILE *fp, struct RSAKey *key, |
| 35 | char **commentptr, char *passphrase) { |
| 36 | unsigned char buf[16384]; |
| 37 | unsigned char keybuf[16]; |
| 38 | int len; |
| 39 | int i, j, ciphertype; |
| 40 | int ret = 0; |
| 41 | struct MD5Context md5c; |
| 42 | char *comment; |
| 43 | |
| 44 | /* Slurp the whole file (minus the header) into a buffer. */ |
| 45 | len = fread(buf, 1, sizeof(buf), fp); |
| 46 | fclose(fp); |
| 47 | if (len < 0 || len == sizeof(buf)) |
| 48 | goto end; /* file too big or not read */ |
| 49 | |
| 50 | i = 0; |
| 51 | |
| 52 | /* |
| 53 | * A zero byte. (The signature includes a terminating NUL.) |
| 54 | */ |
| 55 | if (len-i < 1 || buf[i] != 0) |
| 56 | goto end; |
| 57 | i++; |
| 58 | |
| 59 | /* One byte giving encryption type, and one reserved uint32. */ |
| 60 | if (len-i < 1) |
| 61 | goto end; |
| 62 | ciphertype = buf[i]; |
| 63 | if (ciphertype != 0 && ciphertype != SSH_CIPHER_3DES) |
| 64 | goto end; |
| 65 | i++; |
| 66 | if (len-i < 4) |
| 67 | goto end; /* reserved field not present */ |
| 68 | if (buf[i] != 0 || buf[i+1] != 0 || buf[i+2] != 0 || buf[i+3] != 0) |
| 69 | goto end; /* reserved field nonzero, panic! */ |
| 70 | i += 4; |
| 71 | |
| 72 | /* Now the serious stuff. An ordinary SSH 1 public key. */ |
| 73 | i += makekey(buf+i, key, NULL, 1); |
| 74 | if (len-i < 0) |
| 75 | goto end; /* overran */ |
| 76 | |
| 77 | /* Next, the comment field. */ |
| 78 | j = GET_32BIT(buf+i); |
| 79 | i += 4; |
| 80 | if (len-i < j) goto end; |
| 81 | comment = smalloc(j+1); |
| 82 | if (comment) { |
| 83 | memcpy(comment, buf+i, j); |
| 84 | comment[j] = '\0'; |
| 85 | } |
| 86 | i += j; |
| 87 | if (commentptr) |
| 88 | *commentptr = comment; |
| 89 | if (key) |
| 90 | key->comment = comment; |
| 91 | if (!key) { |
| 92 | return ciphertype != 0; |
| 93 | } |
| 94 | |
| 95 | /* |
| 96 | * Decrypt remainder of buffer. |
| 97 | */ |
| 98 | if (ciphertype) { |
| 99 | MD5Init(&md5c); |
| 100 | MD5Update(&md5c, passphrase, strlen(passphrase)); |
| 101 | MD5Final(keybuf, &md5c); |
| 102 | des3_decrypt_pubkey(keybuf, buf+i, (len-i+7)&~7); |
| 103 | memset(keybuf, 0, sizeof(keybuf)); /* burn the evidence */ |
| 104 | } |
| 105 | |
| 106 | /* |
| 107 | * We are now in the secret part of the key. The first four |
| 108 | * bytes should be of the form a, b, a, b. |
| 109 | */ |
| 110 | if (len-i < 4) goto end; |
| 111 | if (buf[i] != buf[i+2] || buf[i+1] != buf[i+3]) { ret = -1; goto end; } |
| 112 | i += 4; |
| 113 | |
| 114 | /* |
| 115 | * After that, we have one further bignum which is our |
| 116 | * decryption exponent, and then the three auxiliary values |
| 117 | * (iqmp, q, p). |
| 118 | */ |
| 119 | i += makeprivate(buf+i, key); |
| 120 | if (len-i < 0) goto end; |
| 121 | i += ssh1_read_bignum(buf+i, &key->iqmp); |
| 122 | if (len-i < 0) goto end; |
| 123 | i += ssh1_read_bignum(buf+i, &key->q); |
| 124 | if (len-i < 0) goto end; |
| 125 | i += ssh1_read_bignum(buf+i, &key->p); |
| 126 | if (len-i < 0) goto end; |
| 127 | |
| 128 | if (!rsa_verify(key)) { |
| 129 | freersakey(key); |
| 130 | ret = 0; |
| 131 | } else |
| 132 | ret = 1; |
| 133 | |
| 134 | end: |
| 135 | memset(buf, 0, sizeof(buf)); /* burn the evidence */ |
| 136 | return ret; |
| 137 | } |
| 138 | |
| 139 | int loadrsakey(char *filename, struct RSAKey *key, char *passphrase) { |
| 140 | FILE *fp; |
| 141 | unsigned char buf[64]; |
| 142 | |
| 143 | fp = fopen(filename, "rb"); |
| 144 | if (!fp) |
| 145 | return 0; /* doesn't even exist */ |
| 146 | |
| 147 | /* |
| 148 | * Read the first line of the file and see if it's a v1 private |
| 149 | * key file. |
| 150 | */ |
| 151 | if (fgets(buf, sizeof(buf), fp) && |
| 152 | !strcmp(buf, rsa_signature)) { |
| 153 | return loadrsakey_main(fp, key, NULL, passphrase); |
| 154 | } |
| 155 | |
| 156 | /* |
| 157 | * Otherwise, we have nothing. Return empty-handed. |
| 158 | */ |
| 159 | fclose(fp); |
| 160 | return 0; |
| 161 | } |
| 162 | |
| 163 | /* |
| 164 | * See whether an RSA key is encrypted. Return its comment field as |
| 165 | * well. |
| 166 | */ |
| 167 | int rsakey_encrypted(char *filename, char **comment) { |
| 168 | FILE *fp; |
| 169 | unsigned char buf[64]; |
| 170 | |
| 171 | fp = fopen(filename, "rb"); |
| 172 | if (!fp) |
| 173 | return 0; /* doesn't even exist */ |
| 174 | |
| 175 | /* |
| 176 | * Read the first line of the file and see if it's a v1 private |
| 177 | * key file. |
| 178 | */ |
| 179 | if (fgets(buf, sizeof(buf), fp) && |
| 180 | !strcmp(buf, rsa_signature)) { |
| 181 | return loadrsakey_main(fp, NULL, comment, NULL); |
| 182 | } |
| 183 | fclose(fp); |
| 184 | return 0; /* wasn't the right kind of file */ |
| 185 | } |
| 186 | |
| 187 | /* |
| 188 | * Save an RSA key file. Return nonzero on success. |
| 189 | */ |
| 190 | int saversakey(char *filename, struct RSAKey *key, char *passphrase) { |
| 191 | unsigned char buf[16384]; |
| 192 | unsigned char keybuf[16]; |
| 193 | struct MD5Context md5c; |
| 194 | unsigned char *p, *estart; |
| 195 | FILE *fp; |
| 196 | |
| 197 | /* |
| 198 | * Write the initial signature. |
| 199 | */ |
| 200 | p = buf; |
| 201 | memcpy(p, rsa_signature, sizeof(rsa_signature)); |
| 202 | p += sizeof(rsa_signature); |
| 203 | |
| 204 | /* |
| 205 | * One byte giving encryption type, and one reserved (zero) |
| 206 | * uint32. |
| 207 | */ |
| 208 | *p++ = (passphrase ? SSH_CIPHER_3DES : 0); |
| 209 | PUT_32BIT(p, 0); p += 4; |
| 210 | |
| 211 | /* |
| 212 | * An ordinary SSH 1 public key consists of: a uint32 |
| 213 | * containing the bit count, then two bignums containing the |
| 214 | * modulus and exponent respectively. |
| 215 | */ |
| 216 | PUT_32BIT(p, bignum_bitcount(key->modulus)); p += 4; |
| 217 | p += ssh1_write_bignum(p, key->modulus); |
| 218 | p += ssh1_write_bignum(p, key->exponent); |
| 219 | |
| 220 | /* |
| 221 | * A string containing the comment field. |
| 222 | */ |
| 223 | if (key->comment) { |
| 224 | PUT_32BIT(p, strlen(key->comment)); p += 4; |
| 225 | memcpy(p, key->comment, strlen(key->comment)); |
| 226 | p += strlen(key->comment); |
| 227 | } else { |
| 228 | PUT_32BIT(p, 0); p += 4; |
| 229 | } |
| 230 | |
| 231 | /* |
| 232 | * The encrypted portion starts here. |
| 233 | */ |
| 234 | estart = p; |
| 235 | |
| 236 | /* |
| 237 | * Two bytes, then the same two bytes repeated. |
| 238 | */ |
| 239 | *p++ = random_byte(); |
| 240 | *p++ = random_byte(); |
| 241 | p[0] = p[-2]; p[1] = p[-1]; p += 2; |
| 242 | |
| 243 | /* |
| 244 | * Four more bignums: the decryption exponent, then iqmp, then |
| 245 | * q, then p. |
| 246 | */ |
| 247 | p += ssh1_write_bignum(p, key->private_exponent); |
| 248 | p += ssh1_write_bignum(p, key->iqmp); |
| 249 | p += ssh1_write_bignum(p, key->q); |
| 250 | p += ssh1_write_bignum(p, key->p); |
| 251 | |
| 252 | /* |
| 253 | * Now write zeros until the encrypted portion is a multiple of |
| 254 | * 8 bytes. |
| 255 | */ |
| 256 | while ((p-estart) % 8) |
| 257 | *p++ = '\0'; |
| 258 | |
| 259 | /* |
| 260 | * Now encrypt the encrypted portion. |
| 261 | */ |
| 262 | if (passphrase) { |
| 263 | MD5Init(&md5c); |
| 264 | MD5Update(&md5c, passphrase, strlen(passphrase)); |
| 265 | MD5Final(keybuf, &md5c); |
| 266 | des3_encrypt_pubkey(keybuf, estart, p-estart); |
| 267 | memset(keybuf, 0, sizeof(keybuf)); /* burn the evidence */ |
| 268 | } |
| 269 | |
| 270 | /* |
| 271 | * Done. Write the result to the file. |
| 272 | */ |
| 273 | fp = fopen(filename, "wb"); |
| 274 | if (fp) { |
| 275 | int ret = (fwrite(buf, 1, p-buf, fp) == (size_t)(p-buf)); |
| 276 | ret = ret && (fclose(fp) == 0); |
| 277 | return ret; |
| 278 | } else |
| 279 | return 0; |
| 280 | } |
| 281 | |
| 282 | /* ---------------------------------------------------------------------- |
| 283 | * SSH2 private key load/store functions. |
| 284 | */ |
| 285 | |
| 286 | /* |
| 287 | * PuTTY's own format for SSH2 keys is as follows: |
| 288 | * |
| 289 | * The file is text. Lines are terminated by CRLF, although CR-only |
| 290 | * and LF-only are tolerated on input. |
| 291 | * |
| 292 | * The first line says "PuTTY-User-Key-File-1: " plus the name of the |
| 293 | * algorithm ("ssh-dss", "ssh-rsa" etc. Although, of course, this |
| 294 | * being PuTTY, "ssh-dss" is not supported.) |
| 295 | * |
| 296 | * The next line says "Encryption: " plus an encryption type. |
| 297 | * Currently the only supported encryption types are "aes256-cbc" |
| 298 | * and "none". |
| 299 | * |
| 300 | * The next line says "Comment: " plus the comment string. |
| 301 | * |
| 302 | * Next there is a line saying "Public-Lines: " plus a number N. |
| 303 | * The following N lines contain a base64 encoding of the public |
| 304 | * part of the key. This is encoded as the standard SSH2 public key |
| 305 | * blob (with no initial length): so for RSA, for example, it will |
| 306 | * read |
| 307 | * |
| 308 | * string "ssh-rsa" |
| 309 | * mpint exponent |
| 310 | * mpint modulus |
| 311 | * |
| 312 | * Next, there is a line saying "Private-Lines: " plus a number N, |
| 313 | * and then N lines containing the (potentially encrypted) private |
| 314 | * part of the key. For the key type "ssh-rsa", this will be |
| 315 | * composed of |
| 316 | * |
| 317 | * mpint private_exponent |
| 318 | * mpint p (the larger of the two primes) |
| 319 | * mpint q (the smaller prime) |
| 320 | * mpint iqmp (the inverse of q modulo p) |
| 321 | * data padding (to reach a multiple of the cipher block size) |
| 322 | * |
| 323 | * Finally, there is a line saying "Private-Hash: " plus a hex |
| 324 | * representation of a SHA-1 hash of the plaintext version of the |
| 325 | * private part, including the final padding. |
| 326 | * |
| 327 | * If the key is encrypted, the encryption key is derived from the |
| 328 | * passphrase by means of a succession of SHA-1 hashes. Each hash |
| 329 | * is the hash of: |
| 330 | * |
| 331 | * uint32 sequence-number |
| 332 | * string passphrase |
| 333 | * |
| 334 | * where the sequence-number increases from zero. As many of these |
| 335 | * hashes are used as necessary. |
| 336 | * |
| 337 | * NOTE! It is important that all _public_ data can be verified |
| 338 | * with reference to the _private_ data. There exist attacks based |
| 339 | * on modifying the public key but leaving the private section |
| 340 | * intact. |
| 341 | * |
| 342 | * With RSA, this is easy: verify that n = p*q, and also verify |
| 343 | * that e*d == 1 modulo (p-1)(q-1). With DSA (if we were ever to |
| 344 | * support it), we would need to store extra data in the private |
| 345 | * section other than just x. |
| 346 | */ |
| 347 | |
| 348 | static int read_header(FILE *fp, char *header) { |
| 349 | int len = 39; |
| 350 | int c; |
| 351 | |
| 352 | while (len > 0) { |
| 353 | c = fgetc(fp); |
| 354 | if (c == '\n' || c == '\r' || c == EOF) |
| 355 | return 0; /* failure */ |
| 356 | if (c == ':') { |
| 357 | c = fgetc(fp); |
| 358 | if (c != ' ') |
| 359 | return 0; |
| 360 | *header = '\0'; |
| 361 | return 1; /* success! */ |
| 362 | } |
| 363 | if (len == 0) |
| 364 | return 0; /* failure */ |
| 365 | *header++ = c; |
| 366 | len--; |
| 367 | } |
| 368 | return 0; /* failure */ |
| 369 | } |
| 370 | |
| 371 | static char *read_body(FILE *fp) { |
| 372 | char *text; |
| 373 | int len; |
| 374 | int size; |
| 375 | int c; |
| 376 | |
| 377 | size = 128; |
| 378 | text = smalloc(size); |
| 379 | len = 0; |
| 380 | text[len] = '\0'; |
| 381 | |
| 382 | while (1) { |
| 383 | c = fgetc(fp); |
| 384 | if (c == '\r' || c == '\n') { |
| 385 | c = fgetc(fp); |
| 386 | if (c != '\r' && c != '\n' && c != EOF) |
| 387 | ungetc(c, fp); |
| 388 | return text; |
| 389 | } |
| 390 | if (c == EOF) { |
| 391 | sfree(text); |
| 392 | return NULL; |
| 393 | } |
| 394 | if (len + 1 > size) { |
| 395 | size += 128; |
| 396 | text = srealloc(text, size); |
| 397 | } |
| 398 | text[len++] = c; |
| 399 | text[len] = '\0'; |
| 400 | } |
| 401 | } |
| 402 | |
| 403 | int base64_decode_atom(char *atom, unsigned char *out) { |
| 404 | int vals[4]; |
| 405 | int i, v, len; |
| 406 | unsigned word; |
| 407 | char c; |
| 408 | |
| 409 | for (i = 0; i < 4; i++) { |
| 410 | c = atom[i]; |
| 411 | if (c >= 'A' && c <= 'Z') |
| 412 | v = c - 'A'; |
| 413 | else if (c >= 'a' && c <= 'z') |
| 414 | v = c - 'a' + 26; |
| 415 | else if (c >= '0' && c <= '9') |
| 416 | v = c - '0' + 52; |
| 417 | else if (c == '+') |
| 418 | v = 62; |
| 419 | else if (c == '/') |
| 420 | v = 63; |
| 421 | else if (c == '=') |
| 422 | v = -1; |
| 423 | else |
| 424 | return 0; /* invalid atom */ |
| 425 | vals[i] = v; |
| 426 | } |
| 427 | |
| 428 | if (vals[0] == -1 || vals[1] == -1) |
| 429 | return 0; |
| 430 | if (vals[2] == -1 && vals[3] != -1) |
| 431 | return 0; |
| 432 | |
| 433 | if (vals[3] != -1) |
| 434 | len = 3; |
| 435 | else if (vals[2] != -1) |
| 436 | len = 2; |
| 437 | else |
| 438 | len = 1; |
| 439 | |
| 440 | word = ((vals[0] << 18) | |
| 441 | (vals[1] << 12) | |
| 442 | ((vals[2] & 0x3F) << 6) | |
| 443 | (vals[3] & 0x3F)); |
| 444 | out[0] = (word >> 16) & 0xFF; |
| 445 | if (len > 1) |
| 446 | out[1] = (word >> 8) & 0xFF; |
| 447 | if (len > 2) |
| 448 | out[2] = word & 0xFF; |
| 449 | return len; |
| 450 | } |
| 451 | |
| 452 | static char *read_blob(FILE *fp, int nlines, int *bloblen) { |
| 453 | unsigned char *blob; |
| 454 | char *line; |
| 455 | int linelen, len; |
| 456 | int i, j, k; |
| 457 | |
| 458 | /* We expect at most 64 base64 characters, ie 48 real bytes, per line. */ |
| 459 | blob = smalloc(48 * nlines); |
| 460 | len = 0; |
| 461 | for (i = 0; i < nlines; i++) { |
| 462 | line = read_body(fp); |
| 463 | if (!line) { |
| 464 | sfree(blob); |
| 465 | return NULL; |
| 466 | } |
| 467 | linelen = strlen(line); |
| 468 | if (linelen % 4 != 0 || linelen > 64) { |
| 469 | sfree(blob); |
| 470 | sfree(line); |
| 471 | return NULL; |
| 472 | } |
| 473 | for (j = 0; j < linelen; j += 4) { |
| 474 | k = base64_decode_atom(line+j, blob+len); |
| 475 | if (!k) { |
| 476 | sfree(line); |
| 477 | sfree(blob); |
| 478 | return NULL; |
| 479 | } |
| 480 | len += k; |
| 481 | } |
| 482 | sfree(line); |
| 483 | } |
| 484 | *bloblen = len; |
| 485 | return blob; |
| 486 | } |
| 487 | |
| 488 | /* |
| 489 | * Magic error return value for when the passphrase is wrong. |
| 490 | */ |
| 491 | struct ssh2_userkey ssh2_wrong_passphrase = { |
| 492 | NULL, NULL, NULL |
| 493 | }; |
| 494 | |
| 495 | struct ssh2_userkey *ssh2_load_userkey(char *filename, char *passphrase) { |
| 496 | FILE *fp; |
| 497 | char header[40], *b, *comment, *hash; |
| 498 | const struct ssh_signkey *alg; |
| 499 | struct ssh2_userkey *ret; |
| 500 | int cipher, cipherblk; |
| 501 | unsigned char *public_blob, *private_blob; |
| 502 | int public_blob_len, private_blob_len; |
| 503 | int i; |
| 504 | |
| 505 | ret = NULL; /* return NULL for most errors */ |
| 506 | comment = hash = NULL; |
| 507 | public_blob = private_blob = NULL; |
| 508 | |
| 509 | fp = fopen(filename, "rb"); |
| 510 | if (!fp) |
| 511 | goto error; |
| 512 | |
| 513 | /* Read the first header line which contains the key type. */ |
| 514 | if (!read_header(fp, header) || 0!=strcmp(header, "PuTTY-User-Key-File-1")) |
| 515 | goto error; |
| 516 | if ((b = read_body(fp)) == NULL) |
| 517 | goto error; |
| 518 | /* Select key algorithm structure. Currently only ssh-rsa. */ |
| 519 | if (!strcmp(b, "ssh-rsa")) |
| 520 | alg = &ssh_rsa; |
| 521 | else { |
| 522 | sfree(b); |
| 523 | goto error; |
| 524 | } |
| 525 | sfree(b); |
| 526 | |
| 527 | /* Read the Encryption header line. */ |
| 528 | if (!read_header(fp, header) || 0!=strcmp(header, "Encryption")) |
| 529 | goto error; |
| 530 | if ((b = read_body(fp)) == NULL) |
| 531 | goto error; |
| 532 | if (!strcmp(b, "aes256-cbc")) { |
| 533 | cipher = 1; cipherblk = 16; |
| 534 | } else if (!strcmp(b, "none")) { |
| 535 | cipher = 0; cipherblk = 1; |
| 536 | } else { |
| 537 | sfree(b); |
| 538 | goto error; |
| 539 | } |
| 540 | sfree(b); |
| 541 | |
| 542 | /* Read the Comment header line. */ |
| 543 | if (!read_header(fp, header) || 0!=strcmp(header, "Comment")) |
| 544 | goto error; |
| 545 | if ((comment = read_body(fp)) == NULL) |
| 546 | goto error; |
| 547 | |
| 548 | /* Read the Public-Lines header line and the public blob. */ |
| 549 | if (!read_header(fp, header) || 0!=strcmp(header, "Public-Lines")) |
| 550 | goto error; |
| 551 | if ((b = read_body(fp)) == NULL) |
| 552 | goto error; |
| 553 | i = atoi(b); |
| 554 | sfree(b); |
| 555 | if ((public_blob = read_blob(fp, i, &public_blob_len)) == NULL) |
| 556 | goto error; |
| 557 | |
| 558 | /* Read the Private-Lines header line and the Private blob. */ |
| 559 | if (!read_header(fp, header) || 0!=strcmp(header, "Private-Lines")) |
| 560 | goto error; |
| 561 | if ((b = read_body(fp)) == NULL) |
| 562 | goto error; |
| 563 | i = atoi(b); |
| 564 | sfree(b); |
| 565 | if ((private_blob = read_blob(fp, i, &private_blob_len)) == NULL) |
| 566 | goto error; |
| 567 | |
| 568 | /* Read the Private-Hash header line. */ |
| 569 | if (!read_header(fp, header) || 0!=strcmp(header, "Private-Hash")) |
| 570 | goto error; |
| 571 | if ((hash = read_body(fp)) == NULL) |
| 572 | goto error; |
| 573 | |
| 574 | fclose(fp); |
| 575 | fp = NULL; |
| 576 | |
| 577 | /* |
| 578 | * Decrypt the private blob. |
| 579 | */ |
| 580 | if (cipher) { |
| 581 | unsigned char key[40]; |
| 582 | SHA_State s; |
| 583 | int passlen; |
| 584 | |
| 585 | if (!passphrase) |
| 586 | goto error; |
| 587 | if (private_blob_len % cipherblk) |
| 588 | goto error; |
| 589 | |
| 590 | passlen = strlen(passphrase); |
| 591 | |
| 592 | SHA_Init(&s); |
| 593 | SHA_Bytes(&s, "\0\0\0\0", 4); |
| 594 | SHA_Bytes(&s, passphrase, passlen); |
| 595 | SHA_Final(&s, key+0); |
| 596 | SHA_Init(&s); |
| 597 | SHA_Bytes(&s, "\0\0\0\1", 4); |
| 598 | SHA_Bytes(&s, passphrase, passlen); |
| 599 | SHA_Final(&s, key+20); |
| 600 | aes256_decrypt_pubkey(key, private_blob, private_blob_len); |
| 601 | } |
| 602 | |
| 603 | /* |
| 604 | * Verify the private hash. |
| 605 | */ |
| 606 | { |
| 607 | char realhash[41]; |
| 608 | unsigned char binary[20]; |
| 609 | |
| 610 | SHA_Simple(private_blob, private_blob_len, binary); |
| 611 | for (i = 0; i < 20; i++) |
| 612 | sprintf(realhash+2*i, "%02x", binary[i]); |
| 613 | |
| 614 | if (strcmp(hash, realhash)) { |
| 615 | /* An incorrect hash is an unconditional Error if the key is |
| 616 | * unencrypted. Otherwise, it means Wrong Passphrase. */ |
| 617 | ret = cipher ? SSH2_WRONG_PASSPHRASE : NULL; |
| 618 | goto error; |
| 619 | } |
| 620 | } |
| 621 | sfree(hash); |
| 622 | |
| 623 | /* |
| 624 | * Create and return the key. |
| 625 | */ |
| 626 | ret = smalloc(sizeof(struct ssh2_userkey)); |
| 627 | ret->alg = alg; |
| 628 | ret->comment = comment; |
| 629 | ret->data = alg->createkey(public_blob, public_blob_len, |
| 630 | private_blob, private_blob_len); |
| 631 | if (!ret->data) { |
| 632 | sfree(ret->comment); |
| 633 | sfree(ret); |
| 634 | ret = NULL; |
| 635 | } |
| 636 | sfree(public_blob); |
| 637 | sfree(private_blob); |
| 638 | return ret; |
| 639 | |
| 640 | /* |
| 641 | * Error processing. |
| 642 | */ |
| 643 | error: |
| 644 | if (fp) fclose(fp); |
| 645 | if (comment) sfree(comment); |
| 646 | if (hash) sfree(hash); |
| 647 | if (public_blob) sfree(public_blob); |
| 648 | if (private_blob) sfree(private_blob); |
| 649 | return ret; |
| 650 | } |
| 651 | |
| 652 | char *ssh2_userkey_loadpub(char *filename, char **algorithm, int *pub_blob_len) { |
| 653 | FILE *fp; |
| 654 | char header[40], *b; |
| 655 | const struct ssh_signkey *alg; |
| 656 | unsigned char *public_blob; |
| 657 | int public_blob_len; |
| 658 | int i; |
| 659 | |
| 660 | public_blob = NULL; |
| 661 | |
| 662 | fp = fopen(filename, "rb"); |
| 663 | if (!fp) |
| 664 | goto error; |
| 665 | |
| 666 | /* Read the first header line which contains the key type. */ |
| 667 | if (!read_header(fp, header) || 0!=strcmp(header, "PuTTY-User-Key-File-1")) |
| 668 | goto error; |
| 669 | if ((b = read_body(fp)) == NULL) |
| 670 | goto error; |
| 671 | /* Select key algorithm structure. Currently only ssh-rsa. */ |
| 672 | if (!strcmp(b, "ssh-rsa")) |
| 673 | alg = &ssh_rsa; |
| 674 | else { |
| 675 | sfree(b); |
| 676 | goto error; |
| 677 | } |
| 678 | sfree(b); |
| 679 | |
| 680 | /* Read the Encryption header line. */ |
| 681 | if (!read_header(fp, header) || 0!=strcmp(header, "Encryption")) |
| 682 | goto error; |
| 683 | if ((b = read_body(fp)) == NULL) |
| 684 | goto error; |
| 685 | sfree(b); /* we don't care */ |
| 686 | |
| 687 | /* Read the Comment header line. */ |
| 688 | if (!read_header(fp, header) || 0!=strcmp(header, "Comment")) |
| 689 | goto error; |
| 690 | if ((b = read_body(fp)) == NULL) |
| 691 | goto error; |
| 692 | sfree(b); /* we don't care */ |
| 693 | |
| 694 | /* Read the Public-Lines header line and the public blob. */ |
| 695 | if (!read_header(fp, header) || 0!=strcmp(header, "Public-Lines")) |
| 696 | goto error; |
| 697 | if ((b = read_body(fp)) == NULL) |
| 698 | goto error; |
| 699 | i = atoi(b); |
| 700 | sfree(b); |
| 701 | if ((public_blob = read_blob(fp, i, &public_blob_len)) == NULL) |
| 702 | goto error; |
| 703 | |
| 704 | fclose(fp); |
| 705 | *pub_blob_len = public_blob_len; |
| 706 | *algorithm = alg->name; |
| 707 | return public_blob; |
| 708 | |
| 709 | /* |
| 710 | * Error processing. |
| 711 | */ |
| 712 | error: |
| 713 | if (fp) fclose(fp); |
| 714 | if (public_blob) sfree(public_blob); |
| 715 | return NULL; |
| 716 | } |
| 717 | |
| 718 | int ssh2_userkey_encrypted(char *filename, char **commentptr) { |
| 719 | FILE *fp; |
| 720 | char header[40], *b, *comment; |
| 721 | int ret; |
| 722 | |
| 723 | if (commentptr) *commentptr = NULL; |
| 724 | |
| 725 | fp = fopen(filename, "rb"); |
| 726 | if (!fp) |
| 727 | return 0; |
| 728 | if (!read_header(fp, header) || 0!=strcmp(header, "PuTTY-User-Key-File-1")) { |
| 729 | fclose(fp); return 0; |
| 730 | } |
| 731 | if ((b = read_body(fp)) == NULL) { |
| 732 | fclose(fp); return 0; |
| 733 | } |
| 734 | sfree(b); /* we don't care about key type here */ |
| 735 | /* Read the Encryption header line. */ |
| 736 | if (!read_header(fp, header) || 0!=strcmp(header, "Encryption")) { |
| 737 | fclose(fp); return 0; |
| 738 | } |
| 739 | if ((b = read_body(fp)) == NULL) { |
| 740 | fclose(fp); return 0; |
| 741 | } |
| 742 | |
| 743 | /* Read the Comment header line. */ |
| 744 | if (!read_header(fp, header) || 0!=strcmp(header, "Comment")) { |
| 745 | fclose(fp); sfree(b); return 1; |
| 746 | } |
| 747 | if ((comment = read_body(fp)) == NULL) { |
| 748 | fclose(fp); sfree(b); return 1; |
| 749 | } |
| 750 | |
| 751 | if (commentptr) *commentptr = comment; |
| 752 | |
| 753 | fclose(fp); |
| 754 | if (!strcmp(b, "aes256-cbc")) |
| 755 | ret = 1; |
| 756 | else |
| 757 | ret = 0; |
| 758 | sfree(b); |
| 759 | return ret; |
| 760 | } |
| 761 | |
| 762 | int base64_lines(int datalen) { |
| 763 | /* When encoding, we use 64 chars/line, which equals 48 real chars. */ |
| 764 | return (datalen+47) / 48; |
| 765 | } |
| 766 | |
| 767 | void base64_encode_atom(unsigned char *data, int n, char *out) { |
| 768 | static const char base64_chars[] = |
| 769 | "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/"; |
| 770 | |
| 771 | unsigned word; |
| 772 | |
| 773 | word = data[0] << 16; |
| 774 | if (n > 1) |
| 775 | word |= data[1] << 8; |
| 776 | if (n > 2) |
| 777 | word |= data[2]; |
| 778 | out[0] = base64_chars[(word >> 18) & 0x3F]; |
| 779 | out[1] = base64_chars[(word >> 12) & 0x3F]; |
| 780 | if (n > 1) |
| 781 | out[2] = base64_chars[(word >> 6) & 0x3F]; |
| 782 | else |
| 783 | out[2] = '='; |
| 784 | if (n > 2) |
| 785 | out[3] = base64_chars[word & 0x3F]; |
| 786 | else |
| 787 | out[3] = '='; |
| 788 | } |
| 789 | |
| 790 | void base64_encode(FILE *fp, unsigned char *data, int datalen) { |
| 791 | int linelen = 0; |
| 792 | char out[4]; |
| 793 | int n; |
| 794 | |
| 795 | while (datalen > 0) { |
| 796 | if (linelen >= 64) { |
| 797 | linelen = 0; |
| 798 | fputc('\n', fp); |
| 799 | } |
| 800 | n = (datalen < 3 ? datalen : 3); |
| 801 | base64_encode_atom(data, n, out); |
| 802 | data += n; |
| 803 | datalen -= n; |
| 804 | fwrite(out, 1, 4, fp); |
| 805 | linelen += 4; |
| 806 | } |
| 807 | fputc('\n', fp); |
| 808 | } |
| 809 | |
| 810 | int ssh2_save_userkey(char *filename, struct ssh2_userkey *key, char *passphrase) { |
| 811 | FILE *fp; |
| 812 | unsigned char *pub_blob, *priv_blob, *priv_blob_encrypted; |
| 813 | int pub_blob_len, priv_blob_len, priv_encrypted_len; |
| 814 | int passlen; |
| 815 | int cipherblk; |
| 816 | int i; |
| 817 | char *cipherstr; |
| 818 | unsigned char priv_hash[20]; |
| 819 | |
| 820 | /* |
| 821 | * Fetch the key component blobs. |
| 822 | */ |
| 823 | pub_blob = key->alg->public_blob(key->data, &pub_blob_len); |
| 824 | priv_blob = key->alg->private_blob(key->data, &priv_blob_len); |
| 825 | if (!pub_blob || !priv_blob) { |
| 826 | sfree(pub_blob); |
| 827 | sfree(priv_blob); |
| 828 | return 0; |
| 829 | } |
| 830 | |
| 831 | /* |
| 832 | * Determine encryption details, and encrypt the private blob. |
| 833 | */ |
| 834 | if (passphrase) { |
| 835 | cipherstr = "aes256-cbc"; |
| 836 | cipherblk = 16; |
| 837 | } else { |
| 838 | cipherstr = "none"; |
| 839 | cipherblk = 1; |
| 840 | } |
| 841 | priv_encrypted_len = priv_blob_len + cipherblk - 1; |
| 842 | priv_encrypted_len -= priv_encrypted_len % cipherblk; |
| 843 | priv_blob_encrypted = smalloc(priv_encrypted_len); |
| 844 | memset(priv_blob_encrypted, 0, priv_encrypted_len); |
| 845 | memcpy(priv_blob_encrypted, priv_blob, priv_blob_len); |
| 846 | /* Create padding based on the SHA hash of the unpadded blob. This prevents |
| 847 | * too easy a known-plaintext attack on the last block. */ |
| 848 | SHA_Simple(priv_blob, priv_blob_len, priv_hash); |
| 849 | assert(priv_encrypted_len - priv_blob_len < 20); |
| 850 | memcpy(priv_blob_encrypted + priv_blob_len, priv_hash, |
| 851 | priv_encrypted_len - priv_blob_len); |
| 852 | |
| 853 | /* Now create the _real_ private hash. */ |
| 854 | SHA_Simple(priv_blob_encrypted, priv_encrypted_len, priv_hash); |
| 855 | |
| 856 | if (passphrase) { |
| 857 | char key[40]; |
| 858 | SHA_State s; |
| 859 | |
| 860 | passlen = strlen(passphrase); |
| 861 | |
| 862 | SHA_Init(&s); |
| 863 | SHA_Bytes(&s, "\0\0\0\0", 4); |
| 864 | SHA_Bytes(&s, passphrase, passlen); |
| 865 | SHA_Final(&s, key+0); |
| 866 | SHA_Init(&s); |
| 867 | SHA_Bytes(&s, "\0\0\0\1", 4); |
| 868 | SHA_Bytes(&s, passphrase, passlen); |
| 869 | SHA_Final(&s, key+20); |
| 870 | aes256_encrypt_pubkey(key, priv_blob_encrypted, priv_encrypted_len); |
| 871 | } |
| 872 | |
| 873 | fp = fopen(filename, "w"); |
| 874 | if (!fp) |
| 875 | return 0; |
| 876 | fprintf(fp, "PuTTY-User-Key-File-1: %s\n", key->alg->name); |
| 877 | fprintf(fp, "Encryption: %s\n", cipherstr); |
| 878 | fprintf(fp, "Comment: %s\n", key->comment); |
| 879 | fprintf(fp, "Public-Lines: %d\n", base64_lines(pub_blob_len)); |
| 880 | base64_encode(fp, pub_blob, pub_blob_len); |
| 881 | fprintf(fp, "Private-Lines: %d\n", base64_lines(priv_encrypted_len)); |
| 882 | base64_encode(fp, priv_blob_encrypted, priv_encrypted_len); |
| 883 | fprintf(fp, "Private-Hash: "); |
| 884 | for (i = 0; i < 20; i++) |
| 885 | fprintf(fp, "%02x", priv_hash[i]); |
| 886 | fprintf(fp, "\n"); |
| 887 | fclose(fp); |
| 888 | return 1; |
| 889 | } |
| 890 | |
| 891 | /* ---------------------------------------------------------------------- |
| 892 | * A function to determine which version of SSH to try on a private |
| 893 | * key file. Returns 0 on failure, 1 or 2 on success. |
| 894 | */ |
| 895 | int keyfile_version(char *filename) { |
| 896 | FILE *fp; |
| 897 | int i; |
| 898 | |
| 899 | fp = fopen(filename, "r"); |
| 900 | if (!fp) |
| 901 | return 0; |
| 902 | i = fgetc(fp); |
| 903 | fclose(fp); |
| 904 | if (i == 'S') |
| 905 | return 1; /* "SSH PRIVATE KEY FORMAT" etc */ |
| 906 | if (i == 'P') /* "PuTTY-User-Key-File" etc */ |
| 907 | return 2; |
| 908 | return 0; /* unrecognised or EOF */ |
| 909 | } |