| /* 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) { |
| /* 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; |
| } |
| } |
| |
| 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; |
| } |