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Diffstat (limited to 'openssl/crypto/bn/bn_lib.c')
| -rw-r--r-- | openssl/crypto/bn/bn_lib.c | 916 |
1 files changed, 916 insertions, 0 deletions
diff --git a/openssl/crypto/bn/bn_lib.c b/openssl/crypto/bn/bn_lib.c new file mode 100644 index 0000000..10b78f5 --- /dev/null +++ b/openssl/crypto/bn/bn_lib.c @@ -0,0 +1,916 @@ +/* crypto/bn/bn_lib.c */ +/* 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.] + */ + +#ifndef BN_DEBUG +# undef NDEBUG /* avoid conflicting definitions */ +# define NDEBUG +#endif + +#include <assert.h> +#include <limits.h> +#include <stdio.h> +#include "cryptlib.h" +#include "bn_lcl.h" + +const char BN_version[] = "Big Number" OPENSSL_VERSION_PTEXT; + +/* This stuff appears to be completely unused, so is deprecated */ +#ifndef OPENSSL_NO_DEPRECATED +/*- + * For a 32 bit machine + * 2 - 4 == 128 + * 3 - 8 == 256 + * 4 - 16 == 512 + * 5 - 32 == 1024 + * 6 - 64 == 2048 + * 7 - 128 == 4096 + * 8 - 256 == 8192 + */ +static int bn_limit_bits = 0; +static int bn_limit_num = 8; /* (1<<bn_limit_bits) */ +static int bn_limit_bits_low = 0; +static int bn_limit_num_low = 8; /* (1<<bn_limit_bits_low) */ +static int bn_limit_bits_high = 0; +static int bn_limit_num_high = 8; /* (1<<bn_limit_bits_high) */ +static int bn_limit_bits_mont = 0; +static int bn_limit_num_mont = 8; /* (1<<bn_limit_bits_mont) */ + +void BN_set_params(int mult, int high, int low, int mont) +{ + if (mult >= 0) { + if (mult > (int)(sizeof(int) * 8) - 1) + mult = sizeof(int) * 8 - 1; + bn_limit_bits = mult; + bn_limit_num = 1 << mult; + } + if (high >= 0) { + if (high > (int)(sizeof(int) * 8) - 1) + high = sizeof(int) * 8 - 1; + bn_limit_bits_high = high; + bn_limit_num_high = 1 << high; + } + if (low >= 0) { + if (low > (int)(sizeof(int) * 8) - 1) + low = sizeof(int) * 8 - 1; + bn_limit_bits_low = low; + bn_limit_num_low = 1 << low; + } + if (mont >= 0) { + if (mont > (int)(sizeof(int) * 8) - 1) + mont = sizeof(int) * 8 - 1; + bn_limit_bits_mont = mont; + bn_limit_num_mont = 1 << mont; + } +} + +int BN_get_params(int which) +{ + if (which == 0) + return (bn_limit_bits); + else if (which == 1) + return (bn_limit_bits_high); + else if (which == 2) + return (bn_limit_bits_low); + else if (which == 3) + return (bn_limit_bits_mont); + else + return (0); +} +#endif + +const BIGNUM *BN_value_one(void) +{ + static const BN_ULONG data_one = 1L; + static const BIGNUM const_one = + { (BN_ULONG *)&data_one, 1, 1, 0, BN_FLG_STATIC_DATA }; + + return (&const_one); +} + +int BN_num_bits_word(BN_ULONG l) +{ + static const unsigned char bits[256] = { + 0, 1, 2, 2, 3, 3, 3, 3, 4, 4, 4, 4, 4, 4, 4, 4, + 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, + 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, + 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, + 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, + 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, + 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, + 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, + 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, + 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, + 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, + 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, + 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, + 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, + 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, + 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, + }; + +#if defined(SIXTY_FOUR_BIT_LONG) + if (l & 0xffffffff00000000L) { + if (l & 0xffff000000000000L) { + if (l & 0xff00000000000000L) { + return (bits[(int)(l >> 56)] + 56); + } else + return (bits[(int)(l >> 48)] + 48); + } else { + if (l & 0x0000ff0000000000L) { + return (bits[(int)(l >> 40)] + 40); + } else + return (bits[(int)(l >> 32)] + 32); + } + } else +#else +# ifdef SIXTY_FOUR_BIT + if (l & 0xffffffff00000000LL) { + if (l & 0xffff000000000000LL) { + if (l & 0xff00000000000000LL) { + return (bits[(int)(l >> 56)] + 56); + } else + return (bits[(int)(l >> 48)] + 48); + } else { + if (l & 0x0000ff0000000000LL) { + return (bits[(int)(l >> 40)] + 40); + } else + return (bits[(int)(l >> 32)] + 32); + } + } else +# endif +#endif + { +#if defined(THIRTY_TWO_BIT) || defined(SIXTY_FOUR_BIT) || defined(SIXTY_FOUR_BIT_LONG) + if (l & 0xffff0000L) { + if (l & 0xff000000L) + return (bits[(int)(l >> 24L)] + 24); + else + return (bits[(int)(l >> 16L)] + 16); + } else +#endif + { +#if defined(THIRTY_TWO_BIT) || defined(SIXTY_FOUR_BIT) || defined(SIXTY_FOUR_BIT_LONG) + if (l & 0xff00L) + return (bits[(int)(l >> 8)] + 8); + else +#endif + return (bits[(int)(l)]); + } + } +} + +int BN_num_bits(const BIGNUM *a) +{ + int i = a->top - 1; + bn_check_top(a); + + if (BN_is_zero(a)) + return 0; + return ((i * BN_BITS2) + BN_num_bits_word(a->d[i])); +} + +void BN_clear_free(BIGNUM *a) +{ + int i; + + if (a == NULL) + return; + bn_check_top(a); + if (a->d != NULL) { + OPENSSL_cleanse(a->d, a->dmax * sizeof(a->d[0])); + if (!(BN_get_flags(a, BN_FLG_STATIC_DATA))) + OPENSSL_free(a->d); + } + i = BN_get_flags(a, BN_FLG_MALLOCED); + OPENSSL_cleanse(a, sizeof(BIGNUM)); + if (i) + OPENSSL_free(a); +} + +void BN_free(BIGNUM *a) +{ + if (a == NULL) + return; + bn_check_top(a); + if ((a->d != NULL) && !(BN_get_flags(a, BN_FLG_STATIC_DATA))) + OPENSSL_free(a->d); + if (a->flags & BN_FLG_MALLOCED) + OPENSSL_free(a); + else { +#ifndef OPENSSL_NO_DEPRECATED + a->flags |= BN_FLG_FREE; +#endif + a->d = NULL; + } +} + +void BN_init(BIGNUM *a) +{ + memset(a, 0, sizeof(BIGNUM)); + bn_check_top(a); +} + +BIGNUM *BN_new(void) +{ + BIGNUM *ret; + + if ((ret = (BIGNUM *)OPENSSL_malloc(sizeof(BIGNUM))) == NULL) { + BNerr(BN_F_BN_NEW, ERR_R_MALLOC_FAILURE); + return (NULL); + } + ret->flags = BN_FLG_MALLOCED; + ret->top = 0; + ret->neg = 0; + ret->dmax = 0; + ret->d = NULL; + bn_check_top(ret); + return (ret); +} + +/* This is used both by bn_expand2() and bn_dup_expand() */ +/* The caller MUST check that words > b->dmax before calling this */ +static BN_ULONG *bn_expand_internal(const BIGNUM *b, int words) +{ + BN_ULONG *A, *a = NULL; + const BN_ULONG *B; + int i; + + bn_check_top(b); + + if (words > (INT_MAX / (4 * BN_BITS2))) { + BNerr(BN_F_BN_EXPAND_INTERNAL, BN_R_BIGNUM_TOO_LONG); + return NULL; + } + if (BN_get_flags(b, BN_FLG_STATIC_DATA)) { + BNerr(BN_F_BN_EXPAND_INTERNAL, BN_R_EXPAND_ON_STATIC_BIGNUM_DATA); + return (NULL); + } + a = A = (BN_ULONG *)OPENSSL_malloc(sizeof(BN_ULONG) * words); + if (A == NULL) { + BNerr(BN_F_BN_EXPAND_INTERNAL, ERR_R_MALLOC_FAILURE); + return (NULL); + } +#ifdef PURIFY + /* + * Valgrind complains in BN_consttime_swap because we process the whole + * array even if it's not initialised yet. This doesn't matter in that + * function - what's important is constant time operation (we're not + * actually going to use the data) + */ + memset(a, 0, sizeof(BN_ULONG) * words); +#endif + +#if 1 + B = b->d; + /* Check if the previous number needs to be copied */ + if (B != NULL) { + for (i = b->top >> 2; i > 0; i--, A += 4, B += 4) { + /* + * The fact that the loop is unrolled + * 4-wise is a tribute to Intel. It's + * the one that doesn't have enough + * registers to accomodate more data. + * I'd unroll it 8-wise otherwise:-) + * + * <appro@fy.chalmers.se> + */ + BN_ULONG a0, a1, a2, a3; + a0 = B[0]; + a1 = B[1]; + a2 = B[2]; + a3 = B[3]; + A[0] = a0; + A[1] = a1; + A[2] = a2; + A[3] = a3; + } + /* + * workaround for ultrix cc: without 'case 0', the optimizer does + * the switch table by doing a=top&3; a--; goto jump_table[a]; + * which fails for top== 0 + */ + switch (b->top & 3) { + case 3: + A[2] = B[2]; + case 2: + A[1] = B[1]; + case 1: + A[0] = B[0]; + case 0: + ; + } + } +#else + memset(A, 0, sizeof(BN_ULONG) * words); + memcpy(A, b->d, sizeof(b->d[0]) * b->top); +#endif + + return (a); +} + +/* + * This is an internal function that can be used instead of bn_expand2() when + * there is a need to copy BIGNUMs instead of only expanding the data part, + * while still expanding them. Especially useful when needing to expand + * BIGNUMs that are declared 'const' and should therefore not be changed. The + * reason to use this instead of a BN_dup() followed by a bn_expand2() is + * memory allocation overhead. A BN_dup() followed by a bn_expand2() will + * allocate new memory for the BIGNUM data twice, and free it once, while + * bn_dup_expand() makes sure allocation is made only once. + */ + +#ifndef OPENSSL_NO_DEPRECATED +BIGNUM *bn_dup_expand(const BIGNUM *b, int words) +{ + BIGNUM *r = NULL; + + bn_check_top(b); + + /* + * This function does not work if words <= b->dmax && top < words because + * BN_dup() does not preserve 'dmax'! (But bn_dup_expand() is not used + * anywhere yet.) + */ + + if (words > b->dmax) { + BN_ULONG *a = bn_expand_internal(b, words); + + if (a) { + r = BN_new(); + if (r) { + r->top = b->top; + r->dmax = words; + r->neg = b->neg; + r->d = a; + } else { + /* r == NULL, BN_new failure */ + OPENSSL_free(a); + } + } + /* + * If a == NULL, there was an error in allocation in + * bn_expand_internal(), and NULL should be returned + */ + } else { + r = BN_dup(b); + } + + bn_check_top(r); + return r; +} +#endif + +/* + * This is an internal function that should not be used in applications. It + * ensures that 'b' has enough room for a 'words' word number and initialises + * any unused part of b->d with leading zeros. It is mostly used by the + * various BIGNUM routines. If there is an error, NULL is returned. If not, + * 'b' is returned. + */ + +BIGNUM *bn_expand2(BIGNUM *b, int words) +{ + bn_check_top(b); + + if (words > b->dmax) { + BN_ULONG *a = bn_expand_internal(b, words); + if (!a) + return NULL; + if (b->d) + OPENSSL_free(b->d); + b->d = a; + b->dmax = words; + } + +/* None of this should be necessary because of what b->top means! */ +#if 0 + /* + * NB: bn_wexpand() calls this only if the BIGNUM really has to grow + */ + if (b->top < b->dmax) { + int i; + BN_ULONG *A = &(b->d[b->top]); + for (i = (b->dmax - b->top) >> 3; i > 0; i--, A += 8) { + A[0] = 0; + A[1] = 0; + A[2] = 0; + A[3] = 0; + A[4] = 0; + A[5] = 0; + A[6] = 0; + A[7] = 0; + } + for (i = (b->dmax - b->top) & 7; i > 0; i--, A++) + A[0] = 0; + assert(A == &(b->d[b->dmax])); + } +#endif + bn_check_top(b); + return b; +} + +BIGNUM *BN_dup(const BIGNUM *a) +{ + BIGNUM *t; + + if (a == NULL) + return NULL; + bn_check_top(a); + + t = BN_new(); + if (t == NULL) + return NULL; + if (!BN_copy(t, a)) { + BN_free(t); + return NULL; + } + bn_check_top(t); + return t; +} + +BIGNUM *BN_copy(BIGNUM *a, const BIGNUM *b) +{ + int i; + BN_ULONG *A; + const BN_ULONG *B; + + bn_check_top(b); + + if (a == b) + return (a); + if (bn_wexpand(a, b->top) == NULL) + return (NULL); + +#if 1 + A = a->d; + B = b->d; + for (i = b->top >> 2; i > 0; i--, A += 4, B += 4) { + BN_ULONG a0, a1, a2, a3; + a0 = B[0]; + a1 = B[1]; + a2 = B[2]; + a3 = B[3]; + A[0] = a0; + A[1] = a1; + A[2] = a2; + A[3] = a3; + } + /* ultrix cc workaround, see comments in bn_expand_internal */ + switch (b->top & 3) { + case 3: + A[2] = B[2]; + case 2: + A[1] = B[1]; + case 1: + A[0] = B[0]; + case 0:; + } +#else + memcpy(a->d, b->d, sizeof(b->d[0]) * b->top); +#endif + + a->top = b->top; + a->neg = b->neg; + bn_check_top(a); + return (a); +} + +void BN_swap(BIGNUM *a, BIGNUM *b) +{ + int flags_old_a, flags_old_b; + BN_ULONG *tmp_d; + int tmp_top, tmp_dmax, tmp_neg; + + bn_check_top(a); + bn_check_top(b); + + flags_old_a = a->flags; + flags_old_b = b->flags; + + tmp_d = a->d; + tmp_top = a->top; + tmp_dmax = a->dmax; + tmp_neg = a->neg; + + a->d = b->d; + a->top = b->top; + a->dmax = b->dmax; + a->neg = b->neg; + + b->d = tmp_d; + b->top = tmp_top; + b->dmax = tmp_dmax; + b->neg = tmp_neg; + + a->flags = + (flags_old_a & BN_FLG_MALLOCED) | (flags_old_b & BN_FLG_STATIC_DATA); + b->flags = + (flags_old_b & BN_FLG_MALLOCED) | (flags_old_a & BN_FLG_STATIC_DATA); + bn_check_top(a); + bn_check_top(b); +} + +void BN_clear(BIGNUM *a) +{ + bn_check_top(a); + if (a->d != NULL) + OPENSSL_cleanse(a->d, a->dmax * sizeof(a->d[0])); + a->top = 0; + a->neg = 0; +} + +BN_ULONG BN_get_word(const BIGNUM *a) +{ + if (a->top > 1) + return BN_MASK2; + else if (a->top == 1) + return a->d[0]; + /* a->top == 0 */ + return 0; +} + +int BN_set_word(BIGNUM *a, BN_ULONG w) +{ + bn_check_top(a); + if (bn_expand(a, (int)sizeof(BN_ULONG) * 8) == NULL) + return (0); + a->neg = 0; + a->d[0] = w; + a->top = (w ? 1 : 0); + bn_check_top(a); + return (1); +} + +BIGNUM *BN_bin2bn(const unsigned char *s, int len, BIGNUM *ret) +{ + unsigned int i, m; + unsigned int n; + BN_ULONG l; + BIGNUM *bn = NULL; + + if (ret == NULL) + ret = bn = BN_new(); + if (ret == NULL) + return (NULL); + bn_check_top(ret); + l = 0; + n = len; + if (n == 0) { + ret->top = 0; + return (ret); + } + i = ((n - 1) / BN_BYTES) + 1; + m = ((n - 1) % (BN_BYTES)); + if (bn_wexpand(ret, (int)i) == NULL) { + if (bn) + BN_free(bn); + return NULL; + } + ret->top = i; + ret->neg = 0; + while (n--) { + l = (l << 8L) | *(s++); + if (m-- == 0) { + ret->d[--i] = l; + l = 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); +} + +/* ignore negative */ +int BN_bn2bin(const BIGNUM *a, unsigned char *to) +{ + int n, i; + BN_ULONG l; + + bn_check_top(a); + n = i = BN_num_bytes(a); + while (i--) { + l = a->d[i / BN_BYTES]; + *(to++) = (unsigned char)(l >> (8 * (i % BN_BYTES))) & 0xff; + } + return (n); +} + +int BN_ucmp(const BIGNUM *a, const BIGNUM *b) +{ + int i; + BN_ULONG t1, t2, *ap, *bp; + + bn_check_top(a); + bn_check_top(b); + + i = a->top - b->top; + if (i != 0) + return (i); + ap = a->d; + bp = b->d; + for (i = a->top - 1; i >= 0; i--) { + t1 = ap[i]; + t2 = bp[i]; + if (t1 != t2) + return ((t1 > t2) ? 1 : -1); + } + return (0); +} + +int BN_cmp(const BIGNUM *a, const BIGNUM *b) +{ + int i; + int gt, lt; + BN_ULONG t1, t2; + + if ((a == NULL) || (b == NULL)) { + if (a != NULL) + return (-1); + else if (b != NULL) + return (1); + else + return (0); + } + + bn_check_top(a); + bn_check_top(b); + + if (a->neg != b->neg) { + if (a->neg) + return (-1); + else + return (1); + } + if (a->neg == 0) { + gt = 1; + lt = -1; + } else { + gt = -1; + lt = 1; + } + + if (a->top > b->top) + return (gt); + if (a->top < b->top) + return (lt); + for (i = a->top - 1; i >= 0; i--) { + t1 = a->d[i]; + t2 = b->d[i]; + if (t1 > t2) + return (gt); + if (t1 < t2) + return (lt); + } + return (0); +} + +int BN_set_bit(BIGNUM *a, int n) +{ + int i, j, k; + + if (n < 0) + return 0; + + i = n / BN_BITS2; + j = n % BN_BITS2; + if (a->top <= i) { + if (bn_wexpand(a, i + 1) == NULL) + return (0); + for (k = a->top; k < i + 1; k++) + a->d[k] = 0; + a->top = i + 1; + } + + a->d[i] |= (((BN_ULONG)1) << j); + bn_check_top(a); + return (1); +} + +int BN_clear_bit(BIGNUM *a, int n) +{ + int i, j; + + bn_check_top(a); + if (n < 0) + return 0; + + i = n / BN_BITS2; + j = n % BN_BITS2; + if (a->top <= i) + return (0); + + a->d[i] &= (~(((BN_ULONG)1) << j)); + bn_correct_top(a); + return (1); +} + +int BN_is_bit_set(const BIGNUM *a, int n) +{ + int i, j; + + bn_check_top(a); + if (n < 0) + return 0; + i = n / BN_BITS2; + j = n % BN_BITS2; + if (a->top <= i) + return 0; + return (int)(((a->d[i]) >> j) & ((BN_ULONG)1)); +} + +int BN_mask_bits(BIGNUM *a, int n) +{ + int b, w; + + bn_check_top(a); + if (n < 0) + return 0; + + w = n / BN_BITS2; + b = n % BN_BITS2; + if (w >= a->top) + return 0; + if (b == 0) + a->top = w; + else { + a->top = w + 1; + a->d[w] &= ~(BN_MASK2 << b); + } + bn_correct_top(a); + return (1); +} + +void BN_set_negative(BIGNUM *a, int b) +{ + if (b && !BN_is_zero(a)) + a->neg = 1; + else + a->neg = 0; +} + +int bn_cmp_words(const BN_ULONG *a, const BN_ULONG *b, int n) +{ + int i; + BN_ULONG aa, bb; + + aa = a[n - 1]; + bb = b[n - 1]; + if (aa != bb) + return ((aa > bb) ? 1 : -1); + for (i = n - 2; i >= 0; i--) { + aa = a[i]; + bb = b[i]; + if (aa != bb) + return ((aa > bb) ? 1 : -1); + } + return (0); +} + +/* + * Here follows a specialised variants of bn_cmp_words(). It has the + * property of performing the operation on arrays of different sizes. The + * sizes of those arrays is expressed through cl, which is the common length + * ( basicall, min(len(a),len(b)) ), and dl, which is the delta between the + * two lengths, calculated as len(a)-len(b). All lengths are the number of + * BN_ULONGs... + */ + +int bn_cmp_part_words(const BN_ULONG *a, const BN_ULONG *b, int cl, int dl) +{ + int n, i; + n = cl - 1; + + if (dl < 0) { + for (i = dl; i < 0; i++) { + if (b[n - i] != 0) + return -1; /* a < b */ + } + } + if (dl > 0) { + for (i = dl; i > 0; i--) { + if (a[n + i] != 0) + return 1; /* a > b */ + } + } + return bn_cmp_words(a, b, cl); +} + +/* + * Constant-time conditional swap of a and b. + * a and b are swapped if condition is not 0. The code assumes that at most one bit of condition is set. + * nwords is the number of words to swap. The code assumes that at least nwords are allocated in both a and b, + * and that no more than nwords are used by either a or b. + * a and b cannot be the same number + */ +void BN_consttime_swap(BN_ULONG condition, BIGNUM *a, BIGNUM *b, int nwords) +{ + BN_ULONG t; + int i; + + bn_wcheck_size(a, nwords); + bn_wcheck_size(b, nwords); + + assert(a != b); + assert((condition & (condition - 1)) == 0); + assert(sizeof(BN_ULONG) >= sizeof(int)); + + condition = ((condition - 1) >> (BN_BITS2 - 1)) - 1; + + t = (a->top ^ b->top) & condition; + a->top ^= t; + b->top ^= t; + +#define BN_CONSTTIME_SWAP(ind) \ + do { \ + t = (a->d[ind] ^ b->d[ind]) & condition; \ + a->d[ind] ^= t; \ + b->d[ind] ^= t; \ + } while (0) + + switch (nwords) { + default: + for (i = 10; i < nwords; i++) + BN_CONSTTIME_SWAP(i); + /* Fallthrough */ + case 10: + BN_CONSTTIME_SWAP(9); /* Fallthrough */ + case 9: + BN_CONSTTIME_SWAP(8); /* Fallthrough */ + case 8: + BN_CONSTTIME_SWAP(7); /* Fallthrough */ + case 7: + BN_CONSTTIME_SWAP(6); /* Fallthrough */ + case 6: + BN_CONSTTIME_SWAP(5); /* Fallthrough */ + case 5: + BN_CONSTTIME_SWAP(4); /* Fallthrough */ + case 4: + BN_CONSTTIME_SWAP(3); /* Fallthrough */ + case 3: + BN_CONSTTIME_SWAP(2); /* Fallthrough */ + case 2: + BN_CONSTTIME_SWAP(1); /* Fallthrough */ + case 1: + BN_CONSTTIME_SWAP(0); + } +#undef BN_CONSTTIME_SWAP +} |