CN104269150B - The secret protection display of a kind of view-based access control model password realizes method - Google Patents

The secret protection display of a kind of view-based access control model password realizes method Download PDF

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CN104269150B
CN104269150B CN201410542752.0A CN201410542752A CN104269150B CN 104269150 B CN104269150 B CN 104269150B CN 201410542752 A CN201410542752 A CN 201410542752A CN 104269150 B CN104269150 B CN 104269150B
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interface card
liquid crystal
display interface
module
crystal layer
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CN201410542752.0A
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CN104269150A (en
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刘峰
郭腾
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中国科学院信息工程研究所
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Abstract

The present invention relates to the secret protection display of a kind of view-based access control model password and realize method; a preset Pseudo-Random Number PRNG between encrypting module 1 and encrypting module 2; configure module by viewing area and the distance parameter between two liquid crystal layers is set as d; thus controlling the size of viewing area, two are shown, and in interface card, the refreshing frequency of screen is configured to 60Hz.Selected common browse mode or privacy browse mode by security configuration module, after being completed by above-mentioned deployment, the secret protection display of view-based access control model password gets final product normal operation.The present invention can realize the dual purpose preventing taking and prevent electromagnetic leakage on the sly, and it will not reduce the brightness of screen, and without increasing radiation in large quantities, its cost is also much lower than building screened room.

Description

The secret protection display of a kind of view-based access control model password realizes method

Technical field

The present invention relates to the secret protection display of a kind of view-based access control model password and realize method; belong to safe Display Technique field; the superposition of two liquid crystal layers particularly relating to view-based access control model password is analyzed with viewing area; this technology is applicable to concerning security matters occasion; prevent the content on display from not peeped by side by other people, it may have the advantage of electromagnetic leakage.

Background technology

In computer systems, display device is the important channel that user obtains information.And general display devices foregoing is easy to be peeped from the side by other people, thus causing the leakage of sensitive information.Therefore, the secret protection display that design viewing area is controlled, thus realizing the safeguard protection of content on display device is an important research contents.

Along with technological and manufacturing level constantly improves, the volume of minisize pick-up head is more and more less, and should not discover, and the phenomenon that use minisize pick-up head steals secret information is also increasingly general.Consider that current minisize pick-up head is of a great variety, with low cost, all it is widely used in a lot of occasions, the threat getting rid of concealed camera needs to expend concerning security matters personnel's great effort.The existing method preventing minisize pick-up head from stealing secret information includes, over the display attached one layer of anti-peeping film, and this method is simple, but a disadvantage is that and can cause that screen is dimmed, thus affecting the visual effect of viewing.

In computer systems, computer video signal contains abundant useful information, in transmitting procedure, drives electric current big, and more than cruelly blank, emittance is big, it is easy to is trapped and restores, and its electromagnetic leakage of main red signal is the serious threat of information security.Abroad special steal receiving unit can from several meters to tens meters, steal and receive reduction and be equipped with the desktop computer of liquid crystal display and the video information of notebook computer.The measure of existing anti-electromagnetic radiation includes installing video information interference unit additional and building screened room to process classified information.Wherein installing the video information interference unit designed for liquid crystal display and notebook computer additional, generally have deployment difficulty, Health cost is big, the shortcoming that protection effect is low.Building screened room then to involve great expense, every square meter cost several ten thousand to hundreds of thousands not etc., and then reduces the convenience that confidential data is read.

At present, processing of China's security information generally adopts the method for simple physical isolation and the method for information one-way flow, although reduces the risk of secret information leakage, but brings inconvenience also to the Working Life of reality.When concerning security matters personnel consult secrecy message, usually dare not obtain security information by the computer (computer under the threat of electromagnetic leakage and concealed camera) of non-trusted owing to worrying to divulge a secret.And anti-means of stealing secret information that classified document is checked are numerous and diverse and fragile, it does not have ageing (when especially receiving provisional orders).These all can affect abroad and process the efficiency of security information under other non-trusted environment, even at crucial moment, owing to formality is numerous and diverse and lose opportunity of combat, cause serious consequence.And secret protection display can reduce the threat of concealed camera and the risk of electromagnetic leakage, also provide facility for consulting of classified document.

Visual cryptography is proposed ([1] M.Naor by document [1], A.Shamir, VisualCryptography, EUROCRYPT'94, Springer-VerlagBerlin, LNCS950, pp.1-12,1995.), a Secret Image can be decomposed into two parts, accidental enciphering image and random factor image by it.Owing to image is encrypted by random factor, any one part does not comprise the information in Secret Image.But, when two part physical alignment cover, secret picture just can be reconstructed.

Patent documentation [2] proposes a kind of method ([2] G.J.Schrijen utilizing visual cryptography to carry out reconstructing image information, P.T.Tuyls, T.A.M.Kevenaar, M.T.Johnson, SecureVisualMessageCommunicationMethodAndDevice.Patentwi thInternationalApplicationNo.:PCT/IB2003/000261,2003.), which employs the vision reconfiguration technique proposed in document [1].The method first passes through visual cryptography and black and white secret picture is decomposed into two parts, and one of them part shows on the first liquid crystal layer, and another part shows on the second liquid crystal layer.First liquid crystal layer is filled with by common computer, and the second liquid crystal layer is then filled with by a credible equipment.Therefore, even if this computer is controlled by potential attacker, the second liquid crystal layer that credible equipment controls has still ensured that the privacy of display information on screen.It is pointed out that this patented method is only applicable to black and white picture, and it is more four times greater than original private image to reconstruct image.

Present invention employs vision reconfiguration technique ([3] P.Tuyls proposed in document [3], H.D.L.Hollmann, J.H.VanLint, L.Tolhuizen, XOR-basedVisualCryptographySchemes, Designs, CodesandCryptography, Vol.37, pp.169 186,2005.), wherein reconstruct image is the same with original private image big.Different from patent documentation [2], the present invention is absorbed in portraying of viewing area so that Secret Image only can be clearly visible that by people in viewing area, will be unable to see secret information in not visible region.By regulating the size of viewing area, it is possible to reduce and peeped by other people or the risk of concealed camera shooting secret information.Additionally, due to the ELECTROMAGNETIC RADIATION SIGNATURE between two liquid crystal layers can interfere with each other, this has been greatly reduced the risk of classified information electromagnetic leakage.

Summary of the invention

The technology of the present invention solves problem;For existing safe Display Technique preventing the technology of taking on the sly and preventing the problem that electromagnetic leakage technology reduces screen intensity, radiation is big, Health cost is big and involves great expense; the secret protection display providing a kind of view-based access control model password realizes method; the dual purpose preventing taking and prevent electromagnetic leakage on the sly can be realized; and it will not reduce the brightness of screen; without increasing radiation in large quantities, its cost is also much lower than building screened room.

The technical scheme is that the secret protection display of a kind of view-based access control model password realizes method, described secret protection display includes: the first encrypting module, the second encrypting module, synchronised clock module, security configuration module, viewing area configuration module, the first display interface card, the second display interface card, the first liquid crystal layer and the second liquid crystal layer;Wherein security configuration module accepts the configuration information of user, and shows that interface card sends the control signal closed or open to first, sends encryption or the control signal do not encrypted to the second encrypting module simultaneously;Viewing area configuration module accepts the configuration information of user, and controls the physical distance between the first liquid crystal layer and the second liquid crystal layer according to this;Synchronised clock module does not input, and exports the first encrypting module and the second encrypting module its clock signal synchronization sent;The output of the first encrypting module is as the first input showing interface card, and the output of the first display interface card inputs as the first liquid crystal layer;The output of the second encrypting module is as the second input showing interface card, and the output of the second display interface card inputs as the second liquid crystal layer;First liquid crystal layer is arranged on screen by inner position, and the second liquid crystal layer is substantially parallel with it, and is arranged on the position that screen is outer;Described secret protection display has two kinds of mode of operations: common browse mode and privacy browse mode, and security configuration module is used for controlling to select common browse mode or privacy browse mode;Wherein the operation principle of common browse mode and general display is identical, and privacy browse mode then can control the size of viewing area by configuring the distance parameter d between the first liquid crystal layer and the second liquid crystal layer, and d is more big, then viewing area is more little;The each preset Pseudo-Random Number PRNG of difference inside the first encrypting module and the second encrypting module, synchronised clock module is as a standalone module, to the first encrypting module and the second encrypting module tranmitting data register signal;Wherein secret protection display job step under privacy browse mode includes:

(1) synchronised clock module tranmitting data register signal CLK to first encrypting module and the second encrypting module;

(2) input using clock signal clk as Pseudo-Random Number PRNG on the first encrypting module, is designated as S by the output of Pseudo-Random Number PRNG1, wherein, the first display interface card S the most at last1Being shown on the first liquid crystal layer, the input of a regular length is elongated the output sequence of the approximate random being an index length by Pseudo-Random Number PRNG;Existing a lot of technology can realize PRNG at present: stream cipher arithmetic Rabbit, Salsa20/12, Grainv1 and linear shift register etc..

(3) first encrypting modules are by image S1Send to the first display interface card;

(4) input using clock signal clk as Pseudo-Random Number PRNG on the second encrypting module, is designated as R by the output of Pseudo-Random Number PRNG, then calculates S for each sub-pixel on the second encrypting module2[i]=255m [i]/R [i], 255m [i] represent that 255 are multiplied by numerical value m [i], and/represent division, wherein, the second display interface card S the most at last2Being shown on the second liquid crystal layer, i represents image S2, image m and the position of pixel on random image R;S2[i] represents image S2The pixel value of upper ith pixel, it is the random number of 8 bit long, between 0 to 255;M [i] represents the pixel value of ith pixel on image m, and it is the numerical value of 8 bits, between 0 to 255;R [i] represents the pixel value of ith pixel on random image R, and it is the numerical value of 8 bits, between 0 to 255;

(5) described second encrypting module is by image S2Send to the second display interface card;

(6) described first display interface card is according to image S1Control the content on the first liquid crystal layer;

(7) described second display interface card is according to image S2Control the content on the second liquid crystal layer;

(8) namely user can be observed to need the image m of display in viewing area, in not visible region then not it is observed that any significant information.

Job step under common browse mode includes:

(1) the first display interface card is closed, so that the first liquid crystal layer is in complete light transmission state;

(2) synchronised clock module and the first encrypting module are closed;

Image m is directly sent to the second display interface card by (3) second encrypting modules;

(4) second display interface cards control the content on the second liquid crystal layer according to sending the image information come;

(5) user with use that ordinary screen is the same observes image m.

Described clock signal clk is the clock information that precision is higher than millisecond.

Described first display interface card and second display interface card video memory bandwidth reach 2.2GB/s and more than, thus two display interface cards can process the data sent here in time.

In described first display interface card and the second display interface card the refreshing frequency of screen be configured to 60Hz and more than, thus the refreshing flicker on the imperceptible screen of user.

According to the resolution of actual screen in the first display interface card and the second display interface card, the output bit length of selected Pseudo-Random Number PRNG is different.

Present invention advantage compared with prior art is in that:

(1) brightness of screen is not affected, and existing anti-peeping membrane technology, can cause that screen is dimmed, thus affecting the visual effect of viewing.

(2) size of viewing area can be adjusted by configuring distance parameter d, and in existing anti-peeping membrane technology, the size of viewing area is fixing.

(3) by the electromagnetic interference between two liquid crystal layers, it is achieved that the function of anti-electromagnetic exposure, to build screened room technology much lower than existing for its cost.

(4) owing to merely add a liquid crystal layer, in the present invention, amount of radiation increases little, will health environment-friendly more than existing forceful electric power magnetic source perturbation technique.

Accompanying drawing explanation

Fig. 1 is the workflow block diagram of security display.

Fig. 2 is the viewing area principle schematic of security display.

Fig. 3 is a simplified example of security display.

Fig. 4 is the displaying principle schematic diagram of single pixel in security display.

Fig. 5 is the arrangement mode of standard RGB screen sub-pixel, for instance: LGP880, Fructus Mali pumilae iphone4/4s etc..

Table 1 is that horizontal-shift angle [alpha] is how many times under different liquid crystal display screen spacing d, and sub-pixel is just to superposition area exactly 0;Offset of vertical angle beta is how many times, and sub-pixel is just to superposition area exactly 0.

Detailed description of the invention

The present invention, in specific implementation process, because the output of PRNG is a secondary image being full of screen in Fig. 1, so requiring that the computational efficiency of this PRNG is significantly high, generally can choose stream cipher arithmetic and realizing, for instance: Rabbit, Salsa20/12, Grainv1 etc..Secondly, it is necessary to reference to viewing area allocation list, i.e. table 1, configure the distance parameter d between two liquid crystal layers in Fig. 1, thus controlling the size of viewing area in Fig. 2, i.e. the size of visual deviation angle (α, β).

Table 1

Embodiment 1: using stream cipher arithmetic Rabbit as the standard RGB screen security display of the parameter d=2 of PRNG in Fig. 1, wherein the arrangement of RGB sub-pixel is as it is shown in figure 5, screen size is 1280 × 1024, and pixel color is very color 24 bits.In Fig. 1 two are shown, and in interface card, the refreshing frequency of screen is configured to 60Hz, selects privacy browse mode by security configuration module in Fig. 1, by viewing area configuration module in Fig. 1, the distance between two liquid crystal layers is set to 2 pixel length of sides.In Fig. 1, the specific works flow process of modules is in this operating mode:

(1) the random initial vector IV of preset 64 bits between encrypting module 1 and encrypting module 2;

(2) synchronised clock module sends 72 bit clock signal CLK (time: point: second: millisecond) to encrypting module 1 and encrypting module 2;

(3) first this clock signal clk is elongated 128 bits by Reed-solomom error correcting code by encrypting module 1, is designated as RS [CLK];

(4) encrypting module 1 is using RS [CLK] as key, encrypts preset initial vector IV, obtains an output bit sequence, takes its front 1280 × 1024 × 24 bits as S1, then by S1Send to display interface card 1;

(5) first this clock signal clk is elongated 128 bits by Reed-solomom error correcting code by encrypting module 2, is designated as RS [CLK];

(6) encrypting module 2 is using RS [CLK] as key, encrypts preset initial vector IV, obtains an output bit sequence, takes its front 1280 × 1024 × 24 bits as ST, then by m and STRegard two sequences that 8 bit integer are constituted as, and each 8 bit sub-pixels are calculated S2[i]=255m [i]/ST[i], wherein 1≤i≤1280 × 1024 × 3;Afterwards by S2Send to display interface card 2;

(7) display interface card 1 is according to S1Control the display of content on liquid crystal layer 1;

(8) display interface card 2 is according to S2Control the display of content on liquid crystal layer 2;

(9) namely user can be observed image m in viewing area, then not it is observed that significant information in not visible region.

Concrete analysis result for this embodiment is given below: note screen level direction is x, and vertical direction is y, and vertical outwardly direction is z, and the length and width of pixel are 1, and the distance between two liquid crystal layers is d length in pixels.Observer from z angle observe time, the entire area of pixel is just to superposition, and contrast is 1;When observer deviates the α angle observation of z direction in the x direction, pixel has area of (1-3d tan α) part just to superposition;When observer deviates the β angle observation of z direction in y-direction, pixel has area of (1-d tan β) part just to superposition;When observer deviates z direction α angle in the x direction and deviates the β angle observation of z direction in y-direction, pixel has area of (1-3d tan α) (1-d tan β) part just to superposition.

For identical deviation angle (α, β), the distance d between two liquid crystal layers is more big, then just that the area of superposition is more little, visual quality is more poor, and viewing area is more little.For the distance d between two identical liquid crystal layers, deviation angle (α, β) is more big, then just that the area of superposition is more little, visual quality is more poor, and viewing area is more little.The angle deviateed in the x direction is bigger on the impact of visual quality.

Fig. 3 illustrates the simplified example of 3 × 3 block of pixels encryption process on original private picture, and wherein 0 represents a white pixel, and namely rgb value is the pixel of (255,255,255);And 1 represents a black pixel, namely rgb value is the pixel of (0,0,0).First, each pixel is broken down into two pixels, and by first, one of them pixel shows that interface card controls, and be shown on the first liquid crystal layer, and by second, one other pixel shows that interface card controls, and is shown on the second liquid crystal layer.Then, subscriber station just to position, namely during deviation angle (α=0, β=0), it was observed that screen content be shown in Fig. 3 screen output.

Fig. 4 illustrates the displaying principle of single pixel in security display, and wherein optical filter ensure that only have HONGGUANG to pass through in Zone R territory, only has green glow to pass through in G region, only has blue light to pass through in B region.First, each color component in secret pixel is encrypted to two parts, and is respectively displayed on two liquid crystal layers.Then, subscriber station just to position, namely during deviation angle (α=0, β=0), it was observed that pixel content be the display pixel shown in Fig. 4.

Fig. 5 illustrates in standard RGB screen the spatial relation of four square pixel in 2 × 2 block of pixels, and each square pixel is comprised the spatial relation of three RGB rectangle sub-pixels, wherein each sub-pixel occupies a length-width ratio is the coffin of 1:3, and three sub-pixels are arranged in order according to the order of RGB.

There is provided above example to be only used to describe the purpose of the present invention, and be not intended to limit the scope of the present invention.The scope of the invention limits.The various equivalent alterations and modifications made without departing from spirit and the principle of the present invention, all should contain within the scope of the present invention.

Claims (6)

1. the secret protection display of a view-based access control model password realizes method, it is characterised in that: described secret protection display includes: the first encrypting module, the second encrypting module, synchronised clock module, security configuration module, viewing area configuration module, the first display interface card, the second display interface card, the first liquid crystal layer and the second liquid crystal layer;Wherein security configuration module accepts the configuration information of user, and shows that interface card sends the control signal closed or open to first, sends encryption or the control signal do not encrypted to the second encrypting module simultaneously;Viewing area configuration module accepts the configuration information of user, and controls the physical distance between the first liquid crystal layer and the second liquid crystal layer according to this;Synchronised clock module does not input, and exports the first encrypting module and the second encrypting module its clock signal synchronization sent;The output of the first encrypting module is as the first input showing interface card, and the output of the first display interface card inputs as the first liquid crystal layer;The output of the second encrypting module is as the second input showing interface card, and the output of the second display interface card inputs as the second liquid crystal layer;First liquid crystal layer is arranged on screen by inner position, and the second liquid crystal layer is substantially parallel with it, and is arranged on the position that screen is outer;Described secret protection display has two kinds of mode of operations: common browse mode and privacy browse mode, and security configuration module is used for controlling to select common browse mode or privacy browse mode;Wherein the operation principle of common browse mode and general display is identical, and privacy browse mode then controls the size of viewing area by configuring the distance parameter d between the first liquid crystal layer and the second liquid crystal layer, and d is more big, then viewing area is more little;The each preset Pseudo-Random Number PRNG of difference inside the first encrypting module and the second encrypting module, synchronised clock module is as a standalone module, to the first encrypting module and the second encrypting module tranmitting data register signal;Wherein secret protection display job step under privacy browse mode includes:
(1) synchronised clock module tranmitting data register signal CLK to first encrypting module and the second encrypting module;
(2) input using clock signal clk as Pseudo-Random Number PRNG on the first encrypting module, is designated as S by the output of Pseudo-Random Number PRNG1, wherein, the first display interface card S the most at last1Being shown on the first liquid crystal layer, the input of a regular length is elongated the output sequence of the approximate random being an index length by Pseudo-Random Number PRNG;
(3) first encrypting modules are by image S1Send to the first display interface card;
(4) first, input using clock signal clk as Pseudo-Random Number PRNG on the second encrypting module, the output of Pseudo-Random Number PRNG is designated as R, then on the second encrypting module, S is calculated for each sub-pixel2[i]=255m [i]/R [i], 255m [i] represent that 255 are multiplied by numerical value m [i], and/represent division, the second last display interface card S the most at last2Being shown on the second liquid crystal layer, i represents image S2, image m and the position of pixel on random image R;S2[i] represents image S2The pixel value of upper ith pixel, it is the random number of 8 bit long, between 0 to 255;M [i] represents the pixel value of ith pixel on image m, and it is the numerical value of 8 bits, between 0 to 255;R [i] represents the pixel value of ith pixel on random image R, and it is the numerical value of 8 bits, between 0 to 255;
(5) described second encrypting module is by image S2Send to the second display interface card;
(6) described first display interface card is according to image S1Control the content on the first liquid crystal layer;
(7) described second display interface card is according to image S2Control the content on the second liquid crystal layer;
(8) namely user can be observed to need the image m of display in viewing area, in not visible region then not it is observed that any significant information.
2. the secret protection display of view-based access control model password as claimed in claim 1 realizes method, it is characterised in that: the job step under common browse mode includes:
(1) the first display interface card is closed, so that the first liquid crystal layer is in complete light transmission state;
(2) synchronised clock module and the first encrypting module are closed;
Image m is directly sent to the second display interface card by (3) second encrypting modules;
(4) second display interface cards control the content on the second liquid crystal layer according to sending the image information come;
(5) user with use that ordinary screen is the same observes image m.
3. the secret protection display of view-based access control model password as claimed in claim 1 or 2 realizes method, it is characterised in that: described clock signal clk is the clock information that precision is higher than millisecond.
4. the secret protection display of view-based access control model password as claimed in claim 1 or 2 realizes method; it is characterized in that: described first display interface card and second display interface card video memory bandwidth reach 2.2GB/s and more than, thus two display interface cards can process the data sent here in time.
5. the secret protection display of view-based access control model password as claimed in claim 1 or 2 realizes method; it is characterized in that: described first display interface card and in the second display interface card the refreshing frequency of screen be configured to 60Hz and more than, thus the refreshing flicker on the imperceptible screen of user.
6. the secret protection display of view-based access control model password as claimed in claim 1 realizes method; it is characterized in that: according to the resolution of actual screen in the first display interface card and the second display interface card, the output bit length of selected Pseudo-Random Number PRNG is different.
CN201410542752.0A 2014-10-14 2014-10-14 The secret protection display of a kind of view-based access control model password realizes method CN104269150B (en)

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