1 /* Copyright (C) 1995-1998 Eric Young (eay (at) cryptsoft.com) 2 * All rights reserved. 3 * 4 * This package is an SSL implementation written 5 * by Eric Young (eay (at) cryptsoft.com). 6 * The implementation was written so as to conform with Netscapes SSL. 7 * 8 * This library is free for commercial and non-commercial use as long as 9 * the following conditions are aheared to. The following conditions 10 * apply to all code found in this distribution, be it the RC4, RSA, 11 * lhash, DES, etc., code; not just the SSL code. The SSL documentation 12 * included with this distribution is covered by the same copyright terms 13 * except that the holder is Tim Hudson (tjh (at) cryptsoft.com). 14 * 15 * Copyright remains Eric Young's, and as such any Copyright notices in 16 * the code are not to be removed. 17 * If this package is used in a product, Eric Young should be given attribution 18 * as the author of the parts of the library used. 19 * This can be in the form of a textual message at program startup or 20 * in documentation (online or textual) provided with the package. 21 * 22 * Redistribution and use in source and binary forms, with or without 23 * modification, are permitted provided that the following conditions 24 * are met: 25 * 1. Redistributions of source code must retain the copyright 26 * notice, this list of conditions and the following disclaimer. 27 * 2. Redistributions in binary form must reproduce the above copyright 28 * notice, this list of conditions and the following disclaimer in the 29 * documentation and/or other materials provided with the distribution. 30 * 3. All advertising materials mentioning features or use of this software 31 * must display the following acknowledgement: 32 * "This product includes cryptographic software written by 33 * Eric Young (eay (at) cryptsoft.com)" 34 * The word 'cryptographic' can be left out if the rouines from the library 35 * being used are not cryptographic related :-). 36 * 4. If you include any Windows specific code (or a derivative thereof) from 37 * the apps directory (application code) you must include an acknowledgement: 38 * "This product includes software written by Tim Hudson (tjh (at) cryptsoft.com)" 39 * 40 * THIS SOFTWARE IS PROVIDED BY ERIC YOUNG ``AS IS'' AND 41 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 42 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 43 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 44 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 45 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 46 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 47 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 48 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 49 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 50 * SUCH DAMAGE. 51 * 52 * The licence and distribution terms for any publically available version or 53 * derivative of this code cannot be changed. i.e. this code cannot simply be 54 * copied and put under another distribution licence 55 * [including the GNU Public Licence.] */ 56 57 #include <openssl/bn.h> 58 59 #include <assert.h> 60 #include <ctype.h> 61 #include <limits.h> 62 #include <stdio.h> 63 64 #include <openssl/bio.h> 65 #include <openssl/bytestring.h> 66 #include <openssl/err.h> 67 #include <openssl/mem.h> 68 69 #include "../fipsmodule/bn/internal.h" 70 71 72 int BN_bn2cbb_padded(CBB *out, size_t len, const BIGNUM *in) { 73 uint8_t *ptr; 74 return CBB_add_space(out, &ptr, len) && BN_bn2bin_padded(ptr, len, in); 75 } 76 77 static const char hextable[] = "0123456789abcdef"; 78 79 char *BN_bn2hex(const BIGNUM *bn) { 80 char *buf = OPENSSL_malloc(1 /* leading '-' */ + 1 /* zero is non-empty */ + 81 bn->top * BN_BYTES * 2 + 1 /* trailing NUL */); 82 if (buf == NULL) { 83 OPENSSL_PUT_ERROR(BN, ERR_R_MALLOC_FAILURE); 84 return NULL; 85 } 86 87 char *p = buf; 88 if (bn->neg) { 89 *(p++) = '-'; 90 } 91 92 if (BN_is_zero(bn)) { 93 *(p++) = '0'; 94 } 95 96 int z = 0; 97 for (int i = bn->top - 1; i >= 0; i--) { 98 for (int j = BN_BITS2 - 8; j >= 0; j -= 8) { 99 /* strip leading zeros */ 100 int v = ((int)(bn->d[i] >> (long)j)) & 0xff; 101 if (z || v != 0) { 102 *(p++) = hextable[v >> 4]; 103 *(p++) = hextable[v & 0x0f]; 104 z = 1; 105 } 106 } 107 } 108 *p = '\0'; 109 110 return buf; 111 } 112 113 /* decode_hex decodes |in_len| bytes of hex data from |in| and updates |bn|. */ 114 static int decode_hex(BIGNUM *bn, const char *in, int in_len) { 115 if (in_len > INT_MAX/4) { 116 OPENSSL_PUT_ERROR(BN, BN_R_BIGNUM_TOO_LONG); 117 return 0; 118 } 119 /* |in_len| is the number of hex digits. */ 120 if (!bn_expand(bn, in_len * 4)) { 121 return 0; 122 } 123 124 int i = 0; 125 while (in_len > 0) { 126 /* Decode one |BN_ULONG| at a time. */ 127 int todo = BN_BYTES * 2; 128 if (todo > in_len) { 129 todo = in_len; 130 } 131 132 BN_ULONG word = 0; 133 int j; 134 for (j = todo; j > 0; j--) { 135 char c = in[in_len - j]; 136 137 BN_ULONG hex; 138 if (c >= '0' && c <= '9') { 139 hex = c - '0'; 140 } else if (c >= 'a' && c <= 'f') { 141 hex = c - 'a' + 10; 142 } else if (c >= 'A' && c <= 'F') { 143 hex = c - 'A' + 10; 144 } else { 145 hex = 0; 146 /* This shouldn't happen. The caller checks |isxdigit|. */ 147 assert(0); 148 } 149 word = (word << 4) | hex; 150 } 151 152 bn->d[i++] = word; 153 in_len -= todo; 154 } 155 assert(i <= bn->dmax); 156 bn->top = i; 157 return 1; 158 } 159 160 /* decode_dec decodes |in_len| bytes of decimal data from |in| and updates |bn|. */ 161 static int decode_dec(BIGNUM *bn, const char *in, int in_len) { 162 int i, j; 163 BN_ULONG l = 0; 164 165 /* Decode |BN_DEC_NUM| digits at a time. */ 166 j = BN_DEC_NUM - (in_len % BN_DEC_NUM); 167 if (j == BN_DEC_NUM) { 168 j = 0; 169 } 170 l = 0; 171 for (i = 0; i < in_len; i++) { 172 l *= 10; 173 l += in[i] - '0'; 174 if (++j == BN_DEC_NUM) { 175 if (!BN_mul_word(bn, BN_DEC_CONV) || 176 !BN_add_word(bn, l)) { 177 return 0; 178 } 179 l = 0; 180 j = 0; 181 } 182 } 183 return 1; 184 } 185 186 typedef int (*decode_func) (BIGNUM *bn, const char *in, int in_len); 187 typedef int (*char_test_func) (int c); 188 189 static int bn_x2bn(BIGNUM **outp, const char *in, decode_func decode, char_test_func want_char) { 190 BIGNUM *ret = NULL; 191 int neg = 0, i; 192 int num; 193 194 if (in == NULL || *in == 0) { 195 return 0; 196 } 197 198 if (*in == '-') { 199 neg = 1; 200 in++; 201 } 202 203 for (i = 0; want_char((unsigned char)in[i]) && i + neg < INT_MAX; i++) {} 204 205 num = i + neg; 206 if (outp == NULL) { 207 return num; 208 } 209 210 /* in is the start of the hex digits, and it is 'i' long */ 211 if (*outp == NULL) { 212 ret = BN_new(); 213 if (ret == NULL) { 214 return 0; 215 } 216 } else { 217 ret = *outp; 218 BN_zero(ret); 219 } 220 221 if (!decode(ret, in, i)) { 222 goto err; 223 } 224 225 bn_correct_top(ret); 226 if (!BN_is_zero(ret)) { 227 ret->neg = neg; 228 } 229 230 *outp = ret; 231 return num; 232 233 err: 234 if (*outp == NULL) { 235 BN_free(ret); 236 } 237 238 return 0; 239 } 240 241 int BN_hex2bn(BIGNUM **outp, const char *in) { 242 return bn_x2bn(outp, in, decode_hex, isxdigit); 243 } 244 245 char *BN_bn2dec(const BIGNUM *a) { 246 /* It is easier to print strings little-endian, so we assemble it in reverse 247 * and fix at the end. */ 248 BIGNUM *copy = NULL; 249 CBB cbb; 250 if (!CBB_init(&cbb, 16) || 251 !CBB_add_u8(&cbb, 0 /* trailing NUL */)) { 252 goto cbb_err; 253 } 254 255 if (BN_is_zero(a)) { 256 if (!CBB_add_u8(&cbb, '0')) { 257 goto cbb_err; 258 } 259 } else { 260 copy = BN_dup(a); 261 if (copy == NULL) { 262 goto err; 263 } 264 265 while (!BN_is_zero(copy)) { 266 BN_ULONG word = BN_div_word(copy, BN_DEC_CONV); 267 if (word == (BN_ULONG)-1) { 268 goto err; 269 } 270 271 const int add_leading_zeros = !BN_is_zero(copy); 272 for (int i = 0; i < BN_DEC_NUM && (add_leading_zeros || word != 0); i++) { 273 if (!CBB_add_u8(&cbb, '0' + word % 10)) { 274 goto cbb_err; 275 } 276 word /= 10; 277 } 278 assert(word == 0); 279 } 280 } 281 282 if (BN_is_negative(a) && 283 !CBB_add_u8(&cbb, '-')) { 284 goto cbb_err; 285 } 286 287 uint8_t *data; 288 size_t len; 289 if (!CBB_finish(&cbb, &data, &len)) { 290 goto cbb_err; 291 } 292 293 /* Reverse the buffer. */ 294 for (size_t i = 0; i < len/2; i++) { 295 uint8_t tmp = data[i]; 296 data[i] = data[len - 1 - i]; 297 data[len - 1 - i] = tmp; 298 } 299 300 BN_free(copy); 301 return (char *)data; 302 303 cbb_err: 304 OPENSSL_PUT_ERROR(BN, ERR_R_MALLOC_FAILURE); 305 err: 306 BN_free(copy); 307 CBB_cleanup(&cbb); 308 return NULL; 309 } 310 311 int BN_dec2bn(BIGNUM **outp, const char *in) { 312 return bn_x2bn(outp, in, decode_dec, isdigit); 313 } 314 315 int BN_asc2bn(BIGNUM **outp, const char *in) { 316 const char *const orig_in = in; 317 if (*in == '-') { 318 in++; 319 } 320 321 if (in[0] == '0' && (in[1] == 'X' || in[1] == 'x')) { 322 if (!BN_hex2bn(outp, in+2)) { 323 return 0; 324 } 325 } else { 326 if (!BN_dec2bn(outp, in)) { 327 return 0; 328 } 329 } 330 331 if (*orig_in == '-' && !BN_is_zero(*outp)) { 332 (*outp)->neg = 1; 333 } 334 335 return 1; 336 } 337 338 int BN_print(BIO *bp, const BIGNUM *a) { 339 int i, j, v, z = 0; 340 int ret = 0; 341 342 if (a->neg && BIO_write(bp, "-", 1) != 1) { 343 goto end; 344 } 345 346 if (BN_is_zero(a) && BIO_write(bp, "0", 1) != 1) { 347 goto end; 348 } 349 350 for (i = a->top - 1; i >= 0; i--) { 351 for (j = BN_BITS2 - 4; j >= 0; j -= 4) { 352 /* strip leading zeros */ 353 v = ((int)(a->d[i] >> (long)j)) & 0x0f; 354 if (z || v != 0) { 355 if (BIO_write(bp, &hextable[v], 1) != 1) { 356 goto end; 357 } 358 z = 1; 359 } 360 } 361 } 362 ret = 1; 363 364 end: 365 return ret; 366 } 367 368 int BN_print_fp(FILE *fp, const BIGNUM *a) { 369 BIO *b; 370 int ret; 371 372 b = BIO_new(BIO_s_file()); 373 if (b == NULL) { 374 return 0; 375 } 376 BIO_set_fp(b, fp, BIO_NOCLOSE); 377 ret = BN_print(b, a); 378 BIO_free(b); 379 380 return ret; 381 } 382 383 384 size_t BN_bn2mpi(const BIGNUM *in, uint8_t *out) { 385 const size_t bits = BN_num_bits(in); 386 const size_t bytes = (bits + 7) / 8; 387 /* If the number of bits is a multiple of 8, i.e. if the MSB is set, 388 * prefix with a zero byte. */ 389 int extend = 0; 390 if (bytes != 0 && (bits & 0x07) == 0) { 391 extend = 1; 392 } 393 394 const size_t len = bytes + extend; 395 if (len < bytes || 396 4 + len < len || 397 (len & 0xffffffff) != len) { 398 /* If we cannot represent the number then we emit zero as the interface 399 * doesn't allow an error to be signalled. */ 400 if (out) { 401 OPENSSL_memset(out, 0, 4); 402 } 403 return 4; 404 } 405 406 if (out == NULL) { 407 return 4 + len; 408 } 409 410 out[0] = len >> 24; 411 out[1] = len >> 16; 412 out[2] = len >> 8; 413 out[3] = len; 414 if (extend) { 415 out[4] = 0; 416 } 417 BN_bn2bin(in, out + 4 + extend); 418 if (in->neg && len > 0) { 419 out[4] |= 0x80; 420 } 421 return len + 4; 422 } 423 424 BIGNUM *BN_mpi2bn(const uint8_t *in, size_t len, BIGNUM *out) { 425 if (len < 4) { 426 OPENSSL_PUT_ERROR(BN, BN_R_BAD_ENCODING); 427 return NULL; 428 } 429 const size_t in_len = ((size_t)in[0] << 24) | 430 ((size_t)in[1] << 16) | 431 ((size_t)in[2] << 8) | 432 ((size_t)in[3]); 433 if (in_len != len - 4) { 434 OPENSSL_PUT_ERROR(BN, BN_R_BAD_ENCODING); 435 return NULL; 436 } 437 438 int out_is_alloced = 0; 439 if (out == NULL) { 440 out = BN_new(); 441 if (out == NULL) { 442 OPENSSL_PUT_ERROR(BN, ERR_R_MALLOC_FAILURE); 443 return NULL; 444 } 445 out_is_alloced = 1; 446 } 447 448 if (in_len == 0) { 449 BN_zero(out); 450 return out; 451 } 452 453 in += 4; 454 if (BN_bin2bn(in, in_len, out) == NULL) { 455 if (out_is_alloced) { 456 BN_free(out); 457 } 458 return NULL; 459 } 460 out->neg = ((*in) & 0x80) != 0; 461 if (out->neg) { 462 BN_clear_bit(out, BN_num_bits(out) - 1); 463 } 464 return out; 465 } 466