/* * Copyright 1995-2023 The OpenSSL Project Authors. All Rights Reserved. * * Licensed under the Apache License 2.0 (the "License"). You may not use * this file except in compliance with the License. You can obtain a copy * in the file LICENSE in the source distribution or at * https://www.openssl.org/source/license.html */ #include #include #include "internal/cryptlib.h" #include "internal/endian.h" #include "bn_local.h" #include #include "internal/constant_time.h" /* This stuff appears to be completely unused, so is deprecated */ #ifndef OPENSSL_NO_DEPRECATED_0_9_8 /*- * 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<= 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; } /* * Old Visual Studio ARM compiler miscompiles BN_num_bits_word() * https://mta.openssl.org/pipermail/openssl-users/2018-August/008465.html */ #if defined(_MSC_VER) && defined(_ARM_) && defined(_WIN32_WCE) \ && _MSC_VER>=1400 && _MSC_VER<1501 # define MS_BROKEN_BN_num_bits_word # pragma optimize("", off) #endif int BN_num_bits_word(BN_ULONG l) { BN_ULONG x, mask; int bits = (l != 0); #if BN_BITS2 > 32 x = l >> 32; mask = (0 - x) & BN_MASK2; mask = (0 - (mask >> (BN_BITS2 - 1))); bits += 32 & mask; l ^= (x ^ l) & mask; #endif x = l >> 16; mask = (0 - x) & BN_MASK2; mask = (0 - (mask >> (BN_BITS2 - 1))); bits += 16 & mask; l ^= (x ^ l) & mask; x = l >> 8; mask = (0 - x) & BN_MASK2; mask = (0 - (mask >> (BN_BITS2 - 1))); bits += 8 & mask; l ^= (x ^ l) & mask; x = l >> 4; mask = (0 - x) & BN_MASK2; mask = (0 - (mask >> (BN_BITS2 - 1))); bits += 4 & mask; l ^= (x ^ l) & mask; x = l >> 2; mask = (0 - x) & BN_MASK2; mask = (0 - (mask >> (BN_BITS2 - 1))); bits += 2 & mask; l ^= (x ^ l) & mask; x = l >> 1; mask = (0 - x) & BN_MASK2; mask = (0 - (mask >> (BN_BITS2 - 1))); bits += 1 & mask; return bits; } #ifdef MS_BROKEN_BN_num_bits_word # pragma optimize("", on) #endif /* * This function still leaks `a->dmax`: it's caller's responsibility to * expand the input `a` in advance to a public length. */ static ossl_inline int bn_num_bits_consttime(const BIGNUM *a) { int j, ret; unsigned int mask, past_i; int i = a->top - 1; bn_check_top(a); for (j = 0, past_i = 0, ret = 0; j < a->dmax; j++) { mask = constant_time_eq_int(i, j); /* 0xff..ff if i==j, 0x0 otherwise */ ret += BN_BITS2 & (~mask & ~past_i); ret += BN_num_bits_word(a->d[j]) & mask; past_i |= mask; /* past_i will become 0xff..ff after i==j */ } /* * if BN_is_zero(a) => i is -1 and ret contains garbage, so we mask the * final result. */ mask = ~(constant_time_eq_int(i, ((int)-1))); return ret & mask; } int BN_num_bits(const BIGNUM *a) { int i = a->top - 1; bn_check_top(a); if (a->flags & BN_FLG_CONSTTIME) { /* * We assume that BIGNUMs flagged as CONSTTIME have also been expanded * so that a->dmax is not leaking secret information. * * In other words, it's the caller's responsibility to ensure `a` has * been preallocated in advance to a public length if we hit this * branch. * */ return bn_num_bits_consttime(a); } if (BN_is_zero(a)) return 0; return ((i * BN_BITS2) + BN_num_bits_word(a->d[i])); } static void bn_free_d(BIGNUM *a, int clear) { if (BN_get_flags(a, BN_FLG_SECURE)) OPENSSL_secure_clear_free(a->d, a->dmax * sizeof(a->d[0])); else if (clear != 0) OPENSSL_clear_free(a->d, a->dmax * sizeof(a->d[0])); else OPENSSL_free(a->d); } void BN_clear_free(BIGNUM *a) { if (a == NULL) return; if (a->d != NULL && !BN_get_flags(a, BN_FLG_STATIC_DATA)) bn_free_d(a, 1); if (BN_get_flags(a, BN_FLG_MALLOCED)) { OPENSSL_cleanse(a, sizeof(*a)); OPENSSL_free(a); } } void BN_free(BIGNUM *a) { if (a == NULL) return; if (!BN_get_flags(a, BN_FLG_STATIC_DATA)) bn_free_d(a, 0); if (a->flags & BN_FLG_MALLOCED) OPENSSL_free(a); } void bn_init(BIGNUM *a) { static BIGNUM nilbn; *a = nilbn; bn_check_top(a); } BIGNUM *BN_new(void) { BIGNUM *ret; if ((ret = OPENSSL_zalloc(sizeof(*ret))) == NULL) return NULL; ret->flags = BN_FLG_MALLOCED; bn_check_top(ret); return ret; } BIGNUM *BN_secure_new(void) { BIGNUM *ret = BN_new(); if (ret != NULL) ret->flags |= BN_FLG_SECURE; return ret; } /* This is used by bn_expand2() */ /* 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 = NULL; if (words > (INT_MAX / (4 * BN_BITS2))) { ERR_raise(ERR_LIB_BN, BN_R_BIGNUM_TOO_LONG); return NULL; } if (BN_get_flags(b, BN_FLG_STATIC_DATA)) { ERR_raise(ERR_LIB_BN, BN_R_EXPAND_ON_STATIC_BIGNUM_DATA); return NULL; } if (BN_get_flags(b, BN_FLG_SECURE)) a = OPENSSL_secure_zalloc(words * sizeof(*a)); else a = OPENSSL_zalloc(words * sizeof(*a)); if (a == NULL) return NULL; assert(b->top <= words); if (b->top > 0) memcpy(a, b->d, sizeof(*a) * b->top); return a; } /* * 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) { if (words > b->dmax) { BN_ULONG *a = bn_expand_internal(b, words); if (!a) return NULL; if (b->d != NULL) bn_free_d(b, 1); b->d = a; b->dmax = words; } return b; } BIGNUM *BN_dup(const BIGNUM *a) { BIGNUM *t; if (a == NULL) return NULL; bn_check_top(a); t = BN_get_flags(a, BN_FLG_SECURE) ? BN_secure_new() : 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 bn_words; bn_check_top(b); bn_words = BN_get_flags(b, BN_FLG_CONSTTIME) ? b->dmax : b->top; if (a == b) return a; if (bn_wexpand(a, bn_words) == NULL) return NULL; if (b->top > 0) memcpy(a->d, b->d, sizeof(b->d[0]) * bn_words); a->neg = b->neg; a->top = b->top; a->flags |= b->flags & BN_FLG_FIXED_TOP; bn_check_top(a); return a; } #define FLAGS_DATA(flags) ((flags) & (BN_FLG_STATIC_DATA \ | BN_FLG_CONSTTIME \ | BN_FLG_SECURE \ | BN_FLG_FIXED_TOP)) #define FLAGS_STRUCT(flags) ((flags) & (BN_FLG_MALLOCED)) 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_STRUCT(flags_old_a) | FLAGS_DATA(flags_old_b); b->flags = FLAGS_STRUCT(flags_old_b) | FLAGS_DATA(flags_old_a); bn_check_top(a); bn_check_top(b); } void BN_clear(BIGNUM *a) { if (a == NULL) return; bn_check_top(a); if (a->d != NULL) OPENSSL_cleanse(a->d, sizeof(*a->d) * a->dmax); a->neg = 0; a->top = 0; a->flags &= ~BN_FLG_FIXED_TOP; } 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); a->flags &= ~BN_FLG_FIXED_TOP; bn_check_top(a); return 1; } typedef enum {BIG, LITTLE} endianness_t; typedef enum {SIGNED, UNSIGNED} signedness_t; static BIGNUM *bin2bn(const unsigned char *s, int len, BIGNUM *ret, endianness_t endianness, signedness_t signedness) { int inc; const unsigned char *s2; int inc2; int neg = 0, xor = 0, carry = 0; unsigned int i; unsigned int n; BIGNUM *bn = NULL; /* Negative length is not acceptable */ if (len < 0) return NULL; if (ret == NULL) ret = bn = BN_new(); if (ret == NULL) return NULL; bn_check_top(ret); /* * If the input has no bits, the number is considered zero. * This makes calls with s==NULL and len==0 safe. */ if (len == 0) { BN_clear(ret); return ret; } /* * The loop that does the work iterates from least to most * significant BIGNUM chunk, so we adapt parameters to transfer * input bytes accordingly. */ if (endianness == LITTLE) { s2 = s + len - 1; inc2 = -1; inc = 1; } else { s2 = s; inc2 = 1; inc = -1; s += len - 1; } /* Take note of the signedness of the input bytes*/ if (signedness == SIGNED) { neg = !!(*s2 & 0x80); xor = neg ? 0xff : 0x00; carry = neg; } /* * Skip leading sign extensions (the value of |xor|). * This is the only spot where |s2| and |inc2| are used. */ for ( ; len > 0 && *s2 == xor; s2 += inc2, len--) continue; /* * If there was a set of 0xff, we backtrack one byte unless the next * one has a sign bit, as the last 0xff is then part of the actual * number, rather then a mere sign extension. */ if (xor == 0xff) { if (len == 0 || !(*s2 & 0x80)) len++; } /* If it was all zeros, we're done */ if (len == 0) { ret->top = 0; return ret; } n = ((len - 1) / BN_BYTES) + 1; /* Number of resulting bignum chunks */ if (bn_wexpand(ret, (int)n) == NULL) { BN_free(bn); return NULL; } ret->top = n; ret->neg = neg; for (i = 0; n-- > 0; i++) { BN_ULONG l = 0; /* Accumulator */ unsigned int m = 0; /* Offset in a bignum chunk, in bits */ for (; len > 0 && m < BN_BYTES * 8; len--, s += inc, m += 8) { BN_ULONG byte_xored = *s ^ xor; BN_ULONG byte = (byte_xored + carry) & 0xff; carry = byte_xored > byte; /* Implicit 1 or 0 */ l |= (byte << m); } ret->d[i] = l; } /* * 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_bin2bn(const unsigned char *s, int len, BIGNUM *ret) { return bin2bn(s, len, ret, BIG, UNSIGNED); } BIGNUM *BN_signed_bin2bn(const unsigned char *s, int len, BIGNUM *ret) { return bin2bn(s, len, ret, BIG, SIGNED); } static int bn2binpad(const BIGNUM *a, unsigned char *to, int tolen, endianness_t endianness, signedness_t signedness) { int inc; int n, n8; int xor = 0, carry = 0, ext = 0; size_t i, lasti, j, atop, mask; BN_ULONG l; /* * In case |a| is fixed-top, BN_num_bits can return bogus length, * but it's assumed that fixed-top inputs ought to be "nominated" * even for padded output, so it works out... */ n8 = BN_num_bits(a); n = (n8 + 7) / 8; /* This is what BN_num_bytes() does */ /* Take note of the signedness of the bignum */ if (signedness == SIGNED) { xor = a->neg ? 0xff : 0x00; carry = a->neg; /* * if |n * 8 == n|, then the MSbit is set, otherwise unset. * We must compensate with one extra byte if that doesn't * correspond to the signedness of the bignum with regards * to 2's complement. */ ext = (n * 8 == n8) ? !a->neg /* MSbit set on nonnegative bignum */ : a->neg; /* MSbit unset on negative bignum */ } if (tolen == -1) { tolen = n + ext; } else if (tolen < n + ext) { /* uncommon/unlike case */ BIGNUM temp = *a; bn_correct_top(&temp); n8 = BN_num_bits(&temp); n = (n8 + 7) / 8; /* This is what BN_num_bytes() does */ if (tolen < n + ext) return -1; } /* Swipe through whole available data and don't give away padded zero. */ atop = a->dmax * BN_BYTES; if (atop == 0) { if (tolen != 0) memset(to, '\0', tolen); return tolen; } /* * The loop that does the work iterates from least significant * to most significant BIGNUM limb, so we adapt parameters to * transfer output bytes accordingly. */ if (endianness == LITTLE) { inc = 1; } else { inc = -1; to += tolen - 1; /* Move to the last byte, not beyond */ } lasti = atop - 1; atop = a->top * BN_BYTES; for (i = 0, j = 0; j < (size_t)tolen; j++) { unsigned char byte, byte_xored; l = a->d[i / BN_BYTES]; mask = 0 - ((j - atop) >> (8 * sizeof(i) - 1)); byte = (unsigned char)(l >> (8 * (i % BN_BYTES)) & mask); byte_xored = byte ^ xor; *to = (unsigned char)(byte_xored + carry); carry = byte_xored > *to; /* Implicit 1 or 0 */ to += inc; i += (i - lasti) >> (8 * sizeof(i) - 1); /* stay on last limb */ } return tolen; } int BN_bn2binpad(const BIGNUM *a, unsigned char *to, int tolen) { if (tolen < 0) return -1; return bn2binpad(a, to, tolen, BIG, UNSIGNED); } int BN_signed_bn2bin(const BIGNUM *a, unsigned char *to, int tolen) { if (tolen < 0) return -1; return bn2binpad(a, to, tolen, BIG, SIGNED); } int BN_bn2bin(const BIGNUM *a, unsigned char *to) { return bn2binpad(a, to, -1, BIG, UNSIGNED); } BIGNUM *BN_lebin2bn(const unsigned char *s, int len, BIGNUM *ret) { return bin2bn(s, len, ret, LITTLE, UNSIGNED); } BIGNUM *BN_signed_lebin2bn(const unsigned char *s, int len, BIGNUM *ret) { return bin2bn(s, len, ret, LITTLE, SIGNED); } int BN_bn2lebinpad(const BIGNUM *a, unsigned char *to, int tolen) { if (tolen < 0) return -1; return bn2binpad(a, to, tolen, LITTLE, UNSIGNED); } int BN_signed_bn2lebin(const BIGNUM *a, unsigned char *to, int tolen) { if (tolen < 0) return -1; return bn2binpad(a, to, tolen, LITTLE, SIGNED); } BIGNUM *BN_native2bn(const unsigned char *s, int len, BIGNUM *ret) { DECLARE_IS_ENDIAN; if (IS_LITTLE_ENDIAN) return BN_lebin2bn(s, len, ret); return BN_bin2bn(s, len, ret); } BIGNUM *BN_signed_native2bn(const unsigned char *s, int len, BIGNUM *ret) { DECLARE_IS_ENDIAN; if (IS_LITTLE_ENDIAN) return BN_signed_lebin2bn(s, len, ret); return BN_signed_bin2bn(s, len, ret); } int BN_bn2nativepad(const BIGNUM *a, unsigned char *to, int tolen) { DECLARE_IS_ENDIAN; if (IS_LITTLE_ENDIAN) return BN_bn2lebinpad(a, to, tolen); return BN_bn2binpad(a, to, tolen); } int BN_signed_bn2native(const BIGNUM *a, unsigned char *to, int tolen) { DECLARE_IS_ENDIAN; if (IS_LITTLE_ENDIAN) return BN_signed_bn2lebin(a, to, tolen); return BN_signed_bn2bin(a, to, tolen); } int BN_ucmp(const BIGNUM *a, const BIGNUM *b) { int i; BN_ULONG t1, t2, *ap, *bp; ap = a->d; bp = b->d; if (BN_get_flags(a, BN_FLG_CONSTTIME) && a->top == b->top) { int res = 0; for (i = 0; i < b->top; i++) { res = constant_time_select_int(constant_time_lt_bn(ap[i], bp[i]), -1, res); res = constant_time_select_int(constant_time_lt_bn(bp[i], ap[i]), 1, res); } return res; } bn_check_top(a); bn_check_top(b); i = a->top - b->top; if (i != 0) return i; 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->flags &= ~BN_FLG_FIXED_TOP; } 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 ossl_bn_mask_bits_fixed_top(BIGNUM *a, int n) { int b, w; 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); } a->flags |= BN_FLG_FIXED_TOP; return 1; } int BN_mask_bits(BIGNUM *a, int n) { int ret; bn_check_top(a); ret = ossl_bn_mask_bits_fixed_top(a, n); if (ret) bn_correct_top(a); return ret; } 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; if (n == 0) return 0; 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 * capability of performing the operation on arrays of different sizes. The * sizes of those arrays is expressed through cl, which is the common length * ( basically, 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. * nwords is the number of words to swap. * Assumes that at least nwords are allocated in both a and b. * Assumes that no more than nwords are used by either a or b. */ 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); condition = ((~condition & ((condition - 1))) >> (BN_BITS2 - 1)) - 1; t = (a->top ^ b->top) & condition; a->top ^= t; b->top ^= t; t = (a->neg ^ b->neg) & condition; a->neg ^= t; b->neg ^= t; /*- * BN_FLG_STATIC_DATA: indicates that data may not be written to. Intention * is actually to treat it as it's read-only data, and some (if not most) * of it does reside in read-only segment. In other words observation of * BN_FLG_STATIC_DATA in BN_consttime_swap should be treated as fatal * condition. It would either cause SEGV or effectively cause data * corruption. * * BN_FLG_MALLOCED: refers to BN structure itself, and hence must be * preserved. * * BN_FLG_SECURE: must be preserved, because it determines how x->d was * allocated and hence how to free it. * * BN_FLG_CONSTTIME: sufficient to mask and swap * * BN_FLG_FIXED_TOP: indicates that we haven't called bn_correct_top() on * the data, so the d array may be padded with additional 0 values (i.e. * top could be greater than the minimal value that it could be). We should * be swapping it */ #define BN_CONSTTIME_SWAP_FLAGS (BN_FLG_CONSTTIME | BN_FLG_FIXED_TOP) t = ((a->flags ^ b->flags) & BN_CONSTTIME_SWAP_FLAGS) & condition; a->flags ^= t; b->flags ^= t; /* conditionally swap the data */ for (i = 0; i < nwords; i++) { t = (a->d[i] ^ b->d[i]) & condition; a->d[i] ^= t; b->d[i] ^= t; } } #undef BN_CONSTTIME_SWAP_FLAGS /* Bits of security, see SP800-57 */ int BN_security_bits(int L, int N) { int secbits, bits; if (L >= 15360) secbits = 256; else if (L >= 7680) secbits = 192; else if (L >= 3072) secbits = 128; else if (L >= 2048) secbits = 112; else if (L >= 1024) secbits = 80; else return 0; if (N == -1) return secbits; bits = N / 2; if (bits < 80) return 0; return bits >= secbits ? secbits : bits; } void BN_zero_ex(BIGNUM *a) { a->neg = 0; a->top = 0; a->flags &= ~BN_FLG_FIXED_TOP; } int BN_abs_is_word(const BIGNUM *a, const BN_ULONG w) { return ((a->top == 1) && (a->d[0] == w)) || ((w == 0) && (a->top == 0)); } int BN_is_zero(const BIGNUM *a) { return a->top == 0; } int BN_is_one(const BIGNUM *a) { return BN_abs_is_word(a, 1) && !a->neg; } int BN_is_word(const BIGNUM *a, const BN_ULONG w) { return BN_abs_is_word(a, w) && (!w || !a->neg); } int ossl_bn_is_word_fixed_top(const BIGNUM *a, const BN_ULONG w) { int res, i; const BN_ULONG *ap = a->d; if (a->neg || a->top == 0) return 0; res = constant_time_select_int(constant_time_eq_bn(ap[0], w), 1, 0); for (i = 1; i < a->top; i++) res = constant_time_select_int(constant_time_is_zero_bn(ap[i]), res, 0); return res; } int BN_is_odd(const BIGNUM *a) { return (a->top > 0) && (a->d[0] & 1); } int BN_is_negative(const BIGNUM *a) { return (a->neg != 0); } int BN_to_montgomery(BIGNUM *r, const BIGNUM *a, BN_MONT_CTX *mont, BN_CTX *ctx) { return BN_mod_mul_montgomery(r, a, &(mont->RR), mont, ctx); } void BN_with_flags(BIGNUM *dest, const BIGNUM *b, int flags) { dest->d = b->d; dest->top = b->top; dest->dmax = b->dmax; dest->neg = b->neg; dest->flags = ((dest->flags & BN_FLG_MALLOCED) | (b->flags & ~BN_FLG_MALLOCED) | BN_FLG_STATIC_DATA | flags); } BN_GENCB *BN_GENCB_new(void) { BN_GENCB *ret; if ((ret = OPENSSL_malloc(sizeof(*ret))) == NULL) return NULL; return ret; } void BN_GENCB_free(BN_GENCB *cb) { if (cb == NULL) return; OPENSSL_free(cb); } void BN_set_flags(BIGNUM *b, int n) { b->flags |= n; } int BN_get_flags(const BIGNUM *b, int n) { return b->flags & n; } /* Populate a BN_GENCB structure with an "old"-style callback */ void BN_GENCB_set_old(BN_GENCB *gencb, void (*callback) (int, int, void *), void *cb_arg) { BN_GENCB *tmp_gencb = gencb; tmp_gencb->ver = 1; tmp_gencb->arg = cb_arg; tmp_gencb->cb.cb_1 = callback; } /* Populate a BN_GENCB structure with a "new"-style callback */ void BN_GENCB_set(BN_GENCB *gencb, int (*callback) (int, int, BN_GENCB *), void *cb_arg) { BN_GENCB *tmp_gencb = gencb; tmp_gencb->ver = 2; tmp_gencb->arg = cb_arg; tmp_gencb->cb.cb_2 = callback; } void *BN_GENCB_get_arg(BN_GENCB *cb) { return cb->arg; } BIGNUM *bn_wexpand(BIGNUM *a, int words) { return (words <= a->dmax) ? a : bn_expand2(a, words); } void bn_correct_top_consttime(BIGNUM *a) { int j, atop; BN_ULONG limb; unsigned int mask; for (j = 0, atop = 0; j < a->dmax; j++) { limb = a->d[j]; limb |= 0 - limb; limb >>= BN_BITS2 - 1; limb = 0 - limb; mask = (unsigned int)limb; mask &= constant_time_msb(j - a->top); atop = constant_time_select_int(mask, j + 1, atop); } mask = constant_time_eq_int(atop, 0); a->top = atop; a->neg = constant_time_select_int(mask, 0, a->neg); a->flags &= ~BN_FLG_FIXED_TOP; } void bn_correct_top(BIGNUM *a) { BN_ULONG *ftl; int tmp_top = a->top; if (tmp_top > 0) { for (ftl = &(a->d[tmp_top]); tmp_top > 0; tmp_top--) { ftl--; if (*ftl != 0) break; } a->top = tmp_top; } if (a->top == 0) a->neg = 0; a->flags &= ~BN_FLG_FIXED_TOP; bn_pollute(a); }