BN_new() allocates and initializes a BIGNUM structure. BN_secure_new() does the same except that the secure heap OPENSSL_secure_malloc(3) is used to store the value.
BN_clear() is used to destroy sensitive data such as keys when they are no longer needed. It erases the memory used by a and sets it to the value 0. If a is NULL, nothing is done.
BN_free() frees the components of the BIGNUM, and if it was created by BN_new(), also the structure itself. BN_clear_free() additionally overwrites the data before the memory is returned to the system. If a is NULL, nothing is done.
RETURN VALUES
BN_new() and BN_secure_new() return a pointer to the BIGNUM initialised to the value 0. If the allocation fails, they return NULL and set an error code that can be obtained by ERR_get_error(3).
BN_clear(), BN_free() and BN_clear_free() have no return values.
BN_init() was removed in OpenSSL 1.1.0; use BN_new() instead.
COPYRIGHT
Copyright 2000-2019 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.