NAME

       BN_CTX_new, BN_CTX_secure_new, BN_CTX_free - allocate and free BN_CTX structures

SYNOPSIS

        #include <openssl/bn.h>

        BN_CTX *BN_CTX_new(void);

        BN_CTX *BN_CTX_secure_new(void);

        void BN_CTX_free(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_secure_new() allocates
       and initializes a BN_CTX structure but uses the secure heap (see CRYPTO_secure_malloc(3))
       to hold the BIGNUMs.

       BN_CTX_free() frees the components of the BN_CTX and the structure itself.  Since
       BN_CTX_start() is required in order to obtain BIGNUMs from the BN_CTX, in most cases
       BN_CTX_end() must be called before the BN_CTX may be freed by BN_CTX_free().  If c is
       NULL, nothing is done.

       A given BN_CTX must only be used by a single thread of execution.  No locking is
       performed, and the internal pool allocator will not properly handle multiple threads of
       execution.

RETURN VALUES

       BN_CTX_new() and BN_CTX_secure_new() return a pointer to the BN_CTX.  If the allocation
       fails, they return NULL and sets an error code that can be obtained by ERR_get_error(3).

       BN_CTX_free() has no return values.

REMOVED FUNCTIONALITY

        void BN_CTX_init(BN_CTX *c);

       BN_CTX_init() is no longer available as of OpenSSL 1.1.0. Applications should replace use
       of BN_CTX_init with BN_CTX_new instead:

        BN_CTX *ctx;
        ctx = BN_CTX_new();
        if (!ctx)
            /* error */
        ...
        BN_CTX_free(ctx);

SEE ALSO

       ERR_get_error(3), BN_add(3), BN_CTX_start(3)

HISTORY

       BN_CTX_init() was removed in OpenSSL 1.1.0.

COPYRIGHT

       Copyright 2000-2017 The OpenSSL Project Authors. All Rights Reserved.

       Licensed under the OpenSSL license (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 <https://www.openssl.org/source/license.html>.