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BN_CTX_new(3)                       OpenSSL                      BN_CTX_new(3)



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

LIBRARY
       libcrypto, -lcrypto

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>.



1.1.1                             2018-09-17                     BN_CTX_new(3)