4746f25ac6
[skip ci] Reviewed-by: Matt Caswell <matt@openssl.org> (Merged from https://github.com/openssl/openssl/pull/7829)
76 lines
2.2 KiB
Text
76 lines
2.2 KiB
Text
=pod
|
|
|
|
=head1 NAME
|
|
|
|
BN_mod_mul_reciprocal, BN_div_recp, BN_RECP_CTX_new,
|
|
BN_RECP_CTX_free, BN_RECP_CTX_set - modular multiplication using
|
|
reciprocal
|
|
|
|
=head1 SYNOPSIS
|
|
|
|
#include <openssl/bn.h>
|
|
|
|
BN_RECP_CTX *BN_RECP_CTX_new(void);
|
|
void BN_RECP_CTX_free(BN_RECP_CTX *recp);
|
|
|
|
int BN_RECP_CTX_set(BN_RECP_CTX *recp, const BIGNUM *m, BN_CTX *ctx);
|
|
|
|
int BN_div_recp(BIGNUM *dv, BIGNUM *rem, BIGNUM *a, BN_RECP_CTX *recp,
|
|
BN_CTX *ctx);
|
|
|
|
int BN_mod_mul_reciprocal(BIGNUM *r, BIGNUM *a, BIGNUM *b,
|
|
BN_RECP_CTX *recp, BN_CTX *ctx);
|
|
|
|
=head1 DESCRIPTION
|
|
|
|
BN_mod_mul_reciprocal() can be used to perform an efficient
|
|
L<BN_mod_mul(3)> operation when the operation will be performed
|
|
repeatedly with the same modulus. It computes B<r>=(B<a>*B<b>)%B<m>
|
|
using B<recp>=1/B<m>, which is set as described below. B<ctx> is a
|
|
previously allocated B<BN_CTX> used for temporary variables.
|
|
|
|
BN_RECP_CTX_new() allocates and initializes a B<BN_RECP> structure.
|
|
|
|
BN_RECP_CTX_free() frees the components of the B<BN_RECP>, and, if it
|
|
was created by BN_RECP_CTX_new(), also the structure itself.
|
|
If B<recp> is NULL, nothing is done.
|
|
|
|
BN_RECP_CTX_set() stores B<m> in B<recp> and sets it up for computing
|
|
1/B<m> and shifting it left by BN_num_bits(B<m>)+1 to make it an
|
|
integer. The result and the number of bits it was shifted left will
|
|
later be stored in B<recp>.
|
|
|
|
BN_div_recp() divides B<a> by B<m> using B<recp>. It places the quotient
|
|
in B<dv> and the remainder in B<rem>.
|
|
|
|
The B<BN_RECP_CTX> structure cannot be shared between threads.
|
|
|
|
=head1 RETURN VALUES
|
|
|
|
BN_RECP_CTX_new() returns the newly allocated B<BN_RECP_CTX>, and NULL
|
|
on error.
|
|
|
|
BN_RECP_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 L<ERR_get_error(3)>.
|
|
|
|
=head1 SEE ALSO
|
|
|
|
L<ERR_get_error(3)>, L<BN_add(3)>,
|
|
L<BN_CTX_new(3)>
|
|
|
|
=head1 HISTORY
|
|
|
|
BN_RECP_CTX_init() was removed in OpenSSL 1.1.0
|
|
|
|
=head1 COPYRIGHT
|
|
|
|
Copyright 2000-2017 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
|