- NAME
- SYNOPSIS
- DESCRIPTION
- RETURN VALUES
- SEE ALSO
- HISTORY
- COPYRIGHT

# NAME

BN_new, BN_secure_new, BN_clear, BN_free, BN_clear_free - allocate and free BIGNUMs

# SYNOPSIS

     #include <openssl/bn.h>

     BIGNUM *BN_new(void);

     BIGNUM *BN_secure_new(void);

     void BN_clear(BIGNUM *a);

     void BN_free(BIGNUM *a);

     void BN_clear_free(BIGNUM *a);

# DESCRIPTION

`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.

# SEE ALSO

ERR_get_error(3), OPENSSL_secure_malloc(3)

# HISTORY

`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.