1=pod
2
3=head1 NAME
4
5BN_CTX_new, BN_CTX_init, BN_CTX_free - allocate and free BN_CTX structures
6
7=head1 SYNOPSIS
8
9 #include <openssl/bn.h>
10
11 BN_CTX *BN_CTX_new(void);
12
13 void BN_CTX_init(BN_CTX *c);
14
15 void BN_CTX_free(BN_CTX *c);
16
17=head1 DESCRIPTION
18
19A B<BN_CTX> is a structure that holds B<BIGNUM> temporary variables used by
20library functions. Since dynamic memory allocation to create B<BIGNUM>s
21is rather expensive when used in conjunction with repeated subroutine
22calls, the B<BN_CTX> structure is used.
23
24BN_CTX_new() allocates and initializes a B<BN_CTX>
25structure. BN_CTX_init() initializes an existing uninitialized
26B<BN_CTX>.
27
28BN_CTX_free() frees the components of the B<BN_CTX>, and if it was
29created by BN_CTX_new(), also the structure itself.
30If L<BN_CTX_start(3)|BN_CTX_start(3)> has been used on the B<BN_CTX>,
31L<BN_CTX_end(3)|BN_CTX_end(3)> must be called before the B<BN_CTX>
32may be freed by BN_CTX_free().
33
34
35=head1 RETURN VALUES
36
37BN_CTX_new() returns a pointer to the B<BN_CTX>. If the allocation fails,
38it returns B<NULL> and sets an error code that can be obtained by
39L<ERR_get_error(3)|ERR_get_error(3)>.
40
41BN_CTX_init() and BN_CTX_free() have no return values.
42
43=head1 SEE ALSO
44
45L<bn(3)|bn(3)>, L<ERR_get_error(3)|ERR_get_error(3)>, L<BN_add(3)|BN_add(3)>,
46L<BN_CTX_start(3)|BN_CTX_start(3)>
47
48=head1 HISTORY
49
50BN_CTX_new() and BN_CTX_free() are available in all versions on SSLeay
51and OpenSSL. BN_CTX_init() was added in SSLeay 0.9.1b.
52
53=cut
54