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_locl.h"
17 /* This stuff appears to be completely unused, so is deprecated */
18 #if !OPENSSL_API_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
;