-void enable_crypt(int fd, crypt_function *recv, crypt_function *send,
+
+/**
+ * activate encryption for one file descriptor
+ *
+ * \param fd the file descriptor
+ * \param recv_f the function used for decrypting received data
+ * \param send_f the function used for encrypting before sending
+ * \param private_data user data supplied by the caller
+ */
+void enable_crypt(int fd, crypt_function *recv_f, crypt_function *send_f,