Abstract: An encrypted communication is correctly decrypted even when key exchange completion notification is delayed. A key storage (10) stores at least one common key which is shared with another encrypted communication device. A key selecting unit (11) selects an encryption key from the at least one common key stored in the key storage (10). An encrypting unit (12) generates encrypted data by encrypting, by using the encryption key, data to be transmitted to the other encrypted communication device. A transmitting unit (13) transmits, to the other encrypted communication device, the encrypted data with a key index, by which the encryption key is uniquely identified, added thereto. A receiving unit (14) receives the encrypted data with the key index added thereto from the other encrypted communication device. A key obtaining unit (15) obtains, from the at least one common key stored in the key storage (10), a decryption key corresponding to the key index added to the encrypted data.

Abstract: An encrypted communication is correctly decrypted even when key exchange completion notification is delayed. A key storage (10) stores at least one common key which is shared with another encrypted communication device. A key selecting unit (11) selects an encryption key from the at least one common key stored in the key storage (10). An encrypting unit (12) generates encrypted data by encrypting, by using the encryption key, data to be transmitted to the other encrypted communication device. A transmitting unit (13) transmits, to the other encrypted communication device, the encrypted data with a key index, by which the encryption key is uniquely identified, added thereto. A receiving unit (14) receives the encrypted data with the key index added thereto from the other encrypted communication device. A key obtaining unit (15) obtains, from the at least one common key stored in the key storage (10), a decryption key corresponding to the key index added to the encrypted data.

Abstract: A software analysis protection method capable of preventing an illegitimate use of a software reliably, by making a software analysis difficult without complicating or enciphering the software itself. Software parts dividing the software to be used at the user terminal are distributedly stored in the user terminal and the center, and the software parts stored in the center are transmitted to the user terminal and loaded into missing parts among the software parts stored in the user terminal on a memory so as to make the software operable at the user terminal. Then, the software as developed on the memory is operated at the user terminal. The software parts are down-loaded from the center to the user terminal such that an arranged pattern of the software as developed on the memory is changed at each time of a use of the software at the user terminal.

Abstract: A method and a system for cipher key distribution realizing an effective prevention of the illegitimate use and the illegitimate charging. A key request signal containing a first random number generated at each user terminal is transmitted from each user terminal to the key center, so as to indicate the cipher key required at each user terminal to the key center, and a terminal check signal containing a second random number generated at the key center is transmitted from the key center to each user terminal.

Abstract: A pattern recognition method and apparatus wherein an optical correlator and a feedback light path are provided. In the optical correlator, an input pattern whose image is formed on a first spatial light modulator (valve) is read by the irradiation of coherent light, and an image of a correlation peak image of this reading light is formed by the use of a correlation filter on which a plurality of reference patterns are recorded in the form of modified patterns. In the feedback light path, the correlation peak image is formed on a second spatial light modulator (valve), the correlation peak image is read out by the irradiation of coherent light, and the light having read the correlation image is made to pass a display filter on which display reference patterns are recorded.