A.Yu. Grishentsev – Dr. Sc. (Eng.), Associate Professor, ITMO University (Saint Petersburg)
The object of research is the method and result of the synthesis of broadband noise-like signals. The subject of the study is to organize the protected channel of the radio allowing to realize on the basis of a common ideology steganographic and cryptographic security model of the data transmitted.
The method and software implementation of the synthesis of true complex-valued noise-like signals. The proposed method allows to effectively control the range of the broadband signals.
In the aquatic part of the work a comparison of values of the autocorrelation functions of wide-band signals synthesized on the basis of the matrices with a special form of the autocorrelation function (matrix, Hadamard, and Barker codes, etc.) and the values of the autocorrelation functions of wide-band signals was proposed in the work. Comparative analysis indicates a significant advantage of the proposed broadband signal against the Central spike to the side petals. Later in the article, listing the implementation of the method of synthesis of broadband noise-like signals in the MatLab language. As an illustration, graphs of the synthesized signal, its autocorrelation function and spectrum obtained using fast Fourier transform. The next part of the work on the preliminary statistical analysis of the synthesis technique and the synthesis of broadband noise-like signal. Derived empirical laws evaluation of computational complexity of the synthesis algorithm and estimates of the number of broadband noise-like signals with a given bandwidth. Investigated based on the relations of the Central spike of the autocorrelation function side lobes of the width of the signal spectrum. A comparative analysis with some other types of wideband signals. The analysis of the distribution of the Euclidean metric between randomly selected pairs of wideband noise-like signal.
In the next part of the proposed conceptual organization model of a cryptographic channel of transmission of radio signals. Good value Central spike to the side lobes of the autocorrelation function allows you to identify the proposed broadband signals hidden in the noise of the radio that determines the possibility of using signals in the task hidden (steganographic) communications. A relatively small computational complexity of the synthesis algorithm by pseudo-random law, with a significant number of potential broadband signals allows to implement encryption of radio traffic. Encryption radiosonding can be realized by eliminating the transmission of repetitive signal symbols in a communication session.
In conclusion, the work concludes. In the proposed method of synthesis, performed software implementation and study of some cha-racteristics of the broadband noise-like signal synthesized according to the specified parameters: the duration (number of samples), frequency band. The proposed method of synthesis allows to effectively control the frequency band, synthesize the truly noise-like signals which can be effectively hidden in the noise of the radio, i.e. allow to implement steganographic transmission of the broadcast message. A significant number of such signals and sufficient speed of synthesis for implementation on modern computing facilities, allows for encryption of radio traffic using the proposed wideband signals. Thus, it is possible to realize steganographic and cryptographic protection of the communication channel on the basis of a common ideology: the use of a broadband noise signals hidden in the noise of the radio and transmission with low probability of repetition of the signal symbols. Proposed rules for the implementation of a communication channel with a high level of cryptographic security. A significant advantage of the proposed noise signals is high, compared to the autocorrelation of the signals synthesized in other ways, the attitude of the Central spike of the ACF to the lateral petals of the ACF, which contributes to the concealment of noise signals in the noise of radio if possible, effective control of the occupied frequency resource is time. A significant advantage of using complex-valued signals compared to real signals is as follows: in the calculation of the ACF in the result of the complex conjugation by the Central element has always a real value, and the side lobes fall into the imaginary and real part, thus increasing the ratio of Central splash to lateral petals; also complex-valued signals may be effectively used at the polarization separation signals. The work is performed on the basis of the Saint Petersburg National Research University of Information Technologies, Mechanics and Optics (ITMO University).
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