mirror of https://github.com/openssl/openssl
66 lines
2.6 KiB
Plaintext
66 lines
2.6 KiB
Plaintext
=pod
|
|
|
|
=head1 NAME
|
|
|
|
BN_mod_exp_mont, BN_mod_exp_mont_consttime, BN_mod_exp_mont_consttime_x2 -
|
|
Montgomery exponentiation
|
|
|
|
=head1 SYNOPSIS
|
|
|
|
#include <openssl/bn.h>
|
|
|
|
int BN_mod_exp_mont(BIGNUM *rr, const BIGNUM *a, const BIGNUM *p,
|
|
const BIGNUM *m, BN_CTX *ctx, BN_MONT_CTX *in_mont);
|
|
|
|
int BN_mod_exp_mont_consttime(BIGNUM *rr, const BIGNUM *a, const BIGNUM *p,
|
|
const BIGNUM *m, BN_CTX *ctx,
|
|
BN_MONT_CTX *in_mont);
|
|
|
|
int BN_mod_exp_mont_consttime_x2(BIGNUM *rr1, const BIGNUM *a1,
|
|
const BIGNUM *p1, const BIGNUM *m1,
|
|
BN_MONT_CTX *in_mont1, BIGNUM *rr2,
|
|
const BIGNUM *a2, const BIGNUM *p2,
|
|
const BIGNUM *m2, BN_MONT_CTX *in_mont2,
|
|
BN_CTX *ctx);
|
|
|
|
=head1 DESCRIPTION
|
|
|
|
BN_mod_exp_mont() computes I<a> to the I<p>-th power modulo I<m> (C<rr=a^p % m>)
|
|
using Montgomery multiplication. I<in_mont> is a Montgomery context and can be
|
|
NULL. In the case I<in_mont> is NULL, it will be initialized within the
|
|
function, so you can save time on initialization if you provide it in advance.
|
|
|
|
BN_mod_exp_mont_consttime() computes I<a> to the I<p>-th power modulo I<m>
|
|
(C<rr=a^p % m>) using Montgomery multiplication. It is a variant of
|
|
L<BN_mod_exp_mont(3)> that uses fixed windows and the special precomputation
|
|
memory layout to limit data-dependency to a minimum to protect secret exponents.
|
|
It is called automatically when L<BN_mod_exp_mont(3)> is called with parameters
|
|
I<a>, I<p>, I<m>, any of which have B<BN_FLG_CONSTTIME> flag.
|
|
|
|
BN_mod_exp_mont_consttime_x2() computes two independent exponentiations I<a1> to
|
|
the I<p1>-th power modulo I<m1> (C<rr1=a1^p1 % m1>) and I<a2> to the I<p2>-th
|
|
power modulo I<m2> (C<rr2=a2^p2 % m2>) using Montgomery multiplication. For some
|
|
fixed and equal modulus sizes I<m1> and I<m2> it uses optimizations that allow
|
|
to speedup two exponentiations. In all other cases the function reduces to two
|
|
calls of L<BN_mod_exp_mont_consttime(3)>.
|
|
|
|
=head1 RETURN VALUES
|
|
|
|
For all functions 1 is returned for success, 0 on error.
|
|
The error codes can be obtained by L<ERR_get_error(3)>.
|
|
|
|
=head1 SEE ALSO
|
|
|
|
L<ERR_get_error(3)>, L<BN_mod_exp_mont(3)>
|
|
|
|
=head1 COPYRIGHT
|
|
|
|
Copyright 2000-2021 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
|
|
L<https://www.openssl.org/source/license.html>.
|
|
|
|
=cut
|