crypto/bn/bn_print.c

   1 /*
   2  * Copyright 1995-2017 The OpenSSL Project Authors. All Rights Reserved.
   3  *
   4  * Licensed under the Apache License 2.0 (the "License").  You may not use
   5  * this file except in compliance with the License.  You can obtain a copy
   6  * in the file LICENSE in the source distribution or at
   7  * https://www.openssl.org/source/license.html
   8  */
   9
  10 #include <stdio.h>
  11 #include "internal/ctype.h"
  12 #include <limits.h>
  13 #include "internal/cryptlib.h"
  14 #include <openssl/buffer.h>
  15 #include "bn_lcl.h"
  16
  17 static const char Hex[] = "0123456789ABCDEF";
  18
  19 /* Must 'OPENSSL_free' the returned data */
  20 char *BN_bn2hex(const BIGNUM *a)
  21 {
  22     int i, j, v, z = 0;
  23     char *buf;
  24     char *p;
  25
  26     if (BN_is_zero(a))
  27         return OPENSSL_strdup("0");
  28     buf = OPENSSL_malloc(a->top * BN_BYTES * 2 + 2);
  29     if (buf == NULL) {
  30         BNerr(BN_F_BN_BN2HEX, ERR_R_MALLOC_FAILURE);
  31         goto err;
  32     }
  33     p = buf;
  34     if (a->neg)
  35         *p++ = '-';
  36     for (i = a->top - 1; i >= 0; i--) {
  37         for (j = BN_BITS2 - 8; j >= 0; j -= 8) {
  38             /* strip leading zeros */
  39             v = (int)((a->d[i] >> j) & 0xff);
  40             if (z || v != 0) {
  41                 *p++ = Hex[v >> 4];
  42                 *p++ = Hex[v & 0x0f];
  43                 z = 1;
  44             }
  45         }
  46     }
  47     *p = '\0';
  48  err:
  49     return buf;
  50 }
  51
  52 /* Must 'OPENSSL_free' the returned data */
  53 char *BN_bn2dec(const BIGNUM *a)
  54 {
  55     int i = 0, num, ok = 0, n, tbytes;
  56     char *buf = NULL;
  57     char *p;
  58     BIGNUM *t = NULL;
  59     BN_ULONG *bn_data = NULL, *lp;
  60     int bn_data_num;
  61
  62     /*-
  63      * get an upper bound for the length of the decimal integer
  64      * num <= (BN_num_bits(a) + 1) * log(2)
  65      *     <= 3 * BN_num_bits(a) * 0.101 + log(2) + 1     (rounding error)
  66      *     <= 3 * BN_num_bits(a) / 10 + 3 * BN_num_bits / 1000 + 1 + 1
  67      */
  68     i = BN_num_bits(a) * 3;
  69     num = (i / 10 + i / 1000 + 1) + 1;
  70     tbytes = num + 3;   /* negative and terminator and one spare? */
  71     bn_data_num = num / BN_DEC_NUM + 1;
  72     bn_data = OPENSSL_malloc(bn_data_num * sizeof(BN_ULONG));
  73     buf = OPENSSL_malloc(tbytes);
  74     if (buf == NULL || bn_data == NULL) {
  75         BNerr(BN_F_BN_BN2DEC, ERR_R_MALLOC_FAILURE);
  76         goto err;
  77     }
  78     if ((t = BN_dup(a)) == NULL)
  79         goto err;
  80
  81     p = buf;
  82     lp = bn_data;
  83     if (BN_is_zero(t)) {
  84         *p++ = '0';
  85         *p++ = '\0';
  86     } else {
  87         if (BN_is_negative(t))
  88             *p++ = '-';
  89
  90         while (!BN_is_zero(t)) {
  91             if (lp - bn_data >= bn_data_num)
  92                 goto err;
  93             *lp = BN_div_word(t, BN_DEC_CONV);
  94             if (*lp == (BN_ULONG)-1)
  95                 goto err;
  96             lp++;
  97         }
  98         lp--;
  99         /*
 100          * We now have a series of blocks, BN_DEC_NUM chars in length, where
 101          * the last one needs truncation. The blocks need to be reversed in
 102          * order.
 103          */
 104         n = BIO_snprintf(p, tbytes - (size_t)(p - buf), BN_DEC_FMT1, *lp);
 105         if (n < 0)
 106             goto err;
 107         p += n;
 108         while (lp != bn_data) {
 109             lp--;
 110             n = BIO_snprintf(p, tbytes - (size_t)(p - buf), BN_DEC_FMT2, *lp);
 111             if (n < 0)
 112                 goto err;
 113             p += n;
 114         }
 115     }
 116     ok = 1;
 117  err:
 118     OPENSSL_free(bn_data);
 119     BN_free(t);
 120     if (ok)
 121         return buf;
 122     OPENSSL_free(buf);
 123     return NULL;
 124 }
 125
 126 int BN_hex2bn(BIGNUM **bn, const char *a)
 127 {
 128     BIGNUM *ret = NULL;
 129     BN_ULONG l = 0;
 130     int neg = 0, h, m, i, j, k, c;
 131     int num;
 132
 133     if (a == NULL || *a == '\0')
 134         return 0;
 135
 136     if (*a == '-') {
 137         neg = 1;
 138         a++;
 139     }
 140
 141     for (i = 0; i <= INT_MAX / 4 && ossl_isxdigit(a[i]); i++)
 142         continue;
 143
 144     if (i == 0 || i > INT_MAX / 4)
 145         goto err;
 146
 147     num = i + neg;
 148     if (bn == NULL)
 149         return num;
 150
 151     /* a is the start of the hex digits, and it is 'i' long */
 152     if (*bn == NULL) {
 153         if ((ret = BN_new()) == NULL)
 154             return 0;
 155     } else {
 156         ret = *bn;
 157         BN_zero(ret);
 158     }
 159
 160     /* i is the number of hex digits */
 161     if (bn_expand(ret, i * 4) == NULL)
 162         goto err;
 163
 164     j = i;                      /* least significant 'hex' */
 165     m = 0;
 166     h = 0;
 167     while (j > 0) {
 168         m = (BN_BYTES * 2 <= j) ? BN_BYTES * 2 : j;
 169         l = 0;
 170         for (;;) {
 171             c = a[j - m];
 172             k = OPENSSL_hexchar2int(c);
 173             if (k < 0)
 174                 k = 0;          /* paranoia */
 175             l = (l << 4) | k;
 176
 177             if (--m <= 0) {
 178                 ret->d[h++] = l;
 179                 break;
 180             }
 181         }
 182         j -= BN_BYTES * 2;
 183     }
 184     ret->top = h;
 185     bn_correct_top(ret);
 186
 187     *bn = ret;
 188     bn_check_top(ret);
 189     /* Don't set the negative flag if it's zero. */
 190     if (ret->top != 0)
 191         ret->neg = neg;
 192     return num;
 193  err:
 194     if (*bn == NULL)
 195         BN_free(ret);
 196     return 0;
 197 }
 198
 199 int BN_dec2bn(BIGNUM **bn, const char *a)
 200 {
 201     BIGNUM *ret = NULL;
 202     BN_ULONG l = 0;
 203     int neg = 0, i, j;
 204     int num;
 205
 206     if (a == NULL || *a == '\0')
 207         return 0;
 208     if (*a == '-') {
 209         neg = 1;
 210         a++;
 211     }
 212
 213     for (i = 0; i <= INT_MAX / 4 && ossl_isdigit(a[i]); i++)
 214         continue;
 215
 216     if (i == 0 || i > INT_MAX / 4)
 217         goto err;
 218
 219     num = i + neg;
 220     if (bn == NULL)
 221         return num;
 222
 223     /*
 224      * a is the start of the digits, and it is 'i' long. We chop it into
 225      * BN_DEC_NUM digits at a time
 226      */
 227     if (*bn == NULL) {
 228         if ((ret = BN_new()) == NULL)
 229             return 0;
 230     } else {
 231         ret = *bn;
 232         BN_zero(ret);
 233     }
 234
 235     /* i is the number of digits, a bit of an over expand */
 236     if (bn_expand(ret, i * 4) == NULL)
 237         goto err;
 238
 239     j = BN_DEC_NUM - i % BN_DEC_NUM;
 240     if (j == BN_DEC_NUM)
 241         j = 0;
 242     l = 0;
 243     while (--i >= 0) {
 244         l *= 10;
 245         l += *a - '0';
 246         a++;
 247         if (++j == BN_DEC_NUM) {
 248             if (!BN_mul_word(ret, BN_DEC_CONV)
 249                 || !BN_add_word(ret, l))
 250                 goto err;
 251             l = 0;
 252             j = 0;
 253         }
 254     }
 255
 256     bn_correct_top(ret);
 257     *bn = ret;
 258     bn_check_top(ret);
 259     /* Don't set the negative flag if it's zero. */
 260     if (ret->top != 0)
 261         ret->neg = neg;
 262     return num;
 263  err:
 264     if (*bn == NULL)
 265         BN_free(ret);
 266     return 0;
 267 }
 268
 269 int BN_asc2bn(BIGNUM **bn, const char *a)
 270 {
 271     const char *p = a;
 272
 273     if (*p == '-')
 274         p++;
 275
 276     if (p[0] == '0' && (p[1] == 'X' || p[1] == 'x')) {
 277         if (!BN_hex2bn(bn, p + 2))
 278             return 0;
 279     } else {
 280         if (!BN_dec2bn(bn, p))
 281             return 0;
 282     }
 283     /* Don't set the negative flag if it's zero. */
 284     if (*a == '-' && (*bn)->top != 0)
 285         (*bn)->neg = 1;
 286     return 1;
 287 }
 288
 289 # ifndef OPENSSL_NO_STDIO
 290 int BN_print_fp(FILE *fp, const BIGNUM *a)
 291 {
 292     BIO *b;
 293     int ret;
 294
 295     if ((b = BIO_new(BIO_s_file())) == NULL)
 296         return 0;
 297     BIO_set_fp(b, fp, BIO_NOCLOSE);
 298     ret = BN_print(b, a);
 299     BIO_free(b);
 300     return ret;
 301 }
 302 # endif
 303
 304 int BN_print(BIO *bp, const BIGNUM *a)
 305 {
 306     int i, j, v, z = 0;
 307     int ret = 0;
 308
 309     if ((a->neg) && BIO_write(bp, "-", 1) != 1)
 310         goto end;
 311     if (BN_is_zero(a) && BIO_write(bp, "0", 1) != 1)
 312         goto end;
 313     for (i = a->top - 1; i >= 0; i--) {
 314         for (j = BN_BITS2 - 4; j >= 0; j -= 4) {
 315             /* strip leading zeros */
 316             v = (int)((a->d[i] >> j) & 0x0f);
 317             if (z || v != 0) {
 318                 if (BIO_write(bp, &Hex[v], 1) != 1)
 319                     goto end;
 320                 z = 1;
 321             }
 322         }
 323     }
 324     ret = 1;
 325  end:
 326     return ret;
 327 }
 328
 329 char *BN_options(void)
 330 {
 331     static int init = 0;
 332     static char data[16];
 333
 334     if (!init) {
 335         init++;
 336 #ifdef BN_LLONG
 337         BIO_snprintf(data, sizeof(data), "bn(%zu,%zu)",
 338                      sizeof(BN_ULLONG) * 8, sizeof(BN_ULONG) * 8);
 339 #else
 340         BIO_snprintf(data, sizeof(data), "bn(%zu,%zu)",
 341                      sizeof(BN_ULONG) * 8, sizeof(BN_ULONG) * 8);
 342 #endif
 343     }
 344     return data;
 345 }