/* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)
* All rights reserved.
*
* This package is an SSL implementation written
* by Eric Young (eay@cryptsoft.com).
* The implementation was written so as to conform with Netscapes SSL.
*
* This library is free for commercial and non-commercial use as long as
* the following conditions are aheared to. The following conditions
* apply to all code found in this distribution, be it the RC4, RSA,
* lhash, DES, etc., code; not just the SSL code. The SSL documentation
* included with this distribution is covered by the same copyright terms
* except that the holder is Tim Hudson (tjh@cryptsoft.com).
*
* Copyright remains Eric Young's, and as such any Copyright notices in
* the code are not to be removed.
* If this package is used in a product, Eric Young should be given attribution
* as the author of the parts of the library used.
* This can be in the form of a textual message at program startup or
* in documentation (online or textual) provided with the package.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. All advertising materials mentioning features or use of this software
* must display the following acknowledgement:
* "This product includes cryptographic software written by
* Eric Young (eay@cryptsoft.com)"
* The word 'cryptographic' can be left out if the rouines from the library
* being used are not cryptographic related :-).
* 4. If you include any Windows specific code (or a derivative thereof) from
* the apps directory (application code) you must include an acknowledgement:
* "This product includes software written by Tim Hudson (tjh@cryptsoft.com)"
*
* THIS SOFTWARE IS PROVIDED BY ERIC YOUNG ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*
* The licence and distribution terms for any publically available version or
* derivative of this code cannot be changed. i.e. this code cannot simply be
* copied and put under another distribution licence
* [including the GNU Public Licence.] */
#include <openssl/bn.h>
#include <assert.h>
#include <ctype.h>
#include <limits.h>
#include <stdio.h>
#include <string.h>
#include <openssl/bio.h>
#include <openssl/bytestring.h>
#include <openssl/err.h>
#include <openssl/mem.h>
#include "internal.h"
BIGNUM *BN_bin2bn(const uint8_t *in, size_t len, BIGNUM *ret) {
size_t num_words;
unsigned m;
BN_ULONG word = 0;
BIGNUM *bn = NULL;
if (ret == NULL) {
ret = bn = BN_new();
}
if (ret == NULL) {
return NULL;
}
if (len == 0) {
ret->top = 0;
return ret;
}
num_words = ((len - 1) / BN_BYTES) + 1;
m = (len - 1) % BN_BYTES;
if (bn_wexpand(ret, num_words) == NULL) {
if (bn) {
BN_free(bn);
}
return NULL;
}
/* |bn_wexpand| must check bounds on |num_words| to write it into
* |ret->dmax|. */
assert(num_words <= INT_MAX);
ret->top = (int)num_words;
ret->neg = 0;
while (len--) {
word = (word << 8) | *(in++);
if (m-- == 0) {
ret->d[--num_words] = word;
word = 0;
m = BN_BYTES - 1;
}
}
/* need to call this due to clear byte at top if avoiding having the top bit
* set (-ve number) */
bn_correct_top(ret);
return ret;
}
BIGNUM *BN_le2bn(const uint8_t *in, size_t len, BIGNUM *ret) {
BIGNUM *bn = NULL;
if (ret == NULL) {
bn = BN_new();
ret = bn;
}
if (ret == NULL) {
return NULL;
}
if (len == 0) {
ret->top = 0;
ret->neg = 0;
return ret;
}
/* Reserve enough space in |ret|. */
size_t num_words = ((len - 1) / BN_BYTES) + 1;
if (!bn_wexpand(ret, num_words)) {
BN_free(bn);
return NULL;
}
ret->top = num_words;
/* Make sure the top bytes will be zeroed. */
ret->d[num_words - 1] = 0;
/* We only support little-endian platforms, so we can simply memcpy the
* internal representation. */
OPENSSL_memcpy(ret->d, in, len);
bn_correct_top(ret);
return ret;
}
size_t BN_bn2bin(const BIGNUM *in, uint8_t *out) {
size_t n, i;
BN_ULONG l;
n = i = BN_num_bytes(in);
while (i--) {
l = in->d[i / BN_BYTES];
*(out++) = (unsigned char)(l >> (8 * (i % BN_BYTES))) & 0xff;
}
return n;
}
int BN_bn2le_padded(uint8_t *out, size_t len, const BIGNUM *in) {
/* If we don't have enough space, fail out. */
size_t num_bytes = BN_num_bytes(in);
if (len < num_bytes) {
return 0;
}
/* We only support little-endian platforms, so we can simply memcpy into the
* internal representation. */
OPENSSL_memcpy(out, in->d, num_bytes);
/* Pad out the rest of the buffer with zeroes. */
OPENSSL_memset(out + num_bytes, 0, len - num_bytes);
return 1;
}
/* constant_time_select_ulong returns |x| if |v| is 1 and |y| if |v| is 0. Its
* behavior is undefined if |v| takes any other value. */
static BN_ULONG constant_time_select_ulong(int v, BN_ULONG x, BN_ULONG y) {
BN_ULONG mask = v;
mask--;
return (~mask & x) | (mask & y);
}
/* constant_time_le_size_t returns 1 if |x| <= |y| and 0 otherwise. |x| and |y|
* must not have their MSBs set. */
static int constant_time_le_size_t(size_t x, size_t y) {
return ((x - y - 1) >> (sizeof(size_t) * 8 - 1)) & 1;
}
/* read_word_padded returns the |i|'th word of |in|, if it is not out of
* bounds. Otherwise, it returns 0. It does so without branches on the size of
* |in|, however it necessarily does not have the same memory access pattern. If
* the access would be out of bounds, it reads the last word of |in|. |in| must
* not be zero. */
static BN_ULONG read_word_padded(const BIGNUM *in, size_t i) {
/* Read |in->d[i]| if valid. Otherwise, read the last word. */
BN_ULONG l = in->d[constant_time_select_ulong(
constant_time_le_size_t(in->dmax, i), in->dmax - 1, i)];
/* Clamp to zero if above |d->top|. */
return constant_time_select_ulong(constant_time_le_size_t(in->top, i), 0, l);
}
int BN_bn2bin_padded(uint8_t *out, size_t len, const BIGNUM *in) {
/* Special case for |in| = 0. Just branch as the probability is negligible. */
if (BN_is_zero(in)) {
OPENSSL_memset(out, 0, len);
return 1;
}
/* Check if the integer is too big. This case can exit early in non-constant
* time. */
if ((size_t)in->top > (len + (BN_BYTES - 1)) / BN_BYTES) {
return 0;
}
if ((len % BN_BYTES) != 0) {
BN_ULONG l = read_word_padded(in, len / BN_BYTES);
if (l >> (8 * (len % BN_BYTES)) != 0) {
return 0;
}
}
/* Write the bytes out one by one. Serialization is done without branching on
* the bits of |in| or on |in->top|, but if the routine would otherwise read
* out of bounds, the memory access pattern can't be fixed. However, for an
* RSA key of size a multiple of the word size, the probability of BN_BYTES
* leading zero octets is low.
*
* See Falko Stenzke, "Manger's Attack revisited", ICICS 2010. */
size_t i = len;
while (i--) {
BN_ULONG l = read_word_padded(in, i / BN_BYTES);
*(out++) = (uint8_t)(l >> (8 * (i % BN_BYTES))) & 0xff;
}
return 1;
}
int BN_bn2cbb_padded(CBB *out, size_t len, const BIGNUM *in) {
uint8_t *ptr;
return CBB_add_space(out, &ptr, len) && BN_bn2bin_padded(ptr, len, in);
}
static const char hextable[] = "0123456789abcdef";
char *BN_bn2hex(const BIGNUM *bn) {
char *buf = OPENSSL_malloc(1 /* leading '-' */ + 1 /* zero is non-empty */ +
bn->top * BN_BYTES * 2 + 1 /* trailing NUL */);
if (buf == NULL) {
OPENSSL_PUT_ERROR(BN, ERR_R_MALLOC_FAILURE);
return NULL;
}
char *p = buf;
if (bn->neg) {
*(p++) = '-';
}
if (BN_is_zero(bn)) {
*(p++) = '0';
}
int z = 0;
for (int i = bn->top - 1; i >= 0; i--) {
for (int j = BN_BITS2 - 8; j >= 0; j -= 8) {
/* strip leading zeros */
int v = ((int)(bn->d[i] >> (long)j)) & 0xff;
if (z || v != 0) {
*(p++) = hextable[v >> 4];
*(p++) = hextable[v & 0x0f];
z = 1;
}
}
}
*p = '\0';
return buf;
}
/* decode_hex decodes |in_len| bytes of hex data from |in| and updates |bn|. */
static int decode_hex(BIGNUM *bn, const char *in, int in_len) {
if (in_len > INT_MAX/4) {
OPENSSL_PUT_ERROR(BN, BN_R_BIGNUM_TOO_LONG);
return 0;
}
/* |in_len| is the number of hex digits. */
if (bn_expand(bn, in_len * 4) == NULL) {
return 0;
}
int i = 0;
while (in_len > 0) {
/* Decode one |BN_ULONG| at a time. */
int todo = BN_BYTES * 2;
if (todo > in_len) {
todo = in_len;
}
BN_ULONG word = 0;
int j;
for (j = todo; j > 0; j--) {
char c = in[in_len - j];
BN_ULONG hex;
if (c >= '0' && c <= '9') {
hex = c - '0';
} else if (c >= 'a' && c <= 'f') {
hex = c - 'a' + 10;
} else if (c >= 'A' && c <= 'F') {
hex = c - 'A' + 10;
} else {
hex = 0;
/* This shouldn't happen. The caller checks |isxdigit|. */
assert(0);
}
word = (word << 4) | hex;
}
bn->d[i++] = word;
in_len -= todo;
}
assert(i <= bn->dmax);
bn->top = i;
return 1;
}
/* decode_dec decodes |in_len| bytes of decimal data from |in| and updates |bn|. */
static int decode_dec(BIGNUM *bn, const char *in, int in_len) {
int i, j;
BN_ULONG l = 0;
/* Decode |BN_DEC_NUM| digits at a time. */
j = BN_DEC_NUM - (in_len % BN_DEC_NUM);
if (j == BN_DEC_NUM) {
j = 0;
}
l = 0;
for (i = 0; i < in_len; i++) {
l *= 10;
l += in[i] - '0';
if (++j == BN_DEC_NUM) {
if (!BN_mul_word(bn, BN_DEC_CONV) ||
!BN_add_word(bn, l)) {
return 0;
}
l = 0;
j = 0;
}
}
return 1;
}
typedef int (*decode_func) (BIGNUM *bn, const char *in, int in_len);
typedef int (*char_test_func) (int c);
static int bn_x2bn(BIGNUM **outp, const char *in, decode_func decode, char_test_func want_char) {
BIGNUM *ret = NULL;
int neg = 0, i;
int num;
if (in == NULL || *in == 0) {
return 0;
}
if (*in == '-') {
neg = 1;
in++;
}
for (i = 0; want_char((unsigned char)in[i]) && i + neg < INT_MAX; i++) {}
num = i + neg;
if (outp == NULL) {
return num;
}
/* in is the start of the hex digits, and it is 'i' long */
if (*outp == NULL) {
ret = BN_new();
if (ret == NULL) {
return 0;
}
} else {
ret = *outp;
BN_zero(ret);
}
if (!decode(ret, in, i)) {
goto err;
}
bn_correct_top(ret);
if (!BN_is_zero(ret)) {
ret->neg = neg;
}
*outp = ret;
return num;
err:
if (*outp == NULL) {
BN_free(ret);
}
return 0;
}
int BN_hex2bn(BIGNUM **outp, const char *in) {
return bn_x2bn(outp, in, decode_hex, isxdigit);
}
char *BN_bn2dec(const BIGNUM *a) {
/* It is easier to print strings little-endian, so we assemble it in reverse
* and fix at the end. */
BIGNUM *copy = NULL;
CBB cbb;
if (!CBB_init(&cbb, 16) ||
!CBB_add_u8(&cbb, 0 /* trailing NUL */)) {
goto cbb_err;
}
if (BN_is_zero(a)) {
if (!CBB_add_u8(&cbb, '0')) {
goto cbb_err;
}
} else {
copy = BN_dup(a);
if (copy == NULL) {
goto err;
}
while (!BN_is_zero(copy)) {
BN_ULONG word = BN_div_word(copy, BN_DEC_CONV);
if (word == (BN_ULONG)-1) {
goto err;
}
const int add_leading_zeros = !BN_is_zero(copy);
for (int i = 0; i < BN_DEC_NUM && (add_leading_zeros || word != 0); i++) {
if (!CBB_add_u8(&cbb, '0' + word % 10)) {
goto cbb_err;
}
word /= 10;
}
assert(word == 0);
}
}
if (BN_is_negative(a) &&
!CBB_add_u8(&cbb, '-')) {
goto cbb_err;
}
uint8_t *data;
size_t len;
if (!CBB_finish(&cbb, &data, &len)) {
goto cbb_err;
}
/* Reverse the buffer. */
for (size_t i = 0; i < len/2; i++) {
uint8_t tmp = data[i];
data[i] = data[len - 1 - i];
data[len - 1 - i] = tmp;
}
BN_free(copy);
return (char *)data;
cbb_err:
OPENSSL_PUT_ERROR(BN, ERR_R_MALLOC_FAILURE);
err:
BN_free(copy);
CBB_cleanup(&cbb);
return NULL;
}
int BN_dec2bn(BIGNUM **outp, const char *in) {
return bn_x2bn(outp, in, decode_dec, isdigit);
}
int BN_asc2bn(BIGNUM **outp, const char *in) {
const char *const orig_in = in;
if (*in == '-') {
in++;
}
if (in[0] == '0' && (in[1] == 'X' || in[1] == 'x')) {
if (!BN_hex2bn(outp, in+2)) {
return 0;
}
} else {
if (!BN_dec2bn(outp, in)) {
return 0;
}
}
if (*orig_in == '-' && !BN_is_zero(*outp)) {
(*outp)->neg = 1;
}
return 1;
}
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] >> (long)j)) & 0x0f;
if (z || v != 0) {
if (BIO_write(bp, &hextable[v], 1) != 1) {
goto end;
}
z = 1;
}
}
}
ret = 1;
end:
return ret;
}
int BN_print_fp(FILE *fp, const BIGNUM *a) {
BIO *b;
int ret;
b = BIO_new(BIO_s_file());
if (b == NULL) {
return 0;
}
BIO_set_fp(b, fp, BIO_NOCLOSE);
ret = BN_print(b, a);
BIO_free(b);
return ret;
}
BN_ULONG BN_get_word(const BIGNUM *bn) {
switch (bn->top) {
case 0:
return 0;
case 1:
return bn->d[0];
default:
return BN_MASK2;
}
}
int BN_get_u64(const BIGNUM *bn, uint64_t *out) {
switch (bn->top) {
case 0:
*out = 0;
return 1;
case 1:
*out = bn->d[0];
return 1;
#if defined(OPENSSL_32_BIT)
case 2:
*out = (uint64_t) bn->d[0] | (((uint64_t) bn->d[1]) << 32);
return 1;
#endif
default:
return 0;
}
}
size_t BN_bn2mpi(const BIGNUM *in, uint8_t *out) {
const size_t bits = BN_num_bits(in);
const size_t bytes = (bits + 7) / 8;
/* If the number of bits is a multiple of 8, i.e. if the MSB is set,
* prefix with a zero byte. */
int extend = 0;
if (bytes != 0 && (bits & 0x07) == 0) {
extend = 1;
}
const size_t len = bytes + extend;
if (len < bytes ||
4 + len < len ||
(len & 0xffffffff) != len) {
/* If we cannot represent the number then we emit zero as the interface
* doesn't allow an error to be signalled. */
if (out) {
OPENSSL_memset(out, 0, 4);
}
return 4;
}
if (out == NULL) {
return 4 + len;
}
out[0] = len >> 24;
out[1] = len >> 16;
out[2] = len >> 8;
out[3] = len;
if (extend) {
out[4] = 0;
}
BN_bn2bin(in, out + 4 + extend);
if (in->neg && len > 0) {
out[4] |= 0x80;
}
return len + 4;
}
BIGNUM *BN_mpi2bn(const uint8_t *in, size_t len, BIGNUM *out) {
if (len < 4) {
OPENSSL_PUT_ERROR(BN, BN_R_BAD_ENCODING);
return NULL;
}
const size_t in_len = ((size_t)in[0] << 24) |
((size_t)in[1] << 16) |
((size_t)in[2] << 8) |
((size_t)in[3]);
if (in_len != len - 4) {
OPENSSL_PUT_ERROR(BN, BN_R_BAD_ENCODING);
return NULL;
}
int out_is_alloced = 0;
if (out == NULL) {
out = BN_new();
if (out == NULL) {
OPENSSL_PUT_ERROR(BN, ERR_R_MALLOC_FAILURE);
return NULL;
}
out_is_alloced = 1;
}
if (in_len == 0) {
BN_zero(out);
return out;
}
in += 4;
if (BN_bin2bn(in, in_len, out) == NULL) {
if (out_is_alloced) {
BN_free(out);
}
return NULL;
}
out->neg = ((*in) & 0x80) != 0;
if (out->neg) {
BN_clear_bit(out, BN_num_bits(out) - 1);
}
return out;
}