2 * Copyright 1995-2018 The OpenSSL Project Authors. All Rights Reserved.
4 * Licensed under the Apache License 2.0 (the "License"). You may not use
5 * this file except in compliance with the License. You can obtain a copy
6 * in the file LICENSE in the source distribution or at
7 * https://www.openssl.org/source/license.html
12 #include "internal/cryptlib.h"
14 #include <openssl/opensslconf.h>
15 #include "internal/constant_time.h"
17 /* This stuff appears to be completely unused, so is deprecated */
18 #ifndef OPENSSL_NO_DEPRECATED_0_9_8
20 * For a 32 bit machine
29 static int bn_limit_bits = 0;
30 static int bn_limit_num = 8; /* (1<<bn_limit_bits) */
31 static int bn_limit_bits_low = 0;
32 static int bn_limit_num_low = 8; /* (1<<bn_limit_bits_low) */
33 static int bn_limit_bits_high = 0;
34 static int bn_limit_num_high = 8; /* (1<<bn_limit_bits_high) */
35 static int bn_limit_bits_mont = 0;
36 static int bn_limit_num_mont = 8; /* (1<<bn_limit_bits_mont) */
38 void BN_set_params(int mult, int high, int low, int mont)
41 if (mult > (int)(sizeof(int) * 8) - 1)
42 mult = sizeof(int) * 8 - 1;
44 bn_limit_num = 1 << mult;
47 if (high > (int)(sizeof(int) * 8) - 1)
48 high = sizeof(int) * 8 - 1;
49 bn_limit_bits_high = high;
50 bn_limit_num_high = 1 << high;
53 if (low > (int)(sizeof(int) * 8) - 1)
54 low = sizeof(int) * 8 - 1;
55 bn_limit_bits_low = low;
56 bn_limit_num_low = 1 << low;
59 if (mont > (int)(sizeof(int) * 8) - 1)
60 mont = sizeof(int) * 8 - 1;
61 bn_limit_bits_mont = mont;
62 bn_limit_num_mont = 1 << mont;
66 int BN_get_params(int which)
71 return bn_limit_bits_high;
73 return bn_limit_bits_low;
75 return bn_limit_bits_mont;
81 const BIGNUM *BN_value_one(void)
83 static const BN_ULONG data_one = 1L;
84 static const BIGNUM const_one =
85 { (BN_ULONG *)&data_one, 1, 1, 0, BN_FLG_STATIC_DATA };
90 int BN_num_bits_word(BN_ULONG l)
97 mask = (0 - x) & BN_MASK2;
98 mask = (0 - (mask >> (BN_BITS2 - 1)));
104 mask = (0 - x) & BN_MASK2;
105 mask = (0 - (mask >> (BN_BITS2 - 1)));
110 mask = (0 - x) & BN_MASK2;
111 mask = (0 - (mask >> (BN_BITS2 - 1)));
116 mask = (0 - x) & BN_MASK2;
117 mask = (0 - (mask >> (BN_BITS2 - 1)));
122 mask = (0 - x) & BN_MASK2;
123 mask = (0 - (mask >> (BN_BITS2 - 1)));
128 mask = (0 - x) & BN_MASK2;
129 mask = (0 - (mask >> (BN_BITS2 - 1)));
136 * This function still leaks `a->dmax`: it's caller's responsibility to
137 * expand the input `a` in advance to a public length.
140 int bn_num_bits_consttime(const BIGNUM *a)
143 unsigned int mask, past_i;
147 for (j = 0, past_i = 0, ret = 0; j < a->dmax; j++) {
148 mask = constant_time_eq_int(i, j); /* 0xff..ff if i==j, 0x0 otherwise */
150 ret += BN_BITS2 & (~mask & ~past_i);
151 ret += BN_num_bits_word(a->d[j]) & mask;
153 past_i |= mask; /* past_i will become 0xff..ff after i==j */
157 * if BN_is_zero(a) => i is -1 and ret contains garbage, so we mask the
160 mask = ~(constant_time_eq_int(i, ((int)-1)));
165 int BN_num_bits(const BIGNUM *a)
170 if (a->flags & BN_FLG_CONSTTIME) {
172 * We assume that BIGNUMs flagged as CONSTTIME have also been expanded
173 * so that a->dmax is not leaking secret information.
175 * In other words, it's the caller's responsibility to ensure `a` has
176 * been preallocated in advance to a public length if we hit this
180 return bn_num_bits_consttime(a);
186 return ((i * BN_BITS2) + BN_num_bits_word(a->d[i]));
189 static void bn_free_d(BIGNUM *a, int clear)
191 if (BN_get_flags(a, BN_FLG_SECURE))
192 OPENSSL_secure_clear_free(a->d, a->dmax * sizeof(a->d[0]));
194 OPENSSL_clear_free(a->d, a->dmax * sizeof(a->d[0]));
200 void BN_clear_free(BIGNUM *a)
204 if (a->d != NULL && !BN_get_flags(a, BN_FLG_STATIC_DATA))
206 if (BN_get_flags(a, BN_FLG_MALLOCED)) {
207 OPENSSL_cleanse(a, sizeof(*a));
212 void BN_free(BIGNUM *a)
216 if (!BN_get_flags(a, BN_FLG_STATIC_DATA))
218 if (a->flags & BN_FLG_MALLOCED)
222 void bn_init(BIGNUM *a)
234 if ((ret = OPENSSL_zalloc(sizeof(*ret))) == NULL) {
235 BNerr(BN_F_BN_NEW, ERR_R_MALLOC_FAILURE);
238 ret->flags = BN_FLG_MALLOCED;
243 BIGNUM *BN_secure_new(void)
245 BIGNUM *ret = BN_new();
247 ret->flags |= BN_FLG_SECURE;
251 /* This is used by bn_expand2() */
252 /* The caller MUST check that words > b->dmax before calling this */
253 static BN_ULONG *bn_expand_internal(const BIGNUM *b, int words)
257 if (words > (INT_MAX / (4 * BN_BITS2))) {
258 BNerr(BN_F_BN_EXPAND_INTERNAL, BN_R_BIGNUM_TOO_LONG);
261 if (BN_get_flags(b, BN_FLG_STATIC_DATA)) {
262 BNerr(BN_F_BN_EXPAND_INTERNAL, BN_R_EXPAND_ON_STATIC_BIGNUM_DATA);
265 if (BN_get_flags(b, BN_FLG_SECURE))
266 a = OPENSSL_secure_zalloc(words * sizeof(*a));
268 a = OPENSSL_zalloc(words * sizeof(*a));
270 BNerr(BN_F_BN_EXPAND_INTERNAL, ERR_R_MALLOC_FAILURE);
274 assert(b->top <= words);
276 memcpy(a, b->d, sizeof(*a) * b->top);
282 * This is an internal function that should not be used in applications. It
283 * ensures that 'b' has enough room for a 'words' word number and initialises
284 * any unused part of b->d with leading zeros. It is mostly used by the
285 * various BIGNUM routines. If there is an error, NULL is returned. If not,
289 BIGNUM *bn_expand2(BIGNUM *b, int words)
291 if (words > b->dmax) {
292 BN_ULONG *a = bn_expand_internal(b, words);
304 BIGNUM *BN_dup(const BIGNUM *a)
312 t = BN_get_flags(a, BN_FLG_SECURE) ? BN_secure_new() : BN_new();
315 if (!BN_copy(t, a)) {
323 BIGNUM *BN_copy(BIGNUM *a, const BIGNUM *b)
329 if (bn_wexpand(a, b->top) == NULL)
333 memcpy(a->d, b->d, sizeof(b->d[0]) * b->top);
337 a->flags |= b->flags & BN_FLG_FIXED_TOP;
342 #define FLAGS_DATA(flags) ((flags) & (BN_FLG_STATIC_DATA \
346 #define FLAGS_STRUCT(flags) ((flags) & (BN_FLG_MALLOCED))
348 void BN_swap(BIGNUM *a, BIGNUM *b)
350 int flags_old_a, flags_old_b;
352 int tmp_top, tmp_dmax, tmp_neg;
357 flags_old_a = a->flags;
358 flags_old_b = b->flags;
375 a->flags = FLAGS_STRUCT(flags_old_a) | FLAGS_DATA(flags_old_b);
376 b->flags = FLAGS_STRUCT(flags_old_b) | FLAGS_DATA(flags_old_a);
381 void BN_clear(BIGNUM *a)
387 OPENSSL_cleanse(a->d, sizeof(*a->d) * a->dmax);
390 a->flags &= ~BN_FLG_FIXED_TOP;
393 BN_ULONG BN_get_word(const BIGNUM *a)
397 else if (a->top == 1)
403 int BN_set_word(BIGNUM *a, BN_ULONG w)
406 if (bn_expand(a, (int)sizeof(BN_ULONG) * 8) == NULL)
410 a->top = (w ? 1 : 0);
411 a->flags &= ~BN_FLG_FIXED_TOP;
416 BIGNUM *BN_bin2bn(const unsigned char *s, int len, BIGNUM *ret)
428 /* Skip leading zero's. */
429 for ( ; len > 0 && *s == 0; s++, len--)
436 i = ((n - 1) / BN_BYTES) + 1;
437 m = ((n - 1) % (BN_BYTES));
438 if (bn_wexpand(ret, (int)i) == NULL) {
446 l = (l << 8L) | *(s++);
454 * need to call this due to clear byte at top if avoiding having the top
455 * bit set (-ve number)
461 typedef enum {big, little} endianess_t;
463 /* ignore negative */
465 int bn2binpad(const BIGNUM *a, unsigned char *to, int tolen, endianess_t endianess)
468 size_t i, lasti, j, atop, mask;
472 * In case |a| is fixed-top, BN_num_bytes can return bogus length,
473 * but it's assumed that fixed-top inputs ought to be "nominated"
474 * even for padded output, so it works out...
479 } else if (tolen < n) { /* uncommon/unlike case */
482 bn_correct_top(&temp);
483 n = BN_num_bytes(&temp);
488 /* Swipe through whole available data and don't give away padded zero. */
489 atop = a->dmax * BN_BYTES;
491 OPENSSL_cleanse(to, tolen);
496 atop = a->top * BN_BYTES;
497 if (endianess == big)
498 to += tolen; /* start from the end of the buffer */
499 for (i = 0, j = 0; j < (size_t)tolen; j++) {
501 l = a->d[i / BN_BYTES];
502 mask = 0 - ((j - atop) >> (8 * sizeof(i) - 1));
503 val = (unsigned char)(l >> (8 * (i % BN_BYTES)) & mask);
504 if (endianess == big)
508 i += (i - lasti) >> (8 * sizeof(i) - 1); /* stay on last limb */
514 int BN_bn2binpad(const BIGNUM *a, unsigned char *to, int tolen)
518 return bn2binpad(a, to, tolen, big);
521 int BN_bn2bin(const BIGNUM *a, unsigned char *to)
523 return bn2binpad(a, to, -1, big);
526 BIGNUM *BN_lebin2bn(const unsigned char *s, int len, BIGNUM *ret)
539 /* Skip trailing zeroes. */
540 for ( ; len > 0 && s[-1] == 0; s--, len--)
547 i = ((n - 1) / BN_BYTES) + 1;
548 m = ((n - 1) % (BN_BYTES));
549 if (bn_wexpand(ret, (int)i) == NULL) {
566 * need to call this due to clear byte at top if avoiding having the top
567 * bit set (-ve number)
573 int BN_bn2lebinpad(const BIGNUM *a, unsigned char *to, int tolen)
577 return bn2binpad(a, to, tolen, little);
580 BIGNUM *BN_native2bn(const unsigned char *s, int len, BIGNUM *ret)
583 return BN_bin2bn(s, len, ret);
585 return BN_lebin2bn(s, len, ret);
589 int BN_bn2nativepad(const BIGNUM *a, unsigned char *to, int tolen)
592 return BN_bn2binpad(a, to, tolen);
594 return BN_bn2lebinpad(a, to, tolen);
598 int BN_ucmp(const BIGNUM *a, const BIGNUM *b)
601 BN_ULONG t1, t2, *ap, *bp;
611 for (i = a->top - 1; i >= 0; i--) {
615 return ((t1 > t2) ? 1 : -1);
620 int BN_cmp(const BIGNUM *a, const BIGNUM *b)
626 if ((a == NULL) || (b == NULL)) {
638 if (a->neg != b->neg) {
656 for (i = a->top - 1; i >= 0; i--) {
667 int BN_set_bit(BIGNUM *a, int n)
677 if (bn_wexpand(a, i + 1) == NULL)
679 for (k = a->top; k < i + 1; k++)
682 a->flags &= ~BN_FLG_FIXED_TOP;
685 a->d[i] |= (((BN_ULONG)1) << j);
690 int BN_clear_bit(BIGNUM *a, int n)
703 a->d[i] &= (~(((BN_ULONG)1) << j));
708 int BN_is_bit_set(const BIGNUM *a, int n)
719 return (int)(((a->d[i]) >> j) & ((BN_ULONG)1));
722 int BN_mask_bits(BIGNUM *a, int n)
738 a->d[w] &= ~(BN_MASK2 << b);
744 void BN_set_negative(BIGNUM *a, int b)
746 if (b && !BN_is_zero(a))
752 int bn_cmp_words(const BN_ULONG *a, const BN_ULONG *b, int n)
763 return ((aa > bb) ? 1 : -1);
764 for (i = n - 2; i >= 0; i--) {
768 return ((aa > bb) ? 1 : -1);
774 * Here follows a specialised variants of bn_cmp_words(). It has the
775 * capability of performing the operation on arrays of different sizes. The
776 * sizes of those arrays is expressed through cl, which is the common length
777 * ( basically, min(len(a),len(b)) ), and dl, which is the delta between the
778 * two lengths, calculated as len(a)-len(b). All lengths are the number of
782 int bn_cmp_part_words(const BN_ULONG *a, const BN_ULONG *b, int cl, int dl)
788 for (i = dl; i < 0; i++) {
790 return -1; /* a < b */
794 for (i = dl; i > 0; i--) {
796 return 1; /* a > b */
799 return bn_cmp_words(a, b, cl);
803 * Constant-time conditional swap of a and b.
804 * a and b are swapped if condition is not 0.
805 * nwords is the number of words to swap.
806 * Assumes that at least nwords are allocated in both a and b.
807 * Assumes that no more than nwords are used by either a or b.
809 void BN_consttime_swap(BN_ULONG condition, BIGNUM *a, BIGNUM *b, int nwords)
817 bn_wcheck_size(a, nwords);
818 bn_wcheck_size(b, nwords);
820 condition = ((~condition & ((condition - 1))) >> (BN_BITS2 - 1)) - 1;
822 t = (a->top ^ b->top) & condition;
826 t = (a->neg ^ b->neg) & condition;
831 * BN_FLG_STATIC_DATA: indicates that data may not be written to. Intention
832 * is actually to treat it as it's read-only data, and some (if not most)
833 * of it does reside in read-only segment. In other words observation of
834 * BN_FLG_STATIC_DATA in BN_consttime_swap should be treated as fatal
835 * condition. It would either cause SEGV or effectively cause data
838 * BN_FLG_MALLOCED: refers to BN structure itself, and hence must be
841 * BN_FLG_SECURE: must be preserved, because it determines how x->d was
842 * allocated and hence how to free it.
844 * BN_FLG_CONSTTIME: sufficient to mask and swap
846 * BN_FLG_FIXED_TOP: indicates that we haven't called bn_correct_top() on
847 * the data, so the d array may be padded with additional 0 values (i.e.
848 * top could be greater than the minimal value that it could be). We should
852 #define BN_CONSTTIME_SWAP_FLAGS (BN_FLG_CONSTTIME | BN_FLG_FIXED_TOP)
854 t = ((a->flags ^ b->flags) & BN_CONSTTIME_SWAP_FLAGS) & condition;
858 /* conditionally swap the data */
859 for (i = 0; i < nwords; i++) {
860 t = (a->d[i] ^ b->d[i]) & condition;
866 #undef BN_CONSTTIME_SWAP_FLAGS
868 /* Bits of security, see SP800-57 */
870 int BN_security_bits(int L, int N)
890 return bits >= secbits ? secbits : bits;
893 void BN_zero_ex(BIGNUM *a)
897 a->flags &= ~BN_FLG_FIXED_TOP;
900 int BN_abs_is_word(const BIGNUM *a, const BN_ULONG w)
902 return ((a->top == 1) && (a->d[0] == w)) || ((w == 0) && (a->top == 0));
905 int BN_is_zero(const BIGNUM *a)
910 int BN_is_one(const BIGNUM *a)
912 return BN_abs_is_word(a, 1) && !a->neg;
915 int BN_is_word(const BIGNUM *a, const BN_ULONG w)
917 return BN_abs_is_word(a, w) && (!w || !a->neg);
920 int BN_is_odd(const BIGNUM *a)
922 return (a->top > 0) && (a->d[0] & 1);
925 int BN_is_negative(const BIGNUM *a)
927 return (a->neg != 0);
930 int BN_to_montgomery(BIGNUM *r, const BIGNUM *a, BN_MONT_CTX *mont,
933 return BN_mod_mul_montgomery(r, a, &(mont->RR), mont, ctx);
936 void BN_with_flags(BIGNUM *dest, const BIGNUM *b, int flags)
940 dest->dmax = b->dmax;
942 dest->flags = ((dest->flags & BN_FLG_MALLOCED)
943 | (b->flags & ~BN_FLG_MALLOCED)
944 | BN_FLG_STATIC_DATA | flags);
947 BN_GENCB *BN_GENCB_new(void)
951 if ((ret = OPENSSL_malloc(sizeof(*ret))) == NULL) {
952 BNerr(BN_F_BN_GENCB_NEW, ERR_R_MALLOC_FAILURE);
959 void BN_GENCB_free(BN_GENCB *cb)
966 void BN_set_flags(BIGNUM *b, int n)
971 int BN_get_flags(const BIGNUM *b, int n)
976 /* Populate a BN_GENCB structure with an "old"-style callback */
977 void BN_GENCB_set_old(BN_GENCB *gencb, void (*callback) (int, int, void *),
980 BN_GENCB *tmp_gencb = gencb;
982 tmp_gencb->arg = cb_arg;
983 tmp_gencb->cb.cb_1 = callback;
986 /* Populate a BN_GENCB structure with a "new"-style callback */
987 void BN_GENCB_set(BN_GENCB *gencb, int (*callback) (int, int, BN_GENCB *),
990 BN_GENCB *tmp_gencb = gencb;
992 tmp_gencb->arg = cb_arg;
993 tmp_gencb->cb.cb_2 = callback;
996 void *BN_GENCB_get_arg(BN_GENCB *cb)
1001 BIGNUM *bn_wexpand(BIGNUM *a, int words)
1003 return (words <= a->dmax) ? a : bn_expand2(a, words);
1006 void bn_correct_top(BIGNUM *a)
1009 int tmp_top = a->top;
1012 for (ftl = &(a->d[tmp_top]); tmp_top > 0; tmp_top--) {
1021 a->flags &= ~BN_FLG_FIXED_TOP;