RU2434266C2 - Method of protecting information from unauthorised access - Google Patents

Abstract

FIELD: information technology.

SUBSTANCE: original message is distorted at the transmitting side using a pin-code P. The i-th word is mapped, where

and I is the number of words in the original message, into the corresponding code D_i based on a table of possible values, code D_i is replaced with code D_Ki by shifting the code D_i on a ring by a number of lines given in the pin-code P in the forward direction, the distorted message is transmitted to a communication channel, and at the receiving side, code D_i is restored by shifting code D_Ki on a ring by a number of lines given in the pin-code P in the reverse direction, code D_i is mapped into the corresponding word based on a table of possible values.

EFFECT: more secure information transmission.

1 dwg, 2 tbl

Description

The invention relates to non-cryptographic methods for protecting information from unauthorized access and can be used in secure data transmission systems of text data.

Closest to the proposed combination of features is a method of protecting information from unauthorized access (RF patent No. 2130641, CL G06F 13/00, G09C 1/00, H04L 9/00, 1999). The method consists in the fact that, on the transmitting side, the original message is distorted using a pin code by breaking the original message into blocks of variable length, performing, in each block, a shift of the ASCII code of each character along the ring number specified in the pin code in the number of digits specified on direction to the transmitting side, and on the receiving side, the distorted message is restored using the same pin code, while the reverse shifts of each character in each block are performed, the conversion result is presented user. The known method has minimal information redundancy and inertia, the ability to perform both distortion and information recovery with maximum speed, no information loss with minimal hardware and energy costs and maximum reliability.

Common with the claimed method are the signs: distortion of the original message by shifting the ring of possible values on the transmitting side, transferring it to the communication channel, restoring the distorted message by reverse biasing the ring along the ring of possible values on the receiving side and presenting the original message to the user.

Significant disadvantages of this method is that it is not protected from an attack on the spelling dictionary, which consists in selecting a pin code and checking the correctness of the message recovered using the selected pin code for errors, while if the recovered message contains a lot of spelling errors, then it concludes that the selected pin code is incorrect. Error checking can be done by any automated spell checker. In modern conditions of development of computer technology, automation of the analysis of the correctness of the recovered messages will significantly reduce the time to restore the message.

The problem to which this invention is directed is to increase the security of information transfer by ensuring the impossibility or significant difficulty of recovering a distorted message without knowing the pin code by carrying out an attack on the spelling dictionary.

а I - количество слов в исходном сообщении, в соответствующий код D_i по таблице возможных значений, заменяют код D_i на код

путем сдвига кода D_i по кольцу на заданное в пин-коде Р количество строк в прямом направлении, передают искаженное сообщение в канал связи, а на принимающей стороне восстанавливают код D_i путем сдвига кода

по кольцу на заданное в пин-коде Р количество строк в обратном направлении, осуществляют отображение кода D_i в соответствующее слово по таблице возможных значений.The solution to this problem is achieved by the fact that in the known method of protecting information from unauthorized access, which consists in distortion on the transmitting side of the original message using a PIN code P, according to the invention, the i-th word is displayed, where

and I is the number of words in the original message, in the corresponding code D _i according to the table of possible values, replace the code D _i with the code

by shifting the code D _i along the ring by the number of lines in the forward direction specified in the PIN code P, a distorted message is transmitted to the communication channel, and on the receiving side, the code D _{i is} restored by shifting the code

on the ring for the number of lines in the reverse direction specified in the PIN code P, the code D _i is mapped to the corresponding word in the table of possible values.

In the aggregate of the features of the claimed method, the following terminology and notation are used:

- a table of possible meanings - a table of correspondence of words in the Russian language in simple form (and, possibly, of any (any) foreign language (s)), arranged in alphabetical order by which the code is assigned W, equal to the logarithm of the base 2 of the serial number of the word, and the calculation of the logarithm is performed in the Galois fields, with the number of elements not less than the number of rows N in the table, and for which the part of speech that they are;

- a simple form of the word - for nouns - the nominative case of the singular, for the numerals - the nominative case, for adjectives - the nominative case of the singular masculine positive degree of comparison; for verbs - infinitive; for adverbs - a positive degree of comparison; for morphologically unchanged words (prepositions, conjunctions, particles, pronouns, nouns, interjections) - the usual (dictionary) form;

- mapping the word into code D _i according to the table of possible values - sequentially replacing the word of the source text with its corresponding simple form with storing morphological inconsistencies (case, number, declension, etc.) between the word of the source text and its simple form, replacing the simple form words to the corresponding code W according to the table of possible values and replacing the memorized morphological inconsistencies between the word of the source text and its simple form with the morphological code M, equal for the noun

M = S _p + S _c · 6 + k · 12, k∈ Z ₊ , k <18,

for the name of the adjective

M = S _p + S _c · 6 + S _r · 12 + S _s · 36 + k · 72, k∈Z ₊ , k <3;

for a numeral name

M = S _p + k · 6, k∈ Z ₊ , k <36;

for adverb

M = S _s + k · 2, k∈Z ₊ , k <108;

for the verb

M = S _c + S _r · 2 + S _f · 6 + S _t · 18 + S _n · 54 + k · 108, k∈Z ₊ , k <2;

for the rest of the speech

M = k, k∈Z ₊ , k <216,

the morphological parameters S of the word are selected in accordance with table 1, and the parameter k is chosen arbitrarily from a given range, obtaining a display code D by

D _i = M · N + W;

- mapping code D _i ; per word on the table of possible values - a sequential decomposition of the code D _i into the morphological code M by dividing the whole code D _i by the number of lines N in the table of possible values and the code W of a simple form of the word by taking the remainder of dividing the code D _i by the number of lines N, replacing the table of possible values of the code W with the corresponding simple word form, decoding the morphological parameters S from the morphological code M for the part of speech indicated in the line with the obtained simple word form of the table of possible values, according to the formulas

for a noun

S _p = M mod 6;

S _c = (M mod l2) div 6;

for the name of the adjective

S _p = M mod 6;

S _c = (M mod 12) div 6;

S _r = (M mod 36) div l2;

S _s = (M mod 72) div 36;

for a numeral name

S _p = M mod 6;

for adverb

S _s = M mod 2;

for the verb

S _c = M mod 2;

S _r = (M mod 6) div 2;

S _f = (M mod l8) div 6;

S _t = (M mod 54) div 18;

S _n = (M mod l08) div 54,

and morphological changes in the obtained simple word form in accordance with the decoded morphological parameters S;

- shift the code D _{i of the} word in the ring by m lines in the forward direction - replace the value of the code of the simple form of the word W in the Kth row in the table of possible values with the number W * equal to the logarithm of base 2 of number B equal to

which is equivalent to replacing the value of the simple form code of the word W in the Kth row in the table of possible values with the value of the code of the simple form of the word W * in the (m + K) th row if m <K + N, or - on the value of the code of the simple form of the word W *, standing in the (m + KN) -th line, if m≥K + N;

- shifting the code D _{i of the} word in the ring by m lines in the opposite direction - replacing the value of the code of the simple form of the word W in the Kth row in the table of possible values by the number W * equal to the logarithm of base 2 of the number B equal to

which is equivalent to replacing the code value of the simple form of the word W in the Kth row in the table of possible values with the value of the code of the simple form of the word W * in the (m-K) row if m≥K, or - by the value code of the simple form of the word W * in the (m-K + N) -th line if m <K;

- Z ₊ is the set of non-negative integers.

The listed set of essential features in this order excludes the possibility of determining a secret PIN code P, since when recovering an intercepted message transmitted over a communication channel, a lot of texts will be received, the words in which are related grammatically and, possibly, in meaning, with an automated analysis of the received texts impossible, i.e. analysis can only be carried out by expert means, and the expert should have qualifications similar to those of the author of the message, since specialized texts can often be perceived as a set of words without meaning.

It is a new property of a set of features that leads to a significant difficulty in unauthorized access to information transmitted via a communication line by eliminating the possibility of using automation in the analysis of distorted encoded messages allows us to conclude that the proposed technical solution meets the criterion of "inventive step".

The proposed method of protecting information from unauthorized access was tested in laboratory conditions. The method can be implemented programmatically using a computer or a computing device, the structure of which is shown in the drawing, where it is indicated:

1 - encoding device;

2 - distorting device;

3 - transmitter;

4 - communication line;

5 - receiver;

6 - recovery device;

7 - decoding device.

For simplicity of description of the operation of the device, we will use a dictionary with a small number of lines and the random parameter k will be equal to 1.

The protected information is sent to the encoding device 1, in which the source text is divided into words and their coding by replacing each word with its code display. Next, the encoded information enters the distorting device 2, where it occurs. Then, the transmitter 3 sends a distorted message to the communication line 4. At the other end of the communication line, the distorted message through the receiver 5 enters the recovery device 6, where each code is shifted backward along the ring. Next, the recovered information enters the decoding device 7, where the decoding of the words of the message by their codes.

Original message

EUSTAS ALEXU ALPHA OPERATION CANCELED

served on the encoding device 1, in which the text is divided into words, where they are encoded using table 2. The encoded message

100 119 98 96 979

enters the device 2, where they perform the distortion procedure using the PIN code P = 1

103 112 99 97 982.

The distorted message through the transmitter 3, the communication line 4 and the receiver 5 enters the recovery device 6, after which the restored message

100 119 98 96 979

arrives at device 7, from where the decoded message

EUSTAS ALEXU ALPHA OPERATION CANCELED

transmitted to the recipient.

If the message transmitted over the communication line is intercepted, then without knowing the PIN code P after recovery, the following texts can be received

1) ALEX ALPHE CANCELED IT PASSED

2) SHE GREEN EUSTAS OPERATION ALEXU

...

k) WAS YUSTAS GREEN ALEX OF OPERATION

etc.

table 2 No. p / p Word Part of speech The code one ALEX noun 7 2 ALPHA noun 0 3 SHE pronoun one four GREEN adjective 5 5 OPERATION noun 2 6 CANCEL verb 3 7 GO verb 6 8 EUSTACE noun four

Since, after decoding distorted messages without knowing the PIN code P, the possibility of using automation in the analysis of recovered distorted messages is excluded, unauthorized access to information transmitted via the communication line is significantly complicated.

To ensure control of random distortions of the transmitted information in the channel with interference, it is possible to use the method of checksumming. At the same time, in order to maintain the level of security against unauthorized access to information, the checksum before transmission should be encrypted using a cryptographic algorithm, for example [2]. Moreover, the speed of the proposed method does not significantly decrease.

The implementation of the proposed method does not cause difficulties, since all the blocks can easily be performed programmatically in the form of a network gateway for subsequent use in standard communication line equipment.

Information sources

1. The method and device for protecting information from unauthorized access. Patent for invention No. 2130641 dated 05/20/1999.

2. GOST 28147-89. Information processing systems. Cryptographic protection. Cryptographic conversion algorithm.

Claims (1)

A method of protecting information from unauthorized access, which consists in distortion on the transmitting side of the original message using a PIN code P, characterized in that the i-th word is displayed, where

and I is the number of words in the original message, in the corresponding code D _i according to the table of possible values, replace the code D _i with the code D _Ki by shifting the code D _i in the ring by the number of lines in the forward direction specified in the PIN code P, transmit the distorted message in the communication channel, and on the receiving side, the code D _{i is} restored by shifting the code D _Ki along the ring by the number of lines specified in the PIN code P, the code D _i is mapped to the corresponding word according to the table of possible values.

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