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 nonnegative 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 2000-2020 The OpenSSL Project Authors. All Rights Reserved.
Licensed under the Apache License 2.0 (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>.