crypto/bn/bn_print.c

   1 /*
   2  * Copyright 1995-2016 The OpenSSL Project Authors. All Rights Reserved.
   3  *
   4  * Licensed under the OpenSSL license (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 <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 (a->neg && BN_is_zero(a)) {
  27         /* "-0" == 3 bytes including NULL terminator */
  28         buf = OPENSSL_malloc(3);
  29     } else {
  30         buf = OPENSSL_malloc(a->top * BN_BYTES * 2 + 2);
  31     }
  32     if (buf == NULL) {
  33         BNerr(BN_F_BN_BN2HEX, ERR_R_MALLOC_FAILURE);
  34         goto err;
  35     }
  36     p = buf;
  37     if (a->neg)
  38         *(p++) = '-';
  39     if (BN_is_zero(a))
  40         *(p++) = '0';
  41     for (i = a->top - 1; i >= 0; i--) {
  42         for (j = BN_BITS2 - 8; j >= 0; j -= 8) {
  43             /* strip leading zeros */
  44             v = ((int)(a->d[i] >> (long)j)) & 0xff;
  45             if (z || (v != 0)) {
  46                 *(p++) = Hex[v >> 4];
  47                 *(p++) = Hex[v & 0x0f];
  48                 z = 1;
  49             }
  50         }
  51     }
  52     *p = '\0';
  53  err:
  54     return (buf);
  55 }
  56
  57 /* Must 'OPENSSL_free' the returned data */
  58 char *BN_bn2dec(const BIGNUM *a)
  59 {
  60     int i = 0, num, ok = 0;
  61     char *buf = NULL;
  62     char *p;
  63     BIGNUM *t = NULL;
  64     BN_ULONG *bn_data = NULL, *lp;
  65
  66     /*-
  67      * get an upper bound for the length of the decimal integer
  68      * num <= (BN_num_bits(a) + 1) * log(2)
  69      *     <= 3 * BN_num_bits(a) * 0.1001 + log(2) + 1     (rounding error)
  70      *     <= BN_num_bits(a)/10 + BN_num_bits/1000 + 1 + 1
  71      */
  72     i = BN_num_bits(a) * 3;
  73     num = (i / 10 + i / 1000 + 1) + 1;
  74     bn_data = OPENSSL_malloc((num / BN_DEC_NUM + 1) * sizeof(BN_ULONG));
  75     buf = OPENSSL_malloc(num + 3);
  76     if ((buf == NULL) || (bn_data == NULL)) {
  77         BNerr(BN_F_BN_BN2DEC, ERR_R_MALLOC_FAILURE);
  78         goto err;
  79     }
  80     if ((t = BN_dup(a)) == NULL)
  81         goto err;
  82
  83 #define BUF_REMAIN (num+3 - (size_t)(p - buf))
  84     p = buf;
  85     lp = bn_data;
  86     if (BN_is_zero(t)) {
  87         *(p++) = '0';
  88         *(p++) = '\0';
  89     } else {
  90         if (BN_is_negative(t))
  91             *p++ = '-';
  92
  93         i = 0;
  94         while (!BN_is_zero(t)) {
  95             *lp = BN_div_word(t, BN_DEC_CONV);
  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         BIO_snprintf(p, BUF_REMAIN, BN_DEC_FMT1, *lp);
 105         while (*p)
 106             p++;
 107         while (lp != bn_data) {
 108             lp--;
 109             BIO_snprintf(p, BUF_REMAIN, BN_DEC_FMT2, *lp);
 110             while (*p)
 111                 p++;
 112         }
 113     }
 114     ok = 1;
 115  err:
 116     OPENSSL_free(bn_data);
 117     BN_free(t);
 118     if (ok)
 119         return buf;
 120     OPENSSL_free(buf);
 121     return NULL;
 122 }
 123
 124 int BN_hex2bn(BIGNUM **bn, const char *a)
 125 {
 126     BIGNUM *ret = NULL;
 127     BN_ULONG l = 0;
 128     int neg = 0, h, m, i, j, k, c;
 129     int num;
 130
 131     if ((a == NULL) || (*a == '\0'))
 132         return (0);
 133
 134     if (*a == '-') {
 135         neg = 1;
 136         a++;
 137     }
 138
 139     for (i = 0; i <= (INT_MAX/4) && isxdigit((unsigned char)a[i]); i++)
 140         continue;
 141
 142     if (i > INT_MAX/4)
 143         goto err;
 144
 145     num = i + neg;
 146     if (bn == NULL)
 147         return (num);
 148
 149     /* a is the start of the hex digits, and it is 'i' long */
 150     if (*bn == NULL) {
 151         if ((ret = BN_new()) == NULL)
 152             return (0);
 153     } else {
 154         ret = *bn;
 155         BN_zero(ret);
 156     }
 157
 158     /* i is the number of hex digits */
 159     if (bn_expand(ret, i * 4) == NULL)
 160         goto err;
 161
 162     j = i;                      /* least significant 'hex' */
 163     m = 0;
 164     h = 0;
 165     while (j > 0) {
 166         m = ((BN_BYTES * 2) <= j) ? (BN_BYTES * 2) : j;
 167         l = 0;
 168         for (;;) {
 169             c = a[j - m];
 170             k = OPENSSL_hexchar2int(c);
 171             if (k < 0)
 172                 k = 0;          /* paranoia */
 173             l = (l << 4) | k;
 174
 175             if (--m <= 0) {
 176                 ret->d[h++] = l;
 177                 break;
 178             }
 179         }
 180         j -= (BN_BYTES * 2);
 181     }
 182     ret->top = h;
 183     bn_correct_top(ret);
 184     ret->neg = neg;
 185
 186     *bn = ret;
 187     bn_check_top(ret);
 188     return (num);
 189  err:
 190     if (*bn == NULL)
 191         BN_free(ret);
 192     return (0);
 193 }
 194
 195 int BN_dec2bn(BIGNUM **bn, const char *a)
 196 {
 197     BIGNUM *ret = NULL;
 198     BN_ULONG l = 0;
 199     int neg = 0, i, j;
 200     int num;
 201
 202     if ((a == NULL) || (*a == '\0'))
 203         return (0);
 204     if (*a == '-') {
 205         neg = 1;
 206         a++;
 207     }
 208
 209     for (i = 0; i <= (INT_MAX/4) && isdigit((unsigned char)a[i]); i++)
 210         continue;
 211
 212     if (i > INT_MAX/4)
 213         goto err;
 214
 215     num = i + neg;
 216     if (bn == NULL)
 217         return (num);
 218
 219     /*
 220      * a is the start of the digits, and it is 'i' long. We chop it into
 221      * BN_DEC_NUM digits at a time
 222      */
 223     if (*bn == NULL) {
 224         if ((ret = BN_new()) == NULL)
 225             return (0);
 226     } else {
 227         ret = *bn;
 228         BN_zero(ret);
 229     }
 230
 231     /* i is the number of digits, a bit of an over expand */
 232     if (bn_expand(ret, i * 4) == NULL)
 233         goto err;
 234
 235     j = BN_DEC_NUM - (i % BN_DEC_NUM);
 236     if (j == BN_DEC_NUM)
 237         j = 0;
 238     l = 0;
 239     while (*a) {
 240         l *= 10;
 241         l += *a - '0';
 242         a++;
 243         if (++j == BN_DEC_NUM) {
 244             BN_mul_word(ret, BN_DEC_CONV);
 245             BN_add_word(ret, l);
 246             l = 0;
 247             j = 0;
 248         }
 249     }
 250     ret->neg = neg;
 251
 252     bn_correct_top(ret);
 253     *bn = ret;
 254     bn_check_top(ret);
 255     return (num);
 256  err:
 257     if (*bn == NULL)
 258         BN_free(ret);
 259     return (0);
 260 }
 261
 262 int BN_asc2bn(BIGNUM **bn, const char *a)
 263 {
 264     const char *p = a;
 265     if (*p == '-')
 266         p++;
 267
 268     if (p[0] == '0' && (p[1] == 'X' || p[1] == 'x')) {
 269         if (!BN_hex2bn(bn, p + 2))
 270             return 0;
 271     } else {
 272         if (!BN_dec2bn(bn, p))
 273             return 0;
 274     }
 275     if (*a == '-')
 276         (*bn)->neg = 1;
 277     return 1;
 278 }
 279
 280 # ifndef OPENSSL_NO_STDIO
 281 int BN_print_fp(FILE *fp, const BIGNUM *a)
 282 {
 283     BIO *b;
 284     int ret;
 285
 286     if ((b = BIO_new(BIO_s_file())) == NULL)
 287         return (0);
 288     BIO_set_fp(b, fp, BIO_NOCLOSE);
 289     ret = BN_print(b, a);
 290     BIO_free(b);
 291     return (ret);
 292 }
 293 # endif
 294
 295 int BN_print(BIO *bp, const BIGNUM *a)
 296 {
 297     int i, j, v, z = 0;
 298     int ret = 0;
 299
 300     if ((a->neg) && (BIO_write(bp, "-", 1) != 1))
 301         goto end;
 302     if (BN_is_zero(a) && (BIO_write(bp, "0", 1) != 1))
 303         goto end;
 304     for (i = a->top - 1; i >= 0; i--) {
 305         for (j = BN_BITS2 - 4; j >= 0; j -= 4) {
 306             /* strip leading zeros */
 307             v = ((int)(a->d[i] >> (long)j)) & 0x0f;
 308             if (z || (v != 0)) {
 309                 if (BIO_write(bp, &(Hex[v]), 1) != 1)
 310                     goto end;
 311                 z = 1;
 312             }
 313         }
 314     }
 315     ret = 1;
 316  end:
 317     return (ret);
 318 }
 319
 320 char *BN_options(void)
 321 {
 322     static int init = 0;
 323     static char data[16];
 324
 325     if (!init) {
 326         init++;
 327 #ifdef BN_LLONG
 328         BIO_snprintf(data, sizeof data, "bn(%d,%d)",
 329                      (int)sizeof(BN_ULLONG) * 8, (int)sizeof(BN_ULONG) * 8);
 330 #else
 331         BIO_snprintf(data, sizeof data, "bn(%d,%d)",
 332                      (int)sizeof(BN_ULONG) * 8, (int)sizeof(BN_ULONG) * 8);
 333 #endif
 334     }
 335     return (data);
 336 }