CN111654707B - Information hiding method and terminal based on Russian blocks - Google Patents

Abstract

According to the information hiding method and the terminal based on the Russian blocks, the squares filled by the Russian blocks according to the preset rules are constructed, and the magic matrix is constructed according to the squares; selecting a corresponding magic matrix according to the size of the secret information, and converting the secret information to obtain converted secret information; and embedding the converted secret information into the original image for hiding to obtain a secret image, thereby flexibly hiding more secret messages while ensuring the information security.

Description

Information hiding method and terminal based on Russian blocks

Technical Field

The invention relates to the technical field of information security, in particular to an information hiding method and terminal based on a Russian block.

Background

The rapid development of the information age and the complexity and changeability of the internet environment, and the problem of information security protection has become the focus of attention of researchers.

The information hiding technology, which is one of the important components in the information security field, emphasizes that the hidden information is embedded into a specific carrier by using a certain hiding means, so that not only is the hidden data protected from being damaged, but also the information security transmission is ensured, and meanwhile, the discovery of an illegal attacker is prevented. That is, the existence of the covert information is hidden. Therefore, compared with an encryption technology, the information hiding technology has more advantages.

Disclosure of Invention

Technical problem to be solved

In order to solve the above problems in the prior art, the present invention provides an information hiding method and a terminal based on a tetris, which can flexibly hide more secret messages while ensuring information security.

(II) technical scheme

In order to achieve the purpose, the invention adopts a technical scheme that:

a tetris-based information hiding method comprises the following steps:

s1, constructing squares filled by Russian squares according to a preset rule, and constructing a magic matrix according to the squares;

s2, selecting a corresponding magic matrix according to the size of the secret information, and converting the secret information to obtain converted secret information;

s3, embedding the converted secret information into the original image for hiding to obtain a secret image.

In order to achieve the purpose, the invention adopts another technical scheme as follows:

a tetris-based information hiding terminal comprising a memory, a processor and a computer program stored on the memory and executable on the processor, the processor implementing the following steps when executing the program:

s1, constructing squares filled by Russian squares according to a preset rule, and constructing a magic matrix according to the squares;

s2, selecting a corresponding magic matrix according to the size of the secret information, and converting the secret information to obtain converted secret information;

s3, embedding the converted secret information into the original image for hiding to obtain a secret image.

(III) advantageous effects

The invention has the beneficial effects that: constructing a square grid filled by a Russian square according to a preset rule, and constructing a magic matrix according to the square grid; selecting a corresponding magic matrix according to the size of the secret information, and converting the secret information to obtain converted secret information; and embedding the converted secret information into the original image for hiding to obtain a secret image, thereby flexibly hiding more secret messages while ensuring the information security.

Drawings

FIG. 1 is a flowchart of an embodiment of a method for hiding information based on Tetris;

FIG. 2 is a schematic view of the rotation angle and shape of a basic Russian block according to an embodiment of the present invention;

FIG. 3 shows Q in an embodiment of the present invention₄Schematic diagrams of filling squares and the naming of squares of (a);

FIG. 4 shows Q in an embodiment of the present invention₆Schematic diagrams of filling squares and the naming of squares of (a);

FIG. 5 shows Q in an embodiment of the present invention₄(Q₆) Corresponding magic matrix MT₄(MT₆) A schematic diagram of (a);

FIG. 6 shows Q in an embodiment of the present invention₄(Q₆) Corresponding look-up table LUT₄(LUT₆) A schematic diagram of (a);

FIG. 7 illustrates an embodiment of the present invention using an MT₄Embedding a secret information schematic diagram;

FIG. 8 illustrates an embodiment of the present invention using an MT₆Embedding a secret information schematic diagram;

fig. 9 is a schematic structural diagram of an information hiding terminal based on a tetris according to an embodiment of the present invention.

[ description of reference ]

1: the information hiding terminal is based on a Russian square;

2: a memory;

3: a processor.

Detailed Description

For the purpose of better explaining the present invention and to facilitate understanding, the present invention will be described in detail by way of specific embodiments with reference to the accompanying drawings.

Example one

Referring to fig. 1, a tetris-based information hiding method includes the steps of:

s01, selecting a square;

s02, defining the rotation angle and the shape of different basic Tetris, wherein the basic Tetris comprises a plurality of basic units with different values.

S1, constructing squares filled by Russian squares according to a preset rule, and constructing a magic matrix according to the squares;

step S1 specifically includes:

a square completely and seamlessly filled by a plurality of basic Russian squares is constructed, and a magic matrix and a corresponding lookup table are constructed according to the square.

S2, converting the secret information according to the magic matrix to obtain converted secret information;

s3, embedding the converted secret information into the image for hiding to obtain a secret image.

Step S3 further includes:

s31, acquiring an original image with the size of H multiplied by W;

and S32, cutting the image into a plurality of non-overlapping pixel pairs.

Step S3 includes:

s33, determining a corresponding basic Russian block from the lookup table according to the converted secret information;

s34, mapping the pixel pairs into the magic matrix to obtain a plurality of candidate pixel pairs;

and S35, selecting a pixel pair from the candidate pixel pairs according to the minimum distance principle as the pixel value of the converted secret information at the corresponding position of the secret image, and obtaining the secret image after all the secret information is embedded.

Example two

The embodiment further illustrates how the tetris-based information hiding method of the present invention is implemented in combination with a specific application scenario:

1. selecting a square grid Q with the size of L_Q×L_QWherein L is_QThe value is 4 or 6, and can be adjusted according to actual needs;

2. the rotation angle and the shape of 7 basic tetris are defined, wherein each tetris contains 4 basic unit cells.

As shown in fig. 2, the definition of the basic russian square of class 7 is shown in fig. 2(a), and it is taken as a basic shape. At the same time, the basic russian squares of each type of shape can be rotated by 4 angles 0 °,90 °,180 °,270 °. Taking Russian 'T' as an example, the rotation is performed counterclockwise to obtain four shapes derived from the Russian 'T', as shown in FIG. 2 (b). All the 7 kinds of basic Russian blocks are rotated and defined according to the rule, and the purpose is to form a unified lookup table design rule.

3. From the defined 7 basic russian squares, several russian squares are selected to completely fill the selected square Q and leave no gaps in Q.

Specifically, if L_QIf the value is 4, selecting 4 squares from the defined Tetris to fill in Q; if L is_QWith a value of 6,9 squares are selected from the defined tetris to fill in Q. Whether L_QThe value of 4 or 6 is selected, the filling schemes meeting the conditions are all provided with a plurality of types, and Q is respectively shown in figure 3 and figure 4₄And Q₆And for each selected Russian square named "T₁”,“T₂”,“T₃”,“T₄”,“SQ”,“RS₁”,“RS₂”,“LS₁"and" LS₂", to facilitate the discussion that follows. Meanwhile, different numbers are given to 4 basic cells of each Russian square, and the values are normalized to [0,3]]The numerical assignment rule may be performed in a pseudo-random manner.

Also worth noting is the resulting Q (Q)₄Or Q₆) A secure sharing of sender and receiver is required to serve the hiding and extraction of secret information.

4. And constructing a magic matrix.

Q determined according to step 3₄Or Q₆Constructing a magic matrix MT with a size of 256 × 256 by a copy operation₄(MT₆) As shown in fig. 5, the following features exist:

with Q₄For example, the following steps are carried out:

1) at MT₄In any 4 multiplied by 4 area, 4 Russian areas with different shapes can be foundDice, and thus can be used to carry logs₂4-2 bits of secret information;

2) each Russian square shape contains 4 elementary cells, including the numbers (0-3), and can therefore also be used to carry the log₂4-2 bits of secret information.

With Q₆For example, the following steps are carried out:

1) at MT ₆9 Russian squares of mutually different shapes can be found in any 6x 6 region in the region, and thus can be used to carry the log₂Secret information of 9 bits;

2) each Russian square shape contains 4 elementary cells, including the numbers (0-3), and can therefore also be used to carry the log₂4-2 bits of secret information.

5. And constructing a lookup table.

Q determined according to step 3₄Or Q₆Constructing a corresponding look-up table LUT₄Or LUT₆As shown in fig. 6. The rules are constructed as follows:

1) scan Q (Q)₄Or Q₆) All russian cubes used in (a);

2) performing a first round of sorting on all the Russian blocks derived from 1) according to the order of appearance of the various Russian blocks in FIG. 2 (a);

3) for the similar Russian diamonds, carrying out a second round of sequencing according to the rotation angles of the Russian diamonds;

4) for the arranged Russian square sequence, the longitudinal element is used as the longitudinal element of the lookup table, and longitudinal coordinate values [0, L ] are given in sequence²Q/4]。

5) For the Russian square with the same shape, the Russian squares with different numbers are disassembled into 4 Russian squares, the Russian squares are arranged from small to large according to the numerical values of the Russian squares to form the row-direction elements of the lookup table, the row coordinate values [0,3] are sequentially given, and the construction of the lookup table can be completed through the steps.

6. And (6) secret information conversion.

Taking a gray image as an example, assume that the size of an original image I is H × W, binary secret information is B, and the length is L_BAccording to L_BSelecting a corresponding magic matrix MT and carrying out corresponding secret information conversion, wherein the specific process is as follows:

1) if L is_BLess than or equal to 2. H.W, MT will be selected₄To obtain a high quality stego image. Accordingly, the bit stream B is converted into 4-ary secret numbers via a 4-ary number conversion system. Next, every two consecutive 4-ary secret numbers are paired, and are denoted as S { (S)_t,s_t+1)|t＝1,2,3,…,L_B/4}, wherein s_tAnd s_t+1Are all 4-ary secret numbers.

2) If 2. H. W < L_B≤(log₂9+ 2). H.W/2, MT will be selected₆To obtain higher-stock covert images. Accordingly, the bit stream B is sequentially circulated to be converted into the secret numbers of the 9 system and the 4 system through the digital conversion system of the 9 system and the 4 system, and the circulation is performed. Then, the continuous secret numbers of 9 system and 4 system are combined into a pair and recorded as

Wherein s is_tIs a secret number of 9, s_t+1Is a 4-ary secret number.

7. And embedding secret information.

The method comprises the following steps:

1) cutting an original image I into a plurality of non-overlapping pixel pairs in a raster scanning order, and marking as I { (p)_i,p_i+1)|i＝1,3,5,7,…,(H·W-1)}。

2) According to the length L of the secret information_BSelecting the corresponding magic matrix MT and converting the secret into S { (S)_t,s_t+1)}。

3) Secret information s_tAnd s_t+1The look-up table LUT is searched and the corresponding tetris is determined as ordinate and line coordinate, respectively.

4) Couple the pixels p_iAnd p_i+1Mapped into the MT as ordinate and line coordinate, respectively. According to the characteristics of MT, in MT (p)_i,p_i+1) Several candidate pixel pairs (p'_i,p′_i+1). Wherein the candidate imagesThe Russian square in which the pair of elements is located is the same as the Russian square determined in step 3, and MT (p'_i,p′_i+1) Is the same as the tetris value determined in step 3.

5) Selecting a pixel pair (p ') according to the minimum distance d'_i,p′_i+1) As pixel values of the stego image at corresponding positions, secret information(s) is realized_t,s_t+1) Is hidden. Wherein, the calculation formula of d is as follows:

6) and when all the secret information is completely hidden, obtaining a secret image SI, and sending the secret image SI to a receiving party.

Examples of secret information embedding:

by MT₄(LUT₄) For example, see FIG. 7:

suppose an original pixel pair (p)_i,p_i+1) The secret number to be hidden is(s) when (0,8)_t,s_t+1) (1, 0). Will s_tAs LUT₄Ordinate of (a), s_t+1As LUT (0)₄Can find the definite tetris

Mapping (0,8) to MT₄And find several candidate pixel pairs around it, e.g., (2,9), (2,5), (6,9), etc. The shape of the Russian square in which the candidate pixel pairs are located is the same as the determined Russian square (all are "T₂") and their values are the same. Finally, the pixel pair (0,8) is changed to (2,9) to carry the secret information (1,0) (in binary form '0100').

By MT₆(LUT₆) For example, see FIG. 8:

suppose an original pixel pair (p)_i,p_i+1) The secret number to be hidden is(s) (6,7)_t,s_t+1) (8,0) in binary form ('100000'). Firstly, s is_t＝8As LUTs₆With st +1 being 0 as LUT₆Finding the determined tetris

Mapping (6,7) to MT₆And find several candidate pixel pairs around it, e.g., (6,2), (6,8), (0,8), etc. The Russian squares in which the candidate pixel pairs are located have the same shape as the determined Russian squares (all "LS₂") and their values are the same. Finally, the pixel pair (6,7) is changed to (6,8) to carry the secret information (8,0) (binary form '100000').

Information extraction

After the receiving end acquires the secret image SI, the secret information can be extracted as follows.

1. From the previously shared Q, a reference magic matrix MT and a look-up table LUT are constructed according to the same method.

2. The image SI is sliced into several non-overlapping pixel pairs in raster scan order, denoted as SI { (p'_i,p′_i+1)|i＝1,3,5,7,…,(H·W-1)}。

3. Will pixel pair (p'_i,p′_i+1) Mapping into MT, i.e. MT (p'_i,p′_i+1)。

4. According to MT (p'_i,p′_i+1) The shape and value of the Russian square are the same as the LUT Russian square found in the lookup table.

5. Extracting coordinates(s) of the LUT tetris_t,s_t+1) I.e. is the hidden secret number.

6. The extracted secret number(s)_t,s_t+1) Into a bit stream.

7. After all the pixel pairs are extracted according to the process, the secret information is connected in series, and the extracted secret information is obtained.

Example secret information extraction:

by MT₄(LUT₄) For example, see FIG. 7:

suppose a pixel pair (p ') of a covert image'_i,p′_i+1) (2,9), mapping it to MT₄I.e. MT₄(2,9). From FIG. 7, we can find the MT₄The shape of the (2,9) seat is "T₂"and its value is 0. Thus, LUT₄(1,0) is locked. Extracting its ordinate and line coordinate as secret information, i.e.(s)_t,s_t+1) The binary form is '0100' (1, 0).

By MT₆(LUT₆) For example, see FIG. 8:

suppose a pixel pair (p ') of a covert image'_i,p′_i+1) (6,8), map it to MT₆I.e. MT₆(6,8). From FIG. 8, we can find the MT₆(6,8) the shape of the seat is "LS₂"(line 8) and its value is 0. Thus, LUT₆(8,0) is locked. Extracting its ordinate and line coordinate as secret information, i.e.(s)_t,s_t+1) (8,0), binary form is '100000'.

Comparison of results

1) Compared with the existing tortoise shell-based information hiding method in the aspects of embedding capacity (ER) and image quality (PSNR)

First, 6 test images were compared for the performance of the present invention and 5 tortoise shell-based information methods [ method 1-method 5], as shown in table 1.

As can be seen from table 1, the mean ER of the stego image provided by the present invention is the same as methods 2, 4 and 5, and higher than methods 1 and 3 by 0.5bpp and 0.15bpp, respectively. Moreover, under the same ER, the quality of the covert image provided by the invention is better than that of the methods 2, 4 and 5, and the difference is 1.35dB, 1.50dB and 2.21dB respectively.

Wherein, the method 1 specifically refers to High Capacity Mobile Shell-Based Data High, which is disclosed in IET Image Processing, Liu, Y, Chang, C.C., and Nguyen, T.S.;

method 2 specifically refers to the Data high Based on Extended turbine Shell Matrix Construction Method disclosed in Multimedia Tools and Applications, Liu, L., Chang, C.C., and Wang, A.;

method 3 specifically refers to Liu, L., Wang, L., and Chang, C.C. Data Embedding Scheme Based on Multi-Matrix Structure of tube Shell to Integrated Human Eye Perception, published in Multimedia Tools and Applications;

method 4 specifically refers to the Secure High Capacity Data High Scheme base on Reference Matrix published in International Journal of Network Security, Li, X.S., Chang, C.C., He, M.X., and Lin, C.C.;

method 5 specifically refers to Data high Scheme Based on A Flower-Shaped Reference Matrix, published in Journal of Network organization, Lee, C.F., Li, Y.C., Chu, S.C., and Roddick, J.F.;

table 1 comparison of the present invention with the tortoise shell based information hiding method in terms of embedding capacity and image quality

2) Comparison of the present invention with information hiding method based on Sudoku in terms of embedding capacity (ER) and image quality (PSNR)

Secondly, the present invention and sudoku-based information hiding method [ method 6-method 8] are also compared in terms of ER and PSNR for 4 test images. These methods are all designed based on the concept of a game of chance. Table 2 shows the experimental results of the present invention and sudoku-based information hiding method. Compared with the methods 6 and 8, the invention realizes higher quality of the covert image when the embedding capacity is 1.5 bpp. In addition, both method 7 and the present invention can achieve an embedding capacity of 1.58 bpp. Although the covert image quality of method 7 was slightly higher than the present invention, their ER was limited to 1.58bpp as reported in method 7, as shown in table 2. In contrast, the present invention boosts ER to 2.56bpp while maintaining an average PSNR of 43.12 dB. It is therefore apparent that the present invention is an efficient information hiding scheme with both high embeddability and high stego image quality.

Method 6 specifically refers to An Information high schedule Using Sudoku, published In Proceedings of the 3rd International Conference on Innovative Computing Information and Control;

method 7 specifically refers to Steganograph Using Sudoku review, published In Proceedings of Second International Symposium on Intelligent Information Technology Application;

method 8 specifically refers to A replaceable Data high Scheme Using design Sudoku, disclosed In Proceedings of 2018 International Conference on Network, Communication, Computer Engineering (NCCE 2018);

table 2 comparison of the present invention with sudoku-based information hiding method in terms of embedding capacity and image quality

Finally, we further summarize and compare the image quality and embedding capacity between the present invention and methods 1, 2, 4, 6 and 8-10, as shown in table 3. '-' indicates no usable or relevant data. In Table 3, it can be easily found that the PSNR of the present invention maintains considerable levels, 48.72dB and 46.38dB, respectively, when ER is 1.5bpp and 2.0 bpp. Similarly, when ER is 2.5bpp or 3.0bpp, the visual quality of the stego image provided by the invention reaches 43.22dB and 40.72dB respectively. From methods 6 and 8, it can be seen that the information hiding method based on sudoku has a drawback in embedding capability. For tortoise-shell-based information hiding methods, such as method 9, their embedding capacity and image quality depend on the angle of the octopus shell and the width and height of the octopus shell. Unfortunately, with the expansion of the octopus shell, PSNR decreases significantly, e.g., when ER reaches 3.0bpp, the cryptic image PSNR of this type of approach is about 39.33dB, lower than 40.72dB of the present invention. Likewise, the method 10 proposes an improved method based on the direction modification technique (EMD2) by extending the magic matrix. Although their schemes can achieve ER up to 3.15bpp, they are relatively poor in the visual quality of the covert image, with an average PSNR of 39.89dB (ER ═ 3.0 bpp). Only the present invention and method 4 achieves ER up to 3.0bpp while having PSNR no less than 40.00 dB. However, method 4 has a poor visual quality when ER is set to 1.5bpp, 2.0bpp and 2.5bpp, compared to the present invention. In summary, it is sufficient to see that the present invention is clearly superior to the other latest methods 1, 2, 4, 6 and 8-10.

Method 9 specifically refers to generally characterized Scheme Based on Octagon-Shaped Shell for Data Hiding in Steganographic Applications, as disclosed by Leng, H.S. in Symmetry;

the method 10 specifically refers to Extended Squared Magic Matrix for Embedding Secret Information with Large Payload, published in Multimedia Tools and Applications, Xie, X.Z., Liu, Y, and Chang, C.C.; .

TABLE 3 comparison of quality of stego images at different reserves

EXAMPLE III

Referring to fig. 9, an information hiding terminal based on tetris includes a memory, a processor, and a computer program stored in the memory and running on the processor, where the processor implements the steps in the first embodiment when executing the program.

The above description is only an embodiment of the present invention, and not intended to limit the scope of the present invention, and all equivalent changes made by using the contents of the present specification and the drawings, or applied directly or indirectly to the related technical fields, are included in the scope of the present invention.

Claims (2)

1. A tetris-based information hiding method is characterized by comprising the following steps:

s1, constructing squares filled by Russian squares according to a preset rule, and constructing a magic matrix according to the squares; step S1 specifically includes:

selecting a squareQA size ofL _Q x L _Q WhereinL _Q A value of 4 or 6;

defining the rotation angle and the shape of 7 basic Tetris, wherein each Tetris contains 4 basic cells;

selecting from the defined 7 basic Russian squares a number of Russian squares to completely fill the selected squaresQAnd make it possible toQNo gap is left;

assigning different numbers to 4 basic cells of each Russian square, and taking the value as [0,3 ];

according to the determinationQ ₄OrQ ₆Constructing a magic matrix with the size of 256x256 through a copying operation;

s2, selecting a corresponding magic matrix according to the size of the secret information, and converting the secret information to obtain converted secret information;

s3, embedding the converted secret information into an original image for hiding to obtain a secret image;

step S3 specifically includes:

the original image is processedICut into non-overlapping pairs of pixels in raster-scan order, denotedI = {(p _i , p _i+1)| i= 1, 3, 5, 7, …, (H·W-1)}；

According to the length of secret informationL _B Selecting the corresponding magic matrixMTAnd converts the secret intoS = {(s _t , s _t+1)}；

Secret informations _t Ands _t+1searching the lookup table as a vertical coordinate and a horizontal coordinate, respectivelyLUTAnd determining the corresponding tetris;

couple pixelsp _i Andp _i+1as ordinate and line coordinate, respectively, mapped toMTPerforming the following steps; according toMTIs characterized in thatMT(p _i , p _i+1) Several candidate pixel pairs (can be found nearbyp’ _i , p’ _i+1)；

According to minimum distancedSelecting a pixel pair (p’ _i , p’ _i+1) As pixel values of the stego image at corresponding positions, secret information is realized: (s _t , s _t+1) Is hidden.

2. A tetris-based information hiding terminal comprising a memory, a processor and a computer program stored on the memory and executable on the processor, wherein the processor implements the following steps when executing the program:

s1, constructing squares filled by Russian squares according to a preset rule, and constructing a magic matrix according to the squares; step S1 specifically includes:

selecting a squareQA size ofL _Q x L _Q WhereinL _Q A value of 4 or 6;

defining the rotation angle and the shape of 7 basic Tetris, wherein each Tetris contains 4 basic cells;

selecting from the defined 7 basic Russian squares a number of Russian squares to completely fill the selected squaresQAnd make it possible toQNo gap is left;

assigning different numbers to 4 basic cells of each Russian square, and taking the value as [0,3 ];

according to the determinationQ ₄OrQ ₆Constructing a magic matrix with the size of 256x256 through a copying operation;

s2, selecting a corresponding magic matrix according to the size of the secret information, and converting the secret information to obtain converted secret information;

s3, embedding the converted secret information into an original image for hiding to obtain a secret image;

step S3 specifically includes:

the original image is processedICut into non-overlapping pairs of pixels in raster-scan order, denotedI = {(p _i , p _i+1)| i= 1, 3, 5, 7, …, (H·W-1)}；

According to the length of secret informationL _B Selecting the corresponding magic matrixMTAnd converts the secret intoS = {(s _t , s _t+1)}；

Secret informations _t Ands _t+1searching the lookup table as a vertical coordinate and a horizontal coordinate, respectivelyLUTAnd determining the corresponding tetris;

couple pixelsp _i Andp _i+1as ordinate and line coordinate, respectively, mapped toMTPerforming the following steps; according toMTIs characterized in thatMT(p _i , p _i+1) Several candidate pixel pairs (can be found nearbyp’ _i , p’ _i+1)；

According to minimum distancedSelecting a pixel pair (p’ _i , p’ _i+1) As pixel values of the stego image at corresponding positions, secret information is realized: (s _t , s _t+1) Is hidden.

Images