| 1 | /* |
| 2 | * RSA implementation just sufficient for ssh client-side |
| 3 | * initialisation step |
| 4 | * |
| 5 | * Rewritten for more speed by Joris van Rantwijk, Jun 1999. |
| 6 | */ |
| 7 | |
| 8 | #include <stdio.h> |
| 9 | #include <stdlib.h> |
| 10 | #include <string.h> |
| 11 | #include <assert.h> |
| 12 | |
| 13 | #include "ssh.h" |
| 14 | |
| 15 | |
| 16 | int makekey(unsigned char *data, struct RSAKey *result, |
| 17 | unsigned char **keystr, int order) { |
| 18 | unsigned char *p = data; |
| 19 | int i; |
| 20 | |
| 21 | if (result) { |
| 22 | result->bits = 0; |
| 23 | for (i=0; i<4; i++) |
| 24 | result->bits = (result->bits << 8) + *p++; |
| 25 | } else |
| 26 | p += 4; |
| 27 | |
| 28 | /* |
| 29 | * order=0 means exponent then modulus (the keys sent by the |
| 30 | * server). order=1 means modulus then exponent (the keys |
| 31 | * stored in a keyfile). |
| 32 | */ |
| 33 | |
| 34 | if (order == 0) |
| 35 | p += ssh1_read_bignum(p, result ? &result->exponent : NULL); |
| 36 | if (result) |
| 37 | result->bytes = (((p[0] << 8) + p[1]) + 7) / 8; |
| 38 | if (keystr) *keystr = p+2; |
| 39 | p += ssh1_read_bignum(p, result ? &result->modulus : NULL); |
| 40 | if (order == 1) |
| 41 | p += ssh1_read_bignum(p, result ? &result->exponent : NULL); |
| 42 | |
| 43 | return p - data; |
| 44 | } |
| 45 | |
| 46 | int makeprivate(unsigned char *data, struct RSAKey *result) { |
| 47 | return ssh1_read_bignum(data, &result->private_exponent); |
| 48 | } |
| 49 | |
| 50 | void rsaencrypt(unsigned char *data, int length, struct RSAKey *key) { |
| 51 | Bignum b1, b2; |
| 52 | int i; |
| 53 | unsigned char *p; |
| 54 | |
| 55 | memmove(data+key->bytes-length, data, length); |
| 56 | data[0] = 0; |
| 57 | data[1] = 2; |
| 58 | |
| 59 | for (i = 2; i < key->bytes-length-1; i++) { |
| 60 | do { |
| 61 | data[i] = random_byte(); |
| 62 | } while (data[i] == 0); |
| 63 | } |
| 64 | data[key->bytes-length-1] = 0; |
| 65 | |
| 66 | b1 = bignum_from_bytes(data, key->bytes); |
| 67 | |
| 68 | b2 = modpow(b1, key->exponent, key->modulus); |
| 69 | |
| 70 | p = data; |
| 71 | for (i=key->bytes; i-- ;) { |
| 72 | *p++ = bignum_byte(b2, i); |
| 73 | } |
| 74 | |
| 75 | freebn(b1); |
| 76 | freebn(b2); |
| 77 | } |
| 78 | |
| 79 | Bignum rsadecrypt(Bignum input, struct RSAKey *key) { |
| 80 | Bignum ret; |
| 81 | ret = modpow(input, key->private_exponent, key->modulus); |
| 82 | return ret; |
| 83 | } |
| 84 | |
| 85 | int rsastr_len(struct RSAKey *key) { |
| 86 | Bignum md, ex; |
| 87 | int mdlen, exlen; |
| 88 | |
| 89 | md = key->modulus; |
| 90 | ex = key->exponent; |
| 91 | mdlen = (bignum_bitcount(md)+15) / 16; |
| 92 | exlen = (bignum_bitcount(ex)+15) / 16; |
| 93 | return 4 * (mdlen+exlen) + 20; |
| 94 | } |
| 95 | |
| 96 | void rsastr_fmt(char *str, struct RSAKey *key) { |
| 97 | Bignum md, ex; |
| 98 | int len = 0, i, nibbles; |
| 99 | static const char hex[] = "0123456789abcdef"; |
| 100 | |
| 101 | md = key->modulus; |
| 102 | ex = key->exponent; |
| 103 | |
| 104 | len += sprintf(str+len, "0x"); |
| 105 | |
| 106 | nibbles = (3 + bignum_bitcount(ex))/4; if (nibbles<1) nibbles=1; |
| 107 | for (i=nibbles; i-- ;) |
| 108 | str[len++] = hex[(bignum_byte(ex, i/2) >> (4*(i%2))) & 0xF]; |
| 109 | |
| 110 | len += sprintf(str+len, ",0x"); |
| 111 | |
| 112 | nibbles = (3 + bignum_bitcount(md))/4; if (nibbles<1) nibbles=1; |
| 113 | for (i=nibbles; i-- ;) |
| 114 | str[len++] = hex[(bignum_byte(md, i/2) >> (4*(i%2))) & 0xF]; |
| 115 | |
| 116 | str[len] = '\0'; |
| 117 | } |
| 118 | |
| 119 | /* |
| 120 | * Generate a fingerprint string for the key. Compatible with the |
| 121 | * OpenSSH fingerprint code. |
| 122 | */ |
| 123 | void rsa_fingerprint(char *str, int len, struct RSAKey *key) { |
| 124 | struct MD5Context md5c; |
| 125 | unsigned char digest[16]; |
| 126 | char buffer[16*3+40]; |
| 127 | int numlen, slen, i; |
| 128 | |
| 129 | MD5Init(&md5c); |
| 130 | numlen = ssh1_bignum_length(key->modulus) - 2; |
| 131 | for (i = numlen; i-- ;) { |
| 132 | unsigned char c = bignum_byte(key->modulus, i); |
| 133 | MD5Update(&md5c, &c, 1); |
| 134 | } |
| 135 | numlen = ssh1_bignum_length(key->exponent) - 2; |
| 136 | for (i = numlen; i-- ;) { |
| 137 | unsigned char c = bignum_byte(key->exponent, i); |
| 138 | MD5Update(&md5c, &c, 1); |
| 139 | } |
| 140 | MD5Final(digest, &md5c); |
| 141 | |
| 142 | sprintf(buffer, "%d ", bignum_bitcount(key->modulus)); |
| 143 | for (i = 0; i < 16; i++) |
| 144 | sprintf(buffer+strlen(buffer), "%s%02x", i?":":"", digest[i]); |
| 145 | strncpy(str, buffer, len); str[len-1] = '\0'; |
| 146 | slen = strlen(str); |
| 147 | if (key->comment && slen < len-1) { |
| 148 | str[slen] = ' '; |
| 149 | strncpy(str+slen+1, key->comment, len-slen-1); |
| 150 | str[len-1] = '\0'; |
| 151 | } |
| 152 | } |
| 153 | |
| 154 | /* |
| 155 | * Verify that the public data in an RSA key matches the private |
| 156 | * data. We also check the private data itself: we ensure that p > |
| 157 | * q and that iqmp really is the inverse of q mod p. |
| 158 | */ |
| 159 | int rsa_verify(struct RSAKey *key) { |
| 160 | Bignum n, ed, pm1, qm1; |
| 161 | int cmp; |
| 162 | |
| 163 | /* n must equal pq. */ |
| 164 | n = bigmul(key->p, key->q); |
| 165 | cmp = bignum_cmp(n, key->modulus); |
| 166 | freebn(n); |
| 167 | if (cmp != 0) |
| 168 | return 0; |
| 169 | |
| 170 | /* e * d must be congruent to 1, modulo (p-1) and modulo (q-1). */ |
| 171 | pm1 = copybn(key->p); |
| 172 | decbn(pm1); |
| 173 | ed = modmul(key->exponent, key->private_exponent, pm1); |
| 174 | cmp = bignum_cmp(ed, One); |
| 175 | sfree(ed); |
| 176 | if (cmp != 0) |
| 177 | return 0; |
| 178 | |
| 179 | qm1 = copybn(key->q); |
| 180 | decbn(qm1); |
| 181 | ed = modmul(key->exponent, key->private_exponent, qm1); |
| 182 | cmp = bignum_cmp(ed, One); |
| 183 | sfree(ed); |
| 184 | if (cmp != 0) |
| 185 | return 0; |
| 186 | |
| 187 | /* |
| 188 | * Ensure p > q. |
| 189 | */ |
| 190 | if (bignum_cmp(key->p, key->q) <= 0) |
| 191 | return 0; |
| 192 | |
| 193 | /* |
| 194 | * Ensure iqmp * q is congruent to 1, modulo p. |
| 195 | */ |
| 196 | n = modmul(key->iqmp, key->q, key->p); |
| 197 | cmp = bignum_cmp(n, One); |
| 198 | sfree(n); |
| 199 | if (cmp != 0) |
| 200 | return 0; |
| 201 | |
| 202 | return 1; |
| 203 | } |
| 204 | |
| 205 | void freersakey(struct RSAKey *key) { |
| 206 | if (key->modulus) freebn(key->modulus); |
| 207 | if (key->exponent) freebn(key->exponent); |
| 208 | if (key->private_exponent) freebn(key->private_exponent); |
| 209 | if (key->comment) sfree(key->comment); |
| 210 | } |
| 211 | |
| 212 | /* ---------------------------------------------------------------------- |
| 213 | * Implementation of the ssh-rsa signing key type. |
| 214 | */ |
| 215 | |
| 216 | #define GET_32BIT(cp) \ |
| 217 | (((unsigned long)(unsigned char)(cp)[0] << 24) | \ |
| 218 | ((unsigned long)(unsigned char)(cp)[1] << 16) | \ |
| 219 | ((unsigned long)(unsigned char)(cp)[2] << 8) | \ |
| 220 | ((unsigned long)(unsigned char)(cp)[3])) |
| 221 | |
| 222 | #define PUT_32BIT(cp, value) { \ |
| 223 | (cp)[0] = (unsigned char)((value) >> 24); \ |
| 224 | (cp)[1] = (unsigned char)((value) >> 16); \ |
| 225 | (cp)[2] = (unsigned char)((value) >> 8); \ |
| 226 | (cp)[3] = (unsigned char)(value); } |
| 227 | |
| 228 | static void getstring(char **data, int *datalen, char **p, int *length) { |
| 229 | *p = NULL; |
| 230 | if (*datalen < 4) |
| 231 | return; |
| 232 | *length = GET_32BIT(*data); |
| 233 | *datalen -= 4; *data += 4; |
| 234 | if (*datalen < *length) |
| 235 | return; |
| 236 | *p = *data; |
| 237 | *data += *length; *datalen -= *length; |
| 238 | } |
| 239 | static Bignum getmp(char **data, int *datalen) { |
| 240 | char *p; |
| 241 | int length; |
| 242 | Bignum b; |
| 243 | |
| 244 | getstring(data, datalen, &p, &length); |
| 245 | if (!p) |
| 246 | return NULL; |
| 247 | b = bignum_from_bytes(p, length); |
| 248 | return b; |
| 249 | } |
| 250 | |
| 251 | static void *rsa2_newkey(char *data, int len) { |
| 252 | char *p; |
| 253 | int slen; |
| 254 | struct RSAKey *rsa; |
| 255 | |
| 256 | rsa = smalloc(sizeof(struct RSAKey)); |
| 257 | if (!rsa) return NULL; |
| 258 | getstring(&data, &len, &p, &slen); |
| 259 | |
| 260 | if (!p || slen != 7 || memcmp(p, "ssh-rsa", 7)) { |
| 261 | sfree(rsa); |
| 262 | return NULL; |
| 263 | } |
| 264 | rsa->exponent = getmp(&data, &len); |
| 265 | rsa->modulus = getmp(&data, &len); |
| 266 | rsa->private_exponent = NULL; |
| 267 | rsa->comment = NULL; |
| 268 | |
| 269 | return rsa; |
| 270 | } |
| 271 | |
| 272 | static void rsa2_freekey(void *key) { |
| 273 | struct RSAKey *rsa = (struct RSAKey *)key; |
| 274 | freersakey(rsa); |
| 275 | sfree(rsa); |
| 276 | } |
| 277 | |
| 278 | static char *rsa2_fmtkey(void *key) { |
| 279 | struct RSAKey *rsa = (struct RSAKey *)key; |
| 280 | char *p; |
| 281 | int len; |
| 282 | |
| 283 | len = rsastr_len(rsa); |
| 284 | p = smalloc(len); |
| 285 | rsastr_fmt(p, rsa); |
| 286 | return p; |
| 287 | } |
| 288 | |
| 289 | static unsigned char *rsa2_public_blob(void *key, int *len) { |
| 290 | struct RSAKey *rsa = (struct RSAKey *)key; |
| 291 | int elen, mlen, bloblen; |
| 292 | int i; |
| 293 | unsigned char *blob, *p; |
| 294 | |
| 295 | elen = (bignum_bitcount(rsa->exponent)+8)/8; |
| 296 | mlen = (bignum_bitcount(rsa->modulus)+8)/8; |
| 297 | |
| 298 | /* |
| 299 | * string "ssh-rsa", mpint exp, mpint mod. Total 19+elen+mlen. |
| 300 | * (three length fields, 12+7=19). |
| 301 | */ |
| 302 | bloblen = 19+elen+mlen; |
| 303 | blob = smalloc(bloblen); |
| 304 | p = blob; |
| 305 | PUT_32BIT(p, 7); p += 4; |
| 306 | memcpy(p, "ssh-rsa", 7); p += 7; |
| 307 | PUT_32BIT(p, elen); p += 4; |
| 308 | for (i = elen; i-- ;) *p++ = bignum_byte(rsa->exponent, i); |
| 309 | PUT_32BIT(p, mlen); p += 4; |
| 310 | for (i = mlen; i-- ;) *p++ = bignum_byte(rsa->modulus, i); |
| 311 | assert(p == blob + bloblen); |
| 312 | *len = bloblen; |
| 313 | return blob; |
| 314 | } |
| 315 | |
| 316 | static unsigned char *rsa2_private_blob(void *key, int *len) { |
| 317 | struct RSAKey *rsa = (struct RSAKey *)key; |
| 318 | int dlen, plen, qlen, ulen, bloblen; |
| 319 | int i; |
| 320 | unsigned char *blob, *p; |
| 321 | |
| 322 | dlen = (bignum_bitcount(rsa->private_exponent)+8)/8; |
| 323 | plen = (bignum_bitcount(rsa->p)+8)/8; |
| 324 | qlen = (bignum_bitcount(rsa->q)+8)/8; |
| 325 | ulen = (bignum_bitcount(rsa->iqmp)+8)/8; |
| 326 | |
| 327 | /* |
| 328 | * mpint private_exp, mpint p, mpint q, mpint iqmp. Total 16 + |
| 329 | * sum of lengths. |
| 330 | */ |
| 331 | bloblen = 16+dlen+plen+qlen+ulen; |
| 332 | blob = smalloc(bloblen); |
| 333 | p = blob; |
| 334 | PUT_32BIT(p, dlen); p += 4; |
| 335 | for (i = dlen; i-- ;) *p++ = bignum_byte(rsa->private_exponent, i); |
| 336 | PUT_32BIT(p, plen); p += 4; |
| 337 | for (i = plen; i-- ;) *p++ = bignum_byte(rsa->p, i); |
| 338 | PUT_32BIT(p, qlen); p += 4; |
| 339 | for (i = qlen; i-- ;) *p++ = bignum_byte(rsa->q, i); |
| 340 | PUT_32BIT(p, ulen); p += 4; |
| 341 | for (i = ulen; i-- ;) *p++ = bignum_byte(rsa->iqmp, i); |
| 342 | assert(p == blob + bloblen); |
| 343 | *len = bloblen; |
| 344 | return blob; |
| 345 | } |
| 346 | |
| 347 | static void *rsa2_createkey(unsigned char *pub_blob, int pub_len, |
| 348 | unsigned char *priv_blob, int priv_len) { |
| 349 | struct RSAKey *rsa; |
| 350 | char *pb = (char *)priv_blob; |
| 351 | |
| 352 | rsa = rsa2_newkey((char *)pub_blob, pub_len); |
| 353 | rsa->private_exponent = getmp(&pb, &priv_len); |
| 354 | rsa->p = getmp(&pb, &priv_len); |
| 355 | rsa->q = getmp(&pb, &priv_len); |
| 356 | rsa->iqmp = getmp(&pb, &priv_len); |
| 357 | |
| 358 | if (!rsa_verify(rsa)) { |
| 359 | rsa2_freekey(rsa); |
| 360 | return NULL; |
| 361 | } |
| 362 | |
| 363 | return rsa; |
| 364 | } |
| 365 | |
| 366 | static void *rsa2_openssh_createkey(unsigned char **blob, int *len) { |
| 367 | char **b = (char **)blob; |
| 368 | struct RSAKey *rsa; |
| 369 | |
| 370 | rsa = smalloc(sizeof(struct RSAKey)); |
| 371 | if (!rsa) return NULL; |
| 372 | rsa->comment = NULL; |
| 373 | |
| 374 | rsa->modulus = getmp(b, len); |
| 375 | rsa->exponent = getmp(b, len); |
| 376 | rsa->private_exponent = getmp(b, len); |
| 377 | rsa->iqmp = getmp(b, len); |
| 378 | rsa->p = getmp(b, len); |
| 379 | rsa->q = getmp(b, len); |
| 380 | |
| 381 | if (!rsa->modulus || !rsa->exponent || !rsa->private_exponent || |
| 382 | !rsa->iqmp || !rsa->p || !rsa->q) { |
| 383 | sfree(rsa->modulus); |
| 384 | sfree(rsa->exponent); |
| 385 | sfree(rsa->private_exponent); |
| 386 | sfree(rsa->iqmp); |
| 387 | sfree(rsa->p); |
| 388 | sfree(rsa->q); |
| 389 | sfree(rsa); |
| 390 | return NULL; |
| 391 | } |
| 392 | |
| 393 | return rsa; |
| 394 | } |
| 395 | |
| 396 | static int rsa2_openssh_fmtkey(void *key, unsigned char *blob, int len) { |
| 397 | struct RSAKey *rsa = (struct RSAKey *)key; |
| 398 | int bloblen, i; |
| 399 | |
| 400 | bloblen = |
| 401 | ssh2_bignum_length(rsa->modulus) + |
| 402 | ssh2_bignum_length(rsa->exponent) + |
| 403 | ssh2_bignum_length(rsa->private_exponent) + |
| 404 | ssh2_bignum_length(rsa->iqmp) + |
| 405 | ssh2_bignum_length(rsa->p) + |
| 406 | ssh2_bignum_length(rsa->q); |
| 407 | |
| 408 | if (bloblen > len) |
| 409 | return bloblen; |
| 410 | |
| 411 | bloblen = 0; |
| 412 | #define ENC(x) \ |
| 413 | PUT_32BIT(blob+bloblen, ssh2_bignum_length((x))-4); bloblen += 4; \ |
| 414 | for (i = ssh2_bignum_length((x))-4; i-- ;) blob[bloblen++]=bignum_byte((x),i); |
| 415 | ENC(rsa->modulus); |
| 416 | ENC(rsa->exponent); |
| 417 | ENC(rsa->private_exponent); |
| 418 | ENC(rsa->iqmp); |
| 419 | ENC(rsa->p); |
| 420 | ENC(rsa->q); |
| 421 | |
| 422 | return bloblen; |
| 423 | } |
| 424 | |
| 425 | static char *rsa2_fingerprint(void *key) { |
| 426 | struct RSAKey *rsa = (struct RSAKey *)key; |
| 427 | struct MD5Context md5c; |
| 428 | unsigned char digest[16], lenbuf[4]; |
| 429 | char buffer[16*3+40]; |
| 430 | char *ret; |
| 431 | int numlen, i; |
| 432 | |
| 433 | MD5Init(&md5c); |
| 434 | MD5Update(&md5c, "\0\0\0\7ssh-rsa", 11); |
| 435 | |
| 436 | #define ADD_BIGNUM(bignum) \ |
| 437 | numlen = (bignum_bitcount(bignum)+8)/8; \ |
| 438 | PUT_32BIT(lenbuf, numlen); MD5Update(&md5c, lenbuf, 4); \ |
| 439 | for (i = numlen; i-- ;) { \ |
| 440 | unsigned char c = bignum_byte(bignum, i); \ |
| 441 | MD5Update(&md5c, &c, 1); \ |
| 442 | } |
| 443 | ADD_BIGNUM(rsa->exponent); |
| 444 | ADD_BIGNUM(rsa->modulus); |
| 445 | #undef ADD_BIGNUM |
| 446 | |
| 447 | MD5Final(digest, &md5c); |
| 448 | |
| 449 | sprintf(buffer, "ssh-rsa %d ", bignum_bitcount(rsa->modulus)); |
| 450 | for (i = 0; i < 16; i++) |
| 451 | sprintf(buffer+strlen(buffer), "%s%02x", i?":":"", digest[i]); |
| 452 | ret = smalloc(strlen(buffer)+1); |
| 453 | if (ret) |
| 454 | strcpy(ret, buffer); |
| 455 | return ret; |
| 456 | } |
| 457 | |
| 458 | /* |
| 459 | * This is the magic ASN.1/DER prefix that goes in the decoded |
| 460 | * signature, between the string of FFs and the actual SHA hash |
| 461 | * value. The meaning of it is: |
| 462 | * |
| 463 | * 00 -- this marks the end of the FFs; not part of the ASN.1 bit itself |
| 464 | * |
| 465 | * 30 21 -- a constructed SEQUENCE of length 0x21 |
| 466 | * 30 09 -- a constructed sub-SEQUENCE of length 9 |
| 467 | * 06 05 -- an object identifier, length 5 |
| 468 | * 2B 0E 03 02 1A -- object id { 1 3 14 3 2 26 } |
| 469 | * (the 1,3 comes from 0x2B = 43 = 40*1+3) |
| 470 | * 05 00 -- NULL |
| 471 | * 04 14 -- a primitive OCTET STRING of length 0x14 |
| 472 | * [0x14 bytes of hash data follows] |
| 473 | * |
| 474 | * The object id in the middle there is listed as `id-sha1' in |
| 475 | * ftp://ftp.rsasecurity.com/pub/pkcs/pkcs-1/pkcs-1v2-1d2.asn (the |
| 476 | * ASN module for PKCS #1) and its expanded form is as follows: |
| 477 | * |
| 478 | * id-sha1 OBJECT IDENTIFIER ::= { |
| 479 | * iso(1) identified-organization(3) oiw(14) secsig(3) |
| 480 | * algorithms(2) 26 } |
| 481 | */ |
| 482 | static unsigned char asn1_weird_stuff[] = { |
| 483 | 0x00,0x30,0x21,0x30,0x09,0x06,0x05,0x2B, |
| 484 | 0x0E,0x03,0x02,0x1A,0x05,0x00,0x04,0x14, |
| 485 | }; |
| 486 | |
| 487 | #define ASN1_LEN ( (int) sizeof(asn1_weird_stuff) ) |
| 488 | |
| 489 | static int rsa2_verifysig(void *key, char *sig, int siglen, |
| 490 | char *data, int datalen) { |
| 491 | struct RSAKey *rsa = (struct RSAKey *)key; |
| 492 | Bignum in, out; |
| 493 | char *p; |
| 494 | int slen; |
| 495 | int bytes, i, j, ret; |
| 496 | unsigned char hash[20]; |
| 497 | |
| 498 | getstring(&sig, &siglen, &p, &slen); |
| 499 | if (!p || slen != 7 || memcmp(p, "ssh-rsa", 7)) { |
| 500 | return 0; |
| 501 | } |
| 502 | in = getmp(&sig, &siglen); |
| 503 | out = modpow(in, rsa->exponent, rsa->modulus); |
| 504 | freebn(in); |
| 505 | |
| 506 | ret = 1; |
| 507 | |
| 508 | bytes = bignum_bitcount(rsa->modulus) / 8; |
| 509 | /* Top (partial) byte should be zero. */ |
| 510 | if (bignum_byte(out, bytes-1) != 0) |
| 511 | ret = 0; |
| 512 | /* First whole byte should be 1. */ |
| 513 | if (bignum_byte(out, bytes-2) != 1) |
| 514 | ret = 0; |
| 515 | /* Most of the rest should be FF. */ |
| 516 | for (i = bytes-3; i >= 20 + ASN1_LEN; i--) { |
| 517 | if (bignum_byte(out, i) != 0xFF) |
| 518 | ret = 0; |
| 519 | } |
| 520 | /* Then we expect to see the asn1_weird_stuff. */ |
| 521 | for (i = 20 + ASN1_LEN - 1, j=0; i >= 20; i--,j++) { |
| 522 | if (bignum_byte(out, i) != asn1_weird_stuff[j]) |
| 523 | ret = 0; |
| 524 | } |
| 525 | /* Finally, we expect to see the SHA-1 hash of the signed data. */ |
| 526 | SHA_Simple(data, datalen, hash); |
| 527 | for (i = 19, j=0; i >= 0; i--,j++) { |
| 528 | if (bignum_byte(out, i) != hash[j]) |
| 529 | ret = 0; |
| 530 | } |
| 531 | |
| 532 | return ret; |
| 533 | } |
| 534 | |
| 535 | unsigned char *rsa2_sign(void *key, char *data, int datalen, int *siglen) { |
| 536 | struct RSAKey *rsa = (struct RSAKey *)key; |
| 537 | unsigned char *bytes; |
| 538 | int nbytes; |
| 539 | unsigned char hash[20]; |
| 540 | Bignum in, out; |
| 541 | int i, j; |
| 542 | |
| 543 | SHA_Simple(data, datalen, hash); |
| 544 | |
| 545 | nbytes = (bignum_bitcount(rsa->modulus)-1) / 8; |
| 546 | bytes = smalloc(nbytes); |
| 547 | |
| 548 | bytes[0] = 1; |
| 549 | for (i = 1; i < nbytes-20-ASN1_LEN; i++) |
| 550 | bytes[i] = 0xFF; |
| 551 | for (i = nbytes-20-ASN1_LEN, j=0; i < nbytes-20; i++,j++) |
| 552 | bytes[i] = asn1_weird_stuff[j]; |
| 553 | for (i = nbytes-20, j=0; i < nbytes; i++,j++) |
| 554 | bytes[i] = hash[j]; |
| 555 | |
| 556 | in = bignum_from_bytes(bytes, nbytes); |
| 557 | sfree(bytes); |
| 558 | |
| 559 | out = modpow(in, rsa->private_exponent, rsa->modulus); |
| 560 | freebn(in); |
| 561 | |
| 562 | nbytes = (bignum_bitcount(out)+7)/8; |
| 563 | bytes = smalloc(4+7+4+nbytes); |
| 564 | PUT_32BIT(bytes, 7); |
| 565 | memcpy(bytes+4, "ssh-rsa", 7); |
| 566 | PUT_32BIT(bytes+4+7, nbytes); |
| 567 | for (i = 0; i < nbytes; i++) |
| 568 | bytes[4+7+4+i] = bignum_byte(out, nbytes-1-i); |
| 569 | freebn(out); |
| 570 | |
| 571 | *siglen = 4+7+4+nbytes; |
| 572 | return bytes; |
| 573 | } |
| 574 | |
| 575 | const struct ssh_signkey ssh_rsa = { |
| 576 | rsa2_newkey, |
| 577 | rsa2_freekey, |
| 578 | rsa2_fmtkey, |
| 579 | rsa2_public_blob, |
| 580 | rsa2_private_blob, |
| 581 | rsa2_createkey, |
| 582 | rsa2_openssh_createkey, |
| 583 | rsa2_openssh_fmtkey, |
| 584 | rsa2_fingerprint, |
| 585 | rsa2_verifysig, |
| 586 | rsa2_sign, |
| 587 | "ssh-rsa", |
| 588 | "rsa2" |
| 589 | }; |