BN_new, BN_secure_new, BN_clear, BN_free, BN_clear_free − allocate and free BIGNUMs
void BN_clear(BIGNUM *a);
void BN_free(BIGNUM *a);
void BN_clear_free(BIGNUM *a);
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.
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.
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