The method of discrete information transmission in a radio link with a pseudorandom operating frequency tuning

 

The invention relates to the field of radio communications and computing, and more particularly to methods and devices for data transmission in the computer network by radio with pseudorandom change the operating frequency. The technical result is increased stability of the connection with the active intrusion and ensure confidentiality of transmitted information. The invention consists in the division on the transmitting end of the input signal into blocks, the restructuring of the carrier frequency of the transmitter in accordance with the codes of pseudo random sequences generated by shift register with feedback, modulation of transmitter carrier corresponding package and subsequent radiation in space, the signal at the receiving end of the radio link simultaneously at all frequencies according to the codes of pseudo-random sequences, the selection of the frequency channel on which the transfer was made, converting the signal to an intermediate frequency, amplification, demodulation, decoding package and submission of the information signal on the target device. Differs from known methods in that all pseudo-random sequence is formed as a pseudo-random sequence is rmacie with 8 different bits of the shift register and replace the "0" character "256", alternately convert the blocks of the input signal of length 8 bits by using pseudo-random sequences, finite fields and linear or nonlinear cryptographic transformations, including the operations of addition, multiplication or exponentiation of symbols in a finite field Fpand replace the "0" character "256", modulate the carrier frequency of the transmitter package from the transformed blocks of the input signal, and the code to rebuild the carrier frequency is formed by addition, multiplication or exponentiation with respect to each of the symbols generated pseudo-random sequences in a finite field Fpwith the subsequent conversion of the obtained integers modulo n, where n is the number of frequency channels. 4 C. p. F.-ly, 2 ill., table 1.

The invention relates to the field of radio communications and computing, and more particularly to methods and devices for data transmission in the computer network by radio with pseudorandom change the operating frequency.

Known methods of discrete information transmission in a radio link with pseudorandom change the operating frequency (see, for example, [1] S. 19-35, the application for the invention 99123808/09, IPC7

The closest to the technical nature of the claimed method is a method described in the application 99123808/09 from 10.11.1999. Prototype method includes dividing an input signal at the transmitting end in units, restructuring of the carrier frequency of the transmitter in accordance with the code of one of the two or more pseudo-random sequences generated by shift register with feedback, modulation of transmitter carrier corresponding package and subsequent radiation in space, the signal at the receiving end of the radio link simultaneously at all frequencies according to the codes of pseudo-random sequences, the selection of the frequency channel on which the transfer was made, converting the signal to an intermediate frequency, amplification, demodulation, decoding package and submission of the information signal on the target device.

However, the prototype method has a drawback. Despite the fact that the carrier frequency of the transmitter is reconstructed in accordance with the pseudo-random code sequence, the communication system is unstable when aktivnih frequency noise receptor to suppress the information signal. This is because if the structure of the shift register having n bits and linear or nonlinear feedback known, upon receiving the n symbols of pseudo-random sequence by recording the emitted frequency of the transmitter for one second reveals the structure of the pseudo-random sequence, and the status register at the relevant point in time [3] S. 93. If the structure of the shift register with linear feedback is unknown, upon receiving the 2n symbols of pseudo-random sequence within seconds may be determined by the location of the taps, the number of adders included in the feedback circuit, and the status register at the relevant point in time [3] S. 94. If the shift register uses nonlinear feedback, linear complexity (4n) he creates nonlinear pseudorandom sequence will be slightly different from the linear complexity (2n) linear pseudo-random sequence, because what would the point of the shift register is not filmed least pseudo-random sequence we are dealing with the same pseudo-random sequence, which is cyclically shifted relative to pseudorandom posledovatelnostyu nonlinear pseudorandom sequence can be opened in a few seconds. Because the pseudorandom sequence are opened, they cannot be used for encoding information to ensure its confidentiality.

The invention aims to improve the noise immunity of radio communication with the active intrusion and ensure confidentiality of transmitted information.

This is achieved by the known method of discrete information transmission in a radio link with pseudorandom change the operating frequency, which consists in dividing the input signal at the transmitting end in units, restructuring of the carrier frequency of the transmitter in accordance with the code of one of the two or more pseudo-random sequences generated by shift register with feedback, modulation of transmitter carrier corresponding package and subsequent radiation in space, the signal at the receiving end of the radio link simultaneously at all frequencies according to the codes of pseudo-random sequences, the selection of the frequency channel on which the transfer was made transformation of the signal to an intermediate frequency, amplification, demodulation, decoding the package and applying the information signal on the target device, according to the invention all the dogpwith characteristic p=257 in the form of binary vectors of length 8 bits by removing information from 8 different bits of the shift register and replace the "0" symbol "256", in turn transform the blocks of the input signal of length 8 bits by using pseudo-random sequences, finite fields and linear or nonlinear cryptographic transformations, including the operations of addition, multiplication or exponentiation of symbols in a finite field Fp, modulate the carrier of the transmitter package from the transformed blocks of the input signal, and the code to rebuild the carrier frequency is formed by addition, multiplication or exponentiation with respect to each of the symbols generated pseudo-random sequences in a finite field Fpwith the subsequent conversion of the obtained integers modulo n, where n is the number of frequency channels.

In the aggregate characteristics of the proposed method under a binary vector refers to the signal as a sequence of zeros and a single bit corresponding to the representation of a number in binary.

Listed set of essential features protects the privacy of transmitted information is Yu 8 bits are pseudorandom sequence of symbols {0, 1, 2,..., 255} of a finite field F257have the same period N=2n-1, as a pseudo-random sequence of binary numbers, and provide statistical uniformity of the used symbols. When replacing the symbols of "0" characters "256" produces pseudo-random sequences of characters of the multiplicative group of a finite field F257{1, 2,..., 255}. This allows field F257a variety of options for character encoding of source textincluding the addition of characters modulo p, the multiplication symbol modulo p, the construction of characters in the degree modulo p and their various combinations in contrast to field F2in which to encode a single binary symbol in the source text is the addition modulo two is the only way to build a reversible function decode.

Since one of the shift register may appear several pseudo-random sequences of characters of a finite field {x,..., y}, each of which will be cyclically shifted relative to the other pseudorandom sequences can be implemented both linear and nonlinear cryptographic transformation with the use of the new symbolfinite field Fpx+y(mod p);x+y(mod p);xy(mod p),... As symbols of pseudo-random sequences x and y are elements of the multiplicative group of a finite field Fpyou can be computed inverse x-1xp-2(mod p); y-1yp-2(mod p),... and paired elements x*=R-x; y*=R-y,..., which allow you to implement a cryptographic transformation to decode text characters
(+y*x-1(mod p);


Choice as the characteristic of a finite field of numbers p=257 due to the fact that for playback of multimedia data of modern computing machines use 256 characters and the nearest Prime number to the number 256 is 257.

Since the pseudo-random sequence of characters of a finite field Fpthe AK is the maximum number, represented by 8 binary bits is 255, so remove the pseudo-random sequences are pseudo-random sequences of maximum length in a finite field Fp(M-sequences), and are nonlinear pseudorandom sequence. The total number of possible pseudo-random sequences of characters of a finite field will be determined by the number of possible combinations of the eight bits of the shift register, which can act information, and the number of permutations within the same combinations, each of which determines the order of reading of the information and to the shift register consisting of n=256 bits, the number of different pseudo-random sequences of characters of a finite field F257will be Q = 8!C82561019, while for the field F2from whatever point of the shift register did not remove the information, a pseudo-random sequence of binary numbers will only be cyclically shifted relative to the other pseudo-random sequences of binary numbers, taken from other bits of the shift register.

As cryptographic transformations used two or more pseudemoia source and appropriate symbols of the encoded text may identify symbols of pseudo-random sequences, so as to determine the number of equations will always be two times less than the number of unknowns. This provides resistance code to attacks based on known and selected source, as the opening state of the shift register in this case can only be achieved through a total enumeration of the entire set of possible States of the shift register. Because the U.S. standard data encryption DES involves the use of a shift register with 128bit encryption (key length 128 bits) [4], the cardinality of the set of possible States of the shift register will be 1038. If the opening state of the shift register will be implemented using a computer having a clock frequency of 10 GHz, the number of operations of this computer in the course of the year, will be 31019and time of opening is 1018years.

In accordance with the Russian standard GOST 28147-89 to the shift register, has 256 bits (256-bit key length) [5], the time of opening state of the shift register will be 1057years. This ensures the confidentiality of your information.

As the received pseudo-random sequence of characters of a finite field Fpnot vovania M-sequences of characters of a finite fieldpby skipping (non-use) of cycles of operation of the generator, which should appear playable character. This approach implements a nonlinear pseudorandom sequence due to non-uniform movement of the shift register ("compression generator"). In this case, the linear complexity of the received pseudo-random sequence will have a lower bound of1019for a shift register having n = 256 bits. Because the code to rebuild the carrier frequency determines the pseudo-random sequence that is generated by two or more compressive pseudo-random sequences, its linear complexity will have a lower bound equal to y=N/3, where N=2n-1 - the length of the non-linear pseudo-random sequences of characters of a finite field Fp. This eliminates the opening pseudo-random sequence, the control frequency of the transmitter, the transmission time information, and therefore, eliminates the possibility of creating a sighting of interference, which increases the stability of the connection with the active intrusion.

The possibility of technical realization of the inventive method is explained as follows.

The formation of pseudolocal is of the linear shift register, having n bits, the feedback of which is determined by referring to the selected primitive polynomial of degree n. Finding primitive polynomials of degree n is given in [3] on pages 74 and 75.

The formation of pseudo-random sequences of characters of a finite field F257in the form of binary vectors of length 8 bits can be done by removing information from eight different bits of the shift register numbers that can be defined by the value of the entered security key K. for Example, by defining the parent element
l0K (mod q), if l0<2, i0=2,
calculate the number of digit of the shift register according to the formula
l1=l0, lil0li-1(mod q)
In this case, due to the exponentiation of the parent number of l0we will move from one field item Fqto another. In this case, as shown in [4] S. 44, if l0- an element of order K, then all elements in l0, l02, l03,..., l0K-1will be different. The value of q is selected from the primes and to the shift register, has 256 bits q=257. For a shift register having 128 bits, q=127. In a pseudo-random pic is inih sequences of characters of a finite field Fpyou can also type "compression generator" by removing information from eight bits of the shift register and skip those stages of the shift register, for which at least one of the pseudo-random sequence is present the symbol "0".

Can be used three variants of the formation of pseudo-random sequences of characters of a finite field as binary vectors.

1. The elements of one of the selected and generated pseudo-random sequences of characters of a finite field in the form of binary vectors are used as generating elements of thenfor additional pseudo-random sequence z, the elements of which at each stage of the shift register are defined as child elements of the field Fp.

zzyn(mod p).

If the calculation process at some the first stage of the shift register will be that z=1, then in this case you will have a generating element of thenfield Fp. At the same time as a new generating element of ynaccepted element formed at this stage of the shift register selected pseudo-random sequence of characters of a finite field is any finite field z is used with a cryptographic transformation when converting the data stream in the encoded message, for example,
x+y+z(mod p) orx+z(mod p).
As an additional pseudo-random sequence of a finite field elements are formed by raising to the power generating element innwith the order, all elements of yn, yn2, yn3,..., ynkthere are various on the interval To the stages of the shift register. Because generating elementspcan be of different order in the finite field Fpchanges generating elements will be implemented by a pseudo-random law. This provides statistical uniformity of characters encoded text on the interval R-1 cycles of operation of the shift register, which excludes the application of statistical methods in cryptanalysis to determine the state of the shift register.

2. Change the number of bits of the shift register from which information is collected for one of the pseudo-random sequences of characters of a finite field in accordance with the change of the generating element for more �c="https://img.russianpatents.com/chr/8801.gif">ynli-1(mod q)
3. Change the order of reading data for one of the generated pseudo-random sequences of characters of a finite field in accordance with a change in the destructive element additional pseudo-random sequence of characters, for example, using ratios
li=lk,
kiyn(mod 8),
The formation of pseudo-random sequences of characters of a finite field under item 1, 2 and 3 increases the stability of the code to attacks based on known and selected source when forming the protection key of small length.

Code generation for adjustment of the carrier frequency of the transmitter can be obtained, for example, by adding or multiplying the symbols of all the generated pseudo-random sequences with subsequent conversion of the obtained integers modulo n, where n is the number of frequency channels.

The transformation blocks of the input signalin the encoded message can be done by calculation in a finite field Fpvalues ofin accordance with the selected �https://img.russianpatents.com/chr/946.gif">(mod p). and converting the received number ofin a binary vector for modulation of the carrier frequency of the transmitter.

The proposed method can be implemented using the device represented by the flowchart in Fig.1, where
unit 1 - source,
unit 2 - the first shift register,
unit 3 - the first shaper of pseudo random sequences
unit 4 - the encoder,
unit 5 - the first frequency synthesizer
unit 6 - transmitter
unit 7 - the second frequency synthesizer
unit 8 - receiver
unit 9 - second shift register,
unit 10 - second shaper pseudorandom sequence,
block 11 - decoding device,
unit 12 - the target device.

In Fig.2 shows the structural diagram of the shift register, where 13-18 - blocks of bits 1-6 of the shift register; 19 - unit modulo two.

A device that implements the method works as follows.

For ease of description of the operation of the device will use small numbers. We assume that the shift register is 6 bits (the key length is 6 bits), and the entire alphabet of the source text contains 16 characters, then to send a single character can be used a binary vector of length 4 bits, and ka is gistra shear choose a primitive polynomial of the sixth degree, for example,
6+5+1.
For the selected primitive polynomial structural diagram of the shift register with feedback will be of the form shown in Fig.2. Generated by the random number generator security key length of 6 bits
<6,5,4,3,2,1>
where1= 0,2= 0,3= 0,4= 1,5= 1,6= 1 is supplied to the shift register and is used for initial filling of bits of the shift register. Binary characters 5 and 6 of the discharge of the shift register receives at each stage to the input of the adder 19 modulo two, and from the output of the modulo two characters=56proceed to input the first digit of the shift register (block 13). When this status bits for each measure in the process of registerfly will be shot with a sixth category6the shift register (block 18), the binary pseudo-random sequence, the maximum period will be
{1110000010000110001010011110100011100100101101110110011010101111}
Note that the period of this sequence is any non-zero set of six digits 0 and 1 occurs only once.

If the binary number will be removed from 1, 2, 3 and 4 digits of the shift register (blocks 13, 14, 15, 16) and at each stage of the shift register and with a set of <1,2,3,4> will associate a binary vector (number) x =1+22+223+234the sequence of binary numbers in the process of the register can be viewed as a sequence s of numbers (characters) x{0, 1, 2,..., 15} as
x= {8, 0, 0, 1, 2, 4, 8, 0, 1, 3, 6, 12, 8, 1, 2, 5, 10, 4, 9, 3, 7, 15, 14, 13, 10, 4, 8, 1, 3, 7, 14, 12, 9, 2, 4, 9, 2, 5, 11, 6, 13, 11, 7, 14, 13, 11, 6, 12, 9, 3, 6, 13, 10, 5, 10, 5, 11, 7, 15, 15, 15, 14, 12,...}
If the binary number will be removed simultaneously with 1, 2, 5, 6 discharge of the shift register (blocks 13, 14, 17, 18) and at each stage of the shift register with a set of <6the complete number in the form y =6+25+222+231the sequence of binary numbers in the process of the shift register can be viewed as a sequence of characters in{0, 1, 2,..., 15} as
the= { 3, 3, 1, 8, 4, 0, 0, 2, 9, 12, 4, 0, 2, 11, 5, 8, 4, 2, 9, 14, 13, 12, 6, 11, 7, 3, 1, 10, 13, 12, 4, 2, 11, 7, 1, 8, 6, 9, 12, 6, 9, 14, 15, 5, 10, 15, 7, 1, 10, 15, 5, 8, 6, 11, 5, 10, 13, 14, 13, 14, 15, 7, 3,...}
Analysis of the generated sequences x and y shows that the interval corresponding to a period equal to 63 cycles of operation of the shift register, each of the symbols {1, 2,..., 15} occurs exactly four times. The symbol for zero, both sequences occurs exactly three times, and the sequence x and y can not be obtained from one another in a cyclical shift. In the sequences x and y there are no hidden periodicity and provides statistical uniformity of the characters used. As one of the symbols of pseudo-random sequences of a finite field F17does not play, the symbol "0" in both sequences is replaced by the symbol "16".

In addition to the pseudo-random sequences x, y of a finite field Fptable We generating elements symbols of pseudo-random sequences, as well as the formation of a pseudo-random sequence of characters of a finite fieldby changing the order of reading information for a pseudo-random sequence of characters of a finite field x in accordance with the change of the generating element additional pseudo-random sequence z.

Formulated pseudo-random sequence of characters of a finite field x and y as binary vectors served in the encoder 11, which converts the incoming data stream in the encoded message by using pseudo-random sequences x and y of a finite field F17in accordance with the selected cryptographic transform in a finite field F17. The generated pseudo-random sequence of symbols x and y generate a pseudo-random sequenceby adding the symbols in the finite field Fpwith the subsequent conversion of the obtained numbers modulo 7, where 7 is the number of frequency channels. The character sequencesconverted into binary vectors and serves as a code in the frequency synthesizer for setting the carrier frequency of the transmitter.

�https://img.russianpatents.com/chr/920.gif">in block 10 and use the symbols x and y in a decoding device 11 to recover the transmitted message in accordance with the selected cryptographic transformation, and the symbolsused for frequency setting unit 8 for converting the received signal to an intermediate frequency. Below is the use of pseudo-random sequences x and y in the conversion procedures, frequency (pseudo-random sequence of characters)
= {4, 2, 0, 2, 6, 3, 0, 1, 3, 1, 3, 4, 3, 5, 0, 6, 0, 6, 1, 0, 3, 3, 3, 0, 0, 0, 2, 4, 2, 2, 1, 0, 3, 2, 5, 0, 1, 1, 6, 5, 5, 1, 5, 2, 6, 2, 6, 6, 2, 1, 4, 4, 2, 2, 1, 1, 0, 4, 4, 5, 6, 4, 1,},
and in the procedures for encoding and decoding information (see the end of the description).

Implementation of the proposed method is straightforward, since all the blocks and units included in the device that implements the method, well-known and widely described in the technical literature.

Sources of information
1. Borisov Century. And. Zinchuk, C. M., Lirnarev A. E., N. Mukhin.P., Shestopalov Century. And. the Immunity of radio communication systems with expansion of the range of signals, the method of pseudo-random adjustment of the operating frequency. -M.: Radio and communication, 2000.

2. A method of transferring a discrete INF invention 99123808/09 from 10.11.1999, IPC7N 04 1/713.

3. Voronkov, B. N., Tupot Century. And. Handbook on the development of information security in computer networks. - Voronezh, Voronezh State University, 2000.

4. Muftic C. protection Mechanisms in computer networks. - M., 1993.

5. Russian standard GOST 28147-89. The information processing system. The cryptographic protection. The cryptographic transformation.


Claims

1. The method of discrete information transmission in a radio link with pseudorandom change the operating frequency, comprising at the transmitting end of dividing the input signal into blocks, the restructuring of the carrier frequency of the transmitter in accordance with the codes of pseudo random sequences generated by shift register with feedback, modulation of transmitter carrier corresponding package and subsequent radiation in space, the signal at the receiving end of the radio link simultaneously at all frequencies according to the codes of pseudo-random sequences, the selection of the frequency channel on which the transfer was made, converting the signal to an intermediate frequency, amplification, demodulation, the decoding of the packet and the flow of the information signal on okonek sequence of characters of a finite fieldpwith characteristic p= 257 in the form of binary vectors of length 8 bits by removing information from 8 different bits of the shift register and replace the "0" character "256", in turn transform the blocks of the input signal of length 8 bits by using pseudo-random sequences, finite fields and linear or nonlinear cryptographic transformations, including the operations of addition, multiplication or exponentiation of symbols in a finite field Fp and replace the "0" character "256", modulate the carrier of the transmitter package from the transformed blocks of the input signal, and the code to rebuild the carrier frequency is formed by addition, multiplication or exponentiation with respect to each of the symbols generated pseudo-random sequences in a finite field Fp with subsequent conversion of the obtained integers modulo n, where n is the number of frequency channels.

2. The method according to p. 1, characterized in that in the process of the shift register skip (do not use) the bars of his work, in which at least one of the generated pseudo-random sequences of characters of a finite field Fp is the character "0".

3. The method according to p. 1 or 2, characterized in that one of the characters forbade additional pseudo-random sequence, the characters which at each stage of the shift register is defined as generated by the elements of the finite field Fp.

4. The method according to any of paragraphs. 1-3, characterized in that the change of the number of bits of the shift register from which information is collected for one of the generated pseudo-random sequences of characters of a finite field in accordance with the change of the generating element additional pseudo-random sequence.

5. The method according to any of paragraphs. 1-3, characterized in that changing the order of reading data for one of the generated pseudo-random sequences of characters of a finite field in accordance with the change of the generating element additional pseudo-random sequence.

 

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