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OPENSSL_secure_malloc(3)            OpenSSL           OPENSSL_secure_malloc(3)

       CRYPTO_secure_malloc_init, CRYPTO_secure_malloc_initialized,
       CRYPTO_secure_malloc_done, OPENSSL_secure_malloc, CRYPTO_secure_malloc,
       OPENSSL_secure_zalloc, CRYPTO_secure_zalloc, OPENSSL_secure_free,
       CRYPTO_secure_free, OPENSSL_secure_clear_free,
       CRYPTO_secure_clear_free, OPENSSL_secure_actual_size,
       CRYPTO_secure_allocated, CRYPTO_secure_used - secure heap storage

       libcrypto, -lcrypto

        #include <openssl/crypto.h>

        int CRYPTO_secure_malloc_init(size_t size, int minsize);

        int CRYPTO_secure_malloc_initialized();

        int CRYPTO_secure_malloc_done();

        void *OPENSSL_secure_malloc(size_t num);
        void *CRYPTO_secure_malloc(size_t num, const char *file, int line);

        void *OPENSSL_secure_zalloc(size_t num);
        void *CRYPTO_secure_zalloc(size_t num, const char *file, int line);

        void OPENSSL_secure_free(void* ptr);
        void CRYPTO_secure_free(void *ptr, const char *, int);

        void OPENSSL_secure_clear_free(void* ptr, size_t num);
        void CRYPTO_secure_clear_free(void *ptr, size_t num, const char *, int);

        size_t OPENSSL_secure_actual_size(const void *ptr);

        int CRYPTO_secure_allocated(const void *ptr);
        size_t CRYPTO_secure_used();

       In order to help protect applications (particularly long-running
       servers) from pointer overruns or underruns that could return arbitrary
       data from the program's dynamic memory area, where keys and other
       sensitive information might be stored, OpenSSL supports the concept of
       a "secure heap."  The level and type of security guarantees depend on
       the operating system.  It is a good idea to review the code and see if
       it addresses your threat model and concerns.

       If a secure heap is used, then private key BIGNUM values are stored
       there.  This protects long-term storage of private keys, but will not
       necessarily put all intermediate values and computations there.

       CRYPTO_secure_malloc_init() creates the secure heap, with the specified
       "size" in bytes. The "minsize" parameter is the minimum size to
       allocate from the heap. Both "size" and "minsize" must be a power of

       CRYPTO_secure_malloc_initialized() indicates whether or not the secure
       heap as been initialized and is available.

       CRYPTO_secure_malloc_done() releases the heap and makes the memory
       unavailable to the process if all secure memory has been freed.  It can
       take noticeably long to complete.

       OPENSSL_secure_malloc() allocates "num" bytes from the heap.  If
       CRYPTO_secure_malloc_init() is not called, this is equivalent to
       calling OPENSSL_malloc().  It is a macro that expands to
       CRYPTO_secure_malloc() and adds the "__FILE__" and "__LINE__"

       OPENSSL_secure_zalloc() and CRYPTO_secure_zalloc() are like
       OPENSSL_secure_malloc() and CRYPTO_secure_malloc(), respectively,
       except that they call memset() to zero the memory before returning.

       OPENSSL_secure_free() releases the memory at "ptr" back to the heap.
       It must be called with a value previously obtained from
       OPENSSL_secure_malloc().  If CRYPTO_secure_malloc_init() is not called,
       this is equivalent to calling OPENSSL_free().  It exists for
       consistency with OPENSSL_secure_malloc() , and is a macro that expands
       to CRYPTO_secure_free() and adds the "__FILE__" and "__LINE__"

       OPENSSL_secure_clear_free() is similar to OPENSSL_secure_free() except
       that it has an additional "num" parameter which is used to clear the
       memory if it was not allocated from the secure heap.  If
       CRYPTO_secure_malloc_init() is not called, this is equivalent to
       calling OPENSSL_clear_free().

       OPENSSL_secure_actual_size() tells the actual size allocated to the
       pointer; implementations may allocate more space than initially
       requested, in order to "round up" and reduce secure heap fragmentation.

       OPENSSL_secure_allocated() tells if a pointer is allocated in the
       secure heap.

       CRYPTO_secure_used() returns the number of bytes allocated in the
       secure heap.

       CRYPTO_secure_malloc_init() returns 0 on failure, 1 if successful, and
       2 if successful but the heap could not be protected by memory mapping.

       CRYPTO_secure_malloc_initialized() returns 1 if the secure heap is
       available (that is, if CRYPTO_secure_malloc_init() has been called, but
       CRYPTO_secure_malloc_done() has not been called or failed) or 0 if not.

       OPENSSL_secure_malloc() and OPENSSL_secure_zalloc() return a pointer
       into the secure heap of the requested size, or "NULL" if memory could
       not be allocated.

       CRYPTO_secure_allocated() returns 1 if the pointer is in the secure
       heap, or 0 if not.

       CRYPTO_secure_malloc_done() returns 1 if the secure memory area is
       released, or 0 if not.

       OPENSSL_secure_free() and OPENSSL_secure_clear_free() return no values.

       OPENSSL_malloc(3), BN_new(3)

       The OPENSSL_secure_clear_free() function was added in OpenSSL 1.1.0g.

       Copyright 2015-2016 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

1.1.1i                            2020-03-22          OPENSSL_secure_malloc(3)