Signal processing system

#The present invention relates to a signal processing system.

#In recent years, security in information communication has become more important. A network system forming the Internet is described by an OSI reference model developed by the International Organization for Standardization. In the OSI reference model, classification from a physical layer of a layer 1 to an application layer of a layer 7 is set, and an interface connecting each layer is standardized or normalized by de facto. Of these layers, the lowermost layer is the physical layer undertaking a role for actually transmitting/receiving a signal with or without a wire. Currently, the security (in many cases, by mathematical cryptography) is implemented for a layer 2 or higher, and no security is implemented for the physical layer. However, there is also the risk of eavesdropping in the physical layer. For example, in optical fiber communication as a representative of wired communication, a branch is, in principle, installed on an optical fiber to take out part of signal power so that a mass of information can be stolen at once. For this reason, the present applicant has developed, as an encryption technique in the physical layer, a predetermined protocol described in Patent Document 1, for example. Patent Document 1: Japanese Unexamined Patent Application, Publication No. 2012-085028

#However, in the typical technique including Patent Document 1 above, multivalued information is transmitted as an optical signal so that telesecurity in the physical layer in the case of using the optical fiber can be provided, but telesecurity in the physical layer in wireless communication cannot be provided.

#FIG. 1 is a block diagram showing one example of the configuration of a signal transmission/reception system including a signal transmission system according to one embodiment of a signal processing system of the present invention;

#FIG. 2 shows views for describing the outline of the principle of Y-00 optical communication quantum cryptography applied to the signal transmission system of FIG. 1;

#FIG. 3 is an enlarged view of FIG. 2 so that arrangement of adjacent three symbol points of N symbol points, i.e., 4096 symbol points, in phase modulation of FIG. 2 can be viewed.

#Hereinafter, an embodiment of the present invention will be described. FIG. 1 is a block diagram showing one example of the configuration of a signal transmission/reception system according to one embodiment of a signal processing system of the present invention. The signal transmission/reception system of the example of FIG. 1 includes a signal transmission system 1 and a signal reception system 2. The signal transmission system 1 encrypts a signal targeted for transmission based on a Y-00 optical communication quantum cryptography protocol, and transmits the signal in the form of a radio wave RW. The signal reception system 2 receives the radio wave RW to decrypt the radio wave RW based on the Y-00 optical communication quantum cryptography protocol and receive the signal in the above-described form. Note that although details will be described later, Y-00 optical communication quantum cryptography is an encryption method based on a principle that multivalued information converted from predetermined data as a transmission target based on the Y-00 optical communication quantum cryptography protocol is transmitted as an optical signal and the received signal is an encrypted encryption signal accordingly.

#First, the configuration of the signal transmission system 1 that transmits the radio wave RW encrypted based on the Y-00 optical communication quantum cryptography protocol will be described. The signal transmission system 1 includes an optical signal generation section 11, an optical signal amplification section 12, an O/E conversion section 13, and a radio wave transmission section 14.

#The optical signal generation section 11 generates, as the optical signal, the multivalued information in a multivalued state based on the predetermined data. Although details will be described later, the optical signal is the signal targeted for transmission. The optical signal generation section 11 includes a Y-00 cipher output section 111 and an E/O conversion section 112.