CN111260532B - Privacy image encryption method, device, electronic equipment and computer readable storage medium - Google Patents
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Abstract
The embodiment of the invention relates to the field of information security and discloses a privacy image encryption method. The method comprises the steps of splitting an original image into a plurality of original image blocks, encrypting the plurality of original image blocks by using a pre-built stream cipher and exclusive OR encryption operation to obtain a corresponding number of encrypted image blocks, calculating pixel differences of diagonal pixels in the encrypted image blocks, dividing the encrypted image blocks into a smooth image area and a complex image area according to the pixel differences, embedding a part of pixel sets in a private image into the smooth image area to obtain the private image area, and compressing the other part of pixel sets in the private image into the complex image area and the private image area according to a preset image compression rule. The invention also provides a privacy image encryption electronic device, a device and a computer readable storage medium. The invention can effectively solve the problems of little encryption information quantity and low encryption security of the encrypted privacy image.
Description
Technical Field
The embodiment of the invention relates to the field of information security, in particular to a method, electronic equipment, a device and a computer readable storage medium for encrypting a privacy image.
Background
Along with social progress and information development, image information encryption is widely applied to politics, economy, national defense, education and the like, and two main modes related to image information encryption at present are that the private image is encrypted first and then embedded, and the space reserved for the private image is reserved before encryption. Both encryption methods can protect the privacy image, but the inventor finds that the first method is low in security although the security is guaranteed, but the information amount of the privacy image is not high, and the second method is low in security although the embedding amount of the information amount of the privacy image is improved.
Disclosure of Invention
The embodiment of the invention aims to provide a privacy image encryption method, electronic equipment, device and computer readable storage medium, which effectively solve the problems of low encryption information quantity and low encryption security of an encrypted privacy image.
In order to solve the above technical problems, an embodiment of the present invention provides a method for encrypting a privacy image, including:
Splitting an original image into a plurality of original image blocks;
encrypting a plurality of original image blocks by using a pre-constructed stream cipher and exclusive-or encryption operation to obtain a corresponding number of encrypted image blocks;
calculating pixel differences of diagonal pixels in the encrypted image block, dividing the encrypted image block into a smooth image area and a complex image area according to the pixel differences, and embedding a part of pixel sets in a privacy image into the smooth image area to obtain the privacy image area;
and compressing the other part of the pixel set of the privacy image into the complex image area and the privacy image area according to a preset image compression rule.
In order to solve the above-mentioned problems, the present invention also provides a privacy image encrypting apparatus, the apparatus comprising:
the original image splitting module is used for splitting an original image into a plurality of original image blocks;
the original image encryption module is used for encrypting a plurality of original image blocks by using a pre-constructed stream cipher and exclusive OR encryption operation to obtain a corresponding number of encrypted image blocks;
the pixel difference calculation module is used for calculating the pixel difference of diagonal pixels in the encrypted image block, dividing the encrypted image block into a smooth image area and a complex image area according to the pixel difference, and embedding a part of pixel sets in the private image into the smooth image area to obtain the private image area;
And the privacy image embedding module is used for compressing the other part of the pixel set of the privacy image into the complex image area and the privacy image area according to a preset image compression rule.
In order to solve the above-mentioned problems, the present invention also provides an electronic apparatus including:
a memory storing at least one instruction; and
And the processor executes the instructions stored in the memory to realize the privacy image encryption method.
In order to solve the above-described problems, the present invention also provides a computer-readable storage medium having stored therein at least one instruction that is executed by a processor in an electronic device to implement the above-described privacy image encryption method.
The method comprises the steps of splitting an original image into a plurality of original image blocks, encrypting the original image blocks to obtain encrypted image blocks, calculating pixel differences of the encrypted image blocks to obtain smooth image areas with small pixel differences, and replacing pixels of a privacy image with pixels of the smooth image areas; the whole encryption stage comprises exclusive-or encryption and stream cipher, and the privacy image is hidden in the original image, so that the encryption security is improved.
Preferably, the encrypting the plurality of original image blocks using a pre-constructed stream cipher and exclusive-or encryption operation to obtain a corresponding number of encrypted image blocks includes:
converting each pixel value within one set of diagonals of the original image block to an original fixed bit value;
converting each pixel value within another set of diagonals in the original image block to an original random bit value;
and performing exclusive or encryption operation on the original fixed bit value and the original random bit value according to a stream cipher mode to obtain an encrypted image block.
Before encrypting the original image block, the pixel value of the original image block is changed into the original fixed bit value and the original random bit value, and the exclusive-or encryption operation is carried out on the original fixed bit value and the original random bit value, so that the encryption safety is improved.
Preferably, the exclusive-or encrypting the original fixed bit value and the original random bit value to obtain an encrypted image block includes:
according to the permutation and combination principle, performing exclusive OR operation on the original fixed bit value and the original random bit value to obtain a standard fixed bit value and a primary random bit value;
Calculating a bit difference value of the standard fixed bit value and the primary random bit value;
and filling the primary random bit value with a pre-built key according to the bit difference value, and collecting the standard fixed bit value and the standard random bit value to obtain the encrypted image block.
According to the method, partial bit data of the original random bit value is filled with the pre-built secret key, so that the subsequent privacy image pixels can be conveniently embedded, more privacy image images can be filled with the partial bit data of the original random bit value, and the encryption information quantity of the encrypted privacy image is improved.
Preferably, the calculating the pixel difference of the diagonal pixels in the encrypted image block divides the encrypted image block into a smooth image area and a complex image area according to the pixel difference, including:
calculating pixel differences between standard random bit values within the encrypted image block;
judging whether the pixel difference is larger than a preset pixel difference threshold value or not;
and if the pixel difference is not greater than the pixel difference threshold, the encrypted image block is a smooth image area.
Preferably, the embedding a part of the pixel set of the privacy image into the smooth image area to obtain the privacy image area includes:
traversing out standard random bit values within the smooth image region;
and replacing the value of one bit in the standard random bit values in the smooth image area by a part of pixel sets in the privacy image until the replacement is completed, so as to obtain the privacy image area.
Preferably, the compressing the other part of the pixel set of the privacy image into the complex image area and the privacy image area according to a preset image compression rule includes:
extracting all standard random bit values of the complex image area and the privacy image area to obtain a standard random bit value group;
constructing a binary matrix according to the standard random bit value group;
compressing the binary matrix to obtain a bit number capable of being filled, and filling another part of the pixel set of the privacy image into the bit number capable of being filled.
Preferably, the method further comprises:
receiving a decryption key and judging the category of the decryption key;
if the decryption key is an original image decryption key, decrypting according to the original image decryption key to obtain the original image;
And if the decryption key is a private image decryption key, decrypting according to the private image decryption key to obtain the private image.
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Various embodiments are illustrated by way of example and not by way of limitation in the figures of the accompanying drawings, in which like references indicate similar elements, and in which the figures are not to be considered limiting unless expressly stated otherwise.
Fig. 1 is a schematic flow chart of a privacy image encryption method according to a first embodiment of the present invention;
fig. 2 is a schematic diagram of an original image block of 2×2 in the privacy image encryption method according to the first embodiment of the present invention;
fig. 3 is a schematic diagram of a detailed implementation flow of S2 in the privacy image encryption method according to the second embodiment of the present invention;
FIG. 4 is a flowchart illustrating the detailed implementation of pixel difference calculation in the privacy image encryption method according to the second embodiment of the present invention;
fig. 5 is a schematic diagram of a detailed implementation flow of S4 in the privacy image encryption method according to the third embodiment of the present invention;
fig. 6 is a schematic block diagram of a privacy image encrypting apparatus according to an embodiment of the present invention;
fig. 7 is a schematic diagram of an internal structure of an electronic device for implementing a privacy image encryption method according to an embodiment of the present invention;
The achievement of the objects, functional features and advantages of the present invention will be further described with reference to the accompanying drawings, in conjunction with the embodiments.
Detailed Description
For the purpose of making the objects, technical solutions and advantages of the embodiments of the present invention more apparent, the following detailed description of the embodiments of the present invention will be given with reference to the accompanying drawings. However, those of ordinary skill in the art will understand that in various embodiments of the present invention, numerous technical details have been set forth in order to provide a better understanding of the present application. However, the technical solutions claimed in the present application can be implemented without these technical details and with various changes and modifications based on the following embodiments.
The embodiment of the invention relates to a privacy image encryption method, which is characterized in that an original image block is encrypted to obtain an encrypted image block, and a privacy image is embedded into the encrypted image block to complete privacy image encryption by calculating pixel differences of the encrypted image block, so that the problems of low encryption information quantity and low encryption security of an encrypted privacy image are effectively solved. The implementation details of the privacy image encryption of the present embodiment are specifically described below, and the following description is provided only for easy understanding, and is not necessary to implement the present embodiment.
Referring to fig. 1, fig. 1 is a flowchart of privacy image encryption according to a first embodiment of the present invention, including:
s1, acquiring an original image and a privacy image, and splitting the original image into a plurality of original image blocks.
The private image is an image which is unwilling to be disclosed externally for some reason, for example, company a purchases the core production technology of company B by huge capital, company B sends the core production technology picture to company a safely under the condition that the core production technology is not disclosed externally, and therefore the core production technology picture needs to be encrypted, wherein the core production technology picture is the private picture.
If the encryption operation is simply performed on the private picture, the encryption security is lower, so that the invention preferably obtains an encryption container first, and the security can be improved by embedding the private picture into the encryption container, wherein the encryption container can be a picture generally, namely, the original image described in S1, for example, the core production technology picture is the private picture, and the group photo picture of the company a high-level and the company B high-level is the original image.
In detail, the splitting the original image into a plurality of original image blocks includes: calculating the pixel arrangement specification of the original image, and splitting the original image according to the pixel arrangement specification of the original image to obtain a plurality of original image blocks.
In order to improve the security of the core production technology picture, the group photo picture is split into 2×2 original image blocks, i.e. each original image block includes 4 pixels, each pixel is arranged in a square form, and reference can be made to fig. 2 for a schematic diagram of the 2×2 original image block, where the diagonal pixels are marked with the same symbols, such as the symbols of the circle center and the rectangle in fig. 2, respectively.
S2, encrypting the original image block by using a pre-constructed stream cipher and an exclusive OR encryption operation to obtain an encrypted image block.
In detail, the step S2 may include, as shown in the detailed implementation flowchart of fig. 3:
s21, converting each pixel value in a group of diagonals of the original image block into an original fixed bit value;
s22, converting each pixel value in another set of diagonal lines in the original image block into an original random bit value;
s23, performing exclusive or encryption operation on each group of original fixed bit values and each group of original random bit values according to a stream cipher mode to obtain an encrypted image block.
Further, the conversion mode of converting the original fixed bit value is as follows:
Wherein,,
representing pixels within the original image block, (x, y) representing positions of pixels within the original image block, i, j representing an index of the original image block, as the above-mentioned 2 x 2 original image block includes B in total i,j (0,0) ,B i,j (0,1) ,B i,j (1,0) And B i,j (1,1) Four pixels, B i,j (0,0) Representing pixels in the upper left corner of the 2 x 2 array, B i,j (1,1) Representing pixels at the lower right corner of the 2 x 2 arrangement, and B i,j (0,0) B i,j (1,1) Form diagonal pixels, and so on B i,j (0,1) ,B i,j (1,0) To form diagonal pixels +.>
The original fixed bit value into which a pixel within an original image block having coordinates (x, y) is converted is represented, and u represents the number of bits of the original fixed bit value, which is typically 8.
Such as B i,j (0,0) B i,j (1,1) Form diagonal pixels and select B i,j (0,0) ,B i,j (1,1) Two pixels being converted to original fixed bit values, u being fixed at 8, a further set of diagonal pixels B i,j (0,1) ,B i,j (1,0) Is converted into an original random bit value, wherein the original random bit value is uncertain in terms of u value, and the bits of the original random bit value are necessarily smaller than the bits of the original fixed bit value.
Thus, further, the conversion manner of the original random bit value is as follows:
where f is the bit of the original random bit value and f is less than u.
Further, the exclusive-or encrypting operation is performed on each set of the original fixed bit values and each set of the original random bit values to obtain an encrypted image block, which includes: according to the permutation and combination principle, performing exclusive or operation on each group of original fixed bit values and each group of original random bit values to obtain standard fixed bit values and primary random bit values, calculating bit difference values of the standard fixed bit values and the primary random bit values, filling the primary random bit values with a pre-built key according to the bit difference values to obtain standard random bit values, and collecting the standard fixed bit values and the standard random bit values to obtain the encrypted image block.
In detail, the exclusive-or operation is:
wherein,,
representing exclusive OR operation, ++>
Represents a standard fixed bit value or a primary random bit value, ψ 1 Representing the position and bit number of a pixel within an original fixed bit value, ψ 2 Representing the position and bit number of the pixel within the original random bit value.
The original image blocks of 2×2 as described above include B in total i,j (0,0) ,B i,j (0,1) ,B i,j (1,0) And B i,j (1,1) Four pixels, B i,j (0,0) ,B i,j (1,1) Conversion of two pixels to an original fixed bit value, B i,j (0,1) ,B i,j (1,0) Converted into original random bit values, and the original random bit values are subjected to exclusive OR operation by permutation and combination between every two i,j (0,0) ,B i,j (1,1) Two pixels being converted to standard fixed bit values, B i,j (0,1) ,B i,j (1,0) The bit number of the primary random bit value is still 8, and if the bit number of the primary random bit value is less than 8, the bit difference value of the primary random bit value is 4, so that the remaining 4 bits of the primary random bit value are required to be encrypted and filled i,j A binary random sequence can be used, and the padding method is as follows:
wherein,,
representing a bit-wise inverting operation, e.g. when f=7 +. >
Then take the inverse time according to the bit
Ψ 3 Representing the position of the pixel and the number of remaining bits, ψ, within the original random bit values 1 ,Ψ 2 ,Ψ 3 The relationship of the three is as follows:
Ψ 1 = { (x, y, u) | (x, y) ∈where the coordinates of a set of diagonal pixels and u=0, 1,2, …,7}
Ψ 2 = { (x, y, f) | (x, y) ∈where the coordinates of another set of diagonal pixels and f=0, 1,2, …, t }, where t < 7 ψ 3 = { (x, y, f) | (x, y) ∈where the coordinates of another set of diagonal pixels and f=t+1, t+2, …,7}, where t < 7
Further, the fixed bit values of each group of standards and the random bit values of each group of standards are collected to obtain encrypted image blocks, if the group photo pictures of the company A high layer and the company B high layer are split into 100 original image blocks, 100 encrypted image blocks can be obtained after calculation.
S3, calculating pixel differences of diagonal pixels in the encrypted image block, dividing the encrypted image block into a smooth image area and a complex image area according to the pixel differences, and embedding a part of pixel sets in the privacy image into the smooth image area to obtain the privacy image area.
In detail, the calculating the pixel difference of the diagonal pixel in the encrypted image block divides the encrypted image block into a smooth image area and a complex image area according to the pixel difference, and referring to a detailed implementation flow chart of the 4-pixel difference calculation, including:
S31, calculating pixel differences among standard random bit values in the encrypted image blocks;
s32, judging whether the pixel difference is larger than a preset pixel difference threshold value or not;
s33, if the pixel difference is larger than the pixel difference threshold, the encrypted image block is a complex image area;
and S34, if the pixel difference is not greater than the pixel difference threshold, the encrypted image block is a smooth image area.
And (3) calculating the group photo pictures of the company A high layer and the company B high layer to obtain 100 encrypted image blocks, and respectively performing S3 operation on each encrypted image block to obtain 37 complex image areas and 63 smooth image areas.
Further, the embedding a part of the pixel set of the privacy image into the smooth image area to obtain the privacy image area includes: traversing out the standard random bit value in the smooth image area, and replacing the number of one bit of the standard random bit value in the smooth image area by a part of pixel sets in the privacy image until the replacement is completed to obtain the privacy image area.
Preferably, the number of replacing the one bit is generally the bit where the pre-constructed key pad is located, and as above, the 63 smooth image areas are obtained, 2 standard random bit values are traversed for the first smooth image area, and the number of bits of each standard random bit value is 8, wherein the highest 4 bits are obtained by the pad in S2, so that one bit is selected to be replaced in the highest 4 bits, such as selecting the highest bit to replace the pixel value of the core production technology picture.
S4, compressing the other part of the pixel set of the privacy image to the complex image area and the privacy image area according to a preset image compression rule.
In detail, the compressing the other part of the pixel set of the private image to the complex image area and the private image area according to the preset image compression rule may be performed in detail with reference to fig. 5, which includes:
s41, extracting all standard random bit values of the complex image area and the privacy image area to obtain a standard random bit value group;
s42, constructing a binary matrix according to the standard random bit value group;
s43, compressing the binary matrix to obtain a bit number capable of being filled, and filling the other part of the pixel set of the privacy image into the bit number capable of being filled.
If the standard random bit values are extracted from the 37 complex image areas and the 63 private image areas, further according to the description of S2, the bit values of 0-t bits in the standard random bit values in the 37 complex image areas and the 63 private image areas are preferably extracted, the bit values of 0-t bits are divided into k groups, and each group is v (1, q 1 ),v(2,q 2 ),…v(i,q i ),…,v(k,q k )，q i Representing the number of bit values included in the i-th group.
Further, the binary matrix is:
M＝[I,Q]
wherein M is the binary matrix, I is the identity matrix of the binary matrix, and Q is the random binary matrix.
The compression formula for compressing the binary matrix to obtain the bit number of the fillable bits is as follows:
wherein s is the number of bits of the fillable bit.
S5, receiving the decryption key, and judging whether the decryption key is an original image decryption key or not.
S6, if the decryption key is an original image decryption key, decrypting according to the original image decryption key to obtain the original image.
In detail, if the decryption key is the original image decryption key, the decryption is performed reversely according to the encryption process of S2, but since the original image is subjected to the exclusive or operation in the process of S2, and when the privacy image is embedded, a part of the pixel set of the privacy image is used to replace the number of a part of bits in the original image, so that when the original image is decrypted, the restored image is an approximate image of the original image.
Preferably, the method of recovering and replacing the number of the partial bit in the original image can adopt an eight-neighborhood pixel average value method, namely, eight pixel values adjacent to the replaced pixel are selected from the original image, and the average value of the eight pixel values is taken as the pixel value of the replaced pixel.
And S7, if the decryption key is a private image decryption key, decrypting according to the private image decryption key to obtain the private image.
If the decryption key is a private image decryption key, searching a smooth image area according to the pixel difference threshold value of S3, restoring the replaced pixel value in the smooth image area, and so on, restoring the pixel value according to the compressed bit value in the binary matrix, and further obtaining the private image.
As shown in fig. 6, a functional block diagram of the privacy image encrypting apparatus of the present invention is shown.
The privacy image encrypting apparatus 100 of the present invention may be mounted in an electronic device. The privacy image encrypting means may include an original image splitting module 101, an original image encrypting module 102, a pixel difference calculating module 103, and a privacy image embedding module 104 according to the implemented functions. The module of the present invention may also be referred to as a unit, meaning a series of computer program segments capable of being executed by the processor of the electronic device and of performing fixed functions, stored in the memory of the electronic device.
In the present embodiment, the functions concerning the respective modules/units are as follows:
the original image splitting module 101 is configured to split an original image into a plurality of original image blocks.
The original image encryption module 102 is configured to encrypt a plurality of the original image blocks by using a pre-constructed stream cipher and an exclusive-or encryption operation to obtain a corresponding number of encrypted image blocks.
The pixel difference calculating module 103 is configured to calculate a pixel difference of a diagonal pixel in the encrypted image block, divide the encrypted image block into a smooth image area and a complex image area according to the pixel difference, and embed a part of a pixel set in the private image into the smooth image area to obtain the private image area.
The privacy image embedding module 104 is configured to compress another part of the pixel set of the privacy image into the complex image area and the privacy image area according to a preset image compression rule.
The module in the device can be based on the privacy image encryption method when in use, the original image block is encrypted to obtain the encrypted image block, the privacy image is embedded into the encrypted image block to complete the privacy image encryption by calculating the pixel difference of the encrypted image block, and the same technical effects as those of the embodiment of the method can be achieved when the device is specifically operated, namely the problems of little encryption information quantity and low encryption security of the encrypted privacy image are effectively solved.
Fig. 7 is a schematic structural diagram of an electronic device for implementing the privacy image encryption method according to the present invention.
The electronic device 1 may comprise a processor 12, a memory 11 and a bus, and may further comprise a computer program stored in the memory 11 and executable on the processor 12.
The memory 11 includes at least one type of readable storage medium, including flash memory, a mobile hard disk, a multimedia card, a card memory (e.g., SD or DX memory, etc.), a magnetic memory, a magnetic disk, an optical disk, etc. The memory 11 may in some embodiments be an internal storage unit of the electronic device 1, such as a removable hard disk of the electronic device 1. The memory 11 may in other embodiments also be an external storage device of the electronic device 1, such as a plug-in mobile hard disk, a Smart Media Card (SMC), a Secure Digital (SD) Card, a Flash memory Card (Flash Card) or the like, which are provided on the electronic device 1. Further, the memory 11 may also include both an internal storage unit and an external storage device of the electronic device 1. The memory 11 may be used not only for storing application software installed in the electronic device 1 and various types of data, such as codes of a privacy image encryption program, but also for temporarily storing data that has been output or is to be output.
The processor 12 may be comprised of integrated circuits in some embodiments, for example, a single packaged integrated circuit, or may be comprised of multiple integrated circuits packaged with the same or different functions, including one or more central processing units (Central Processing unit, CPU), microprocessors, digital processing chips, graphics processors, combinations of various control chips, and the like. The processor 12 is a Control Unit (Control Unit) of the electronic device, connects respective components of the entire electronic device using various interfaces and lines, and executes various functions of the electronic device 1 and processes data by running or executing programs or modules (for example, executing a privacy image encryption program or the like) stored in the memory 11, and calling data stored in the memory 11.
The bus may be a peripheral component interconnect standard (peripheral component interconnect, PCI) bus or an extended industry standard architecture (extended industry standard architecture, EISA) bus, among others. The bus may be classified as an address bus, a data bus, a control bus, etc. The bus is arranged to enable a connection communication between the memory 11 and at least one processor 12 etc.
Fig. 7 shows only an electronic device with components, it being understood by a person skilled in the art that the structure shown in fig. 7 does not constitute a limitation of the electronic device 1, and may comprise fewer or more components than shown, or may combine certain components, or may be arranged in different components.
For example, although not shown, the electronic device 1 may further include a power source (such as a battery) for supplying power to each component, and preferably, the power source may be logically connected to the at least one processor 10 through a power management device, so that functions of charge management, discharge management, power consumption management, and the like are implemented through the power management device. The power supply may also include one or more of any of a direct current or alternating current power supply, recharging device, power failure detection circuit, power converter or inverter, power status indicator, etc. The electronic device 1 may further include various sensors, bluetooth modules, wi-Fi modules, etc., which will not be described herein.
Further, the electronic device 1 may also comprise a network interface, optionally the network interface may comprise a wired interface and/or a wireless interface (e.g. WI-FI interface, bluetooth interface, etc.), typically used for establishing a communication connection between the electronic device 1 and other electronic devices.
The electronic device 1 may optionally further comprise a user interface, which may be a Display, an input unit, such as a Keyboard (Keyboard), or a standard wired interface, a wireless interface. Alternatively, in some embodiments, the display may be an LED display, a liquid crystal display, a touch-sensitive liquid crystal display, an OLED (Organic Light-Emitting Diode) touch, or the like. The display may also be referred to as a display screen or display unit, as appropriate, for displaying information processed in the electronic device 1 and for displaying a visual user interface.
It should be understood that the embodiments described are for illustrative purposes only and are not limited to this configuration in the scope of the patent application.
The requested privacy image encryption program 12 stored in the memory 11 of the electronic device 1 is a combination of instructions that, when executed in the processor 10, may implement:
step one, acquiring an original image and a privacy image, and splitting the original image into a plurality of original image blocks.
The private image is an image which is unwilling to be disclosed externally for some reason, for example, company a purchases the core production technology of company B by huge capital, company B sends the core production technology picture to company a safely under the condition that the core production technology is not disclosed externally, and therefore the core production technology picture needs to be encrypted, wherein the core production technology picture is the private picture.
If the encryption operation is simply performed on the private picture, the encryption security is lower, so that the invention preferably obtains an encryption container first, and the security can be improved by embedding the private picture into the encryption container, wherein the encryption container can be a picture generally, namely, the original image described in S1, for example, the core production technology picture is the private picture, and the group photo picture of the company a high-level and the company B high-level is the original image.
In detail, the splitting the original image into a plurality of original image blocks includes: calculating the pixel arrangement specification of the original image, and splitting the original image according to the pixel arrangement specification of the original image to obtain a plurality of original image blocks.
In order to improve the security of the core production technology picture, the group photo picture is split into 2×2 original image blocks, i.e. each original image block includes 4 pixels, each pixel is arranged in a square form, and reference can be made to fig. 2 for the arrangement form of the 2×2 original image blocks, wherein the pixels of diagonal lines are marked with the same symbols, such as the symbols of circle centers and rectangles in fig. 2, respectively.
And secondly, encrypting the original image block by using a pre-constructed stream cipher and an exclusive-or encryption operation to obtain an encrypted image block.
In detail, the second step includes: and converting each pixel value in one group of diagonals of the original image block into an original fixed bit value, converting each pixel value in the other group of diagonals of the original image block into an original random bit value, and carrying out exclusive or encryption operation on each group of original fixed bit values and each group of original random bit values according to a stream cipher mode to obtain the encrypted image block.
Further, the conversion mode of converting the original fixed bit value is as follows:
wherein,,
representing pixels within the original image block, (x, y) representing positions of pixels within the original image block, i, j representing an index of the original image block, as the above-mentioned 2 x 2 original image block includes B in total i,j (0,0) ,B i,j (0,1) ,B i,j (1,0) And B i,j (1,1) Four pixels, B i,j (0,0) Representing pixels in the upper left corner of the 2 x 2 array, B i,j (1,1) Representing pixels at the lower right corner of the 2 x 2 arrangement, and B i,j (0,0) B i,j (1,1) Form diagonal pixels, and so on B i,j (0,1) ,B i,j (1,0) To form diagonal pixels +.>
The original fixed bit value into which a pixel within an original image block having coordinates (x, y) is converted is represented, and u represents the number of bits of the original fixed bit value, which is typically 8.
Such as B i,j (0,0) B i,j (1,1) Form diagonal pixels and select B i,j (0,0) ,B i,j (1,1) Two pixels being converted to original fixed bit values, u being fixed at 8, a further set of diagonal pixels B i,j (0,1) ,B i,j (1,0) Is converted into an original random bit value, wherein the original random bit value is uncertain in terms of u value, and the bits of the original random bit value are necessarily smaller than the bits of the original fixed bit value.
Thus, further, the conversion manner of the original random bit value is as follows:
where f is the bit of the original random bit value and f is less than u.
Further, the exclusive-or encrypting operation is performed on each set of the original fixed bit values and each set of the original random bit values to obtain an encrypted image block, which includes: according to the permutation and combination principle, performing exclusive or operation on each group of original fixed bit values and each group of original random bit values to obtain standard fixed bit values and primary random bit values, calculating bit difference values of the standard fixed bit values and the primary random bit values, filling the primary random bit values with a pre-built key according to the bit difference values to obtain standard random bit values, and collecting the standard fixed bit values and the standard random bit values to obtain the encrypted image block.
In detail, the exclusive-or operation is:
wherein,,
representing exclusive OR operation, ++>
Represents a standard fixed bit value or a primary random bit value, ψ 1 Representing the position and bit number of a pixel within an original fixed bit value, ψ 2 Representing the position and bit number of the pixel within the original random bit value.
The original image blocks of 2×2 as described above include B in total i,j (0,0) ,B i,j (0,1) ,B i,j (1,0) And B i,j (1,1) Four pixels, B i,j (0,0) ,B i,j (1,1) Conversion of two pixels to an original fixed bit value, B i,j (0,1) ,B i,j (1,0) Converted into original random bit values, and the original random bit values are subjected to exclusive OR operation by permutation and combination between every two i,j (0,0) ,B i,j (1,1) Two pixels being converted to standard fixed bit values, B i,j (0,1) ,B i,j (1,0) Converted into a primary random bit value, and the bit number of the standard fixed bit value is still 8, and the primary random bit valueThe bit number of the bit value is smaller than 8, if the bit number is 4, the bit difference value of the primary random bit value is 4, so that the remaining 4 bits of the primary random bit value need to be encrypted and filled, the invention uses a pre-built key to fill the remaining 4 bits of the primary random bit value, the key A i,j A binary random sequence can be used, and the padding method is as follows:
wherein,,
representing a bit-wise inverting operation, e.g. when f=7 +. >
Then take the inverse time according to the bit
Ψ 3 Representing the position of the pixel and the number of remaining bits, ψ, within the original random bit values 1 ,Ψ 2 ,Ψ 3 The relationship of the three is as follows:
Ψ 1 = { (x, y, u) | (x, y) ∈where the coordinates of a set of diagonal pixels and u=0, 1,2, …,7} ψ 2 = { (x, y, f) | (x, y) ∈where the coordinates of another set of diagonal pixels and f=0, 1,2, …, t }, where t < 7 ψ 3 = { (x, y, f) | (x, y) ∈where the coordinates of another set of diagonal pixels and f=t+1, t+2, …,7}, where t < 7
Further, the fixed bit values of each group of standards and the random bit values of each group of standards are collected to obtain encrypted image blocks, if the group photo pictures of the company A high layer and the company B high layer are split into 100 original image blocks, 100 encrypted image blocks can be obtained after calculation.
And thirdly, calculating pixel differences of diagonal pixels in the encrypted image block, dividing the encrypted image block into a smooth image area and a complex image area according to the pixel differences, and embedding a part of pixel sets in the privacy image into the smooth image area to obtain the privacy image area.
In detail, the calculating the pixel difference of the diagonal pixel in the encrypted image block divides the encrypted image block into a smooth image area and a complex image area according to the pixel difference, and includes: calculating pixel differences among standard random bit values in the encrypted image blocks, judging whether the pixel differences are larger than a preset pixel difference threshold, if the pixel differences are larger than the pixel difference threshold, the encrypted image blocks are complex image areas, and if the pixel differences are not larger than the pixel difference threshold, the encrypted image blocks are smooth image areas.
And (3) calculating the group photo pictures of the company A high layer and the company B high layer to obtain 100 encrypted image blocks, and respectively performing S3 operation on each encrypted image block to obtain 37 complex image areas and 63 smooth image areas.
Further, the embedding a part of the pixel set of the privacy image into the smooth image area to obtain the privacy image area includes: traversing out the standard random bit value in the smooth image area, and replacing the number of one bit of the standard random bit value in the smooth image area by a part of pixel sets in the privacy image until the replacement is completed to obtain the privacy image area.
Preferably, the number of replacing one bit is generally the bit where the pre-constructed key pad is located, and as above, the 63 smooth image areas are obtained, 2 standard random bit values are traversed for the first smooth image area, and the number of bits of each standard random bit value is 8, wherein the highest 4 bits are obtained through the pad in the second step, so that one bit is selected to be replaced in the highest 4 bits, such as selecting the highest bit to replace the pixel value of the core production technology picture.
And fourthly, compressing the other part of the pixel set of the privacy image to the complex image area and the privacy image area according to a preset image compression rule.
In detail, the compressing the other part of the pixel set of the privacy image into the complex image area and the privacy image area includes: extracting all standard random bit values of the complex image area and the privacy image area to obtain a standard random bit value group, constructing a binary matrix according to the standard random bit value group, compressing the binary matrix to obtain a fillable bit number, and filling the other part of the pixel set of the privacy image into the fillable bit number.
If the standard random bit values are extracted from the 37 complex image areas and the 63 private image areas, the bit values of 0-t bits in the standard random bit values in the 37 complex image areas and the 63 private image areas are preferably extracted according to the second step, and the bit values of 0-t bits are divided into k groups, wherein each group is v (1, q 1 ),v(2,q 2 ),…v(i,q i ),…,v(k,q k )，q i Representing the number of bit values included in the i-th group.
Further, the binary matrix is:
M＝[I,Q]
wherein M is the binary matrix, I is the identity matrix of the binary matrix, and Q is the random binary matrix.
The compression formula for compressing the binary matrix to obtain the bit number of the fillable bits is as follows:
Wherein s is the number of bits of the fillable bit.
And fifthly, receiving a decryption key, and judging whether the decryption key is an original image decryption key or not.
And step six, if the decryption key is an original image decryption key, decrypting according to the original image decryption key to obtain the original image.
In detail, if the decryption key is the original image decryption key, the decryption is performed reversely according to the encryption process of the second step, but since the exclusive or operation is performed on the original image in the second step, and when the privacy image is embedded, a part of the pixel set of the privacy image is used to replace the number of a part of bits in the original image, so that when the original image is decrypted, the restored image is an approximate image of the original image.
Preferably, the method of recovering and replacing the number of the partial bit in the original image can adopt an eight-neighborhood pixel average value method, namely, eight pixel values adjacent to the replaced pixel are selected from the original image, and the average value of the eight pixel values is taken as the pixel value of the replaced pixel.
And step seven, if the decryption key is a private image decryption key, decrypting according to the private image decryption key to obtain the private image.
If the decryption key is a private image decryption key, searching a smooth image area according to the pixel difference threshold value in the third step, restoring the replaced pixel value in the smooth image area, and so on, restoring the pixel value according to the compressed bit value in the binary matrix, and further obtaining the private image.
In the several embodiments provided in the present invention, it should be understood that the disclosed apparatus, device and method may be implemented in other manners. For example, the above-described apparatus embodiments are merely illustrative, and for example, the division of the modules is merely a logical function division, and there may be other manners of division when actually implemented.
The modules described as separate components may or may not be physically separate, and components shown as modules may or may not be physical units, may be located in one place, or may be distributed over multiple network units. Some or all of the modules may be selected according to actual needs to achieve the purpose of the solution of this embodiment.
In addition, each functional module in the embodiments of the present invention may be integrated in one processing unit, or each unit may exist alone physically, or two or more units may be integrated in one unit. The integrated units can be realized in a form of hardware or a form of hardware and a form of software functional modules.
It will be evident to those skilled in the art that the invention is not limited to the details of the foregoing illustrative embodiments, and that the present invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof.
The present embodiments are, therefore, to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein. Any reference signs in the claims shall not be construed as limiting the claim concerned.
Furthermore, it is evident that the word "comprising" does not exclude other elements or steps, and that the singular does not exclude a plurality. A plurality of units or means recited in the system claims can also be implemented by means of software or hardware by means of one unit or means. The terms second, etc. are used to denote a name, but not any particular order.
Finally, it should be noted that the above-mentioned embodiments are merely for illustrating the technical solution of the present invention and not for limiting the same, and although the present invention has been described in detail with reference to the preferred embodiments, it should be understood by those skilled in the art that modifications and equivalents may be made to the technical solution of the present invention without departing from the spirit and scope of the technical solution of the present invention.
Claims (8)
1. A method of encrypting a private image, the method comprising:
splitting an original image into a plurality of original image blocks;
encrypting a plurality of original image blocks by using a pre-constructed stream cipher and exclusive-or encryption operation to obtain a corresponding number of encrypted image blocks;
calculating pixel differences of diagonal pixels in the encrypted image block, dividing the encrypted image block into a smooth image area and a complex image area according to the pixel differences, and embedding a part of pixel sets in a privacy image into the smooth image area to obtain the privacy image area;
compressing the other part of the pixel sets of the privacy image into the complex image area and the privacy image area according to a preset image compression rule;
the embedding a part of the pixel set of the privacy image into the smooth image area to obtain the privacy image area comprises the following steps: traversing out standard random bit values within the smooth image region; replacing the value of one bit in the standard random bit values in the smooth image area by a part of pixel sets in the privacy image until the privacy image area is obtained after the replacement is completed; the standard random bit value is obtained by filling the primary random bit value with a pre-built key according to a bit difference value of the standard fixed bit value and the primary random bit value;
The compressing the other part of the pixel set of the privacy image to the complex image area and the privacy image area according to a preset image compression rule comprises the following steps: extracting all standard random bit values of the complex image area and the privacy image area to obtain a standard random bit value group; constructing a binary matrix according to the standard random bit value group; compressing the binary matrix to obtain a bit number capable of being filled, and filling another part of the pixel set of the privacy image into the bit number capable of being filled.
2. The method according to claim 1, wherein encrypting the plurality of original image blocks using a pre-constructed stream cipher and exclusive or encryption operation to obtain a corresponding number of encrypted image blocks comprises:
converting each pixel value within one set of diagonals of the original image block to an original fixed bit value;
converting each pixel value within another set of diagonals in the original image block to an original random bit value;
and performing exclusive or encryption operation on the original fixed bit value and the original random bit value according to a stream cipher mode to obtain an encrypted image block.
3. The method for encrypting a private image according to claim 2, wherein said exclusive-or encrypting the original fixed bit value and the original random bit value results in an encrypted image block, comprising:
according to the permutation and combination principle, performing exclusive OR operation on the original fixed bit value and the original random bit value to obtain a standard fixed bit value and a primary random bit value;
calculating a bit difference value of the standard fixed bit value and the primary random bit value;
and filling the primary random bit value with a pre-built key according to the bit difference value, and collecting the standard fixed bit value and the standard random bit value to obtain the encrypted image block.
4. A method of encrypting a private image according to claim 3, wherein said calculating pixel differences for diagonal pixels within said encrypted image block, dividing said encrypted image block into a smooth image region and a complex image region based on said pixel differences, comprises:
calculating pixel differences between standard random bit values within the encrypted image block;
judging whether the pixel difference is larger than a preset pixel difference threshold value or not;
And if the pixel difference is not greater than the pixel difference threshold, the encrypted image block is a smooth image area.
5. The privacy image encryption method of claim 1, further comprising:
receiving a decryption key and judging the category of the decryption key;
if the decryption key is an original image decryption key, decrypting according to the original image decryption key to obtain the original image;
and if the decryption key is a private image decryption key, decrypting according to the private image decryption key to obtain the private image.
6. A privacy image encrypting apparatus, the apparatus comprising:
the original image splitting module is used for splitting an original image into a plurality of original image blocks;
the original image encryption module is used for encrypting a plurality of original image blocks by using a pre-constructed stream cipher and exclusive OR encryption operation to obtain a corresponding number of encrypted image blocks;
the pixel difference calculating module is configured to calculate a pixel difference of a diagonal pixel in the encrypted image block, divide the encrypted image block into a smooth image area and a complex image area according to the pixel difference, and embed a part of a pixel set in a privacy image into the smooth image area to obtain the privacy image area, and includes: traversing out standard random bit values within the smooth image region; replacing the value of one bit in the standard random bit values in the smooth image area by a part of pixel sets in the privacy image until the privacy image area is obtained after the replacement is completed; the standard random bit value is obtained by filling the primary random bit value with a pre-built key according to a bit difference value of the standard fixed bit value and the primary random bit value;
The privacy image embedding module is configured to compress, according to a preset image compression rule, another part of the pixel set of the privacy image into the complex image area and the privacy image area, and includes: extracting all standard random bit values of the complex image area and the privacy image area to obtain a standard random bit value group; constructing a binary matrix according to the standard random bit value group; compressing the binary matrix to obtain a bit number capable of being filled, and filling another part of the pixel set of the privacy image into the bit number capable of being filled.
7. An electronic device, the electronic device comprising:
at least one processor; the method comprises the steps of,
a memory communicatively coupled to the at least one processor; wherein,,
the memory stores instructions executable by the at least one processor to enable the at least one processor to perform the privacy image encryption method of any one of claims 1 to 5.
8. A computer readable storage medium storing a computer program, wherein the computer program when executed by a processor implements the privacy image encryption method according to any one of claims 1 to 5.
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