BN_mod_mul_montgomery, BN_MONT_CTX_new, BN_MONT_CTX_free, BN_MONT_CTX_set,
BN_MONT_CTX_copy, BN_from_montgomery, BN_to_montgomery - Montgomery
multiplication
#include <openssl/bn.h>
BN_MONT_CTX *BN_MONT_CTX_new(void);
void BN_MONT_CTX_free(BN_MONT_CTX *mont);
int BN_MONT_CTX_set(BN_MONT_CTX *mont, const BIGNUM *m, BN_CTX *ctx);
BN_MONT_CTX *BN_MONT_CTX_copy(BN_MONT_CTX *to, BN_MONT_CTX *from);
int BN_mod_mul_montgomery(BIGNUM *r, BIGNUM *a, BIGNUM *b,
BN_MONT_CTX *mont, BN_CTX *ctx);
int BN_from_montgomery(BIGNUM *r, BIGNUM *a, BN_MONT_CTX *mont,
BN_CTX *ctx);
int BN_to_montgomery(BIGNUM *r, BIGNUM *a, BN_MONT_CTX *mont,
BN_CTX *ctx);
These functions implement Montgomery multiplication. They are used automatically
when
BN_mod_exp(3) is called with suitable input, but they may be
useful when several operations are to be performed using the same modulus.
BN_MONT_CTX_new() allocates and initializes a
BN_MONT_CTX
structure.
BN_MONT_CTX_set() sets up the
mont structure from the modulus
m by precomputing its inverse and a value R.
BN_MONT_CTX_copy() copies the
BN_MONT_CTX from to
to.
BN_MONT_CTX_free() frees the components of the
BN_MONT_CTX, and,
if it was created by
BN_MONT_CTX_new(), also the structure itself. If
mont is NULL, nothing is done.
BN_mod_mul_montgomery() computes
Mont(
a,
b):=
a*
b*R^-1 and places the result in
r.
BN_from_montgomery() performs the Montgomery reduction
r =
a*R^-1.
BN_to_montgomery() computes Mont(
a,R^2), i.e.
a*R. Note
that
a must be non-negative and smaller than the modulus.
For all functions,
ctx is a previously allocated
BN_CTX used for
temporary variables.
BN_MONT_CTX_new() returns the newly allocated
BN_MONT_CTX, and
NULL on error.
BN_MONT_CTX_free() has no return value.
For the other functions, 1 is returned for success, 0 on error. The error codes
can be obtained by
ERR_get_error(3).
The inputs must be reduced modulo
m, otherwise the result will be outside
the expected range.
ERR_get_error(3),
BN_add(3),
BN_CTX_new(3)
BN_MONT_CTX_init() was removed in OpenSSL 1.1.0
Copyright 2000-2017 The OpenSSL Project Authors. All Rights Reserved.
Licensed under the OpenSSL license (the "License"). You may not use
this file except in compliance with the License. You can obtain a copy in the
file LICENSE in the source distribution or at
<https://www.openssl.org/source/license.html>.