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1 /* Copyright (C) 1995-1997 Eric Young (eay@cryptsoft.com)
2  * All rights reserved.
3  *
4  * This package is an SSL implementation written
5  * by Eric Young (eay@cryptsoft.com).
6  * The implementation was written so as to conform with Netscapes SSL.
7  *
8  * This library is free for commercial and non-commercial use as long as
9  * the following conditions are aheared to.  The following conditions
10  * apply to all code found in this distribution, be it the RC4, RSA,
11  * lhash, DES, etc., code; not just the SSL code.  The SSL documentation
12  * included with this distribution is covered by the same copyright terms
13  * except that the holder is Tim Hudson (tjh@cryptsoft.com).
14  *
15  * Copyright remains Eric Young's, and as such any Copyright notices in
16  * the code are not to be removed.
17  * If this package is used in a product, Eric Young should be given attribution
18  * as the author of the parts of the library used.
19  * This can be in the form of a textual message at program startup or
20  * in documentation (online or textual) provided with the package.
21  *
22  * Redistribution and use in source and binary forms, with or without
23  * modification, are permitted provided that the following conditions
24  * are met:
25  * 1. Redistributions of source code must retain the copyright
26  *    notice, this list of conditions and the following disclaimer.
27  * 2. Redistributions in binary form must reproduce the above copyright
28  *    notice, this list of conditions and the following disclaimer in the
29  *    documentation and/or other materials provided with the distribution.
30  * 3. All advertising materials mentioning features or use of this software
31  *    must display the following acknowledgement:
32  *    "This product includes cryptographic software written by
33  *     Eric Young (eay@cryptsoft.com)"
34  *    The word 'cryptographic' can be left out if the rouines from the library
35  *    being used are not cryptographic related :-).
36  * 4. If you include any Windows specific code (or a derivative thereof) from
37  *    the apps directory (application code) you must include an acknowledgement:
38  *    "This product includes software written by Tim Hudson (tjh@cryptsoft.com)"
39  *
40  * THIS SOFTWARE IS PROVIDED BY ERIC YOUNG ``AS IS'' AND
41  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
42  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
43  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
44  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
45  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
46  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
47  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
48  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
49  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
50  * SUCH DAMAGE.
51  *
52  * The licence and distribution terms for any publically available version or
53  * derivative of this code cannot be changed.  i.e. this code cannot simply be
54  * copied and put under another distribution licence
55  * [including the GNU Public Licence.]
56  */
57 /* ====================================================================
58  * Copyright (c) 1998-2006 The OpenSSL Project.  All rights reserved.
59  *
60  * Redistribution and use in source and binary forms, with or without
61  * modification, are permitted provided that the following conditions
62  * are met:
63  *
64  * 1. Redistributions of source code must retain the above copyright
65  *    notice, this list of conditions and the following disclaimer.
66  *
67  * 2. Redistributions in binary form must reproduce the above copyright
68  *    notice, this list of conditions and the following disclaimer in
69  *    the documentation and/or other materials provided with the
70  *    distribution.
71  *
72  * 3. All advertising materials mentioning features or use of this
73  *    software must display the following acknowledgment:
74  *    "This product includes software developed by the OpenSSL Project
75  *    for use in the OpenSSL Toolkit. (http://www.openssl.org/)"
76  *
77  * 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to
78  *    endorse or promote products derived from this software without
79  *    prior written permission. For written permission, please contact
80  *    openssl-core@openssl.org.
81  *
82  * 5. Products derived from this software may not be called "OpenSSL"
83  *    nor may "OpenSSL" appear in their names without prior written
84  *    permission of the OpenSSL Project.
85  *
86  * 6. Redistributions of any form whatsoever must retain the following
87  *    acknowledgment:
88  *    "This product includes software developed by the OpenSSL Project
89  *    for use in the OpenSSL Toolkit (http://www.openssl.org/)"
90  *
91  * THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY
92  * EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
93  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
94  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE OpenSSL PROJECT OR
95  * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
96  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
97  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
98  * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
99  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
100  * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
101  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
102  * OF THE POSSIBILITY OF SUCH DAMAGE.
103  * ====================================================================
104  *
105  * This product includes cryptographic software written by Eric Young
106  * (eay@cryptsoft.com).  This product includes software written by Tim
107  * Hudson (tjh@cryptsoft.com).
108  *
109  */
110 /* ====================================================================
111  * Copyright 2002 Sun Microsystems, Inc. ALL RIGHTS RESERVED.
112  *
113  * Portions of the attached software ("Contribution") are developed by
114  * SUN MICROSYSTEMS, INC., and are contributed to the OpenSSL project.
115  *
116  * The Contribution is licensed pursuant to the Eric Young open source
117  * license provided above.
118  *
119  * The binary polynomial arithmetic software is originally written by
120  * Sheueling Chang Shantz and Douglas Stebila of Sun Microsystems
121  * Laboratories. */
122 
123 #ifndef OPENSSL_HEADER_BN_H
124 #define OPENSSL_HEADER_BN_H
125 
126 #include <openssl/base.h>
127 #include <openssl/thread.h>
128 
129 #include <inttypes.h>  // for PRIu64 and friends
130 #include <stdio.h>  // for FILE*
131 
132 #if defined(__cplusplus)
133 extern "C" {
134 #endif
135 
136 
137 // BN provides support for working with arbitrary sized integers. For example,
138 // although the largest integer supported by the compiler might be 64 bits, BN
139 // will allow you to work with numbers until you run out of memory.
140 
141 
142 // BN_ULONG is the native word size when working with big integers.
143 //
144 // Note: on some platforms, inttypes.h does not define print format macros in
145 // C++ unless |__STDC_FORMAT_MACROS| defined. As this is a public header, bn.h
146 // does not define |__STDC_FORMAT_MACROS| itself. C++ source files which use the
147 // FMT macros must define it externally.
148 #if defined(OPENSSL_64_BIT)
149 #define BN_ULONG uint64_t
150 #define BN_BITS2 64
151 #define BN_DEC_FMT1 "%" PRIu64
152 #define BN_DEC_FMT2 "%019" PRIu64
153 #define BN_HEX_FMT1 "%" PRIx64
154 #define BN_HEX_FMT2 "%016" PRIx64
155 #elif defined(OPENSSL_32_BIT)
156 #define BN_ULONG uint32_t
157 #define BN_BITS2 32
158 #define BN_DEC_FMT1 "%" PRIu32
159 #define BN_DEC_FMT2 "%09" PRIu32
160 #define BN_HEX_FMT1 "%" PRIx32
161 #define BN_HEX_FMT2 "%08" PRIx64
162 #else
163 #error "Must define either OPENSSL_32_BIT or OPENSSL_64_BIT"
164 #endif
165 
166 
167 // Allocation and freeing.
168 
169 // BN_new creates a new, allocated BIGNUM and initialises it.
170 OPENSSL_EXPORT BIGNUM *BN_new(void);
171 
172 // BN_init initialises a stack allocated |BIGNUM|.
173 OPENSSL_EXPORT void BN_init(BIGNUM *bn);
174 
175 // BN_free frees the data referenced by |bn| and, if |bn| was originally
176 // allocated on the heap, frees |bn| also.
177 OPENSSL_EXPORT void BN_free(BIGNUM *bn);
178 
179 // BN_clear_free erases and frees the data referenced by |bn| and, if |bn| was
180 // originally allocated on the heap, frees |bn| also.
181 OPENSSL_EXPORT void BN_clear_free(BIGNUM *bn);
182 
183 // BN_dup allocates a new BIGNUM and sets it equal to |src|. It returns the
184 // allocated BIGNUM on success or NULL otherwise.
185 OPENSSL_EXPORT BIGNUM *BN_dup(const BIGNUM *src);
186 
187 // BN_copy sets |dest| equal to |src| and returns |dest| or NULL on allocation
188 // failure.
189 OPENSSL_EXPORT BIGNUM *BN_copy(BIGNUM *dest, const BIGNUM *src);
190 
191 // BN_clear sets |bn| to zero and erases the old data.
192 OPENSSL_EXPORT void BN_clear(BIGNUM *bn);
193 
194 // BN_value_one returns a static BIGNUM with value 1.
195 OPENSSL_EXPORT const BIGNUM *BN_value_one(void);
196 
197 
198 // Basic functions.
199 
200 // BN_num_bits returns the minimum number of bits needed to represent the
201 // absolute value of |bn|.
202 OPENSSL_EXPORT unsigned BN_num_bits(const BIGNUM *bn);
203 
204 // BN_num_bytes returns the minimum number of bytes needed to represent the
205 // absolute value of |bn|.
206 OPENSSL_EXPORT unsigned BN_num_bytes(const BIGNUM *bn);
207 
208 // BN_zero sets |bn| to zero.
209 OPENSSL_EXPORT void BN_zero(BIGNUM *bn);
210 
211 // BN_one sets |bn| to one. It returns one on success or zero on allocation
212 // failure.
213 OPENSSL_EXPORT int BN_one(BIGNUM *bn);
214 
215 // BN_set_word sets |bn| to |value|. It returns one on success or zero on
216 // allocation failure.
217 OPENSSL_EXPORT int BN_set_word(BIGNUM *bn, BN_ULONG value);
218 
219 // BN_set_u64 sets |bn| to |value|. It returns one on success or zero on
220 // allocation failure.
221 OPENSSL_EXPORT int BN_set_u64(BIGNUM *bn, uint64_t value);
222 
223 // BN_set_negative sets the sign of |bn|.
224 OPENSSL_EXPORT void BN_set_negative(BIGNUM *bn, int sign);
225 
226 // BN_is_negative returns one if |bn| is negative and zero otherwise.
227 OPENSSL_EXPORT int BN_is_negative(const BIGNUM *bn);
228 
229 
230 // Conversion functions.
231 
232 // BN_bin2bn sets |*ret| to the value of |len| bytes from |in|, interpreted as
233 // a big-endian number, and returns |ret|. If |ret| is NULL then a fresh
234 // |BIGNUM| is allocated and returned. It returns NULL on allocation
235 // failure.
236 OPENSSL_EXPORT BIGNUM *BN_bin2bn(const uint8_t *in, size_t len, BIGNUM *ret);
237 
238 // BN_bn2bin serialises the absolute value of |in| to |out| as a big-endian
239 // integer, which must have |BN_num_bytes| of space available. It returns the
240 // number of bytes written.
241 OPENSSL_EXPORT size_t BN_bn2bin(const BIGNUM *in, uint8_t *out);
242 
243 // BN_le2bn sets |*ret| to the value of |len| bytes from |in|, interpreted as
244 // a little-endian number, and returns |ret|. If |ret| is NULL then a fresh
245 // |BIGNUM| is allocated and returned. It returns NULL on allocation
246 // failure.
247 OPENSSL_EXPORT BIGNUM *BN_le2bn(const uint8_t *in, size_t len, BIGNUM *ret);
248 
249 // BN_bn2le_padded serialises the absolute value of |in| to |out| as a
250 // little-endian integer, which must have |len| of space available, padding
251 // out the remainder of out with zeros. If |len| is smaller than |BN_num_bytes|,
252 // the function fails and returns 0. Otherwise, it returns 1.
253 OPENSSL_EXPORT int BN_bn2le_padded(uint8_t *out, size_t len, const BIGNUM *in);
254 
255 // BN_bn2bin_padded serialises the absolute value of |in| to |out| as a
256 // big-endian integer. The integer is padded with leading zeros up to size
257 // |len|. If |len| is smaller than |BN_num_bytes|, the function fails and
258 // returns 0. Otherwise, it returns 1.
259 OPENSSL_EXPORT int BN_bn2bin_padded(uint8_t *out, size_t len, const BIGNUM *in);
260 
261 // BN_bn2cbb_padded behaves like |BN_bn2bin_padded| but writes to a |CBB|.
262 OPENSSL_EXPORT int BN_bn2cbb_padded(CBB *out, size_t len, const BIGNUM *in);
263 
264 // BN_bn2hex returns an allocated string that contains a NUL-terminated, hex
265 // representation of |bn|. If |bn| is negative, the first char in the resulting
266 // string will be '-'. Returns NULL on allocation failure.
267 OPENSSL_EXPORT char *BN_bn2hex(const BIGNUM *bn);
268 
269 // BN_hex2bn parses the leading hex number from |in|, which may be proceeded by
270 // a '-' to indicate a negative number and may contain trailing, non-hex data.
271 // If |outp| is not NULL, it constructs a BIGNUM equal to the hex number and
272 // stores it in |*outp|. If |*outp| is NULL then it allocates a new BIGNUM and
273 // updates |*outp|. It returns the number of bytes of |in| processed or zero on
274 // error.
275 OPENSSL_EXPORT int BN_hex2bn(BIGNUM **outp, const char *in);
276 
277 // BN_bn2dec returns an allocated string that contains a NUL-terminated,
278 // decimal representation of |bn|. If |bn| is negative, the first char in the
279 // resulting string will be '-'. Returns NULL on allocation failure.
280 OPENSSL_EXPORT char *BN_bn2dec(const BIGNUM *a);
281 
282 // BN_dec2bn parses the leading decimal number from |in|, which may be
283 // proceeded by a '-' to indicate a negative number and may contain trailing,
284 // non-decimal data. If |outp| is not NULL, it constructs a BIGNUM equal to the
285 // decimal number and stores it in |*outp|. If |*outp| is NULL then it
286 // allocates a new BIGNUM and updates |*outp|. It returns the number of bytes
287 // of |in| processed or zero on error.
288 OPENSSL_EXPORT int BN_dec2bn(BIGNUM **outp, const char *in);
289 
290 // BN_asc2bn acts like |BN_dec2bn| or |BN_hex2bn| depending on whether |in|
291 // begins with "0X" or "0x" (indicating hex) or not (indicating decimal). A
292 // leading '-' is still permitted and comes before the optional 0X/0x. It
293 // returns one on success or zero on error.
294 OPENSSL_EXPORT int BN_asc2bn(BIGNUM **outp, const char *in);
295 
296 // BN_print writes a hex encoding of |a| to |bio|. It returns one on success
297 // and zero on error.
298 OPENSSL_EXPORT int BN_print(BIO *bio, const BIGNUM *a);
299 
300 // BN_print_fp acts like |BIO_print|, but wraps |fp| in a |BIO| first.
301 OPENSSL_EXPORT int BN_print_fp(FILE *fp, const BIGNUM *a);
302 
303 // BN_get_word returns the absolute value of |bn| as a single word. If |bn| is
304 // too large to be represented as a single word, the maximum possible value
305 // will be returned.
306 OPENSSL_EXPORT BN_ULONG BN_get_word(const BIGNUM *bn);
307 
308 // BN_get_u64 sets |*out| to the absolute value of |bn| as a |uint64_t| and
309 // returns one. If |bn| is too large to be represented as a |uint64_t|, it
310 // returns zero.
311 OPENSSL_EXPORT int BN_get_u64(const BIGNUM *bn, uint64_t *out);
312 
313 
314 // ASN.1 functions.
315 
316 // BN_parse_asn1_unsigned parses a non-negative DER INTEGER from |cbs| writes
317 // the result to |ret|. It returns one on success and zero on failure.
318 OPENSSL_EXPORT int BN_parse_asn1_unsigned(CBS *cbs, BIGNUM *ret);
319 
320 // BN_marshal_asn1 marshals |bn| as a non-negative DER INTEGER and appends the
321 // result to |cbb|. It returns one on success and zero on failure.
322 OPENSSL_EXPORT int BN_marshal_asn1(CBB *cbb, const BIGNUM *bn);
323 
324 
325 // BIGNUM pools.
326 //
327 // Certain BIGNUM operations need to use many temporary variables and
328 // allocating and freeing them can be quite slow. Thus such operations typically
329 // take a |BN_CTX| parameter, which contains a pool of |BIGNUMs|. The |ctx|
330 // argument to a public function may be NULL, in which case a local |BN_CTX|
331 // will be created just for the lifetime of that call.
332 //
333 // A function must call |BN_CTX_start| first. Then, |BN_CTX_get| may be called
334 // repeatedly to obtain temporary |BIGNUM|s. All |BN_CTX_get| calls must be made
335 // before calling any other functions that use the |ctx| as an argument.
336 //
337 // Finally, |BN_CTX_end| must be called before returning from the function.
338 // When |BN_CTX_end| is called, the |BIGNUM| pointers obtained from
339 // |BN_CTX_get| become invalid.
340 
341 // BN_CTX_new returns a new, empty BN_CTX or NULL on allocation failure.
342 OPENSSL_EXPORT BN_CTX *BN_CTX_new(void);
343 
344 // BN_CTX_free frees all BIGNUMs contained in |ctx| and then frees |ctx|
345 // itself.
346 OPENSSL_EXPORT void BN_CTX_free(BN_CTX *ctx);
347 
348 // BN_CTX_start "pushes" a new entry onto the |ctx| stack and allows future
349 // calls to |BN_CTX_get|.
350 OPENSSL_EXPORT void BN_CTX_start(BN_CTX *ctx);
351 
352 // BN_CTX_get returns a new |BIGNUM|, or NULL on allocation failure. Once
353 // |BN_CTX_get| has returned NULL, all future calls will also return NULL until
354 // |BN_CTX_end| is called.
355 OPENSSL_EXPORT BIGNUM *BN_CTX_get(BN_CTX *ctx);
356 
357 // BN_CTX_end invalidates all |BIGNUM|s returned from |BN_CTX_get| since the
358 // matching |BN_CTX_start| call.
359 OPENSSL_EXPORT void BN_CTX_end(BN_CTX *ctx);
360 
361 
362 // Simple arithmetic
363 
364 // BN_add sets |r| = |a| + |b|, where |r| may be the same pointer as either |a|
365 // or |b|. It returns one on success and zero on allocation failure.
366 OPENSSL_EXPORT int BN_add(BIGNUM *r, const BIGNUM *a, const BIGNUM *b);
367 
368 // BN_uadd sets |r| = |a| + |b|, where |a| and |b| are non-negative and |r| may
369 // be the same pointer as either |a| or |b|. It returns one on success and zero
370 // on allocation failure.
371 OPENSSL_EXPORT int BN_uadd(BIGNUM *r, const BIGNUM *a, const BIGNUM *b);
372 
373 // BN_add_word adds |w| to |a|. It returns one on success and zero otherwise.
374 OPENSSL_EXPORT int BN_add_word(BIGNUM *a, BN_ULONG w);
375 
376 // BN_sub sets |r| = |a| - |b|, where |r| may be the same pointer as either |a|
377 // or |b|. It returns one on success and zero on allocation failure.
378 OPENSSL_EXPORT int BN_sub(BIGNUM *r, const BIGNUM *a, const BIGNUM *b);
379 
380 // BN_usub sets |r| = |a| - |b|, where |a| and |b| are non-negative integers,
381 // |b| < |a| and |r| may be the same pointer as either |a| or |b|. It returns
382 // one on success and zero on allocation failure.
383 OPENSSL_EXPORT int BN_usub(BIGNUM *r, const BIGNUM *a, const BIGNUM *b);
384 
385 // BN_sub_word subtracts |w| from |a|. It returns one on success and zero on
386 // allocation failure.
387 OPENSSL_EXPORT int BN_sub_word(BIGNUM *a, BN_ULONG w);
388 
389 // BN_mul sets |r| = |a| * |b|, where |r| may be the same pointer as |a| or
390 // |b|. Returns one on success and zero otherwise.
391 OPENSSL_EXPORT int BN_mul(BIGNUM *r, const BIGNUM *a, const BIGNUM *b,
392                           BN_CTX *ctx);
393 
394 // BN_mul_word sets |bn| = |bn| * |w|. It returns one on success or zero on
395 // allocation failure.
396 OPENSSL_EXPORT int BN_mul_word(BIGNUM *bn, BN_ULONG w);
397 
398 // BN_sqr sets |r| = |a|^2 (i.e. squares), where |r| may be the same pointer as
399 // |a|. Returns one on success and zero otherwise. This is more efficient than
400 // BN_mul(r, a, a, ctx).
401 OPENSSL_EXPORT int BN_sqr(BIGNUM *r, const BIGNUM *a, BN_CTX *ctx);
402 
403 // BN_div divides |numerator| by |divisor| and places the result in |quotient|
404 // and the remainder in |rem|. Either of |quotient| or |rem| may be NULL, in
405 // which case the respective value is not returned. The result is rounded
406 // towards zero; thus if |numerator| is negative, the remainder will be zero or
407 // negative. It returns one on success or zero on error.
408 OPENSSL_EXPORT int BN_div(BIGNUM *quotient, BIGNUM *rem,
409                           const BIGNUM *numerator, const BIGNUM *divisor,
410                           BN_CTX *ctx);
411 
412 // BN_div_word sets |numerator| = |numerator|/|divisor| and returns the
413 // remainder or (BN_ULONG)-1 on error.
414 OPENSSL_EXPORT BN_ULONG BN_div_word(BIGNUM *numerator, BN_ULONG divisor);
415 
416 // BN_sqrt sets |*out_sqrt| (which may be the same |BIGNUM| as |in|) to the
417 // square root of |in|, using |ctx|. It returns one on success or zero on
418 // error. Negative numbers and non-square numbers will result in an error with
419 // appropriate errors on the error queue.
420 OPENSSL_EXPORT int BN_sqrt(BIGNUM *out_sqrt, const BIGNUM *in, BN_CTX *ctx);
421 
422 
423 // Comparison functions
424 
425 // BN_cmp returns a value less than, equal to or greater than zero if |a| is
426 // less than, equal to or greater than |b|, respectively.
427 OPENSSL_EXPORT int BN_cmp(const BIGNUM *a, const BIGNUM *b);
428 
429 // BN_cmp_word is like |BN_cmp| except it takes its second argument as a
430 // |BN_ULONG| instead of a |BIGNUM|.
431 OPENSSL_EXPORT int BN_cmp_word(const BIGNUM *a, BN_ULONG b);
432 
433 // BN_ucmp returns a value less than, equal to or greater than zero if the
434 // absolute value of |a| is less than, equal to or greater than the absolute
435 // value of |b|, respectively.
436 OPENSSL_EXPORT int BN_ucmp(const BIGNUM *a, const BIGNUM *b);
437 
438 // BN_equal_consttime returns one if |a| is equal to |b|, and zero otherwise.
439 // It takes an amount of time dependent on the sizes of |a| and |b|, but
440 // independent of the contents (including the signs) of |a| and |b|.
441 OPENSSL_EXPORT int BN_equal_consttime(const BIGNUM *a, const BIGNUM *b);
442 
443 // BN_less_than_consttime returns one if |a| is less than |b|, and zero
444 // otherwise. It takes an amount of time dependent on the sizes and signs of |a|
445 // and |b|, but independent of the contents of |a| and |b|.
446 OPENSSL_EXPORT int BN_less_than_consttime(const BIGNUM *a, const BIGNUM *b);
447 
448 // BN_abs_is_word returns one if the absolute value of |bn| equals |w| and zero
449 // otherwise.
450 OPENSSL_EXPORT int BN_abs_is_word(const BIGNUM *bn, BN_ULONG w);
451 
452 // BN_is_zero returns one if |bn| is zero and zero otherwise.
453 OPENSSL_EXPORT int BN_is_zero(const BIGNUM *bn);
454 
455 // BN_is_one returns one if |bn| equals one and zero otherwise.
456 OPENSSL_EXPORT int BN_is_one(const BIGNUM *bn);
457 
458 // BN_is_word returns one if |bn| is exactly |w| and zero otherwise.
459 OPENSSL_EXPORT int BN_is_word(const BIGNUM *bn, BN_ULONG w);
460 
461 // BN_is_odd returns one if |bn| is odd and zero otherwise.
462 OPENSSL_EXPORT int BN_is_odd(const BIGNUM *bn);
463 
464 // BN_is_pow2 returns 1 if |a| is a power of two, and 0 otherwise.
465 OPENSSL_EXPORT int BN_is_pow2(const BIGNUM *a);
466 
467 // Bitwise operations.
468 
469 // BN_lshift sets |r| equal to |a| << n. The |a| and |r| arguments may be the
470 // same |BIGNUM|. It returns one on success and zero on allocation failure.
471 OPENSSL_EXPORT int BN_lshift(BIGNUM *r, const BIGNUM *a, int n);
472 
473 // BN_lshift1 sets |r| equal to |a| << 1, where |r| and |a| may be the same
474 // pointer. It returns one on success and zero on allocation failure.
475 OPENSSL_EXPORT int BN_lshift1(BIGNUM *r, const BIGNUM *a);
476 
477 // BN_rshift sets |r| equal to |a| >> n, where |r| and |a| may be the same
478 // pointer. It returns one on success and zero on allocation failure.
479 OPENSSL_EXPORT int BN_rshift(BIGNUM *r, const BIGNUM *a, int n);
480 
481 // BN_rshift1 sets |r| equal to |a| >> 1, where |r| and |a| may be the same
482 // pointer. It returns one on success and zero on allocation failure.
483 OPENSSL_EXPORT int BN_rshift1(BIGNUM *r, const BIGNUM *a);
484 
485 // BN_set_bit sets the |n|th, least-significant bit in |a|. For example, if |a|
486 // is 2 then setting bit zero will make it 3. It returns one on success or zero
487 // on allocation failure.
488 OPENSSL_EXPORT int BN_set_bit(BIGNUM *a, int n);
489 
490 // BN_clear_bit clears the |n|th, least-significant bit in |a|. For example, if
491 // |a| is 3, clearing bit zero will make it two. It returns one on success or
492 // zero on allocation failure.
493 OPENSSL_EXPORT int BN_clear_bit(BIGNUM *a, int n);
494 
495 // BN_is_bit_set returns one if the |n|th least-significant bit in |a| exists
496 // and is set. Otherwise, it returns zero.
497 OPENSSL_EXPORT int BN_is_bit_set(const BIGNUM *a, int n);
498 
499 // BN_mask_bits truncates |a| so that it is only |n| bits long. It returns one
500 // on success or zero if |n| is greater than the length of |a| already.
501 OPENSSL_EXPORT int BN_mask_bits(BIGNUM *a, int n);
502 
503 
504 // Modulo arithmetic.
505 
506 // BN_mod_word returns |a| mod |w| or (BN_ULONG)-1 on error.
507 OPENSSL_EXPORT BN_ULONG BN_mod_word(const BIGNUM *a, BN_ULONG w);
508 
509 // BN_mod_pow2 sets |r| = |a| mod 2^|e|. It returns 1 on success and
510 // 0 on error.
511 OPENSSL_EXPORT int BN_mod_pow2(BIGNUM *r, const BIGNUM *a, size_t e);
512 
513 // BN_nnmod_pow2 sets |r| = |a| mod 2^|e| where |r| is always positive.
514 // It returns 1 on success and 0 on error.
515 OPENSSL_EXPORT int BN_nnmod_pow2(BIGNUM *r, const BIGNUM *a, size_t e);
516 
517 // BN_mod is a helper macro that calls |BN_div| and discards the quotient.
518 #define BN_mod(rem, numerator, divisor, ctx) \
519   BN_div(NULL, (rem), (numerator), (divisor), (ctx))
520 
521 // BN_nnmod is a non-negative modulo function. It acts like |BN_mod|, but 0 <=
522 // |rem| < |divisor| is always true. It returns one on success and zero on
523 // error.
524 OPENSSL_EXPORT int BN_nnmod(BIGNUM *rem, const BIGNUM *numerator,
525                             const BIGNUM *divisor, BN_CTX *ctx);
526 
527 // BN_mod_add sets |r| = |a| + |b| mod |m|. It returns one on success and zero
528 // on error.
529 OPENSSL_EXPORT int BN_mod_add(BIGNUM *r, const BIGNUM *a, const BIGNUM *b,
530                               const BIGNUM *m, BN_CTX *ctx);
531 
532 // BN_mod_add_quick acts like |BN_mod_add| but requires that |a| and |b| be
533 // non-negative and less than |m|.
534 OPENSSL_EXPORT int BN_mod_add_quick(BIGNUM *r, const BIGNUM *a, const BIGNUM *b,
535                                     const BIGNUM *m);
536 
537 // BN_mod_sub sets |r| = |a| - |b| mod |m|. It returns one on success and zero
538 // on error.
539 OPENSSL_EXPORT int BN_mod_sub(BIGNUM *r, const BIGNUM *a, const BIGNUM *b,
540                               const BIGNUM *m, BN_CTX *ctx);
541 
542 // BN_mod_sub_quick acts like |BN_mod_sub| but requires that |a| and |b| be
543 // non-negative and less than |m|.
544 OPENSSL_EXPORT int BN_mod_sub_quick(BIGNUM *r, const BIGNUM *a, const BIGNUM *b,
545                                     const BIGNUM *m);
546 
547 // BN_mod_mul sets |r| = |a|*|b| mod |m|. It returns one on success and zero
548 // on error.
549 OPENSSL_EXPORT int BN_mod_mul(BIGNUM *r, const BIGNUM *a, const BIGNUM *b,
550                               const BIGNUM *m, BN_CTX *ctx);
551 
552 // BN_mod_sqr sets |r| = |a|^2 mod |m|. It returns one on success and zero
553 // on error.
554 OPENSSL_EXPORT int BN_mod_sqr(BIGNUM *r, const BIGNUM *a, const BIGNUM *m,
555                               BN_CTX *ctx);
556 
557 // BN_mod_lshift sets |r| = (|a| << n) mod |m|, where |r| and |a| may be the
558 // same pointer. It returns one on success and zero on error.
559 OPENSSL_EXPORT int BN_mod_lshift(BIGNUM *r, const BIGNUM *a, int n,
560                                  const BIGNUM *m, BN_CTX *ctx);
561 
562 // BN_mod_lshift_quick acts like |BN_mod_lshift| but requires that |a| be
563 // non-negative and less than |m|.
564 OPENSSL_EXPORT int BN_mod_lshift_quick(BIGNUM *r, const BIGNUM *a, int n,
565                                        const BIGNUM *m);
566 
567 // BN_mod_lshift1 sets |r| = (|a| << 1) mod |m|, where |r| and |a| may be the
568 // same pointer. It returns one on success and zero on error.
569 OPENSSL_EXPORT int BN_mod_lshift1(BIGNUM *r, const BIGNUM *a, const BIGNUM *m,
570                                   BN_CTX *ctx);
571 
572 // BN_mod_lshift1_quick acts like |BN_mod_lshift1| but requires that |a| be
573 // non-negative and less than |m|.
574 OPENSSL_EXPORT int BN_mod_lshift1_quick(BIGNUM *r, const BIGNUM *a,
575                                         const BIGNUM *m);
576 
577 // BN_mod_sqrt returns a newly-allocated |BIGNUM|, r, such that
578 // r^2 == a (mod p). |p| must be a prime. It returns NULL on error or if |a| is
579 // not a square mod |p|. In the latter case, it will add |BN_R_NOT_A_SQUARE| to
580 // the error queue.
581 OPENSSL_EXPORT BIGNUM *BN_mod_sqrt(BIGNUM *in, const BIGNUM *a, const BIGNUM *p,
582                                    BN_CTX *ctx);
583 
584 
585 // Random and prime number generation.
586 
587 // The following are values for the |top| parameter of |BN_rand|.
588 #define BN_RAND_TOP_ANY    (-1)
589 #define BN_RAND_TOP_ONE     0
590 #define BN_RAND_TOP_TWO     1
591 
592 // The following are values for the |bottom| parameter of |BN_rand|.
593 #define BN_RAND_BOTTOM_ANY  0
594 #define BN_RAND_BOTTOM_ODD  1
595 
596 // BN_rand sets |rnd| to a random number of length |bits|. It returns one on
597 // success and zero otherwise.
598 //
599 // |top| must be one of the |BN_RAND_TOP_*| values. If |BN_RAND_TOP_ONE|, the
600 // most-significant bit, if any, will be set. If |BN_RAND_TOP_TWO|, the two
601 // most significant bits, if any, will be set. If |BN_RAND_TOP_ANY|, no extra
602 // action will be taken and |BN_num_bits(rnd)| may not equal |bits| if the most
603 // significant bits randomly ended up as zeros.
604 //
605 // |bottom| must be one of the |BN_RAND_BOTTOM_*| values. If
606 // |BN_RAND_BOTTOM_ODD|, the least-significant bit, if any, will be set. If
607 // |BN_RAND_BOTTOM_ANY|, no extra action will be taken.
608 OPENSSL_EXPORT int BN_rand(BIGNUM *rnd, int bits, int top, int bottom);
609 
610 // BN_pseudo_rand is an alias for |BN_rand|.
611 OPENSSL_EXPORT int BN_pseudo_rand(BIGNUM *rnd, int bits, int top, int bottom);
612 
613 // BN_rand_range is equivalent to |BN_rand_range_ex| with |min_inclusive| set
614 // to zero and |max_exclusive| set to |range|.
615 OPENSSL_EXPORT int BN_rand_range(BIGNUM *rnd, const BIGNUM *range);
616 
617 // BN_rand_range_ex sets |rnd| to a random value in
618 // [min_inclusive..max_exclusive). It returns one on success and zero
619 // otherwise.
620 OPENSSL_EXPORT int BN_rand_range_ex(BIGNUM *r, BN_ULONG min_inclusive,
621                                     const BIGNUM *max_exclusive);
622 
623 // BN_pseudo_rand_range is an alias for BN_rand_range.
624 OPENSSL_EXPORT int BN_pseudo_rand_range(BIGNUM *rnd, const BIGNUM *range);
625 
626 // BN_GENCB holds a callback function that is used by generation functions that
627 // can take a very long time to complete. Use |BN_GENCB_set| to initialise a
628 // |BN_GENCB| structure.
629 //
630 // The callback receives the address of that |BN_GENCB| structure as its last
631 // argument and the user is free to put an arbitrary pointer in |arg|. The other
632 // arguments are set as follows:
633 //   event=BN_GENCB_GENERATED, n=i:   after generating the i'th possible prime
634 //                                    number.
635 //   event=BN_GENCB_PRIME_TEST, n=-1: when finished trial division primality
636 //                                    checks.
637 //   event=BN_GENCB_PRIME_TEST, n=i:  when the i'th primality test has finished.
638 //
639 // The callback can return zero to abort the generation progress or one to
640 // allow it to continue.
641 //
642 // When other code needs to call a BN generation function it will often take a
643 // BN_GENCB argument and may call the function with other argument values.
644 #define BN_GENCB_GENERATED 0
645 #define BN_GENCB_PRIME_TEST 1
646 
647 struct bn_gencb_st {
648   void *arg;        // callback-specific data
649   int (*callback)(int event, int n, struct bn_gencb_st *);
650 };
651 
652 // BN_GENCB_set configures |callback| to call |f| and sets |callout->arg| to
653 // |arg|.
654 OPENSSL_EXPORT void BN_GENCB_set(BN_GENCB *callback,
655                                  int (*f)(int event, int n,
656                                           struct bn_gencb_st *),
657                                  void *arg);
658 
659 // BN_GENCB_call calls |callback|, if not NULL, and returns the return value of
660 // the callback, or 1 if |callback| is NULL.
661 OPENSSL_EXPORT int BN_GENCB_call(BN_GENCB *callback, int event, int n);
662 
663 // BN_generate_prime_ex sets |ret| to a prime number of |bits| length. If safe
664 // is non-zero then the prime will be such that (ret-1)/2 is also a prime.
665 // (This is needed for Diffie-Hellman groups to ensure that the only subgroups
666 // are of size 2 and (p-1)/2.).
667 //
668 // If |add| is not NULL, the prime will fulfill the condition |ret| % |add| ==
669 // |rem| in order to suit a given generator. (If |rem| is NULL then |ret| %
670 // |add| == 1.)
671 //
672 // If |cb| is not NULL, it will be called during processing to give an
673 // indication of progress. See the comments for |BN_GENCB|. It returns one on
674 // success and zero otherwise.
675 OPENSSL_EXPORT int BN_generate_prime_ex(BIGNUM *ret, int bits, int safe,
676                                         const BIGNUM *add, const BIGNUM *rem,
677                                         BN_GENCB *cb);
678 
679 // BN_prime_checks is magic value that can be used as the |checks| argument to
680 // the primality testing functions in order to automatically select a number of
681 // Miller-Rabin checks that gives a false positive rate of ~2^{-80}.
682 #define BN_prime_checks 0
683 
684 // bn_primality_result_t enumerates the outcomes of primality-testing.
685 enum bn_primality_result_t {
686   bn_probably_prime,
687   bn_composite,
688   bn_non_prime_power_composite,
689 };
690 
691 // BN_enhanced_miller_rabin_primality_test tests whether |w| is probably a prime
692 // number using the Enhanced Miller-Rabin Test (FIPS 186-4 C.3.2) with
693 // |iterations| iterations and returns the result in |out_result|. Enhanced
694 // Miller-Rabin tests primality for odd integers greater than 3, returning
695 // |bn_probably_prime| if the number is probably prime,
696 // |bn_non_prime_power_composite| if the number is a composite that is not the
697 // power of a single prime, and |bn_composite| otherwise.  If |iterations| is
698 // |BN_prime_checks|, then a value that results in a false positive rate lower
699 // than the number-field sieve security level of |w| is used. It returns one on
700 // success and zero on failure. If |cb| is not NULL, then it is called during
701 // each iteration of the primality test.
702 int BN_enhanced_miller_rabin_primality_test(
703     enum bn_primality_result_t *out_result, const BIGNUM *w, int iterations,
704     BN_CTX *ctx, BN_GENCB *cb);
705 
706 // BN_primality_test sets |*is_probably_prime| to one if |candidate| is
707 // probably a prime number by the Miller-Rabin test or zero if it's certainly
708 // not.
709 //
710 // If |do_trial_division| is non-zero then |candidate| will be tested against a
711 // list of small primes before Miller-Rabin tests. The probability of this
712 // function returning a false positive is 2^{2*checks}. If |checks| is
713 // |BN_prime_checks| then a value that results in a false positive rate lower
714 // than the number-field sieve security level of |candidate| is used. If |cb| is
715 // not NULL then it is called during the checking process. See the comment above
716 // |BN_GENCB|.
717 //
718 // The function returns one on success and zero on error.
719 //
720 // (If you are unsure whether you want |do_trial_division|, don't set it.)
721 OPENSSL_EXPORT int BN_primality_test(int *is_probably_prime,
722                                      const BIGNUM *candidate, int checks,
723                                      BN_CTX *ctx, int do_trial_division,
724                                      BN_GENCB *cb);
725 
726 // BN_is_prime_fasttest_ex returns one if |candidate| is probably a prime
727 // number by the Miller-Rabin test, zero if it's certainly not and -1 on error.
728 //
729 // If |do_trial_division| is non-zero then |candidate| will be tested against a
730 // list of small primes before Miller-Rabin tests. The probability of this
731 // function returning one when |candidate| is composite is 2^{2*checks}. If
732 // |checks| is |BN_prime_checks| then a value that results in a false positive
733 // rate lower than the number-field sieve security level of |candidate| is used.
734 // If |cb| is not NULL then it is called during the checking process. See the
735 // comment above |BN_GENCB|.
736 //
737 // WARNING: deprecated. Use |BN_primality_test|.
738 OPENSSL_EXPORT int BN_is_prime_fasttest_ex(const BIGNUM *candidate, int checks,
739                                            BN_CTX *ctx, int do_trial_division,
740                                            BN_GENCB *cb);
741 
742 // BN_is_prime_ex acts the same as |BN_is_prime_fasttest_ex| with
743 // |do_trial_division| set to zero.
744 //
745 // WARNING: deprecated: Use |BN_primality_test|.
746 OPENSSL_EXPORT int BN_is_prime_ex(const BIGNUM *candidate, int checks,
747                                   BN_CTX *ctx, BN_GENCB *cb);
748 
749 
750 // Number theory functions
751 
752 // BN_gcd sets |r| = gcd(|a|, |b|). It returns one on success and zero
753 // otherwise.
754 OPENSSL_EXPORT int BN_gcd(BIGNUM *r, const BIGNUM *a, const BIGNUM *b,
755                           BN_CTX *ctx);
756 
757 // BN_mod_inverse sets |out| equal to |a|^-1, mod |n|. If |out| is NULL, a
758 // fresh BIGNUM is allocated. It returns the result or NULL on error.
759 //
760 // If |n| is even then the operation is performed using an algorithm that avoids
761 // some branches but which isn't constant-time. This function shouldn't be used
762 // for secret values; use |BN_mod_inverse_blinded| instead. Or, if |n| is
763 // guaranteed to be prime, use
764 // |BN_mod_exp_mont_consttime(out, a, m_minus_2, m, ctx, m_mont)|, taking
765 // advantage of Fermat's Little Theorem.
766 OPENSSL_EXPORT BIGNUM *BN_mod_inverse(BIGNUM *out, const BIGNUM *a,
767                                       const BIGNUM *n, BN_CTX *ctx);
768 
769 // BN_mod_inverse_blinded sets |out| equal to |a|^-1, mod |n|, where |n| is the
770 // Montgomery modulus for |mont|. |a| must be non-negative and must be less
771 // than |n|. |n| must be greater than 1. |a| is blinded (masked by a random
772 // value) to protect it against side-channel attacks. On failure, if the failure
773 // was caused by |a| having no inverse mod |n| then |*out_no_inverse| will be
774 // set to one; otherwise it will be set to zero.
775 int BN_mod_inverse_blinded(BIGNUM *out, int *out_no_inverse, const BIGNUM *a,
776                            const BN_MONT_CTX *mont, BN_CTX *ctx);
777 
778 // BN_mod_inverse_odd sets |out| equal to |a|^-1, mod |n|. |a| must be
779 // non-negative and must be less than |n|. |n| must be odd. This function
780 // shouldn't be used for secret values; use |BN_mod_inverse_blinded| instead.
781 // Or, if |n| is guaranteed to be prime, use
782 // |BN_mod_exp_mont_consttime(out, a, m_minus_2, m, ctx, m_mont)|, taking
783 // advantage of Fermat's Little Theorem. It returns one on success or zero on
784 // failure. On failure, if the failure was caused by |a| having no inverse mod
785 // |n| then |*out_no_inverse| will be set to one; otherwise it will be set to
786 // zero.
787 int BN_mod_inverse_odd(BIGNUM *out, int *out_no_inverse, const BIGNUM *a,
788                        const BIGNUM *n, BN_CTX *ctx);
789 
790 
791 // Montgomery arithmetic.
792 
793 // BN_MONT_CTX contains the precomputed values needed to work in a specific
794 // Montgomery domain.
795 
796 // BN_MONT_CTX_new_for_modulus returns a fresh |BN_MONT_CTX| given the modulus,
797 // |mod| or NULL on error.
798 OPENSSL_EXPORT BN_MONT_CTX *BN_MONT_CTX_new_for_modulus(const BIGNUM *mod,
799                                                         BN_CTX *ctx);
800 
801 // BN_MONT_CTX_free frees memory associated with |mont|.
802 OPENSSL_EXPORT void BN_MONT_CTX_free(BN_MONT_CTX *mont);
803 
804 // BN_MONT_CTX_copy sets |to| equal to |from|. It returns |to| on success or
805 // NULL on error.
806 OPENSSL_EXPORT BN_MONT_CTX *BN_MONT_CTX_copy(BN_MONT_CTX *to,
807                                              const BN_MONT_CTX *from);
808 
809 // BN_MONT_CTX_set_locked takes |lock| and checks whether |*pmont| is NULL. If
810 // so, it creates a new |BN_MONT_CTX| and sets the modulus for it to |mod|. It
811 // then stores it as |*pmont|. It returns one on success and zero on error.
812 //
813 // If |*pmont| is already non-NULL then it does nothing and returns one.
814 int BN_MONT_CTX_set_locked(BN_MONT_CTX **pmont, CRYPTO_MUTEX *lock,
815                            const BIGNUM *mod, BN_CTX *bn_ctx);
816 
817 // BN_to_montgomery sets |ret| equal to |a| in the Montgomery domain. |a| is
818 // assumed to be in the range [0, n), where |n| is the Montgomery modulus. It
819 // returns one on success or zero on error.
820 OPENSSL_EXPORT int BN_to_montgomery(BIGNUM *ret, const BIGNUM *a,
821                                     const BN_MONT_CTX *mont, BN_CTX *ctx);
822 
823 // BN_from_montgomery sets |ret| equal to |a| * R^-1, i.e. translates values out
824 // of the Montgomery domain. |a| is assumed to be in the range [0, n), where |n|
825 // is the Montgomery modulus. It returns one on success or zero on error.
826 OPENSSL_EXPORT int BN_from_montgomery(BIGNUM *ret, const BIGNUM *a,
827                                       const BN_MONT_CTX *mont, BN_CTX *ctx);
828 
829 // BN_mod_mul_montgomery set |r| equal to |a| * |b|, in the Montgomery domain.
830 // Both |a| and |b| must already be in the Montgomery domain (by
831 // |BN_to_montgomery|). In particular, |a| and |b| are assumed to be in the
832 // range [0, n), where |n| is the Montgomery modulus. It returns one on success
833 // or zero on error.
834 OPENSSL_EXPORT int BN_mod_mul_montgomery(BIGNUM *r, const BIGNUM *a,
835                                          const BIGNUM *b,
836                                          const BN_MONT_CTX *mont, BN_CTX *ctx);
837 
838 
839 // Exponentiation.
840 
841 // BN_exp sets |r| equal to |a|^{|p|}. It does so with a square-and-multiply
842 // algorithm that leaks side-channel information. It returns one on success or
843 // zero otherwise.
844 OPENSSL_EXPORT int BN_exp(BIGNUM *r, const BIGNUM *a, const BIGNUM *p,
845                           BN_CTX *ctx);
846 
847 // BN_mod_exp sets |r| equal to |a|^{|p|} mod |m|. It does so with the best
848 // algorithm for the values provided. It returns one on success or zero
849 // otherwise. The |BN_mod_exp_mont_consttime| variant must be used if the
850 // exponent is secret.
851 OPENSSL_EXPORT int BN_mod_exp(BIGNUM *r, const BIGNUM *a, const BIGNUM *p,
852                               const BIGNUM *m, BN_CTX *ctx);
853 
854 OPENSSL_EXPORT int BN_mod_exp_mont(BIGNUM *r, const BIGNUM *a, const BIGNUM *p,
855                                    const BIGNUM *m, BN_CTX *ctx,
856                                    const BN_MONT_CTX *mont);
857 
858 OPENSSL_EXPORT int BN_mod_exp_mont_consttime(BIGNUM *rr, const BIGNUM *a,
859                                              const BIGNUM *p, const BIGNUM *m,
860                                              BN_CTX *ctx,
861                                              const BN_MONT_CTX *mont);
862 
863 
864 // Deprecated functions
865 
866 // BN_bn2mpi serialises the value of |in| to |out|, using a format that consists
867 // of the number's length in bytes represented as a 4-byte big-endian number,
868 // and the number itself in big-endian format, where the most significant bit
869 // signals a negative number. (The representation of numbers with the MSB set is
870 // prefixed with null byte). |out| must have sufficient space available; to
871 // find the needed amount of space, call the function with |out| set to NULL.
872 OPENSSL_EXPORT size_t BN_bn2mpi(const BIGNUM *in, uint8_t *out);
873 
874 // BN_mpi2bn parses |len| bytes from |in| and returns the resulting value. The
875 // bytes at |in| are expected to be in the format emitted by |BN_bn2mpi|.
876 //
877 // If |out| is NULL then a fresh |BIGNUM| is allocated and returned, otherwise
878 // |out| is reused and returned. On error, NULL is returned and the error queue
879 // is updated.
880 OPENSSL_EXPORT BIGNUM *BN_mpi2bn(const uint8_t *in, size_t len, BIGNUM *out);
881 
882 // BN_mod_exp_mont_word is like |BN_mod_exp_mont| except that the base |a| is
883 // given as a |BN_ULONG| instead of a |BIGNUM *|. It returns one on success
884 // or zero otherwise.
885 OPENSSL_EXPORT int BN_mod_exp_mont_word(BIGNUM *r, BN_ULONG a, const BIGNUM *p,
886                                         const BIGNUM *m, BN_CTX *ctx,
887                                         const BN_MONT_CTX *mont);
888 
889 // BN_mod_exp2_mont calculates (a1^p1) * (a2^p2) mod m. It returns 1 on success
890 // or zero otherwise.
891 OPENSSL_EXPORT int BN_mod_exp2_mont(BIGNUM *r, const BIGNUM *a1,
892                                     const BIGNUM *p1, const BIGNUM *a2,
893                                     const BIGNUM *p2, const BIGNUM *m,
894                                     BN_CTX *ctx, const BN_MONT_CTX *mont);
895 
896 // BN_MONT_CTX_new returns a fresh |BN_MONT_CTX| or NULL on allocation failure.
897 // Use |BN_MONT_CTX_new_for_modulus| instead.
898 OPENSSL_EXPORT BN_MONT_CTX *BN_MONT_CTX_new(void);
899 
900 // BN_MONT_CTX_set sets up a Montgomery context given the modulus, |mod|. It
901 // returns one on success and zero on error. Use |BN_MONT_CTX_new_for_modulus|
902 // instead.
903 OPENSSL_EXPORT int BN_MONT_CTX_set(BN_MONT_CTX *mont, const BIGNUM *mod,
904                                    BN_CTX *ctx);
905 
906 
907 // Private functions
908 
909 struct bignum_st {
910   BN_ULONG *d; /* Pointer to an array of 'BN_BITS2' bit chunks in little-endian
911                   order. */
912   int top;    // Index of last used element in |d|, plus one.
913   int dmax;   // Size of |d|, in words.
914   int neg;    // one if the number is negative
915   int flags;  // bitmask of BN_FLG_* values
916 };
917 
918 struct bn_mont_ctx_st {
919   // RR is R^2, reduced modulo |N|. It is used to convert to Montgomery form.
920   BIGNUM RR;
921   // N is the modulus. It is always stored in minimal form, so |N.top|
922   // determines R.
923   BIGNUM N;
924   BN_ULONG n0[2];  // least significant words of (R*Ri-1)/N
925 };
926 
927 OPENSSL_EXPORT unsigned BN_num_bits_word(BN_ULONG l);
928 
929 #define BN_FLG_MALLOCED 0x01
930 #define BN_FLG_STATIC_DATA 0x02
931 // |BN_FLG_CONSTTIME| has been removed and intentionally omitted so code relying
932 // on it will not compile. Consumers outside BoringSSL should use the
933 // higher-level cryptographic algorithms exposed by other modules. Consumers
934 // within the library should call the appropriate timing-sensitive algorithm
935 // directly.
936 
937 
938 #if defined(__cplusplus)
939 }  // extern C
940 
941 #if !defined(BORINGSSL_NO_CXX)
942 extern "C++" {
943 
944 namespace bssl {
945 
BORINGSSL_MAKE_DELETER(BIGNUM,BN_free)946 BORINGSSL_MAKE_DELETER(BIGNUM, BN_free)
947 BORINGSSL_MAKE_DELETER(BN_CTX, BN_CTX_free)
948 BORINGSSL_MAKE_DELETER(BN_MONT_CTX, BN_MONT_CTX_free)
949 
950 class BN_CTXScope {
951  public:
952   BN_CTXScope(BN_CTX *ctx) : ctx_(ctx) { BN_CTX_start(ctx_); }
953   ~BN_CTXScope() { BN_CTX_end(ctx_); }
954 
955  private:
956   BN_CTX *ctx_;
957 
958   BN_CTXScope(BN_CTXScope &) = delete;
959   BN_CTXScope &operator=(BN_CTXScope &) = delete;
960 };
961 
962 }  // namespace bssl
963 
964 }  // extern C++
965 #endif
966 
967 #endif
968 
969 #define BN_R_ARG2_LT_ARG3 100
970 #define BN_R_BAD_RECIPROCAL 101
971 #define BN_R_BIGNUM_TOO_LONG 102
972 #define BN_R_BITS_TOO_SMALL 103
973 #define BN_R_CALLED_WITH_EVEN_MODULUS 104
974 #define BN_R_DIV_BY_ZERO 105
975 #define BN_R_EXPAND_ON_STATIC_BIGNUM_DATA 106
976 #define BN_R_INPUT_NOT_REDUCED 107
977 #define BN_R_INVALID_RANGE 108
978 #define BN_R_NEGATIVE_NUMBER 109
979 #define BN_R_NOT_A_SQUARE 110
980 #define BN_R_NOT_INITIALIZED 111
981 #define BN_R_NO_INVERSE 112
982 #define BN_R_PRIVATE_KEY_TOO_LARGE 113
983 #define BN_R_P_IS_NOT_PRIME 114
984 #define BN_R_TOO_MANY_ITERATIONS 115
985 #define BN_R_TOO_MANY_TEMPORARY_VARIABLES 116
986 #define BN_R_BAD_ENCODING 117
987 #define BN_R_ENCODE_ERROR 118
988 #define BN_R_INVALID_INPUT 119
989 
990 #endif  // OPENSSL_HEADER_BN_H
991