- /* 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;
- }
-
- 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;
- }
-
- /* 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) {
- size_t i;
- BN_ULONG l;
-
- /* Special case for |in| = 0. Just branch as the probability is negligible. */
- if (BN_is_zero(in)) {
- 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) {
- 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. */
- i = len;
- while (i--) {
- 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) {
- int i, j, v, z = 0;
- char *buf;
- char *p;
-
- buf = OPENSSL_malloc(bn->top * BN_BYTES * 2 + 2);
- if (buf == NULL) {
- OPENSSL_PUT_ERROR(BN, ERR_R_MALLOC_FAILURE);
- return NULL;
- }
-
- p = buf;
- if (bn->neg) {
- *(p++) = '-';
- }
-
- if (BN_is_zero(bn)) {
- *(p++) = '0';
- }
-
- for (i = bn->top - 1; i >= 0; i--) {
- for (j = BN_BITS2 - 8; j >= 0; j -= 8) {
- /* strip leading zeros */
- 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) {
- int i = 0, num, ok = 0;
- char *buf = NULL;
- char *p;
- BIGNUM *t = NULL;
- BN_ULONG *bn_data = NULL, *lp;
-
- /* get an upper bound for the length of the decimal integer
- * num <= (BN_num_bits(a) + 1) * log(2)
- * <= 3 * BN_num_bits(a) * 0.1001 + log(2) + 1 (rounding error)
- * <= BN_num_bits(a)/10 + BN_num_bits/1000 + 1 + 1
- */
- i = BN_num_bits(a) * 3;
- num = i / 10 + i / 1000 + 1 + 1;
- bn_data = OPENSSL_malloc((num / BN_DEC_NUM + 1) * sizeof(BN_ULONG));
- buf = OPENSSL_malloc(num + 3);
- if ((buf == NULL) || (bn_data == NULL)) {
- OPENSSL_PUT_ERROR(BN, ERR_R_MALLOC_FAILURE);
- goto err;
- }
- t = BN_dup(a);
- if (t == NULL) {
- goto err;
- }
-
- #define BUF_REMAIN (num + 3 - (size_t)(p - buf))
- 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)) {
- *lp = BN_div_word(t, BN_DEC_CONV);
- 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. */
- BIO_snprintf(p, BUF_REMAIN, BN_DEC_FMT1, *lp);
- while (*p) {
- p++;
- }
- while (lp != bn_data) {
- lp--;
- BIO_snprintf(p, BUF_REMAIN, BN_DEC_FMT2, *lp);
- while (*p) {
- p++;
- }
- }
- }
- ok = 1;
-
- err:
- OPENSSL_free(bn_data);
- BN_free(t);
- if (!ok) {
- OPENSSL_free(buf);
- buf = NULL;
- }
-
- return buf;
- }
-
- 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;
- }
- }
-
- 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) {
- 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;
- }
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