=pod

=head1 NAME

BN_new, BN_secure_new, BN_clear, BN_free, BN_clear_free - allocate and free BIGNUMs

=head1 SYNOPSIS

 #include <openssl/bn.h>

 BIGNUM *BN_new(void);

 BIGNUM *BN_secure_new(void);

 void BN_clear(BIGNUM *a);

 void BN_free(BIGNUM *a);

 void BN_clear_free(BIGNUM *a);

=head1 DESCRIPTION

BN_new() allocates and initializes a B<BIGNUM> structure.
BN_secure_new() does the same except that the secure heap
L<OPENSSL_secure_malloc(3)> is used to store the value.

BN_clear() is used to destroy sensitive data such as keys when they
are no longer needed. It erases the memory used by B<a> and sets it
to the value 0.
If B<a> is NULL, nothing is done.

BN_free() frees the components of the B<BIGNUM>, and if it was created
by BN_new(), also the structure itself. BN_clear_free() additionally
overwrites the data before the memory is returned to the system.
If B<a> is NULL, nothing is done.

=head1 RETURN VALUES

BN_new() and BN_secure_new()
return a pointer to the B<BIGNUM> initialised to the value 0.
If the allocation fails,
they return B<NULL> and set an error code that can be obtained
by L<ERR_get_error(3)>.

BN_clear(), BN_free() and BN_clear_free() have no return values.

=head1 SEE ALSO

L<ERR_get_error(3)>, L<OPENSSL_secure_malloc(3)>

=head1 HISTORY

BN_init() was removed in OpenSSL 1.1.0; use BN_new() instead.

=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>.

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