* @info: pointer to info
* @isize: the number of bytes pointed to by @info
*/
-void hkdf_sha256(unsigned char *okm, size_t okm_size,
+void hkdf_sha256(void *okm, size_t okm_size,
const void *s, size_t ssize,
const void *k, size_t ksize,
const void *info, size_t isize);