CN106650343A - DEM scrambling encryption and restoration method - Google Patents

Abstract

The invention discloses a DEM scrambling encryption and restoration method. The method specifically comprises the first step of generating a three-dimensional chaos sequence according to a chaos sequence secret key; the second step of conducting scrambling encryption operation on an elevation value of each point in the DEM through the generated chaos sequence, that is, conducting elevation scrambling encryption; the third step of conducting scrambling on the position of each point of the DEM through the generated chaos sequence after each point of the DEM is subjected to encryption. According to the DEM scrambling encryption and restoration method, a three-dimensional chaos technology is adopted to conduct scrambling on a header file, the elevation and the position respectively, so that the scrambling encryption and restoration aimed at the DEM is formed, and the problem of safety of geographic information in the links of secure transmission and encapsulation storage of the DEM data can be effectively solved.

Description

A kind of DEM scrambling encryptions and method of reducing

Technical field

The invention belongs to field of geographic information safety, and in particular to one kind enters line shuffle based on three-dimensional chaos sequence pair DEM Method of the encryption with reducing.

Background technology

DEM (Digital Elevation Model, i.e. digital elevation model), is represented with one group of orderly array of values A kind of actual ground model of ground elevation value.Because DEM describes ground elevation information, it mapping, the hydrology, meteorology, The national economy such as landforms, geology, soil, engineering construction, communication, military affairs and national defense construction and humane and natural science field have And be widely applied.DEM, as a kind of Fundamental Geographic Information System resource, is mapping with important military value and economic worth Department and the focused protection object using unit, it is necessary to carry out scrambling encryption operation in transmission and storing process.

For a long time, it is very few for the Encryption Technology Research of DEM, and focus primarily upon using the general of conventional flow file Encryption method is encrypted.This simple and crude encryption method, had both broken the ring basic structure of file, and easily caused data The interest of code breaker.Therefore in the urgent need to researching and developing a kind of safe, good concealment DEM scrambling encryptions and method of reducing.

The content of the invention

It is an object of the present invention to overcome the defect that prior art is present, there is provided a kind of DEM scrambling encryptions and reduction side Method, using three-dimensional chaos technology, respectively by header file scramble, to elevation scramble and to position scramble, being formed for DEM's Scrambling encryption with reduction, can effectively solving dem data safe transmission with encapsulation storage link in geography information safety problem.

To achieve these goals, the technical scheme that the present invention takes is as follows：

First, the scrambling encryption method of DEM, its step is as follows：

Step 1：Based on ArcMap softwares, by ArcToolbox->Crossover tool->Produced by grid->Grid turns ASCII is operated, and the dem data of Esri Grid forms is converted into into the txt file of ASCII codings.

Step 2：Txt file is stored in one M × N matrix A with behavior main sequence, wherein M is the line number of DEM, N is DEM's Columns, and the Pixel size cellsize of DEM is read out from the header file of DEM, upper left corner x origin coordinates xllcorner and Upper left corner y origin coordinates yllcorner.

Step 3：Input x₁、y₁、z₁As the initial value of chaos system, and x₁∈ (0,1), y₁∈ (0,1), z₁∈(0,1).It is defeated Enter the value of scramble factor ρ, and ρ ∈ [1,1000].The value of defined parameters σ, and σ ∈ (0,1).

Step 4：According to formula (1), chaos sequence X, Y and Z are generated；Wherein X={ x_k| k=1,2,3 ..., max { M+N+ 13,10000 } }, Y={ y_k| k=1,2,3 ..., max { M+N+13,10000 } }, Z={ z_k| k=1,2,3 ..., max { M+N+ 13,10000 } }；

Step 5：Obtain sequence S, J, Q, J ', Q ', I and T.Wherein S is the sequence for treating to be carried out with Z xor operation.J, Q are right Line number carries out the sequence of position shuffle operation.J ', Q ' are the sequence that position shuffle operation is carried out to row number.I and T are that Z values are entered Line position puts the sequence of shuffle operation.

Step 5.1, according to formula (2) and (3), nonlinear discretization, formation sequence S, S={ s is carried out to chaos sequence Z_k | k=1,2,3 ..., M+N+13 }；

Step 5.2, if the subset X ' of chaos sequence X={ x₁, x₂, x₃..., x₁₀₀₀₀Call number sequence 1,2,3 ..., 10000 } it is sequence J；By constituent element (x_n, j_n) with x_nAscending sort is carried out for primary key, sequence J after sequence is designated as into sequence Row Q.

Step 5.3, if the subset Y '={ y of chaos sequence Y₁, y₂, y₃..., y₁₀₀₀₀Call number sequence 1,2,3 ..., 10000 } it is sequence J '；By constituent element (y_n, j_n') with y_nAscending sort is carried out for primary key, the sequence J ' after sequence is designated as Sequence Q '.

Step 5.4, if the subset Z '={ z of chaos sequence Z₁, z₂, z₃..., z₁₀₀₀₀Call number sequence 1,2,3 ..., 10000 } it is sequence I；By constituent element (z_n, i_n) with z_nAscending sort is carried out for primary key, sequence I after sequence is designated as into sequence Row T.

Step 6：Line shuffle is entered to the header file of dem data

Operation is encrypted to cellsize, xllcorner and yllcorner according to formula (4), encryption data is obtained s_cellsize、s_xllcornerAnd s_yllcorner；

Step 7：Elevation scramble is carried out to matrix A according to sequence S, T

Step 7.1, by height value C of any of matrix A_mnSwitch to the binary number representation of 14, wherein m and n is correspondence Line number and row number；m∈[1,M],n∈[1,N].

Step 7.2, if m+n is odd number, first by C_mnLow 7 swap with high 7；It is constant if m+n is even number； Choose the one 14 seat sequence { s of S_m+n,s_m+n+1,s_m+n+2,…,s_m+n+13Step-by-step and C_mnXOR.

Step 7.3, is converted into the result after XOR decimal number and represents, the height value C ' after being changed_mn。

Step 7.4, based on C '_mn, temporary variable b is generated according to formula (5)；

B=C '_mn modρ (5)。

Step 7.5, travels through element of the searching value for b in sequence T, its serial number is designated as into serialID, then according to public affairs Formula (6) calculates C "_mn；

C″_mn=C '_mn-b+serialID (6)。

Circulation execution step 7.1- step 7.5, all operates as above to the every bit in matrix A, obtains new matrix A ', Wherein m and n is corresponding line number and row number.

Step 8：Position scramble is carried out to matrix A ' according to sequence Q, Q '：

From the beginning of first, execution step 8.1- step 8.4 is circulated, one by one by the middle Elements C of matrix A ' from the first trip of matrix A ' "_mn With C "_m′n′Location swap, obtains matrix A "；Matrix A " is to the final result after DEM scrambles.

Step 8.1, according to formula (7), using each Elements C in matrix A ' "_mnLine number m, generate temporary variable p；

P=m mod ρ (7).

Step 8.2, traversal finds the element equal with p value in sequence Q, remembers and serialID ' is designated as under it, then according to public affairs Formula (8), generates m '；

M '=m-p+serialID ' (8).

Step 8.3, according to formula (9), using the Elements C in matrix A ' "_mnRow number n, generate p '；

P '=n mod ρ (9).

Step 8.4, in the middle traversals of sequence Q ' element equal with p ' values is found, and remembers and serialID is designated as under it ", then basis Formula (10), generates n '；

N '=n-p '+serialID " (10).

Step 9：Based on the data after scrambling encryption, the txt file after scrambling encryption is generated.

Step 10：Based on ArcMap softwares, by " ArcToolbox->Crossover tool->Switch to grid->ASCII turnstilees Lattice " are operated, and txt file is converted to into the dem data of Esri Grid forms.

(2) DEM scrambles method of reducing (reduction process of DEM scrambles), comprises the steps：

Step A：Based on ArcMap softwares, by " ArcToolbox->Crossover tool->Produced by grid->Grid turns ASCII " is operated, and dem data is converted into into the txt file of ASCII codings；Matrix A is read data to from txt ".

Step B：DEM after scramble is stored in into line number as M with behavior main sequence, columns is the matrix A of N " in, wherein M is to put The line number of the DEM after unrest, N is the columns of the DEM after scramble, and the dem data after scramble is read out from the header file of DEM Pixel size s_cellsize, upper left corner x origin coordinates s_xllcornerWith upper left corner y origin coordinates s_yllcorner。

Step C：Input x₁、y₁、z₁As the initial value of chaos system, and x₁∈ (0,1), y₁∈ (0,1), z₁∈(0,1).It is defeated Enter the value of scramble factor ρ, and ρ ∈ [1,10000].The value of defined parameters σ, and σ ∈ (0,1).

Step D：According to formula (1), chaos sequence X, Y and Z are generated；Wherein X={ x_k| k=1,2,3 ..., max { M+N+ 13,10000 } }, Y={ y_k| k=1,2,3 ..., max { M+N+13,10000 } }, Z={ z_k| k=1,2,3 ..., max { M+N+ 13,10000 } }.

Step E：Obtain sequence S, J, Q, J ', Q ', I and T

E.1 step, according to formula (2) and (3), nonlinear discretization, formation sequence S, S={ s is carried out to chaos sequence Z_k | k=1,2,3 ..., M+N+13 }.

Step E.2, if the subset X ' of chaos sequence X={ x₁, x₂, x₃..., x₁₀₀₀₀Call number sequence 1,2,3 ..., 10000 } it is sequence J；By constituent element (x_n, j_n) with x_nAscending sort is carried out for primary key, sequence J after sequence is designated as into sequence Row Q；

Step E.3, if the subset Y '={ y of chaos sequence Y₁, y₂, y₃..., y₁₀₀₀₀Call number sequence 1,2,3 ..., 10000 } it is sequence J '；By constituent element (y_n, j_n') with y_nAscending sort is carried out for primary key, the sequence J ' after sequence is designated as Sequence Q '.

Step E.4, if the subset Z '={ z of chaos sequence Z₁, z₂, z₃..., z₁₀₀₀₀Call number sequence 1,2,3 ..., 10000 } it is sequence I.By constituent element (z_n, i_n) with z_nAscending sort is carried out for primary key, sequence I after sequence is designated as into sequence Row T.

Step F：The header file of DEM is reduced

According to formula (11) to s_cellsize、s_xllcornerAnd s_yllcornerRestoring operation is carried out, restoring data is obtained Cellsize, xllcorner and yllcorner；

Step G：According to sequence Q and Q ' to matrix A " in scramble after position reduce

From matrix A " from the beginning of footline terminal column, circulation execution step G.1- step G.1, one by one forward by the middle element of matrix A ' C″_m′n′With C "_mnExchange, obtain matrix A ', wherein m and n is corresponding line number and row number in matrix A '：

Step G.1, according to formula (12), using matrix A " in Elements C "_m′n′Line number m ', generate serialID '；Its Middle m ' and n ' is corresponding line number and row number

SerialID '=m ' mod ρ (12).

G.2, it is the element of serialID ' to find call number in sequence Q to step, remembers that its value is p, raw according to formula (13) Into m；

M=m '+p-serialID ' (13).

Step G.3, according to formula (14), using matrix A " in Elements C "_m′n′Row number n ', generate serialID "；

SerialID ' '=n ' mod ρ (14).

G.4 step, finds element of the middle call numbers of sequence Q ' for serialID ' ', remembers that its value is p ', according to formula (15), Generate n；

N=n '+p '-serialID " (15).

Step H：Elevation reduction is carried out to the data in matrix A ' according to sequence S, T

H.2- H.5 step, to each dot cycle in matrix A ' aforesaid operations is performed to circulation execution step, obtains matrix A, Square

Final result after battle array A as reduction：

Step H.1, according to formula (16), using the Elements C in matrix A ' "_mn, generate serialID；

SerialID=C "_mn modρ (16)。

H.2 step, finds element of the middle call number of matrix A ' for serialID, remembers that its value is b, then according to formula (17), Obtain

C′_mn=C "_mn+b-serialID (17)。

Step H.3, by C '_mnWith the binary number representation of 14, wherein m ∈ [1, M], n ∈ [1, N].

H.4 step, chooses the one 14 seat sequence { S of S_m+n,S_M+n+1,S_m+n+2,…,S_m+n+13And C '_mn14 binary systems Number, carries out step-by-step xor operation；If m+n is odd number, low 7 of XOR result are swapped with high 7, if m+n is even Number is then constant.

H.5 height value after conversion, is converted into decimal scale and obtains C by step_mn。

Step I：Based on ArcMap softwares, by " ArcToolbox->Crossover tool->Switch to grid->ASCII turnstilees Lattice " are operated, and txt file is converted to into the dem data of Esri Grid forms, complete the reduction treatment of DEM.

The inventive method utilizes three-dimensional chaos technology, respectively by putting to header file scramble, to elevation scramble and to position Disorderly, the scrambling encryption for DEM and reduction are formed, can be in safe transmission and the encapsulation storage link of effectively solving dem data Geography information safety problem.

Description of the drawings

The flow chart (a. scrambling encryption flow processs, b. reduction flow processs) of Fig. 1 present invention.

Fig. 2 experimental datas.

Result after Fig. 3 scrambling encryptions.

Result after Fig. 4 reduction.

Specific embodiment

It is described in further details with reference to the accompanying drawings and examples

Embodiment 1

What this example was chosen is 1：50000 Mount Lushan local dem data, data form is Esri Grid forms.For number According to the conversion of form, digital independent, scrambling encryption, reduction whole process, provide one embodiment of the present of invention.

1st, based on chaos sequence DEM scrambling encryption process

Step 11:

1) data are opened in ArcMap, uses ArcToolbox->Crossover tool->Produced by grid->Grid turns ASCII, will Dem data is converted into the txt file of ASCII codings.The data that this example is chosen three dimensional display such as Fig. 2 in ArcScene.

Step 12：

First, the header file of the dem data of txt forms is read.Wherein xllcorner=390996, yllcorner= 3274219, cellsize=5.Secondly, each point height value is read.What is opened up in the example is 935 rows, the two-dimentional battle arrays of 1220 row Row.

Step 13：The initial value x of input three-dimensional chaos sequence₁=0.21, y₁=0.32, z₁=0.44.And σ=0.45 is set, ρ=10000.

Step 14：According to formula (1), formation sequence length is 2168 chaos sequence X, X=0.21,0.97, 0.81 ..., 0.88 }, sequence length is 2168 chaos sequence Y, Y={ 0.32,0.94,0.63 ..., 0.77 } and sequence length For 2168 chaos sequence Z, Z={ 0.44,0.91,0.45 ..., 0.67 }.

Step 15：Obtain sequence S, J, Q, J ', Q ', I and T

1) nonlinear discretization is carried out to chaos sequence Z.The 0-1 sequences containing 2168 elements are obtained according to formula (2), (3) Row S, S={ 0,1,0,1 ..., 1 }.

2) subset X '={ x of chaos sequence X is set₁, x₂, x₃..., x₁₀₀₀₀In element call number sequence 1,2, 3 ..., 10000 } it is sequence J.By constituent element (x_n, j_n) with x_nAscending sort is carried out for primary key, by sequence J after sequence It is designated as sequence Q, Q={ 2,4,6 ..., 2167,1 }.

3) the subset Y '={ y of chaos sequence Y is set₁, y₂, y₃..., y₁₀₀₀₀In element call number sequence 1,2,3 ..., 10000 } it is sequence J '.By constituent element (y_n, j_n') with y_nAscending sort is carried out for primary key, the sequence J ' after sequence is designated as Sequence Q ', Q '={ 2,4,6 ..., 2167,1 }.

4) the subset Z '={ z of chaos sequence Z is set₁, z₂, z₃..., z₁₀₀₀₀Call number sequence { 1,2,3 ..., 10000 } For sequence I.By constituent element (z_n, i_n) with z_nAscending sort is carried out for primary key, sequence I after sequence is designated as into sequence T, T= { 5,7,9 ..., 3,1 }.

Step 16：Carry out header file scramble.

Cellsize=5, xllcorner=390996 and yllcorner=3274219 are put according to formula (14) Random cryptographic operation, obtains scrambling encryption data S_cellsize=1140697, S_xllcorner=1347720 and S_yllcorner= 2134583。

Step 17：Carry out elevation scramble.

1) with m=15, as a example by n=98.It is with the binary number representation of 14 by the height value 202 at the point 00000011001010, it is designated as C_mn(m, n are respectively ranks number, m ∈ [1,935], n ∈ [1,1220]).

2) m+n=113 is odd number, then swap low 7 with high 7, obtains 10010100000001.Choose discrete Change partial sequence S for producing₁₁₃,S₁₁₄, S₁₁₅..., S₁₂₆With C_mnXOR, will 01010101010101 and 10010100000001 Carry out XOR.

3) result 11000001010100 after XOR is converted into into decimal scale, the height value C ' after being changed_mn= 12372。

4) based on C '_mn, temporary variable b=2372 is generated according to formula (5).

5) traversal searches out the element that value is b, its serial number serialID=7368, then according to formula (6) in sequence T Calculate C '_mn=17368.

6) every bit in matrix A is all operated as above, obtains new matrix A '.Wherein m and n be corresponding line number with Row number.

Step 18：Carry out position scramble.

1) with m=15, as a example by n=98, according to formula (7), using the Elements C in matrix A ' "_mnLine number m generate it is interim Variable p=15.

2) element equal with p value in traversal searching sequence Q, its subscript serialID '=1095, then according to formula (8), Generate m '=1095.

3) according to formula (9), using the Elements C in matrix A ' "_mnRow number n generate p '=98.

4) traversal finds the element equal with p ' values in sequence Q ', its subscript serialID "=48, then according to formula (10), n '=48 are generated.

5) from first trip, first starts the middle Elements Cs of A ' one by one "_mnWith C "_m′n′Location swap, obtains matrix A ".A " is as right Final result after DEM scrambles.

Step 19：Based on the data after scrambling encryption, the txt file after scrambling encryption is generated.

Step 20：Based on ArcMap softwares, by " ArcToolbox->Crossover tool->Switch to grid->ASCII turnstilees Lattice " are operated, and txt file is converted to into the dem data of Esri Grid forms, complete the reduction treatment of DEM.Effect after scramble Check in ArcScene, such as Fig. 3.

2. reduction process

Step 21：Based on ArcMap softwares, by " ArcToolbox->Crossover tool->Produced by grid->Grid turns ASCII " is operated, and dem data is converted into into the txt file of ASCII codings.

Step 22：First, the file header of the dem data of txt forms is read.Wherein S_cellsize=1140697, S_xllcorner =1347720 and S_yllcorner=2134583., relevant parameter is preserved.Secondly, each point height value is read.Open up in the example Be 935 rows, the two-dimensional arraies of 1220 row.

Step 23：Generate chaos sequence.

The initial value x of input three-dimensional chaos sequence₁=0.23, y₁=0.24, z₁=0.25.σ=0.45, ρ=10000 are set.

Step 24：According to formula (1), formation sequence length is 2168 chaos sequence X, X=0.21,0.97, 0.81 ..., 0.88 }, sequence length is 2168 chaos sequence Y, Y={ 0.32,0.94,0.63 ..., 0.77 } and sequence length For 2168 chaos sequence Z, Z={ 0.44,0.91,0.45 ..., 0.67 }.

Step 25：Obtain sequence S, J, Q, J ', Q ', I and T

Nonlinear discretization is carried out to chaos sequence Z.0-1 sequences containing 2168 elements are obtained according to formula (2) and (3) S, S={ 0,1,0,1 ..., 1 }.

2) subset X '={ x of chaos sequence X is set₁, x₂, x₃..., x₁₀₀₀₀In element call number sequence 1,2, 3 ..., 10000 } it is sequence J.By constituent element (x_n, j_n) with x_nAscending sort is carried out for primary key, by sequence J after sequence It is designated as sequence Q, Q={ 2,4,6 ..., 2167,1 }.

3) the subset Y '={ y of chaos sequence Y is set₁, y₂, y_3,..., y₁₀₀₀₀In element call number sequence 1,2, 3 ..., 10000 } it is sequence J '.By constituent element (y_n, j_n') with y_nAscending sort is carried out for primary key, by the sequence after sequence J ' is designated as sequence Q ', Q '={ 2,4,6 ..., 2167,1 }.

4) the subset Z '={ z of chaos sequence Z is set₁, z₂, z₃..., z₁₀₀₀₀Call number sequence 1,2,3 ..., 10000 } it is sequence I.By constituent element (z_n, i_n) with z_nAscending sort is carried out for primary key, sequence I after sequence is designated as into sequence Row T, T={ 5,7,9 ..., 3,1 }.

Step 26：Header file is reduced.

According to formula (14) to S_cellsize=1140697, S_xllcorner=1347720 and S_yllcorner=2134583 are carried out Restoring operation, obtains restoring data cellsize=5, xllcorner=390996 and yllcorner=3274219.

Step 27：Position scramble reduction.

Detailed process is as follows：

1) with m '=1095, as a example by n '=48, according to formula (12), using matrix A " in Elements C "_m′n′Line number m ' =1095 generate serialID '=1095.Wherein m ' and n ' is corresponding line number and row number.

2) it is the element of serialID ' to find call number in sequence Q, generates p=15, then according to formula (13), generate m= 15。

3) according to formula (14), using matrix A " in Elements C "_m′n′Row number n '=48, generate serialID "=48.

4) element of middle Serial No. serialID of searching sequence Q ' ", its value p '=98, then according to formula (15), generates n =98.

5) from footline terminal column one by one forward by the middle Elements Cs of A ' "_m′n′With C "_mnExchange, obtain matrix A '.Wherein m and n is A ' In corresponding line number and row number.

Step 27：Elevation is reduced.

1) with m=15, n=98, correspondence elevation be 17368 as a example by, according to formula (16) generate serialID=7368.

2) element of the middle call numbers of sequence A ' for serialID is found, its value b=2372, then according to formula (17), is obtained C′_mn=12372.

3) by C '_mnWith the binary number representation of 14, wherein m ∈ [1, M], n ∈ [1, N].

4) partial sequence S that discretization is produced is chosen₁₁₃,S₁₁₄, S₁₁₅..., S₁₂₆With C_mnXOR, will 01010101010101 and 11000001010100 carry out XOR, obtain 10010100000001, because m+n is odd number, Exchange the first seven position and latter seven obtain 00000011001010.

3) result after XOR is converted into into decimal scale, the height value C ' after being changed_mn=202；

5) height value after conversion is converted into into decimal scale, obtains matrix A, the final result after A as reduction.

Step 28：Based on the data after reduction treatment, the txt file of the DEM after reduction is generated.

Step 29：ArcToolbox- is used in ArcMap>Crossover tool->Switch to grid->ASCII turnstilees lattice, will The txt file of ASCII codings is converted into Esri Grid forms and shows.The data that this example is chosen are three-dimensional aobvious in ArcScene Show such as Fig. 4.

Beneficial effects of the present invention：By the scrambling encryption for dem data and reduction treatment, can solve safe efficiently Certainly the safe transmission of dem data stores the geography information safety problem in link with encapsulation.

Claims (2)

1. a kind of scrambling encryption method of DEM, its step is as follows：

Step 1：Based on ArcMap softwares, by ArcToolbox->Crossover tool->Produced by grid->Grid turns ASCII behaviour Make, the dem data of Esri Grid forms is converted into into the txt file of ASCII codings；

Step 2：Txt file is stored in one M × N matrix A with behavior main sequence, wherein M is the line number of DEM, N is the columns of DEM, And read out the Pixel size cellsize of DEM, upper left corner x origin coordinates xllcorner and the upper left corner from the header file of DEM Y origin coordinates yllcorner；

Step 3：Input x₁、y₁、z₁As the initial value of chaos system, and x₁∈ (0,1), y₁∈ (0,1), z₁∈(0,1)；Input is put The value of random factor ρ, and ρ ∈ [1,1000]；The value of defined parameters σ, and σ ∈ (0,1)；

Step 4：According to formula (1), chaos sequence X, Y and Z are generated；Wherein X={ x_k| k=1,2,3 ..., max M+N+13, 10000 } }, Y={ y_k| k=1,2,3 ..., max { M+N+13,10000 } }, Z={ z_k| k=1,2,3 ..., max M+N+13, 10000}}；

$\left\{\begin{array}{c}{x}_k=(x_{k-1}+y_{k-1}+z_{k-1})\mathrm{mod}1\\ y_k=(2x_{k-1}+2y_{k-1}+2z_{k-1})\mathrm{mod}1\\ z_k=(3x_{k-1}+3y_{k-1}+3z_{k-1})\mathrm{mod}1\end{array}\right.,(k\≥2)---\left(1\right)$

Step 5：Obtain sequence S, J, Q, J ', Q ', I and T；Wherein S is the sequence for treating to be carried out with sequence Z xor operation, and J, Q are right Line number carries out the sequence of position shuffle operation, and J ', Q ' are the sequence that position shuffle operation is carried out to row number, and I and T is that Z values are entered Line position puts the sequence of shuffle operation；

Step 5.1, according to formula (2) and (3), nonlinear discretization, formation sequence S, S={ s is carried out to chaos sequence Z_k| k= 1,2,3 ..., M+N+13 }；

$s_1=\left\{\begin{array}{cc}0,& z_1<\mathrm{\&sigma;}\\ 1,& z_1\&GreaterEqual;\mathrm{\&sigma;}\end{array}\right.,(k=1)---\left(2\right)$

$s_k=\left\{\begin{array}{cc}0,& z_k<z_{k-1}\\ 1,& z_k\&GreaterEqual;z_{k-1}\end{array}\right.,(k\&GreaterEqual;2)---\left(3\right);$

Step 5.2, if the subset X ' of chaos sequence X={ x₁, x₂, x₃..., x₁₀₀₀₀Call number sequence 1,2,3 ..., 10000 } it is sequence J；By constituent element (x_n, j_n) with x_nAscending sort is carried out for primary key, sequence J after sequence is designated as into sequence Row Q；

Step 5.3, if the subset Y '={ y of chaos sequence Y₁, y₂, y₃..., y₁₀₀₀₀Call number sequence 1,2,3 ..., 10000 } it is sequence J '；By constituent element (y_n, j_n') with y_nAscending sort is carried out for primary key, the sequence J ' after sequence is designated as Sequence Q '；

Step 5.4, if the subset Z '={ z of chaos sequence Z₁, z₂, z₃..., z₁₀₀₀₀Call number sequence { 1,2,3 ..., 10000 } For sequence I；By constituent element (z_n, i_n) with z_nAscending sort is carried out for primary key, sequence I after sequence is designated as into sequence T；Step Rapid 6：Line shuffle is entered to the header file of dem data

Operation is encrypted to cellsize, xllcorner and yllcorner according to formula (4), encryption data is obtained s_cellsize、s_xllcornerAnd s_yllcorner；

$\left\{\begin{array}{c}{s}_{cellsize}=cellsizexorMN\\ s_{xllcorner}=xllcornerxorMN\\ s_{yllcorner}=yllcornerxorMN\end{array}\right.---\left(4\right)$

Step 7：Elevation scramble is carried out to matrix A according to sequence S, T

Step 7.1, by height value C of any of matrix A_mnSwitch to the binary number representation of 14, wherein m and n is corresponding row Number and row number；m∈[1,M],n∈[1,N]；

Step 7.2, if m+n is odd number, first by C_mnLow 7 swap with high 7；It is constant if m+n is even number；Choose The one 14 seat sequence { s of S_m+n,s_m+n+1,s_m+n+2,…,s_m+n+13Step-by-step and C_mnXOR；

Step 7.3, is converted into the result after XOR decimal number and represents, the height value C ' after being changed_mn；

Step 7.4, based on C '_mn, temporary variable b is generated according to formula (5)；

B=C '_mnmod ρ (5)；

Step 7.5, travels through element of the searching value for b in sequence T, its serial number is designated as into serialID, then according to formula (6) Calculate C "_mn；

C″_mn=C '_mn-b+serialID (6)；

Circulation execution step 7.1- step 7.5, all operates as above to the every bit in matrix A, obtains new matrix A ', wherein M and n is corresponding line number and row number；

Step 8：Position scramble is carried out to matrix A ' according to sequence Q, Q '：

From the beginning of first, execution step 8.1- step 8.4 is circulated, one by one by the middle Elements C of matrix A ' from the first trip of matrix A ' "_mnWith C″_m′n′Location swap, obtains matrix A "；Matrix A " is to the final result after DEM scrambles；

Step 8.1, according to formula (7), using each Elements C in matrix A ' "_mnLine number m, generate temporary variable p；

P=m mod ρ (7)；

Step 8.2, traversal finds the element equal with p value in sequence Q, remembers and serialID ' is designated as under it, then according to formula (8), m ' is generated；

M '=m-p+serialID ' (8)；

Step 8.3, according to formula (9), using the Elements C in matrix A ' "_mnRow number n, generate p '；

P '=n mod ρ (9)；

Step 8.4, in the middle traversals of sequence Q ' element equal with p ' values is found, and remembers and serialID is designated as under it ", then according to formula (10), n ' is generated；

N '=n-p '+serialID " (10)；

Step 9：Based on the data after scrambling encryption, the txt file after scrambling encryption is generated；

Step 10：Based on ArcMap softwares, by " ArcToolbox->Crossover tool->Switch to grid->ASCII turnstilees lattice " behaviour Make, txt file is converted to into the dem data of Esri Grid forms.

2. the method for reducing of the DEM scrambles after a kind of scrambling encryption method scrambling encryption of the DEM described in use claim 1, wraps Include following steps：

Step A：Based on ArcMap softwares, by " ArcToolbox->Crossover tool->Produced by grid->Grid turns ASCII " Operation, by dem data the txt file of ASCII codings is converted into；Matrix A is read data to from txt "；

Step B：DEM after scramble is stored in into line number as M with behavior main sequence, columns is the matrix A of N " in, wherein M is after scramble DEM line number, N is the columns of the DEM after scramble, and the pixel of the dem data after scramble is read out from the header file of DEM Size s_cellsize, upper left corner x origin coordinates s_xlAcornerWith upper left corner y origin coordinates s_yllcorner；

Step C：Input x₁、y₁、z₁As the initial value of chaos system, and x₁∈ (0,1), y₁∈ (0,1), z₁∈(0,1)；Input is put The value of random factor ρ, and ρ ∈ [1,10000]；The value of defined parameters σ, and σ ∈ (0,1)；

Step D：According to formula (1), chaos sequence X, Y and Z are generated；Wherein X={ x_k| k=1,2,3 ..., max M+N+13, 10000 } }, Y={ y_k| k=1,2,3 ..., max { M+N+13,10000 } }, Z={ z_k| k=1,2,3 ..., max M+N+13, 10000}}；

Step E：Obtain sequence S, J, Q, J ', Q ', I and T

E.1 step, according to formula (2) and (3), nonlinear discretization, formation sequence S, S={ s is carried out to chaos sequence Z_k| k= 1,2,3 ..., M+N+13 }；

Step E.2, if the subset X ' of chaos sequence X={ x₁, x₂, x₃..., x₁₀₀₀₀Call number sequence 1,2,3 ..., 10000 } it is sequence J；By constituent element (x_n, j_n) with x_nAscending sort is carried out for primary key, sequence J after sequence is designated as into sequence Row Q；

Step E.3, if the subset Y '={ y of chaos sequence Y₁, y₂, y₃..., y₁₀₀₀₀Call number sequence 1,2,3 ..., 10000 } it is sequence J '；By constituent element (y_n, j_n') with y_nAscending sort is carried out for primary key, the sequence J ' after sequence is designated as Sequence Q '；

Step E.4, if the subset Z '={ z of chaos sequence Z₁, z₂, z₃..., z₁₀₀₀₀Call number sequence { 1,2,3 ..., 10000 } For sequence I；By constituent element (z_n, i_n) with z_nAscending sort is carried out for primary key, sequence I after sequence is designated as into sequence T；

Step F：The header file of DEM is reduced

According to formula (11) to s_cellsize、s_xllcornerAnd s_yllcornerCarry out restoring operation, obtain restoring data cellsize, Xllcorner and yllcorner；

$\left\{\begin{array}{c}cellsize=s_{cellsize}xorMN\\ xllcorner=s_{xllcorner}xorMN\\ yllcorner=s_{yllcorner}xorMN\end{array}\right.---\left(11\right);$

Step G：According to sequence Q and Q ' to matrix A " in scramble after position reduce

From matrix A " from the beginning of footline terminal column, circulation execution step G.1- step G.1, one by one forward by the middle Elements C of matrix A ' "_m′n′With C″_mnExchange, obtain matrix A ', wherein m and n is corresponding line number and row number in matrix A '：

Step G.1, according to formula (12), using matrix A " in Elements C "_m′n′Line number m ', generate serialID '；Wherein m ' It is corresponding line number and row number with n '

SerialID '=m ' mod ρ (12)；

G.2, it is the element of serialID ' to find call number in sequence Q to step, remembers that its value is p, according to formula (13), generates m；

M=m '+p-serialID ' (13)；

Step G.3, according to formula (14), using matrix A " in Elements C "_m′n′Row number n ', generate serialID "；

SerialID "=n ' mod ρ (14)；

G.4, it is serialID to find the middle call numbers of sequence Q ' to step " element, remember its value for p ', according to formula (15), generate n；

N=n '+p '-serialID " (15)；

Step H：Elevation reduction is carried out to the data in matrix A ' according to sequence S, T

H.2- H.5 step, to each dot cycle in matrix A ' aforesaid operations is performed to circulation execution step, obtains matrix A, matrix Final result after A as reduction：

Step H.1, according to formula (16), using the Elements C in matrix A ' "_mn, generate serialID；

SerialID=C "_mnmod ρ (16)；

H.2 step, finds element of the middle call number of matrix A ' for serialID, remembers that its value is b, then according to formula (17), obtain

C′_mn=C "_mn+b-serialID (17)；

Step H.3, by C '_mnWith the binary number representation of 14, wherein m ∈ [1, M], n ∈ [1, N]；

H.4 step, chooses the one 14 seat sequence { S of S_m+n,S_m+n+1, S_m+n+2,…,S_m+n+13And C '_mn14 bits, Carry out step-by-step xor operation；If m+n is odd number, low 7 of XOR result are swapped with high 7, if m+n is even number, It is then constant；

H.5 height value after conversion, is converted into decimal scale and obtains C by step_mn；

Step I：Based on ArcMap softwares, by " ArcToolbox->Crossover tool->Switch to grid->ASCII turnstilees lattice " behaviour Make, txt file is converted to into the dem data of Esri Grid forms, complete the reduction treatment of DEM.