first step of v2 final release

include/openssl/hkdf.h

@@ -0,0 +1,39 @@
+/*
+ * Copyright 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
+ * https://www.openssl.org/source/license.html
+ */
+
+#ifndef HEADER_HKDF_H
+# define HEADER_HKDF_H
+
+#include <string.h>
+#include <openssl/evp.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+unsigned char *HKDF(const EVP_MD *evp_md,
+                    const unsigned char *salt, size_t salt_len,
+                    const unsigned char *key, size_t key_len,
+                    const unsigned char *info, size_t info_len,
+                    unsigned char *okm, size_t okm_len);
+
+unsigned char *HKDF_Extract(const EVP_MD *evp_md,
+                            const unsigned char *salt, size_t salt_len,
+                            const unsigned char *key, size_t key_len,
+                            unsigned char *prk, size_t *prk_len);
+
+unsigned char *HKDF_Expand(const EVP_MD *evp_md,
+                           const unsigned char *prk, size_t prk_len,
+                           const unsigned char *info, size_t info_len,
+                           unsigned char *okm, size_t okm_len);
+
+# ifdef  __cplusplus
+}
+# endif
+#endif