openssl/crypto/bn/bn_print.c

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2023-05-09 22:08:48 +00:00
/*
* Copyright 1995-2017 The OpenSSL Project Authors. All Rights Reserved.
*
* Licensed under the OpenSSL license (the "License"). You may not use
* this file except in compliance with the License. You can obtain a copy
* in the file LICENSE in the source distribution or at
* https://www.openssl.org/source/license.html
*/
#include <stdio.h>
#include "crypto/ctype.h"
#include <limits.h>
#include "internal/cryptlib.h"
#include <openssl/buffer.h>
#include "bn_local.h"
static const char Hex[] = "0123456789ABCDEF";
/* Must 'OPENSSL_free' the returned data */
char *BN_bn2hex(const BIGNUM *a)
{
int i, j, v, z = 0;
char *buf;
char *p;
if (BN_is_zero(a))
return OPENSSL_strdup("0");
buf = OPENSSL_malloc(a->top * BN_BYTES * 2 + 2);
if (buf == NULL) {
BNerr(BN_F_BN_BN2HEX, ERR_R_MALLOC_FAILURE);
goto err;
}
p = buf;
if (a->neg)
*p++ = '-';
for (i = a->top - 1; i >= 0; i--) {
for (j = BN_BITS2 - 8; j >= 0; j -= 8) {
/* strip leading zeros */
v = (int)((a->d[i] >> j) & 0xff);
if (z || v != 0) {
*p++ = Hex[v >> 4];
*p++ = Hex[v & 0x0f];
z = 1;
}
}
}
*p = '\0';
err:
return buf;
}
/* Must 'OPENSSL_free' the returned data */
char *BN_bn2dec(const BIGNUM *a)
{
int i = 0, num, ok = 0, n, tbytes;
char *buf = NULL;
char *p;
BIGNUM *t = NULL;
BN_ULONG *bn_data = NULL, *lp;
int bn_data_num;
/*-
* get an upper bound for the length of the decimal integer
* num <= (BN_num_bits(a) + 1) * log(2)
* <= 3 * BN_num_bits(a) * 0.101 + log(2) + 1 (rounding error)
* <= 3 * BN_num_bits(a) / 10 + 3 * BN_num_bits / 1000 + 1 + 1
*/
i = BN_num_bits(a) * 3;
num = (i / 10 + i / 1000 + 1) + 1;
tbytes = num + 3; /* negative and terminator and one spare? */
bn_data_num = num / BN_DEC_NUM + 1;
bn_data = OPENSSL_malloc(bn_data_num * sizeof(BN_ULONG));
buf = OPENSSL_malloc(tbytes);
if (buf == NULL || bn_data == NULL) {
BNerr(BN_F_BN_BN2DEC, ERR_R_MALLOC_FAILURE);
goto err;
}
if ((t = BN_dup(a)) == NULL)
goto err;
p = buf;
lp = bn_data;
if (BN_is_zero(t)) {
*p++ = '0';
*p++ = '\0';
} else {
if (BN_is_negative(t))
*p++ = '-';
while (!BN_is_zero(t)) {
if (lp - bn_data >= bn_data_num)
goto err;
*lp = BN_div_word(t, BN_DEC_CONV);
if (*lp == (BN_ULONG)-1)
goto err;
lp++;
}
lp--;
/*
* We now have a series of blocks, BN_DEC_NUM chars in length, where
* the last one needs truncation. The blocks need to be reversed in
* order.
*/
n = BIO_snprintf(p, tbytes - (size_t)(p - buf), BN_DEC_FMT1, *lp);
if (n < 0)
goto err;
p += n;
while (lp != bn_data) {
lp--;
n = BIO_snprintf(p, tbytes - (size_t)(p - buf), BN_DEC_FMT2, *lp);
if (n < 0)
goto err;
p += n;
}
}
ok = 1;
err:
OPENSSL_free(bn_data);
BN_free(t);
if (ok)
return buf;
OPENSSL_free(buf);
return NULL;
}
int BN_hex2bn(BIGNUM **bn, const char *a)
{
BIGNUM *ret = NULL;
BN_ULONG l = 0;
int neg = 0, h, m, i, j, k, c;
int num;
if (a == NULL || *a == '\0')
return 0;
if (*a == '-') {
neg = 1;
a++;
}
for (i = 0; i <= INT_MAX / 4 && ossl_isxdigit(a[i]); i++)
continue;
if (i == 0 || i > INT_MAX / 4)
return 0;
num = i + neg;
if (bn == NULL)
return num;
/* a is the start of the hex digits, and it is 'i' long */
if (*bn == NULL) {
if ((ret = BN_new()) == NULL)
return 0;
} else {
ret = *bn;
BN_zero(ret);
}
/* i is the number of hex digits */
if (bn_expand(ret, i * 4) == NULL)
goto err;
j = i; /* least significant 'hex' */
m = 0;
h = 0;
while (j > 0) {
m = (BN_BYTES * 2 <= j) ? BN_BYTES * 2 : j;
l = 0;
for (;;) {
c = a[j - m];
k = OPENSSL_hexchar2int(c);
if (k < 0)
k = 0; /* paranoia */
l = (l << 4) | k;
if (--m <= 0) {
ret->d[h++] = l;
break;
}
}
j -= BN_BYTES * 2;
}
ret->top = h;
bn_correct_top(ret);
*bn = ret;
bn_check_top(ret);
/* Don't set the negative flag if it's zero. */
if (ret->top != 0)
ret->neg = neg;
return num;
err:
if (*bn == NULL)
BN_free(ret);
return 0;
}
int BN_dec2bn(BIGNUM **bn, const char *a)
{
BIGNUM *ret = NULL;
BN_ULONG l = 0;
int neg = 0, i, j;
int num;
if (a == NULL || *a == '\0')
return 0;
if (*a == '-') {
neg = 1;
a++;
}
for (i = 0; i <= INT_MAX / 4 && ossl_isdigit(a[i]); i++)
continue;
if (i == 0 || i > INT_MAX / 4)
goto err;
num = i + neg;
if (bn == NULL)
return num;
/*
* a is the start of the digits, and it is 'i' long. We chop it into
* BN_DEC_NUM digits at a time
*/
if (*bn == NULL) {
if ((ret = BN_new()) == NULL)
return 0;
} else {
ret = *bn;
BN_zero(ret);
}
/* i is the number of digits, a bit of an over expand */
if (bn_expand(ret, i * 4) == NULL)
goto err;
j = BN_DEC_NUM - i % BN_DEC_NUM;
if (j == BN_DEC_NUM)
j = 0;
l = 0;
while (--i >= 0) {
l *= 10;
l += *a - '0';
a++;
if (++j == BN_DEC_NUM) {
if (!BN_mul_word(ret, BN_DEC_CONV)
|| !BN_add_word(ret, l))
goto err;
l = 0;
j = 0;
}
}
bn_correct_top(ret);
*bn = ret;
bn_check_top(ret);
/* Don't set the negative flag if it's zero. */
if (ret->top != 0)
ret->neg = neg;
return num;
err:
if (*bn == NULL)
BN_free(ret);
return 0;
}
int BN_asc2bn(BIGNUM **bn, const char *a)
{
const char *p = a;
if (*p == '-')
p++;
if (p[0] == '0' && (p[1] == 'X' || p[1] == 'x')) {
if (!BN_hex2bn(bn, p + 2))
return 0;
} else {
if (!BN_dec2bn(bn, p))
return 0;
}
/* Don't set the negative flag if it's zero. */
if (*a == '-' && (*bn)->top != 0)
(*bn)->neg = 1;
return 1;
}
# ifndef OPENSSL_NO_STDIO
int BN_print_fp(FILE *fp, const BIGNUM *a)
{
BIO *b;
int ret;
if ((b = BIO_new(BIO_s_file())) == NULL)
return 0;
BIO_set_fp(b, fp, BIO_NOCLOSE);
ret = BN_print(b, a);
BIO_free(b);
return ret;
}
# endif
int BN_print(BIO *bp, const BIGNUM *a)
{
int i, j, v, z = 0;
int ret = 0;
if ((a->neg) && BIO_write(bp, "-", 1) != 1)
goto end;
if (BN_is_zero(a) && BIO_write(bp, "0", 1) != 1)
goto end;
for (i = a->top - 1; i >= 0; i--) {
for (j = BN_BITS2 - 4; j >= 0; j -= 4) {
/* strip leading zeros */
v = (int)((a->d[i] >> j) & 0x0f);
if (z || v != 0) {
if (BIO_write(bp, &Hex[v], 1) != 1)
goto end;
z = 1;
}
}
}
ret = 1;
end:
return ret;
}
char *BN_options(void)
{
static int init = 0;
static char data[16];
if (!init) {
init++;
#ifdef BN_LLONG
BIO_snprintf(data, sizeof(data), "bn(%zu,%zu)",
sizeof(BN_ULLONG) * 8, sizeof(BN_ULONG) * 8);
#else
BIO_snprintf(data, sizeof(data), "bn(%zu,%zu)",
sizeof(BN_ULONG) * 8, sizeof(BN_ULONG) * 8);
#endif
}
return data;
}