openssl/doc/crypto/BN_new.pod
Matt Caswell e35af275d5 Update documentation following BN opaquify
Reviewed-by: Tim Hudson <tjh@openssl.org>
2014-12-08 21:41:36 +00:00

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=pod
=head1 NAME
BN_new, BN_init, BN_clear, BN_free, BN_clear_free - allocate and free BIGNUMs
=head1 SYNOPSIS
#include <openssl/bn.h>
BIGNUM *BN_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_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.
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.
=head1 RETURN VALUES
BN_new() returns a pointer to the B<BIGNUM>. If the allocation fails,
it returns B<NULL> and sets an error code that can be obtained
by L<ERR_get_error(3)|ERR_get_error(3)>.
BN_clear(), BN_free() and BN_clear_free() have no return values.
=head1 REMOVED FUNCTIONALITY
void BN_init(BIGNUM *);
BN_init() is no longer available as of OpenSSL 1.1.0. It was used to initialize
an existing uninitialized B<BIGNUM>. Typically this would be done as follows:
BIGNUM a;
BN_init(&a);
Applications should replace use of BN_init with BN_new instead:
BIGNUM *a;
a = BN_new();
if(!a) /* Handle error */
...
BN_free(a);
=head1 SEE ALSO
L<bn(3)|bn(3)>, L<ERR_get_error(3)|ERR_get_error(3)>
=head1 HISTORY
BN_new(), BN_clear(), BN_free() and BN_clear_free() are available in
all versions on SSLeay and OpenSSL. BN_init() was added in SSLeay
0.9.1b and removed in OpenSSL 1.1.0.
=cut