RU2552145C2 - Secure information transmission method - Google Patents

Abstract

FIELD: radio engineering, communication.

SUBSTANCE: if the bits of a digital image signal byte and message signal byte coincide, then the logical "1" value is assigned. Otherwise, the logical "0" is assigned. Then, a {F} array is formed to record the logical values. The latter are stored in the {F} array after comparison of the digital image signal and message signal bytes. Afterwards, the logical values are read from the {F} array. Then, a message marker packet is formed with recording the logical values from the {F} array to the information field of the packet. The marker packet and digital image packet are transmitted using different communication channels.

EFFECT: higher security of confidential information transmission.

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Description

The invention relates to telecommunications and can be used to organize covert transmission of confidential information through open communication channels.

There is a method for embedding additional information in digital images, in which to counteract some analysis methods when recording information, only a part of the least significant bits in bytes of the color representation of the original image is used, the remaining bits are used for subsequent correction of the most important statistical parameters (See Provos N. Defending Against Statistical Steganalysis, Proceeding of the 10 USENIX Security Symposium, 2001, p. 323-335).

The disadvantage of this method is that the corrective changes lead to additional distortion of the digital image and reduce the bandwidth of the stegano channel using part of the free space for the corrective information. In addition, corrective corrections aimed at counteracting any of the methods of statistical analysis by correcting one of the parameters can lead to an even greater distortion of other parameters and, as a result, to more likely detection of a hidden channel by other analysis methods. In particular, the distortions introduced by the introduction of additional information and corrective changes when using this method can be noticeable when conducting a visual analysis of the bit layers of the resulting image.

There is also a method of introducing additional information into digital images according to the patent of the Russian Federation No. 2285844, publ. 11/27/2006, bull. No. 33), which consists in the fact that the original digital image is decomposed into bit layers, one of the received bit layers is selected for recording additional information, which is presented in the form of a bit sequence, additional information is recorded using a code, and in this bit sequence located at the boundaries of all transitions of the same sequences of zeros and ones, replace, in accordance with the bits of the additional information recorded, the remaining bits of the underlying bits output layers, if necessary, are used to correct the original image or to record other additional information.

The disadvantage of this method is the need for correction of statistical characteristics, which leads to an increase in image processing time, as well as to a decrease in the amount of embedded information. At the same time, an increase in the volume of embedded information is achieved through the use of high-order bit layers, which leads to an even greater change in the original image.

The closest in technical essence to the proposed method is a method of embedding a message in a digital image according to the patent of the Russian Federation No. 2407216, publ. December 20, 2010, bull. No. 35, which consists in replacing the least significant bit in bytes of the original digital image, while the least significant bit in bytes of the original digital image is assigned the flag value “one” when the bit part of the byte of the digital image signal coincides with the message signal bits or the flag value “zero” at mismatch, while adjusting the statistics of the distribution of the least significant bits is carried out for the rest of them, not used as flag values.

The disadvantage of this method is the low secrecy of the transfer of confidential information over open communication channels due to distortion of the statistical parameters of the digital image when embedding a message.

The technical result of the claimed technical solution is to increase the secrecy of the transmission of confidential information due to the lack of direct embedding of the message in a digital image and the transmission of a digital image and a marker packet of the message through different communication channels.

In the claimed invention, the technical result is achieved by the fact that in the known method of embedding a message in a digital image, a flag value of “one” is assigned when a part of the bits of the byte of the signal of the digital image coincides with the bits of the message signal or the flag value is “zero” when they do not match, additionally form an array {F} to remember flag values. The obtained flag values are written to the array {F} after comparing a part of the byte bits of the digital image signal and the bits of the message signal. A marker message packet is formed after filling the array {F} with flag values, while reading flag values from the array {F} and writing them to the packet information field. A marker packet and a digital image packet are transmitted over different communication channels.

A new set of essential features allows you to achieve the specified technical result due to the lack of direct embedding of the message in a digital image and the transmission of a digital image and a marker message packet over different communication channels.

The analysis of the prior art made it possible to establish that analogues that are characterized by a set of features identical to all the features of the claimed technical solution are absent, which indicates the compliance of the claimed method with the condition of patentability “novelty”.

Search results for known solutions in this and related fields of technology in order to identify features that match the distinctive features of the claimed object from the prototype showed that they do not follow explicitly from the prior art. The prior art also did not reveal the fame of the distinctive essential features that determine the same technical result that is achieved in the claimed method. Therefore, the claimed invention meets the condition of patentability "inventive step".

The claimed method is illustrated by drawings, which show:

figure 1 is a block diagram of an algorithm that implements the claimed method of covert transmission of information;

figure 2 is a drawing explaining the process of generating a bit sequence of a marker message {F};

figure 3 - block diagram of an algorithm that implements a method of extracting messages from a digital image.

The implementation of the claimed method is explained as follows. Arrays are formed for storing the bit sequence of the digital image {C _i }, where i = 1, 2 ... K, the bit sequence of the message {T _j }, where j = 1, 2 ... N, the bit sequence of the marker message {F _j }, where i = 1, 2 ... K (Fig. 1, block 1). Next, the arrays {C} and {T} are filled with bit sequences (Fig. 1, blocks 2, 3). Install the counters in the initial state i = 1 and j = 1 (Fig. 1, block 4). Consistently read from the corresponding arrays the values of C _i and T _j and compare them (figure 1, blocks 5, 6). If the bit values match, then the flag value F _{i is} set to “one” and the counters i and j are increased by one (Fig. 1, blocks 7, 9, 10).

If the bit values do not match, then the flag value F _{i is} set to “zero” and only the value of counter i is increased by one (Fig. 1, blocks 8, 10). After the entire bit sequence of the message is reflected in the bit sequence of the digital image (Fig. 1, block 11), a marker message packet containing the data of the array {F} (Fig. 1, block 12) is formed, for which purpose the packet information field network layer sequentially write data from the array {F}. Next, an informational message packet containing a digital image is formed (Fig. 1, block 13), for which data from the array {C} are sequentially recorded in the information field of the network layer packet. Then carry out the transfer of packets on different communication channels (figure 1, block 14).

Consider an example of the formation of a bit sequence of a marker message. Figure 2 presents the bit sequences of the message and the digital image. For illustrative purposes, a message and a digital image are grouped in two bits. Next, two bits of the message are compared sequentially with two bits of the digital image. If the bits are not equal, then zero is written to the array of marker message sequence {F} and the next two bits of the digital image are taken for comparison. If the bits are equal, then one is written to the array of marker message sequence {F}, and for comparison, the next two bits of the message and the digital image are taken. After all bits of the message sequence have been mapped to the flag value in the array {F}, a packet of marker messages containing the data of the array is formed.

The process of extracting a message from a digital image using a marker message is presented in figure 3 and is explained as follows. Arrays are formed for storing the bit sequence of the digital image {PQ}, where i = 1, 2 ... K, the bit sequence of the marker message {PFf}, where i = 1, 2 ... N, the bit sequence of the message {PT _j }, where j = 1 , 2 ... N (Fig. 3, block 1). Next, receive from different communication channels packets of information messages and marker messages (figure 3, block 2, 4). The data of these packets are recorded in the corresponding arrays (figure 3, block 3, 5). Install the counters in the initial state i = 1 and j = 1 (Fig. 1, block 6). The values of PQ and PF are sequentially read from the corresponding arrays (Fig. 1, block 7). If the value of the flag PF _j is equal to one (Fig. 1, block 8), then the value of the bit sequence PQ is written into the cell of the array PT _j (Fig. 1, block 9) and the counters i and j are increased by one (Fig. 1, block 10, 11). If the value of the flag PF _j is equal to zero, then only the value of counter i is increased by one (Fig. 1, block 11). After all the flag values have been read (Fig. 1, block 12), a decision is made to receive the message (Fig. 1, block 13).

Thus, the claimed method due to the lack of directly embedding the message in a digital image and transmitting a digital image and a marker packet of messages through different communication channels can increase the secrecy of the transmission of confidential information, thereby achieving a technical result.

Claims (1)

The method of covert information transmission, which consists in assigning a flag value of “one” when a part of the bits of a byte of the digital image signal and bits of the message signal coincide, or a flag value of “zero” when they do not match, characterized in that they form an array {F} for storing flag values write the obtained flag values to the array {F} after comparing a part of the bits of the byte of the digital image signal and the bits of the message signal, read the flag values from the array {F}, form a marker message packet, for why are flag values from the {F} array written to the packet information field, the marker packet and the packet with the digital image are transmitted over different communication channels.

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