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author | Adam Langley <agl@google.com> | 2015-01-22 14:27:53 -0800 |
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committer | Adam Langley <agl@google.com> | 2015-01-30 16:52:14 -0800 |
commit | d9e397b599b13d642138480a28c14db7a136bf05 (patch) | |
tree | 34bab61dc4ce323b123ad4614dbc07e86ea2f9ef /src/crypto/bn/convert.c | |
download | external_boringssl-d9e397b599b13d642138480a28c14db7a136bf05.zip external_boringssl-d9e397b599b13d642138480a28c14db7a136bf05.tar.gz external_boringssl-d9e397b599b13d642138480a28c14db7a136bf05.tar.bz2 |
Initial commit of BoringSSL for Android.
Diffstat (limited to 'src/crypto/bn/convert.c')
-rw-r--r-- | src/crypto/bn/convert.c | 504 |
1 files changed, 504 insertions, 0 deletions
diff --git a/src/crypto/bn/convert.c b/src/crypto/bn/convert.c new file mode 100644 index 0000000..f764eed --- /dev/null +++ b/src/crypto/bn/convert.c @@ -0,0 +1,504 @@ +/* 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 <ctype.h> +#include <stdio.h> +#include <string.h> + +#include <openssl/bio.h> +#include <openssl/err.h> +#include <openssl/mem.h> + +#include "internal.h" + +BIGNUM *BN_bin2bn(const uint8_t *in, size_t len, BIGNUM *ret) { + unsigned num_words, 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; + } + + ret->top = 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; +} + +static const char hextable[] = "0123456789abcdef"; + +char *BN_bn2hex(const BIGNUM *bn) { + int i, j, v, z = 0; + char *buf; + char *p; + + buf = (char *)OPENSSL_malloc(bn->top * BN_BYTES * 2 + 2); + if (buf == NULL) { + OPENSSL_PUT_ERROR(BN, BN_bn2hex, 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 |i| bytes of hex data from |in| and updates |bn|. */ +static void decode_hex(BIGNUM *bn, const char *in, int i) { + int h, m, j, k, c; + BN_ULONG l=0; + + j = i; /* least significant 'hex' */ + h = 0; + while (j > 0) { + m = ((BN_BYTES * 2) <= j) ? (BN_BYTES * 2) : j; + l = 0; + for (;;) { + c = in[j - m]; + if ((c >= '0') && (c <= '9')) { + k = c - '0'; + } else if ((c >= 'a') && (c <= 'f')) { + k = c - 'a' + 10; + } else if ((c >= 'A') && (c <= 'F')) { + k = c - 'A' + 10; + } else { + k = 0; /* paranoia */ + } + + l = (l << 4) | k; + + if (--m <= 0) { + bn->d[h++] = l; + break; + } + } + + j -= (BN_BYTES * 2); + } + + bn->top = h; +} + +/* decode_dec decodes |i| bytes of decimal data from |in| and updates |bn|. */ +static void decode_dec(BIGNUM *bn, const char *in, int i) { + int j; + BN_ULONG l = 0; + + j = BN_DEC_NUM - (i % BN_DEC_NUM); + if (j == BN_DEC_NUM) { + j = 0; + } + l = 0; + while (*in) { + l *= 10; + l += *in - '0'; + in++; + if (++j == BN_DEC_NUM) { + BN_mul_word(bn, BN_DEC_CONV); + BN_add_word(bn, l); + l = 0; + j = 0; + } + } +} + +typedef void (*decode_func) (BIGNUM *bn, const char *in, int i); +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++) {} + + 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); + } + ret->neg = neg; + + /* i is the number of hex digests; */ + if (bn_expand(ret, i * 4) == NULL) { + goto err; + } + + decode(ret, in, i); + + bn_correct_top(ret); + + *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 = + (BN_ULONG *)OPENSSL_malloc((num / BN_DEC_NUM + 1) * sizeof(BN_ULONG)); + buf = (char *)OPENSSL_malloc(num + 3); + if ((buf == NULL) || (bn_data == NULL)) { + OPENSSL_PUT_ERROR(BN, BN_bn2dec, 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: + if (bn_data != NULL) { + OPENSSL_free(bn_data); + } + if (t != NULL) { + BN_free(t); + } + if (!ok && buf) { + 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 == '-') { + (*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; + } +} |