  In the Internet-of-Things, the number of connected devices is expected to be
extremely huge, i.e., more than a couple of ten billion. It is however
well-known that the security for the Internet-of-Things is still open problem.
In particular, it is difficult to certify the identification of connected
devices and to prevent the illegal spoofing. It is because the conventional
security technologies have advanced for mainly protecting logical network and
not for physical network like the Internet-of-Things. In order to protect the
Internet-of-Things with advanced security technologies, we propose a new
concept (datachain layer) which is a well-designed combination of physical chip
identification and blockchain. With a proposed solution of the physical chip
identification, the physical addresses of connected devices are uniquely
connected to the logical addresses to be protected by blockchain.
