2 * Copyright 1995-2018 The OpenSSL Project Authors. All Rights Reserved.
4 * Licensed under the OpenSSL license (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_locl.h"
17 /* This stuff appears to be completely unused, so is deprecated */
18 #if OPENSSL_API_COMPAT < 0x00908000L
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)));
135 int BN_num_bits(const BIGNUM *a)
142 return ((i * BN_BITS2) + BN_num_bits_word(a->d[i]));
145 static void bn_free_d(BIGNUM *a)
147 if (BN_get_flags(a, BN_FLG_SECURE))
148 OPENSSL_secure_free(a->d);
154 void BN_clear_free(BIGNUM *a)
158 if (a->d != NULL && !BN_get_flags(a, BN_FLG_STATIC_DATA)) {
159 OPENSSL_cleanse(a->d, a->dmax * sizeof(a->d[0]));
162 if (BN_get_flags(a, BN_FLG_MALLOCED)) {
163 OPENSSL_cleanse(a, sizeof(*a));
168 void BN_free(BIGNUM *a)
172 if (!BN_get_flags(a, BN_FLG_STATIC_DATA))
174 if (a->flags & BN_FLG_MALLOCED)
178 void bn_init(BIGNUM *a)
190 if ((ret = OPENSSL_zalloc(sizeof(*ret))) == NULL) {
191 BNerr(BN_F_BN_NEW, ERR_R_MALLOC_FAILURE);
194 ret->flags = BN_FLG_MALLOCED;
199 BIGNUM *BN_secure_new(void)
201 BIGNUM *ret = BN_new();
203 ret->flags |= BN_FLG_SECURE;
207 /* This is used by bn_expand2() */
208 /* The caller MUST check that words > b->dmax before calling this */
209 static BN_ULONG *bn_expand_internal(const BIGNUM *b, int words)
213 if (words > (INT_MAX / (4 * BN_BITS2))) {
214 BNerr(BN_F_BN_EXPAND_INTERNAL, BN_R_BIGNUM_TOO_LONG);
217 if (BN_get_flags(b, BN_FLG_STATIC_DATA)) {
218 BNerr(BN_F_BN_EXPAND_INTERNAL, BN_R_EXPAND_ON_STATIC_BIGNUM_DATA);
221 if (BN_get_flags(b, BN_FLG_SECURE))
222 a = OPENSSL_secure_zalloc(words * sizeof(*a));
224 a = OPENSSL_zalloc(words * sizeof(*a));
226 BNerr(BN_F_BN_EXPAND_INTERNAL, ERR_R_MALLOC_FAILURE);
230 assert(b->top <= words);
232 memcpy(a, b->d, sizeof(*a) * b->top);
238 * This is an internal function that should not be used in applications. It
239 * ensures that 'b' has enough room for a 'words' word number and initialises
240 * any unused part of b->d with leading zeros. It is mostly used by the
241 * various BIGNUM routines. If there is an error, NULL is returned. If not,
245 BIGNUM *bn_expand2(BIGNUM *b, int words)
247 if (words > b->dmax) {
248 BN_ULONG *a = bn_expand_internal(b, words);
252 OPENSSL_cleanse(b->d, b->dmax * sizeof(b->d[0]));
262 BIGNUM *BN_dup(const BIGNUM *a)
270 t = BN_get_flags(a, BN_FLG_SECURE) ? BN_secure_new() : BN_new();
273 if (!BN_copy(t, a)) {
281 BIGNUM *BN_copy(BIGNUM *a, const BIGNUM *b)
287 if (bn_wexpand(a, b->top) == NULL)
291 memcpy(a->d, b->d, sizeof(b->d[0]) * b->top);
295 a->flags |= b->flags & BN_FLG_FIXED_TOP;
300 #define FLAGS_DATA(flags) ((flags) & (BN_FLG_STATIC_DATA \
304 #define FLAGS_STRUCT(flags) ((flags) & (BN_FLG_MALLOCED))
306 void BN_swap(BIGNUM *a, BIGNUM *b)
308 int flags_old_a, flags_old_b;
310 int tmp_top, tmp_dmax, tmp_neg;
315 flags_old_a = a->flags;
316 flags_old_b = b->flags;
333 a->flags = FLAGS_STRUCT(flags_old_a) | FLAGS_DATA(flags_old_b);
334 b->flags = FLAGS_STRUCT(flags_old_b) | FLAGS_DATA(flags_old_a);
339 void BN_clear(BIGNUM *a)
343 OPENSSL_cleanse(a->d, sizeof(*a->d) * a->dmax);
346 a->flags &= ~BN_FLG_FIXED_TOP;
349 BN_ULONG BN_get_word(const BIGNUM *a)
353 else if (a->top == 1)
359 int BN_set_word(BIGNUM *a, BN_ULONG w)
362 if (bn_expand(a, (int)sizeof(BN_ULONG) * 8) == NULL)
366 a->top = (w ? 1 : 0);
367 a->flags &= ~BN_FLG_FIXED_TOP;
372 BIGNUM *BN_bin2bn(const unsigned char *s, int len, BIGNUM *ret)
384 /* Skip leading zero's. */
385 for ( ; len > 0 && *s == 0; s++, len--)
392 i = ((n - 1) / BN_BYTES) + 1;
393 m = ((n - 1) % (BN_BYTES));
394 if (bn_wexpand(ret, (int)i) == NULL) {
402 l = (l << 8L) | *(s++);
410 * need to call this due to clear byte at top if avoiding having the top
411 * bit set (-ve number)
417 /* ignore negative */
418 static int bn2binpad(const BIGNUM *a, unsigned char *to, int tolen)
421 size_t i, lasti, j, atop, mask;
425 * In case |a| is fixed-top, BN_num_bytes can return bogus length,
426 * but it's assumed that fixed-top inputs ought to be "nominated"
427 * even for padded output, so it works out...
432 } else if (tolen < n) { /* uncommon/unlike case */
435 bn_correct_top(&temp);
436 n = BN_num_bytes(&temp);
441 /* Swipe through whole available data and don't give away padded zero. */
442 atop = a->dmax * BN_BYTES;
444 OPENSSL_cleanse(to, tolen);
449 atop = a->top * BN_BYTES;
450 for (i = 0, j = 0, to += tolen; j < (size_t)tolen; j++) {
451 l = a->d[i / BN_BYTES];
452 mask = 0 - ((j - atop) >> (8 * sizeof(i) - 1));
453 *--to = (unsigned char)(l >> (8 * (i % BN_BYTES)) & mask);
454 i += (i - lasti) >> (8 * sizeof(i) - 1); /* stay on last limb */
460 int BN_bn2binpad(const BIGNUM *a, unsigned char *to, int tolen)
464 return bn2binpad(a, to, tolen);
467 int BN_bn2bin(const BIGNUM *a, unsigned char *to)
469 return bn2binpad(a, to, -1);
472 BIGNUM *BN_lebin2bn(const unsigned char *s, int len, BIGNUM *ret)
485 /* Skip trailing zeroes. */
486 for ( ; len > 0 && s[-1] == 0; s--, len--)
493 i = ((n - 1) / BN_BYTES) + 1;
494 m = ((n - 1) % (BN_BYTES));
495 if (bn_wexpand(ret, (int)i) == NULL) {
512 * need to call this due to clear byte at top if avoiding having the top
513 * bit set (-ve number)
519 int BN_bn2lebinpad(const BIGNUM *a, unsigned char *to, int tolen)
527 /* Add trailing zeroes if necessary */
529 memset(to + i, 0, tolen - i);
532 l = a->d[i / BN_BYTES];
534 *to = (unsigned char)(l >> (8 * (i % BN_BYTES))) & 0xff;
539 int BN_ucmp(const BIGNUM *a, const BIGNUM *b)
542 BN_ULONG t1, t2, *ap, *bp;
552 for (i = a->top - 1; i >= 0; i--) {
556 return ((t1 > t2) ? 1 : -1);
561 int BN_cmp(const BIGNUM *a, const BIGNUM *b)
567 if ((a == NULL) || (b == NULL)) {
579 if (a->neg != b->neg) {
597 for (i = a->top - 1; i >= 0; i--) {
608 int BN_set_bit(BIGNUM *a, int n)
618 if (bn_wexpand(a, i + 1) == NULL)
620 for (k = a->top; k < i + 1; k++)
623 a->flags &= ~BN_FLG_FIXED_TOP;
626 a->d[i] |= (((BN_ULONG)1) << j);
631 int BN_clear_bit(BIGNUM *a, int n)
644 a->d[i] &= (~(((BN_ULONG)1) << j));
649 int BN_is_bit_set(const BIGNUM *a, int n)
660 return (int)(((a->d[i]) >> j) & ((BN_ULONG)1));
663 int BN_mask_bits(BIGNUM *a, int n)
679 a->d[w] &= ~(BN_MASK2 << b);
685 void BN_set_negative(BIGNUM *a, int b)
687 if (b && !BN_is_zero(a))
693 int bn_cmp_words(const BN_ULONG *a, const BN_ULONG *b, int n)
701 return ((aa > bb) ? 1 : -1);
702 for (i = n - 2; i >= 0; i--) {
706 return ((aa > bb) ? 1 : -1);
712 * Here follows a specialised variants of bn_cmp_words(). It has the
713 * capability of performing the operation on arrays of different sizes. The
714 * sizes of those arrays is expressed through cl, which is the common length
715 * ( basically, min(len(a),len(b)) ), and dl, which is the delta between the
716 * two lengths, calculated as len(a)-len(b). All lengths are the number of
720 int bn_cmp_part_words(const BN_ULONG *a, const BN_ULONG *b, int cl, int dl)
726 for (i = dl; i < 0; i++) {
728 return -1; /* a < b */
732 for (i = dl; i > 0; i--) {
734 return 1; /* a > b */
737 return bn_cmp_words(a, b, cl);
741 * Constant-time conditional swap of a and b.
742 * a and b are swapped if condition is not 0. The code assumes that at most one bit of condition is set.
743 * nwords is the number of words to swap. The code assumes that at least nwords are allocated in both a and b,
744 * and that no more than nwords are used by either a or b.
745 * a and b cannot be the same number
747 void BN_consttime_swap(BN_ULONG condition, BIGNUM *a, BIGNUM *b, int nwords)
752 bn_wcheck_size(a, nwords);
753 bn_wcheck_size(b, nwords);
756 assert((condition & (condition - 1)) == 0);
757 assert(sizeof(BN_ULONG) >= sizeof(int));
759 condition = ((condition - 1) >> (BN_BITS2 - 1)) - 1;
761 t = (a->top ^ b->top) & condition;
765 t = (a->neg ^ b->neg) & condition;
770 * BN_FLG_STATIC_DATA: indicates that data may not be written to. Intention
771 * is actually to treat it as it's read-only data, and some (if not most)
772 * of it does reside in read-only segment. In other words observation of
773 * BN_FLG_STATIC_DATA in BN_consttime_swap should be treated as fatal
774 * condition. It would either cause SEGV or effectively cause data
777 * BN_FLG_MALLOCED: refers to BN structure itself, and hence must be
780 * BN_FLG_SECURE: must be preserved, because it determines how x->d was
781 * allocated and hence how to free it.
783 * BN_FLG_CONSTTIME: sufficient to mask and swap
785 * BN_FLG_FIXED_TOP: indicates that we haven't called bn_correct_top() on
786 * the data, so the d array may be padded with additional 0 values (i.e.
787 * top could be greater than the minimal value that it could be). We should
791 #define BN_CONSTTIME_SWAP_FLAGS (BN_FLG_CONSTTIME | BN_FLG_FIXED_TOP)
793 t = ((a->flags ^ b->flags) & BN_CONSTTIME_SWAP_FLAGS) & condition;
797 #define BN_CONSTTIME_SWAP(ind) \
799 t = (a->d[ind] ^ b->d[ind]) & condition; \
806 for (i = 10; i < nwords; i++)
807 BN_CONSTTIME_SWAP(i);
810 BN_CONSTTIME_SWAP(9); /* Fallthrough */
812 BN_CONSTTIME_SWAP(8); /* Fallthrough */
814 BN_CONSTTIME_SWAP(7); /* Fallthrough */
816 BN_CONSTTIME_SWAP(6); /* Fallthrough */
818 BN_CONSTTIME_SWAP(5); /* Fallthrough */
820 BN_CONSTTIME_SWAP(4); /* Fallthrough */
822 BN_CONSTTIME_SWAP(3); /* Fallthrough */
824 BN_CONSTTIME_SWAP(2); /* Fallthrough */
826 BN_CONSTTIME_SWAP(1); /* Fallthrough */
828 BN_CONSTTIME_SWAP(0);
830 #undef BN_CONSTTIME_SWAP
833 /* Bits of security, see SP800-57 */
835 int BN_security_bits(int L, int N)
855 return bits >= secbits ? secbits : bits;
858 void BN_zero_ex(BIGNUM *a)
862 a->flags &= ~BN_FLG_FIXED_TOP;
865 int BN_abs_is_word(const BIGNUM *a, const BN_ULONG w)
867 return ((a->top == 1) && (a->d[0] == w)) || ((w == 0) && (a->top == 0));
870 int BN_is_zero(const BIGNUM *a)
875 int BN_is_one(const BIGNUM *a)
877 return BN_abs_is_word(a, 1) && !a->neg;
880 int BN_is_word(const BIGNUM *a, const BN_ULONG w)
882 return BN_abs_is_word(a, w) && (!w || !a->neg);
885 int BN_is_odd(const BIGNUM *a)
887 return (a->top > 0) && (a->d[0] & 1);
890 int BN_is_negative(const BIGNUM *a)
892 return (a->neg != 0);
895 int BN_to_montgomery(BIGNUM *r, const BIGNUM *a, BN_MONT_CTX *mont,
898 return BN_mod_mul_montgomery(r, a, &(mont->RR), mont, ctx);
901 void BN_with_flags(BIGNUM *dest, const BIGNUM *b, int flags)
905 dest->dmax = b->dmax;
907 dest->flags = ((dest->flags & BN_FLG_MALLOCED)
908 | (b->flags & ~BN_FLG_MALLOCED)
909 | BN_FLG_STATIC_DATA | flags);
912 BN_GENCB *BN_GENCB_new(void)
916 if ((ret = OPENSSL_malloc(sizeof(*ret))) == NULL) {
917 BNerr(BN_F_BN_GENCB_NEW, ERR_R_MALLOC_FAILURE);
924 void BN_GENCB_free(BN_GENCB *cb)
931 void BN_set_flags(BIGNUM *b, int n)
936 int BN_get_flags(const BIGNUM *b, int n)
941 /* Populate a BN_GENCB structure with an "old"-style callback */
942 void BN_GENCB_set_old(BN_GENCB *gencb, void (*callback) (int, int, void *),
945 BN_GENCB *tmp_gencb = gencb;
947 tmp_gencb->arg = cb_arg;
948 tmp_gencb->cb.cb_1 = callback;
951 /* Populate a BN_GENCB structure with a "new"-style callback */
952 void BN_GENCB_set(BN_GENCB *gencb, int (*callback) (int, int, BN_GENCB *),
955 BN_GENCB *tmp_gencb = gencb;
957 tmp_gencb->arg = cb_arg;
958 tmp_gencb->cb.cb_2 = callback;
961 void *BN_GENCB_get_arg(BN_GENCB *cb)
966 BIGNUM *bn_wexpand(BIGNUM *a, int words)
968 return (words <= a->dmax) ? a : bn_expand2(a, words);
971 void bn_correct_top(BIGNUM *a)
974 int tmp_top = a->top;
977 for (ftl = &(a->d[tmp_top]); tmp_top > 0; tmp_top--) {
986 a->flags &= ~BN_FLG_FIXED_TOP;