* \brief Block of functions related with HKDF utilities and operations.
**/
-#include "crypto_hkdf.h"
-#include "crypto_util.h"
-#include "crypto_digest.h"
+#include "common/crypto_hkdf.h"
+#include "common/crypto_util.h"
+#include "common/crypto_digest.h"
+
+ #include "crypto_openssl_mgt.h"
+ #include <openssl/opensslv.h>
+
+ #if OPENSSL_VERSION_NUMBER >= OPENSSL_V_SERIES(1,1,0)
+ #define HAVE_OPENSSL_HKDF 1
+ #include <openssl/kdf.h>
+ #endif
+
/** Given <b>key_in_len</b> bytes of negotiated randomness in <b>key_in</b>
* ("K"), expand it into <b>key_out_len</b> bytes of negotiated key material in
* <b>key_out</b> by taking the first <b>key_out_len</b> bytes of