1/* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com) 2 * All rights reserved. 3 * 4 * This package is an SSL implementation written 5 * by Eric Young (eay@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@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@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@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 <ctype.h> 60#include <stdio.h> 61#include <string.h> 62 63#include <openssl/bio.h> 64#include <openssl/err.h> 65#include <openssl/mem.h> 66 67#include "internal.h" 68 69BIGNUM *BN_bin2bn(const uint8_t *in, size_t len, BIGNUM *ret) { 70 unsigned num_words, m; 71 BN_ULONG word = 0; 72 BIGNUM *bn = NULL; 73 74 if (ret == NULL) { 75 ret = bn = BN_new(); 76 } 77 78 if (ret == NULL) { 79 return NULL; 80 } 81 82 if (len == 0) { 83 ret->top = 0; 84 return ret; 85 } 86 87 num_words = ((len - 1) / BN_BYTES) + 1; 88 m = (len - 1) % BN_BYTES; 89 if (bn_wexpand(ret, num_words) == NULL) { 90 if (bn) { 91 BN_free(bn); 92 } 93 return NULL; 94 } 95 96 ret->top = num_words; 97 ret->neg = 0; 98 99 while (len--) { 100 word = (word << 8) | *(in++); 101 if (m-- == 0) { 102 ret->d[--num_words] = word; 103 word = 0; 104 m = BN_BYTES - 1; 105 } 106 } 107 108 /* need to call this due to clear byte at top if avoiding having the top bit 109 * set (-ve number) */ 110 bn_correct_top(ret); 111 return ret; 112} 113 114size_t BN_bn2bin(const BIGNUM *in, uint8_t *out) { 115 size_t n, i; 116 BN_ULONG l; 117 118 n = i = BN_num_bytes(in); 119 while (i--) { 120 l = in->d[i / BN_BYTES]; 121 *(out++) = (unsigned char)(l >> (8 * (i % BN_BYTES))) & 0xff; 122 } 123 return n; 124} 125 126/* constant_time_select_ulong returns |x| if |v| is 1 and |y| if |v| is 0. Its 127 * behavior is undefined if |v| takes any other value. */ 128static BN_ULONG constant_time_select_ulong(int v, BN_ULONG x, BN_ULONG y) { 129 BN_ULONG mask = v; 130 mask--; 131 132 return (~mask & x) | (mask & y); 133} 134 135/* constant_time_le_size_t returns 1 if |x| <= |y| and 0 otherwise. |x| and |y| 136 * must not have their MSBs set. */ 137static int constant_time_le_size_t(size_t x, size_t y) { 138 return ((x - y - 1) >> (sizeof(size_t) * 8 - 1)) & 1; 139} 140 141/* read_word_padded returns the |i|'th word of |in|, if it is not out of 142 * bounds. Otherwise, it returns 0. It does so without branches on the size of 143 * |in|, however it necessarily does not have the same memory access pattern. If 144 * the access would be out of bounds, it reads the last word of |in|. |in| must 145 * not be zero. */ 146static BN_ULONG read_word_padded(const BIGNUM *in, size_t i) { 147 /* Read |in->d[i]| if valid. Otherwise, read the last word. */ 148 BN_ULONG l = in->d[constant_time_select_ulong( 149 constant_time_le_size_t(in->dmax, i), in->dmax - 1, i)]; 150 151 /* Clamp to zero if above |d->top|. */ 152 return constant_time_select_ulong(constant_time_le_size_t(in->top, i), 0, l); 153} 154 155int BN_bn2bin_padded(uint8_t *out, size_t len, const BIGNUM *in) { 156 size_t i; 157 BN_ULONG l; 158 159 /* Special case for |in| = 0. Just branch as the probability is negligible. */ 160 if (BN_is_zero(in)) { 161 memset(out, 0, len); 162 return 1; 163 } 164 165 /* Check if the integer is too big. This case can exit early in non-constant 166 * time. */ 167 if ((size_t)in->top > (len + (BN_BYTES - 1)) / BN_BYTES) { 168 return 0; 169 } 170 if ((len % BN_BYTES) != 0) { 171 l = read_word_padded(in, len / BN_BYTES); 172 if (l >> (8 * (len % BN_BYTES)) != 0) { 173 return 0; 174 } 175 } 176 177 /* Write the bytes out one by one. Serialization is done without branching on 178 * the bits of |in| or on |in->top|, but if the routine would otherwise read 179 * out of bounds, the memory access pattern can't be fixed. However, for an 180 * RSA key of size a multiple of the word size, the probability of BN_BYTES 181 * leading zero octets is low. 182 * 183 * See Falko Stenzke, "Manger's Attack revisited", ICICS 2010. */ 184 i = len; 185 while (i--) { 186 l = read_word_padded(in, i / BN_BYTES); 187 *(out++) = (uint8_t)(l >> (8 * (i % BN_BYTES))) & 0xff; 188 } 189 return 1; 190} 191 192static const char hextable[] = "0123456789abcdef"; 193 194char *BN_bn2hex(const BIGNUM *bn) { 195 int i, j, v, z = 0; 196 char *buf; 197 char *p; 198 199 buf = (char *)OPENSSL_malloc(bn->top * BN_BYTES * 2 + 2); 200 if (buf == NULL) { 201 OPENSSL_PUT_ERROR(BN, BN_bn2hex, ERR_R_MALLOC_FAILURE); 202 return NULL; 203 } 204 205 p = buf; 206 if (bn->neg) { 207 *(p++) = '-'; 208 } 209 210 if (BN_is_zero(bn)) { 211 *(p++) = '0'; 212 } 213 214 for (i = bn->top - 1; i >= 0; i--) { 215 for (j = BN_BITS2 - 8; j >= 0; j -= 8) { 216 /* strip leading zeros */ 217 v = ((int)(bn->d[i] >> (long)j)) & 0xff; 218 if (z || v != 0) { 219 *(p++) = hextable[v >> 4]; 220 *(p++) = hextable[v & 0x0f]; 221 z = 1; 222 } 223 } 224 } 225 *p = '\0'; 226 227 return buf; 228} 229 230/* decode_hex decodes |i| bytes of hex data from |in| and updates |bn|. */ 231static void decode_hex(BIGNUM *bn, const char *in, int i) { 232 int h, m, j, k, c; 233 BN_ULONG l=0; 234 235 j = i; /* least significant 'hex' */ 236 h = 0; 237 while (j > 0) { 238 m = ((BN_BYTES * 2) <= j) ? (BN_BYTES * 2) : j; 239 l = 0; 240 for (;;) { 241 c = in[j - m]; 242 if ((c >= '0') && (c <= '9')) { 243 k = c - '0'; 244 } else if ((c >= 'a') && (c <= 'f')) { 245 k = c - 'a' + 10; 246 } else if ((c >= 'A') && (c <= 'F')) { 247 k = c - 'A' + 10; 248 } else { 249 k = 0; /* paranoia */ 250 } 251 252 l = (l << 4) | k; 253 254 if (--m <= 0) { 255 bn->d[h++] = l; 256 break; 257 } 258 } 259 260 j -= (BN_BYTES * 2); 261 } 262 263 bn->top = h; 264} 265 266/* decode_dec decodes |in_len| bytes of decimal data from |in| and updates |bn|. */ 267static void decode_dec(BIGNUM *bn, const char *in, int in_len) { 268 int i, j; 269 BN_ULONG l = 0; 270 271 j = BN_DEC_NUM - (in_len % BN_DEC_NUM); 272 if (j == BN_DEC_NUM) { 273 j = 0; 274 } 275 l = 0; 276 for (i = 0; i < in_len; i++) { 277 l *= 10; 278 l += in[i] - '0'; 279 if (++j == BN_DEC_NUM) { 280 BN_mul_word(bn, BN_DEC_CONV); 281 BN_add_word(bn, l); 282 l = 0; 283 j = 0; 284 } 285 } 286} 287 288typedef void (*decode_func) (BIGNUM *bn, const char *in, int i); 289typedef int (*char_test_func) (int c); 290 291static int bn_x2bn(BIGNUM **outp, const char *in, decode_func decode, char_test_func want_char) { 292 BIGNUM *ret = NULL; 293 int neg = 0, i; 294 int num; 295 296 if (in == NULL || *in == 0) { 297 return 0; 298 } 299 300 if (*in == '-') { 301 neg = 1; 302 in++; 303 } 304 305 for (i = 0; want_char((unsigned char)in[i]); i++) {} 306 307 num = i + neg; 308 if (outp == NULL) { 309 return num; 310 } 311 312 /* in is the start of the hex digits, and it is 'i' long */ 313 if (*outp == NULL) { 314 ret = BN_new(); 315 if (ret == NULL) { 316 return 0; 317 } 318 } else { 319 ret = *outp; 320 BN_zero(ret); 321 } 322 323 /* i is the number of hex digests; */ 324 if (bn_expand(ret, i * 4) == NULL) { 325 goto err; 326 } 327 328 decode(ret, in, i); 329 330 bn_correct_top(ret); 331 if (!BN_is_zero(ret)) { 332 ret->neg = neg; 333 } 334 335 *outp = ret; 336 return num; 337 338err: 339 if (*outp == NULL) { 340 BN_free(ret); 341 } 342 343 return 0; 344} 345 346int BN_hex2bn(BIGNUM **outp, const char *in) { 347 return bn_x2bn(outp, in, decode_hex, isxdigit); 348} 349 350char *BN_bn2dec(const BIGNUM *a) { 351 int i = 0, num, ok = 0; 352 char *buf = NULL; 353 char *p; 354 BIGNUM *t = NULL; 355 BN_ULONG *bn_data = NULL, *lp; 356 357 /* get an upper bound for the length of the decimal integer 358 * num <= (BN_num_bits(a) + 1) * log(2) 359 * <= 3 * BN_num_bits(a) * 0.1001 + log(2) + 1 (rounding error) 360 * <= BN_num_bits(a)/10 + BN_num_bits/1000 + 1 + 1 361 */ 362 i = BN_num_bits(a) * 3; 363 num = i / 10 + i / 1000 + 1 + 1; 364 bn_data = 365 (BN_ULONG *)OPENSSL_malloc((num / BN_DEC_NUM + 1) * sizeof(BN_ULONG)); 366 buf = (char *)OPENSSL_malloc(num + 3); 367 if ((buf == NULL) || (bn_data == NULL)) { 368 OPENSSL_PUT_ERROR(BN, BN_bn2dec, ERR_R_MALLOC_FAILURE); 369 goto err; 370 } 371 t = BN_dup(a); 372 if (t == NULL) { 373 goto err; 374 } 375 376#define BUF_REMAIN (num + 3 - (size_t)(p - buf)) 377 p = buf; 378 lp = bn_data; 379 if (BN_is_zero(t)) { 380 *(p++) = '0'; 381 *(p++) = '\0'; 382 } else { 383 if (BN_is_negative(t)) { 384 *p++ = '-'; 385 } 386 387 while (!BN_is_zero(t)) { 388 *lp = BN_div_word(t, BN_DEC_CONV); 389 lp++; 390 } 391 lp--; 392 /* We now have a series of blocks, BN_DEC_NUM chars 393 * in length, where the last one needs truncation. 394 * The blocks need to be reversed in order. */ 395 BIO_snprintf(p, BUF_REMAIN, BN_DEC_FMT1, *lp); 396 while (*p) { 397 p++; 398 } 399 while (lp != bn_data) { 400 lp--; 401 BIO_snprintf(p, BUF_REMAIN, BN_DEC_FMT2, *lp); 402 while (*p) { 403 p++; 404 } 405 } 406 } 407 ok = 1; 408 409err: 410 OPENSSL_free(bn_data); 411 BN_free(t); 412 if (!ok) { 413 OPENSSL_free(buf); 414 buf = NULL; 415 } 416 417 return buf; 418} 419 420int BN_dec2bn(BIGNUM **outp, const char *in) { 421 return bn_x2bn(outp, in, decode_dec, isdigit); 422} 423 424int BN_asc2bn(BIGNUM **outp, const char *in) { 425 const char *const orig_in = in; 426 if (*in == '-') { 427 in++; 428 } 429 430 if (in[0] == '0' && (in[1] == 'X' || in[1] == 'x')) { 431 if (!BN_hex2bn(outp, in+2)) { 432 return 0; 433 } 434 } else { 435 if (!BN_dec2bn(outp, in)) { 436 return 0; 437 } 438 } 439 440 if (*orig_in == '-' && !BN_is_zero(*outp)) { 441 (*outp)->neg = 1; 442 } 443 444 return 1; 445} 446 447int BN_print(BIO *bp, const BIGNUM *a) { 448 int i, j, v, z = 0; 449 int ret = 0; 450 451 if (a->neg && BIO_write(bp, "-", 1) != 1) { 452 goto end; 453 } 454 455 if (BN_is_zero(a) && BIO_write(bp, "0", 1) != 1) { 456 goto end; 457 } 458 459 for (i = a->top - 1; i >= 0; i--) { 460 for (j = BN_BITS2 - 4; j >= 0; j -= 4) { 461 /* strip leading zeros */ 462 v = ((int)(a->d[i] >> (long)j)) & 0x0f; 463 if (z || v != 0) { 464 if (BIO_write(bp, &hextable[v], 1) != 1) { 465 goto end; 466 } 467 z = 1; 468 } 469 } 470 } 471 ret = 1; 472 473end: 474 return ret; 475} 476 477int BN_print_fp(FILE *fp, const BIGNUM *a) { 478 BIO *b; 479 int ret; 480 481 b = BIO_new(BIO_s_file()); 482 if (b == NULL) { 483 return 0; 484 } 485 BIO_set_fp(b, fp, BIO_NOCLOSE); 486 ret = BN_print(b, a); 487 BIO_free(b); 488 489 return ret; 490} 491 492BN_ULONG BN_get_word(const BIGNUM *bn) { 493 switch (bn->top) { 494 case 0: 495 return 0; 496 case 1: 497 return bn->d[0]; 498 default: 499 return BN_MASK2; 500 } 501} 502