摘要:
A data communication apparatus, performing a secret communication, is provided to reduce a random number generation speed using a plurality of random number generators. The data communication apparatus includes random number generation sections generating random numbers, which are each a multi-level pseudo random number, using predetermined key information includes a multi-level signal modulation section selecting a level, from among multi-levels previously prepared, selected level corresponding to information data and a multi-level sequence, which is composed of a combination of values of the random numbers and generating a multi-level modulated signal including a noise having a predetermined noise level using the selected level. Levels of a multi-level signal are in a range of the noise level, and a signal point allocation is set such that all values which are possibly taken by each of the random numbers are allocated to the plurality of levels of the multi-level signal.
摘要:
A data communication system is provided in which a time required for a wiretapper to decrypt an encrypted text is significantly increased so that concealment is improved. In a data transmitting apparatus (17105), a multilevel encoding part (111) switches a plurality of key information to generate a multilevel code sequence in which the average values of signal levels are different, and then combines the generated multilevel code sequence with information data to generate a multilevel signal having a level corresponding to the combination of the two signal levels. A light modulating part (125) converts the multilevel signal into a modulated signal of a predetermined modulation scheme and transmits it. In a data receiving apparatus (17205), a light demodulating part (219) demodulates the received modulated signal into the multilevel signal. A multilevel decoding part (212) switches a plurality of key information to generate a multilevel code sequence in which the average values of signal levels are different, and then identifies the multilevel signal based on this generated multilevel code sequence to regenerate the information data.
摘要:
A data transmitting apparatus which improves security against eavesdropping is provided for secret communication using Y-00 protocol. The multi-level code generation section 111 generates, based on key information 11, a multi-level code sequence 12 in which a signal level changes so as to be approximately random numbers. The multi-level processing section 112 generates a multi-level signal 13 having a level which corresponds to a combination between information data 10 and the multi-level code sequence 12. The error signal generation section 113 generates an error signal 21 which changes randomly. The accumulation section 114 accumulates the error signal 21, and outputs an accumulated error signal 22. The adding section 116 adds the accumulated error signal 22 to the multi-level signal 13, and outputs a variable multi-level signal 23. The modulator section 117 modulates the variable multi-level signal 23, and outputs a modulated signal 14.
摘要:
A highly concealable data communication apparatus which is based on an astronomical complexity and causes an eavesdropper to take a significantly increased time to analyze a cipher text, is provided. In a multi-level code generation section 111a, a random number sequence generation section 141 generates, based on predetermined key information 11, a plurality of modulation pseudo-random number sequences. The plurality of modulation pseudo-random number sequences is inputted to a multi-level conversion section 142 as a part of an input bit sequence which is converted into a multi-level code sequence 12. A multi-level processing section 111b combines the multi-level code sequence 12 and information data 10, and generates a multi-level signal 13 having a plurality of levels corresponding to a combination of the multi-level code sequence 12 and the information data 10.
摘要:
There provided are transmission and reception apparatuses which can realize performing key distribution and encrypted communication in a simultaneous manner. A transmission apparatus overlaps minute amplitude modulation based on a random number signal on a multi-level signal generated based on information data and key information. A reception apparatus, in addition to data identification, performs, by using 2 threshold values between which a sufficiently larger interval than a modulation amplitude by a random number is provided, 3 kinds of identification for the random number signal: “1”, “0”, and “identification impossible”, sends back information of bits with which the identification has succeeded, and shares the sent bits as a new key. Thus, the common device including the transmission and reception apparatuses can realize performing the key distribution and the encrypted communication in the simultaneous manner.
摘要:
An optical transmission system including an optical transmitting device (2) and an optical receiving device (3). The optical transmitting device (2) includes: a data signal splitting section (11, 12) for splitting information included in the data signal into at least two pieces of information and generating at least two electrical signals having different center frequencies and bands; a frequency multiplexing section (13) for performing frequency multiplexing for the at least two electrical signals; and an electrical-to-optical conversion section (14) for converting the frequency-multiplexed signal to an optical signal and sending it to an optical transmission path. The optical receiving device (3) includes: an optical-to-electrical conversion section (31) for converting the optical signal transmitted via the optical transmission path to the a frequency-multiplexed signal; a band demultiplexing section (32) for demultiplexing the frequency-multiplexed signal to obtain at least two electrical signals; and a data signal recovering section (33, 34) for recovering the data signal based on the at least two demultiplexed electrical signals. The data signal splitting section (11, 12) generates at least two electrical signals so that each electrical signal is located in a frequency band away from a local minimum in a frequency response of the optical transmission path.
摘要:
A data communication apparatus wherein stealthiness is enhanced by significantly increasing the time required for a wiretapper to decrypt an encrypted text. The data communication apparatus is constituted by connecting a data transmitting apparatus and a data receiving apparatus via a transmission path. The data transmitting apparatus receives a first predetermined initial value (key information) and information data, generates a multi-valued signal, the level of which varies substantially in a random number manner, and converts the multi-valued signal to a modulated signal of a predetermined modulation format for transmission. The data receiving apparatus demodulates the modulated signal to output the multi-valued signal, and then reproduces the information data from the multi-valued signal and a received second predetermined initial value (key information).
摘要:
A data communication apparatus improves security against eavesdropping for secret communication by using Y-00 protocol. A multi-level code generation section generates, based on key information, a multi-level code sequence in which a signal level changes so as to be approximately random numbers. A level conversion section irreversibly converts the multi-level code sequence such that a converted multi-level code sequence does not constitute a mapping of the multi-level code sequence. A multi-level processing section generates a multi-level signal having a plurality of levels each corresponding to a combination between the information data and the multi-level code sequence. A modulator section modulates a multi-level signal in a predetermined modulation method and outputs a modulated signal.
摘要:
A data communication apparatus which causes the eavesdropper to take a significantly increased time to analyze a cipher text and provides high concealability is provided. A multi-level code generation section 111a generates, based on predetermined key information 11, a multi-level code sequence 12 in which a signal level changes so as to be approximately random numbers. A multi-level processing section 111b combines the multi-level code sequence 12 and information data 10, and generates a multi-level signal 13 having a plurality of levels corresponding to the combination of the multi-level code sequence 12 and the information data 10. A modulator section 112 treats the multi-level signal a predetermined modulating processing and generates a modulated signal. The multi-level code generation section 111a generates the multi-level code sequence 12 in accordance with a changed random number sequence which results from changing a bit series of a binary random number sequence generated based on the predetermined key information.
摘要:
Provided is a data communication apparatus which is highly concealable and significantly increases time necessary for an eavesdropper to analyze cipher text. A multi-level code generation section (156a) generates, by using predetermined key information, a multi-level code sequence in which a signal level changes so as to be random numbers. The multi-level processing section (111b) combines a multi-level code sequence and information data, and generates a multi-level signal having a level corresponding to a combination of the multi-level code sequence and the information data. In the multi-level code generation section (156a), a random number sequence generation section (157) generates a binary random number sequence by using the predetermined key information. A multi-level conversion section (158) generates a multi-level code sequence from the binary random number sequence in accordance with a predetermined encoding rule.