RU2577187C1 - Method for encryption/decryption of analogue signals, transmitted over communication channels - Google Patents

Abstract

FIELD: information technology.

SUBSTANCE: invention relates to information security. Method of encryption/decryption of analogue signals, consisting of flow areas with n-multiple digital data sampling cycles as per Kotelnikov consists in the fact that when encrypting from flow of incoming data dimension n-cycles quantisation encryption frame is formed from said n-quantisation cycles by means of calculation operations a sufficient quantity of coded quantisation cycles, having characterised by from other cycles quantisation encryption frames then, encryption frames are subject to relative moving the order of their repetition in accordance the encryption key representing an array of set of control codewords this algorithm cryptographic coding and in step-by-step mode to-analogue conversion in the form of a continuous flow inseparably following encryption frames is supplied to the communication channel, as-like output analogue signal. At the receiving side of the communication channel q: decryption process data flow starts from the mode of step-by-step operations cycles quantisation for searching for and extracting from a stream of incoming data encryption frame using the corresponding encryption key distribution coded quantisation cycles with distinctive features. In these step-by-step search operations and determining frame coding process is used for calculating the correlation function of coincidence of sets of code words keys transmitting and receiving sides, the array of set of code words decryption key is a cryptographic algorithm decoding received encrypted data. After determination of flow of incoming data encryption and frame match set of code words keys, is carried out by forming to-analogue conversion of recovered decoded output of analogue signals of voice communication. To protect codes encryption key from possible reading and "breaking" at the inlet of the transmitting channel provides for a special program digital a filtration flow data, possibility to use a large number of versions of encryption keys.

EFFECT: technical result is high level of cryptographic protection taking processes from their interception due to usage of cryptographic algorithms of coding.

2 cl

Description

The invention relates to the field of information security, in particular, to a method for protecting analog signals transmitted over communication channels from unauthorized access to them by encrypting / decrypting them, for example, voice communication signals over telephones. The proposed method will allow for tactical security of the requirements of devices, for example, military applications, communications of various state power structures, as well as the requirements of any commercial application. Also, the method can find application in the activities of various commercial organizations, manufacturing enterprises, financiers, entrepreneurs, business people, politicians and others, which in a market economy will protect and preserve their commercial, production secrets, know-how, etc. from their possible interception by their competitors.

Known methods and devices for protecting analog speech signals over wire channels and radio communications from listening, based on the use of masking into the output speech signal by generating a noise-like output speech signal using special additional sources for generating noise-free signals.

The closest analogue of the invention is the patent [1], where the masking of the transmitted signal is carried out by noise of the communication line in the speech frequency range, by linear addition of the speech information signal with a noise signal exceeding it in level. A patent is also known [2], in which a separate noise generator is used to mask the transmitted information, which effectively protects the negotiation process. Another patent is also known [3], where created artificial noise is used, masking and protecting the channel of speech information leakage.

The disadvantage of the above patents and other similar ones is the hardware complication of such devices - scramblers, due to the use of separate special noise sources that form a masking noise-like signal on the communication line to protect against listening. In the general case, hardware complication is also associated with the presence of many associated elements for the formation of the necessary noise-like signal. Another disadvantage of the cited patents is the low level of protection of negotiation processes due to the lack of cryptographic algorithms for encoding speech signals. In addition, the lack of cryptography limits the ability to use many options for encryption keys, which in turn also reduces the level of protection of negotiation processes.

The aim of the invention is to increase the level of cryptographic strength of encrypted output noise-like signals without the use of special sources of generation, masking noise signals.

This goal is achieved by the fact that in the proposed method of encryption / decryption of analog signals transmitted over communication channels, consisting of a stream of regions with an n-set of digitized data of quantization cycles according to Kotelnikov, is that when encrypting from the data stream region of incoming data of dimension n- quantization cycles an encryption frame is formed. Then, from these n-quantization cycles, a sufficient number of coded quantization cycles having distinctive features from other quantization cycles of encryption frames are generated by means of computational operations. Further, the data converted in this way, the encryption frames, are subjected to a relative rearrangement of their sequence in accordance with the encryption key, which is an array of a set of control code words for this cryptographic encoding algorithm and in a step-by-step mode of digital-to-analog conversion, in the form of a continuous stream of inextricably following encryption frames is transmitted to the channel communication as a noise-like analog output signal. On the receiving side of the communication channel, the decryption process of the incoming data stream begins with a step-by-step operation of quantization cycles to search for and extract an encryption frame from the incoming data stream, using the encryption corresponding to the key and the distribution of the encoded quantization cycles having their own distinctive features. In these step-by-step operations for searching and determining the encryption frame, the process of calculating the correlation function for matching the sets of codewords of the keys of the transmitting and receiving sides is used, while the array of the set of codewords of the decryption key is a cryptographic decoding algorithm for the incoming encrypted data. After determining the encryption frame from the incoming data stream and matching the set of code words for the keys, the restored decrypted output analog voice signals are generated by digital-to-analog conversion. To protect the encryption key codes from possible reading and “hacking”, a special program of digital barrage filtering of the incoming data stream is provided at the input of the transmitting channel.

A comparative analysis of the proposed method for encrypting / decrypting analog signals with respect to known methods shows that in the proposed method due to the use of cryptographic coding algorithms, a high level of protection of negotiation processes from interception is achieved, as well as the possibility of using a large number of encryption key options. It should also be noted the absence of external synchronizing signals in the data stream in an explicit form. The synchronization elements hidden in the stream of incoming data, so necessary for restoring the original signal during their decoding, are extracted from the incoming stream by means of corresponding computational operations. The area of relative permutation of the data sequence within the dimension of the received encryption frame mainly determines the level of cryptographic strength of this encryption method. To quantify the level of cryptographic strength, we will carry out the following calculations based on counting the number of bits covered by the encryption frame. This total number of bits involved in the encoding is determined by simply multiplying the number of quantization cycles in the encryption frame by the number of bits of the analog-to-digital conversion. In the practical implementation of devices based on the proposed encryption method, it is possible to set various levels of protection for negotiation processes by user groups. So, for example, the first protection group for voice communication users will be provided by a program with a 512-1024-bit encoding algorithm. The second group of protection from 1024-2048-bit coding algorithm. The third group of protection against 2000-4000-bit coding algorithm. And the fourth group of protection against 4000-8000-bit coding algorithm. So, for example, with the dimension of an encryption frame consisting of 64 quantization cycles with an 8-bit ADC, the level of protection of the negotiation process will be provided by a 512-bit analog encoding algorithm. In this case, in each group of protection levels, a large number of encryption key options can be formed, which differ in different options for the relative permutation of the data in the encryption frame. The proposed method also allows you to encrypt digital data and transmit them at a speed determined by the frequency band of the communication channel.

The analysis of the prior art, including a search by patent and scientific and technical sources of information and identification of sources containing information about analogues of the claimed invention, allows us to establish that the applicant has not found technical solutions characterized by features identical to all the essential features of the claimed invention. The definition from the list of identified analogues of the prototype made it possible to identify a set of essential (with respect to the technical result perceived by the applicant) distinctive features in the claimed object set forth in the claims. Therefore, the claimed invention meets the requirement of "novelty" under applicable law. Information about the fame of the distinguishing features of the known technical solutions with the achievement of the same as that of the claimed device, there is no positive effect. Based on this, it was concluded that the proposed technical solution meets the criterion of "inventive step".

Information sources

1. Patent RU 2249307 C1, Н04М 1/68, Н04К 1/02, Н04К 3/00.

2. Patent RU 2195785 C1, Н04М 1/68, Н04К 1/02, Н04К 3/00.

3. Patent RU 2310282 C2, H04K 1/02.

Claims (2)

1. The method of encryption of analog signals transmitted over communication channels, consisting of a stream of regions with an n-set of digitized data of quantization cycles according to Kotelnikov, characterized in that for their encryption it is necessary to sequentially perform the following computational and logical operations:
- perform the corresponding computational operations of barrage digital filtering of incoming data to identify specially organized scanning code parcels of the data stream with the aim of “breaking” the code words of the encryption key, in case of detection of these data, the digital filtering computational operations “loop”, and in the absence of such, the transition the next step of the encryption algorithm;
- an encryption frame is formed from the incoming data stream with the dimension of n-quantization cycles;
- the formation by means of computational operations of a sufficient number of coded quantization cycles having distinctive features from the remaining quantization cycles of the encryption frame, then the data of the encryption frame converted in this way are subject to relative rearrangement of their sequence in accordance with the encryption key, which is an array of a set of control code words for this cryptographic algorithm encoding, which is stored in a memory area protected from external reading computing device;
- Further, in a step-by-step mode of digital-to-analog conversion, it is issued to the communication channel as a noise-like output analog signal. 2. The method of decryption of analog signals transmitted and received via communication channels, consisting of a stream of areas with n-set of digitized data of quantization cycles according to Kotelnikov, received encrypted in accordance with paragraph 1 of this method, characterized in that for their decryption all the same computational and logical operations of the encryption process in the reverse order of their execution and opposite action:
- in step-by-step mode of quantization cycles of incoming data for searching and extracting an encryption frame from the stream of incoming data, using the distribution of coded quantization cycles corresponding to the encryption key, which have their own distinctive features, in these step-by-step operations for searching and determining the encryption frame, the correlation function calculation function is used sets of code words for the keys of the transmitting and receiving sides, while an array of a set of code words for the decryption key for implementing cryptographic Its decoding algorithm for the incoming data stream is also stored in the read-protected memory region of this computing device;
- after determining the encryption frame from the incoming data stream and matching the set of key code words, the keys are generated by digital-to-analog conversion of the restored decrypted output analog voice signals.