BN_CTX_NEW(3)

NAME
BN_CTX_new, BN_CTX_free, BN_CTX_init - allocate and free BN_CTX structures

SYNOPSIS
#include <openssl/bn.h>
BN_CTX *
BN_CTX_new(void);
void
BN_CTX_free(BN_CTX *c);

Deprecated:

void
BN_CTX_init(BN_CTX *c);

DESCRIPTION
A BN_CTX is a structure that holds BIGNUM temporary variables used by library functions. Since dynamic memory allocation to create BIGNUMs is rather expensive when used in conjunction with repeated subroutine calls, the BN_CTX structure is used.

BN_CTX_new() allocates and initializes a BN_CTX structure.

BN_CTX_free() frees the components of the BN_CTX and, if it was created by BN_CTX_new(), also the structure itself. If BN_CTX_start(3) has been used on the BN_CTX, BN_CTX_end(3) must be called before the BN_CTX may be freed by BN_CTX_free(). If c is a NULL pointer, no action occurs.

BN_CTX_init() (deprecated) initializes an existing uninitialized BN_CTX. This should not be used for new programs. Use BN_CTX_new() instead.

RETURN VALUES
BN_CTX_new() returns a pointer to the BN_CTX. If the allocation fails, it returns NULL and sets an error code that can be obtained by ERR_get_error(3).

SEE ALSO
BN_add(3), BN_CTX_start(3), BN_new(3), ERR_get_error(3)

HISTORY
BN_CTX_new() and BN_CTX_free() appeared before SSLeay 0.8 and have been available since OpenBSD 2.4.

BN_CTX_init() first appeared in SSLeay 0.9.1 and has been available since OpenBSD 2.6.