5 BN_mod_mul_montgomery, BN_MONT_CTX_new,
6 BN_MONT_CTX_free, BN_MONT_CTX_set, BN_MONT_CTX_copy,
7 BN_from_montgomery, BN_to_montgomery - Montgomery multiplication
11 #include <openssl/bn.h>
13 BN_MONT_CTX *BN_MONT_CTX_new(void);
14 void BN_MONT_CTX_free(BN_MONT_CTX *mont);
16 int BN_MONT_CTX_set(BN_MONT_CTX *mont, const BIGNUM *m, BN_CTX *ctx);
17 BN_MONT_CTX *BN_MONT_CTX_copy(BN_MONT_CTX *to, BN_MONT_CTX *from);
19 int BN_mod_mul_montgomery(BIGNUM *r, BIGNUM *a, BIGNUM *b,
20 BN_MONT_CTX *mont, BN_CTX *ctx);
22 int BN_from_montgomery(BIGNUM *r, BIGNUM *a, BN_MONT_CTX *mont,
25 int BN_to_montgomery(BIGNUM *r, BIGNUM *a, BN_MONT_CTX *mont,
30 These functions implement Montgomery multiplication. They are used
31 automatically when L<BN_mod_exp(3)> is called with suitable input,
32 but they may be useful when several operations are to be performed
33 using the same modulus.
35 BN_MONT_CTX_new() allocates and initializes a B<BN_MONT_CTX> structure.
37 BN_MONT_CTX_set() sets up the I<mont> structure from the modulus I<m>
38 by precomputing its inverse and a value R.
40 BN_MONT_CTX_copy() copies the B<BN_MONT_CTX> I<from> to I<to>.
42 BN_MONT_CTX_free() frees the components of the B<BN_MONT_CTX>, and, if
43 it was created by BN_MONT_CTX_new(), also the structure itself.
44 If B<mont> is NULL, nothing is done.
46 BN_mod_mul_montgomery() computes Mont(I<a>,I<b>):=I<a>*I<b>*R^-1 and places
49 BN_from_montgomery() performs the Montgomery reduction I<r> = I<a>*R^-1.
51 BN_to_montgomery() computes Mont(I<a>,R^2), i.e. I<a>*R.
52 Note that I<a> must be non-negative and smaller than the modulus.
54 For all functions, I<ctx> is a previously allocated B<BN_CTX> used for
59 BN_MONT_CTX_new() returns the newly allocated B<BN_MONT_CTX>, and NULL
62 BN_MONT_CTX_free() has no return value.
64 For the other functions, 1 is returned for success, 0 on error.
65 The error codes can be obtained by L<ERR_get_error(3)>.
69 The inputs must be reduced modulo B<m>, otherwise the result will be
70 outside the expected range.
74 L<bn(3)>, L<ERR_get_error(3)>, L<BN_add(3)>,
79 BN_MONT_CTX_init() was removed in OpenSSL 1.1.0
83 Copyright 2000-2016 The OpenSSL Project Authors. All Rights Reserved.
85 Licensed under the OpenSSL license (the "License"). You may not use
86 this file except in compliance with the License. You can obtain a copy
87 in the file LICENSE in the source distribution or at
88 L<https://www.openssl.org/source/license.html>.