Name

BN_CTX_new, BN_CTX_init
BN_CTX_free

allocate and free BN_CTX structures

Library

libcrypto.lib

Synopsis

#include <openssl/bn.h>

BN_CTX *BN_CTX_new(void);

void BN_CTX_init(BN_CTX *c);

void BN_CTX_free(BN_CTX *c);

Detailed 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_init() initializes an existing uninitialized BN_CTX.

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() has been used on the BN_CTX, BN_CTX_end() must be called before the BN_CTX may be freed by BN_CTX_free().

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().

BN_CTX_init() and BN_CTX_free() have no return values.

See Also

bn(), ERR_get_error(), BN_add(), BN_CTX_start()

History

BN_CTX_new() and BN_CTX_free() are available in all versions on SSLeay and OpenSSL. BN_CTX_init() was added in SSLeay 0.9.1b.

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