}

    @Override
    public int _ENGINE_set_default(final PointerByReference rdrandEngine, final int flags) {
        return ENGINE_set_default(rdrandEngine, flags);
    }

    @Override
    public String _ERR_error_string(final NativeLong err, final char[] buff) {
        return ERR_error_string(err, buff);
    }

    @Override
    public NativeLong _ERR_peek_error() {
        return ERR_peek_error();
    }

    @Override
    public PointerByReference _EVP_aes_128_cbc() {
        return EVP_aes_128_cbc();
    }

    @Override
    public PointerByReference _EVP_aes_128_ctr() {
        return EVP_aes_128_ctr();
    }

    @Override
    public PointerByReference _EVP_aes_192_cbc() {
        return EVP_aes_192_cbc();
    }

    @Override
    public PointerByReference _EVP_aes_192_ctr() {
        return EVP_aes_192_ctr();
    }

    @Override
    public PointerByReference _EVP_aes_256_cbc() {
        return EVP_aes_256_cbc();
    }

    @Override
    public PointerByReference _EVP_aes_256_ctr() {
        return EVP_aes_256_ctr();
    }

    @Override
    public void _EVP_CIPHER_CTX_cleanup(final PointerByReference context) {
        EVP_CIPHER_CTX_cleanup(context);
    }

    @Override
    public void _EVP_CIPHER_CTX_free(final PointerByReference context) {
        EVP_CIPHER_CTX_free(context);
    }

    @Override
    public PointerByReference _EVP_CIPHER_CTX_new() {
        return EVP_CIPHER_CTX_new();
    }

    @Override
    public int _EVP_CIPHER_CTX_set_padding(final PointerByReference context, final int padding) {
        return EVP_CIPHER_CTX_set_padding(context, padding);
    }

    @Override
    public int _EVP_CipherFinal_ex(final PointerByReference context, final ByteBuffer outBuffer, final int[] outlen) {
        return EVP_CipherFinal_ex(context, outBuffer, outlen);
    }

    @Override
    public int _EVP_CipherInit_ex(final PointerByReference context, final PointerByReference algo, final PointerByReference impl, final byte[] encoded,
            final byte[] iv, final int cipherMode) {
        return EVP_CipherInit_ex(context, algo, impl, encoded, iv, cipherMode);
    }

    @Override
    public int _EVP_CipherUpdate(final PointerByReference context, final ByteBuffer outBuffer, final int[] outlen, final ByteBuffer inBuffer,
            final int remaining) {
        return EVP_CipherUpdate(context, outBuffer, outlen, inBuffer, remaining);
    }

    @Override
    public Throwable _INIT_ERROR() {
        return INIT_ERROR;
    }

    @Override
    public boolean _INIT_OK() {
        return INIT_OK;
    }

    @Override
    public String _OpenSSL_version(final int i) {
        return SSLeay_version(i);
    }

    @Override
    public int _RAND_bytes(final ByteBuffer buf, final int length) {
        return RAND_bytes(buf, length) ;
    }

    @Override
    public PointerByReference _RAND_get_rand_method() {
        return RAND_get_rand_method();
    }

    @Override
    public PointerByReference _RAND_SSLeay() {
        return RAND_SSLeay();
    }
}

public static native void ENGINE_load_rdrand();

    /**
     * Sets the engine as the default for random number generation.
     *
     * @param e
     *            engine reference
     * @param flags
     *            ENGINE_METHOD_RAND
     * @return zero if failed.
     */
    public static native int ENGINE_set_default(PointerByReference e, int flags);

    /**
     * Generates a human-readable string representing the error code e.
     *
     * @see <a href="https://www.openssl.org/docs/man1.0.2/man3/ERR_error_string.html">ERR_error_string</a>
     *
     * @param err
     *            the error code
     * @param null_
     *            buf is NULL, the error string is placed in a static buffer
     * @return the human-readable error messages.
     */
    public static native String ERR_error_string(NativeLong err, char[] null_);

    // TODO: NOT USED?
    /**
     * Registers the error strings for all libcrypto functions.
     */
    public static native void ERR_load_crypto_strings();

    /**
     * @return the earliest error code from the thread's error queue without modifying it.
     */
    public static native NativeLong ERR_peek_error();

    /**
     * @return an OpenSSL AES EVP cipher instance with a 128-bit key CBC mode
     */
    public static native PointerByReference EVP_aes_128_cbc();

    /**
     * @return an OpenSSL AES EVP cipher instance with a 128-bit key CTR mode
     */
    public static native PointerByReference EVP_aes_128_ctr();

    /**
     * @return an OpenSSL AES EVP cipher instance with a 192-bit key CBC mode
     */
    public static native PointerByReference EVP_aes_192_cbc();

    /**
     * @return an OpenSSL AES EVP cipher instance with a 192-bit key CTR mode
     */
    public static native PointerByReference EVP_aes_192_ctr();

    /**
     * @return an OpenSSL AES EVP cipher instance with a 256-bit key CBC mode
     */
    public static native PointerByReference EVP_aes_256_cbc();

    /**
     * @return an OpenSSL AES EVP cipher instance with a 256-bit key CTR mode
     */
    public static native PointerByReference EVP_aes_256_ctr();

    /**
     * Clears all information from a cipher context and free up any allocated * memory associate
     * with it.
     *
     * @param c
     *            openssl evp cipher
     */
    public static native void EVP_CIPHER_CTX_cleanup(PointerByReference c);

    /**
     * Clears all information from a cipher context and free up any allocated memory associate with
     * it, including ctx itself.
     *
     * @param c
     *            openssl evp cipher
     */
    public static native void EVP_CIPHER_CTX_free(PointerByReference c);

    // TODO: NOT USED?
    /**
     * EVP_CIPHER_CTX_init() remains as an alias for EVP_CIPHER_CTX_reset
     *
     * @param p
     *            cipher context
     */
    public static native void EVP_CIPHER_CTX_init(PointerByReference p);

    /**
     * Creates a cipher context.
     *
     * @return a pointer to a newly created EVP_CIPHER_CTX for success and NULL for failure.
     */
    public static native PointerByReference EVP_CIPHER_CTX_new();

    /**
     * Enables or disables padding
     *
     * @param c
     *            cipher context
     * @param pad
     *            If the pad parameter is zero then no padding is performed
     * @return always returns 1
     */
    public static native int EVP_CIPHER_CTX_set_padding(PointerByReference c, int pad);

    /**
     * Finishes a multiple-part operation.
     *
     * @param ctx
     *            cipher context
     * @param bout
     *            output byte buffer
     * @param outl
     *            output length
     * @return 1 for success and 0 for failure.
     */
    public static native int EVP_CipherFinal_ex(PointerByReference ctx, ByteBuffer bout,
            int[] outl);

    // ENGINE API: https://www.openssl.org/docs/man1.0.2/man3/engine.html

    /**
     * Init a cipher.
     *
     * @param ctx
     *            cipher context
     * @param cipher
     *            evp cipher instance
     * @param impl
     *            engine
     * @param key
     *            key
     * @param iv
     *            iv
     * @param enc
     *            1 for encryption, 0 for decryption
     * @return 1 for success and 0 for failure.
     */
    public static native int EVP_CipherInit_ex(PointerByReference ctx, PointerByReference cipher,
            PointerByReference impl, byte[] key, byte[] iv, int enc);

    /**
     * Continues a multiple-part encryption/decryption operation.
     *
     * @param ctx
     *            cipher context
     * @param bout
     *            output byte buffer
     * @param outl
     *            output length
     * @param in
     *            input byte buffer
     * @param inl
     *            input length
     * @return 1 for success and 0 for failure.
     */
    public static native int EVP_CipherUpdate(PointerByReference ctx, ByteBuffer bout, int[] outl,
            ByteBuffer in, int inl);

    /**
     * Generates random data
     *
     * @param buf
     *            the bytes for generated random.
     * @param num
     *            buffer length
     * @return 1 on success, 0 otherwise.
     */
    public static native int RAND_bytes(ByteBuffer buf, int num);

    // Random generator
    /**
     * OpenSSL uses for random number generation
     *
     * @return pointers to the respective methods
     */
    public static native PointerByReference RAND_get_rand_method();

    /**
     * OpenSSL uses for random number generation.
     *
     * @return pointers to the respective methods
     */
    public static native PointerByReference RAND_SSLeay();

    /**
     * @see <a href="https://www.openssl.org/docs/man1.0.2/man3/SSLeay.html">Version Number</a>
     * TODO (does not appear to be used yet)
     * @return OPENSSL_VERSION_NUMBER which is a numeric release version identifier
     */
    public static native NativeLong SSLeay();

    /**
     * Retrieves version/build information about OpenSSL library.
     * This is returned by {@link OpenSslNativeJna#OpenSSLVersion(int)}
     *
     * @see <a href="https://www.openssl.org/docs/man1.0.2/man3/SSLeay_version.html">Version Info</a>
     *
     * @param type
     *            type can be SSLEAY_VERSION, SSLEAY_CFLAGS, SSLEAY_BUILT_ON...
     * @return A pointer to a constant string describing the version of the OpenSSL library or
     *         giving information about the library build.
     */
    public static native String SSLeay_version(int type);


    // ================== instance interface methods ==================

    @Override
    public PointerByReference _ENGINE_by_id(final String string) {
        return ENGINE_by_id(string);
    }

    @Override
    public int _ENGINE_cleanup() {
        return ENGINE_cleanup();
    }

    @Override
    public int _ENGINE_finish(final PointerByReference rdrandEngine) {
        return ENGINE_finish(rdrandEngine);
    }

    @Override
    public int _ENGINE_free(final PointerByReference rdrandEngine) {
        return ENGINE_free(rdrandEngine);
    }

    @Override
    public int _ENGINE_init(final PointerByReference rdrandEngine) {
        return ENGINE_init(rdrandEngine);
    }

    @Override
    public void _ENGINE_load_rdrand() {