CN107809644A

CN107809644A - A kind of encryption area image reversible data concealing method of double-encryption

Info

Publication number: CN107809644A
Application number: CN201711011109.5A
Authority: CN
Inventors: 徐达文
Original assignee: Ningbo University of Technology
Current assignee: Ningbo University of Technology
Priority date: 2017-10-26
Filing date: 2017-10-26
Publication date: 2018-03-16
Anticipated expiration: 2037-10-26
Also published as: CN107809644B

Abstract

The invention discloses a kind of encryption area image reversible data concealing method of double-encryption, and it includes image encryption, encryption area image hiding reversible data, the extraction of concealed data and original image Distortionless three parts；Double-encryption mechanism is used in image encryption part, enhances security；Secret information can be embedded in directly in the image of encryption, even if image watermarking person does not know original image content, also picture material safety and privacy leakage problem can be efficiently solved, and it is embedded in the expansion that will not also cause view data without complicated agreement, encryption and data between image encryption person and secret information insertion person；It is practical, if only image watermarking key, hiding secret information can be directly extracted in ciphertext area image；If only encryption key, it can directly decrypt and obtain approximate original image；If having image watermarking key and encryption key, it can guarantee that after the hiding secret information of extraction, original image can be recovered without distortions.

Description

A kind of encryption area image reversible data concealing method of double-encryption

Technical field

The present invention relates to a kind of image reversible data hiding technique, more particularly, to a kind of encryption area image of double-encryption Reversible data concealing method.

Background technology

Under cloud computing platform, the supplier of content of multimedia need not be storage person and processor simultaneously.In this Working mould In formula, user data is largely in " out of control " state.Ensure one of best approach of multi-medium data security just It is that multimedia is encrypted.User is encrypted first before sensitive content is uploaded, all processing in high in the clouds and meter Calculate and all carried out in ciphertext domain, and result is supplied to user, user can obtain clear data by decryption side.Such as Medical institutions, the obligation of protection patients' privacy is born, but their data-handling capacity is weaker, to reach preferably medical treatment effect Fruit or scientific research level, third party's (cloud computing center) that they need commission and have stronger data-handling capacity are realized at data Reason, and it is immoral directly to give data to third party, and do not allowed by law, they can be by the number after encryption According to sending to third party, them are returned to after the completion of third party's processing.

In many application scenarios, it is attached that the cloud service managers of some no decrypted rights need to be embedded in some in encryption vector Add message, such as mark or authentication data, works source-information, owner's identity information, for managing and authenticated encryption image Data.Meanwhile in some important application scenarios, such as medical diagnosis, court's certification, military image, remote sensing images and fingerprint image The Sensitive Domains such as picture generally require accurately recover former hosted information after additional message is extracted.It is for example, hidden for protection patient Private, the information such as medical image are encrypted, data base administration person can be embedded in the privacy of patient in corresponding encrypted image Information and authentication information.If the embedded additional message in sensitive image data, need in advance to sensitive image data deciphering, this Mean that in the whole life cycle of sensitive image data, at least part of time be with existing for plaintext version, this Sample can bring about serious privacy concern.In addition, in order to not influence to diagnose, the doctor of mandate wishes decrypting and extracting additional letter After breath, original image content can be recovered completely.Encrypted domain reversible data hiding technique may insure image watermarking, and person is not understanding On the premise of close, the insertion of data is directly carried out to encrypted image and extraction operates, can help solve safety of image and privacy The worry of leakage.Existing encrypted domain reversible data hiding technique can be divided into three classes：The first kind is sought after image is encrypted Data embedded space is looked for, this kind of universal embedding capacity of method is relatively low, and data extraction error can occur；Second class is image encryption Preceding reserved data embedded space, this kind of method embedding capacity is big and distortion is low, but shortcoming be image encryption person and data insertion person Between need complexity agreement；3rd class is to realize ciphertext area image hiding reversible data using homomorphic cryptography, but homomorphism adds It is close to easily cause ciphertext data expansion.

The content of the invention

The technical problems to be solved by the invention are to provide a kind of encryption area image hiding reversible data side of double-encryption Method, it can carry out secret information insertion in area image is encrypted, without multiple between image encryption person and secret information insertion person Miscellaneous agreement, and embedding capacity is big, will not cause to be embedded in the encryption area image generation data expansion after secret information；Receiving terminal energy Enough directly decryption obtain approximate original image or can directly extract secret information or can ensure extracting secret Original image can be recovered after information without distortions.

Technical scheme is used by the present invention solves above-mentioned technical problem：A kind of encryption area image of double-encryption is reversible Data-hiding method, it is characterised in that extracted including image encryption, encryption area image hiding reversible data, concealed data and original Image lossless recovers three parts；Wherein,

The processing procedure of described image encryption part is：

1. the width and height that _ 1, set original image to be encrypted correspond to W and H, if W × H can be whole by g × g Remove, be then divided into original image to be encryptedThe size of individual non-overlapping copies is g × g image block；If W × H can not be divided exactly by g × g, then be divided into original image to be encryptedThe size of individual non-overlapping copies is g × g image block, and the right of original image to be encrypted and lower section size are not also served as into image block for g × g block, It is sharedIndividual image block；Wherein, g value is 2 or 3, symbolTo round symbol, symbol downwardsFor Round up symbol；

1. _ 2, set a first key key1；Then join first key key1 as the input of random () function Number, random () function is set to produce first random sequence；Wherein, the length of the first random sequence is more than original to be encrypted The total number of the image block included in beginning image, the value of each element in the first random sequence is the integer in [0,255]；

1. m-th of image block currently pending in original image to be encrypted _ 3, is defined as current image block, ought Preceding j-th of the element definition taken out from the first random sequence is currentElement；Wherein, m and j is positive integer, m and j just Initial value is 1, and 1≤m≤M, M represent the total number of the image block included in original image to be encrypted, and 1≤j≤J, J represent the The length of one random sequence；

1. _ 4, each pixel in current image block is encrypted using currentElement, in current image block The process that ith pixel point is encrypted is：By the pixel value of ith pixel point and the value of currentElement in current image block To 256 modulus after addition, the then pixel value using obtained value as the ith pixel point in current image block；Wherein, 1≤i ≤I_cur, I_curRepresent the total number of pixel included in current image block；

1. _ 5, making m=m+1, and make j=j+1, using next pending image block in original image to be encrypted as Current image block, using next element taken out from the first random sequence as currentElement, be then back to step 1. _ 4 after It is continuous to perform, until all image blocks in original image to be encrypted are disposed, obtain one-time pad encryption image；Wherein, m=m+ "=" in 1 and j=j+1 is assignment；

1. _ 6, counting the total number for the image block that the size included in one-time pad encryption image is g × g, it is designated as Count；And set a second key key2；Then using the second key key2 as the input parameter of random () function, make Random () function produces second random sequence；Wherein, the length of the second random sequence is Count, the second random sequence In the value of each element be the integer in [0, Count], the value of all elements in the second random sequence do not repeat and in Machine is distributed；

1. _ 7, the image block that all sizes in one-time pad encryption image are g × g is carried out using the second random sequence Scramble, the double-encryption process of original image is so far completed, obtain the encryption area image of double-encryption；It is above-mentioned, first key Key1 and the second key key2 is encryption key；

The processing procedure of described encryption area image hiding reversible data part is：

2. _ 1, the encryption area image of double-encryption is divided intoThe size of individual non-overlapping copies is g × g Image block；Wherein, symbolTo round symbol downwards；

A the 3rd key key3 is set as image watermarking key；Then using the 3rd key key3 as random () letter Several input parameters, random () function is set to produce the 3rd random sequence；Recycle each member in the 3rd random sequence The value of element corresponds to every secret information bit in original secret information and carries out XOR encryption, obtains the hidden of XOR encryption Secret information, as secret information to be embedded；Wherein, the length of the 3rd random sequence is more than or equal to the length of original secret information Degree, and the value of each element in the 3rd random sequence is 0 or 1；

2. the m' image block currently pending in the encryption area image of double-encryption _ 2, is defined as present image Block；Wherein, m' is positive integer, and m' initial value is 1,

2. _ 3, calculate the respective pixel value of the non-central pixels of g × g-1 in current image block and central pixel point The difference of pixel value is to the values of 256 modulus, by the pixel value and center pixel of s-th of non-central pixel in current image block The difference of the pixel value of point is designated as f to the value of 256 modulus_cur(s), f_cur(s)=(h_cur(s)-h_cur,center)mod 256；Its In, s is positive integer, and s initial value is 1,1≤s≤g × g-1, h_cur(s) s-th of non-central picture in current image block is represented The pixel value of vegetarian refreshments, h_cur,centerThe pixel value of the central pixel point in current image block is represented, if the size of current image block Size is 2 × 2, then specifying any one pixel in current image block, rest of pixels point is as non-as central pixel point Central pixel point, mod are modulus symbol；

2. _ 4, according to step 2. _ 3 in g × g-1 value being calculated, determine the secret information insertion of current image block Region, it is designated as Z_cur, Z_cur=[T_p,T_p+β]∪[T_n-β,T_n]；Wherein, symbol " ∪ " is union operation symbol, T_p=0, T_n= 255, β represent regulatory factor, and β value is the integer more than or equal to 0；

2. _ 5, for step 2. _ 3 in g × g-1 value being calculated, be handled as follows：2. _ 3 fallen into a trap for step Obtained f_cur(s), if f_cur(s) it is more than T_p+ β, then correct f_cur(s), process is：Make f'_cur(s)=f_cur(s)+(β+1), F is made again_cur(s)=f'_cur(s)；If f_cur(s) it is less than T_n- β, then correct f_cur(s), process is：Make f'_cur(s)=f_cur(s)-(β + 1), then f is made_cur(s)=f'_cur(s)；If f_cur(s)∈Z_cur, then f is kept_cur(s) it is constant；Wherein, f'_cur(s) in be introduced into Between variable, f_cur(s)=f'_cur(s) "=" in is assignment；

2. secret information bit insertion, specific mistake _ 6, are carried out to g × g-1 non-central pixels in current image block Cheng Wei：For s-th of non-central pixel in current image block, if by step 2. _ 5 in g × g-1 value determining S-th of value f_cur(s) meet：f_cur(s)∈[T_n-β,T_n], then when secret information bit to be embedded is " 0 ", make f "_cur(s) =f_cur(s)-(T_n-f_cur(s)), then to h_cur(s) it is modified to complete the insertion of secret information bit, process is：Order h'_cur(s)=(f "_cur(s)+h_cur,center) mod 256, then make h_cur(s)=h'_cur(s)；When secret information bit to be embedded For " 1 " when, make f "_cur(s)=f_cur(s)-(T_n-f_cur(s)) -1, then to h_cur(s) it is modified to complete secret information ratio Special insertion, process are：Make h'_cur(s)=(f "_cur(s)+h_cur,center) mod 256, then make h_cur(s)=h'_cur(s)；If through S-th of value f in the g × g-1 value determined in crossing step 2. _ 5_cur(s) meet：f_cur(s)∈[T_p,T_p+ β], then when to be embedded Secret information bit when being " 0 ", make f "_cur(s)=f_cur(s)+(f_cur(s)-T_p), then to h_cur(s) it is modified with complete Into the insertion of secret information bit, process is：Make h'_cur(s)=(f "_cur(s)+h_cur,center) mod 256, then make h_cur(s)= h'_cur(s)；When secret information bit to be embedded is " 1 ", f "_cur(s)=f_cur(s)+(f_cur(s)-T_p)+1, then to h_cur (s) it is modified to complete the insertion of secret information bit, process is：Make h'_cur(s)=(f "_cur(s)+h_cur,center)mod 256, then make h_cur(s)=h'_cur(s)；Wherein, f "_curAnd h' (s)_cur(s) be introducing intermediate variable, h_cur(s)=h'_cur (s) "=" in is assignment；

2. _ 7, make m'=m'+1, then using double-encryption encryption area image in next pending image block as Current image block, return again to step and 2. _ 3 continue executing with, until in each image block in the encryption area image of double-encryption Each non-central pixel is embedded with secret information bit, obtains the encryption area image containing secret information；Wherein, in m'=m'+1 "=" be assignment；

There are three kinds of situations described concealed data extraction and original image Distortionless part：

The first situation is that receiving terminal only has encryption key, and only the encryption area image containing secret information is decrypted, had Body process is：

3. the width and height of _ 1_1, encryption area image containing secret information correspond to W and H, if W × H can by g × G is divided exactly, then is divided into the encryption area image containing secret informationThe size of individual non-overlapping copies is g × g image Block；If W × H can not be divided exactly by g × g, the encryption area image containing secret information is divided intoIt is individual mutually not Overlapping size is g × g image block, and by the right of the encryption area image containing secret information and lower section size not Image block is also served as g × g block, is sharedIndividual image block；Wherein, g value is 2 or 3, symbolFor to Under round symbol, symbolFor the symbol that rounds up；

3. _ 1_2, the input parameter using the second key key2 as random () function, random () function is set to produce one Individual 5th random sequence；Wherein, the length of the 5th random sequence is Count, and the value of each element in the 5th random sequence is Integer in [0, Count], the value of all elements in the 5th random sequence do not repeat and are in random distribution；

3. _ 1_3, using the 5th random sequence it is g × g to all sizes in the encryption area image containing secret information Image block carry out scramble, obtain the encryption area image after scramble；

3. _ 1_4, the input parameter using first key key1 as random () function, random () function is set to produce one Individual 4th random sequence；Wherein, the length of the 4th random sequence is more than the image block included in the encryption area image after removing scramble Total number, the value of each element in the 4th random sequence is the integer in [0,255]；

3. _ 1_5, m-th of image block currently pending in the encryption area image after scramble will be gone to be defined as present image Block, it is currentElement by j-th of the element definition currently taken out from the 4th random sequence；Wherein, m and j is positive integer, m Initial value with j is 1, and 1≤m≤M, M represent to go in the encryption area image after scramble the total number of the image block included, 1≤j ≤ J, J represent the length of the 4th random sequence；

3. _ 1_6, using currentElement each pixel in current image block is decrypted, in current image block The process that is decrypted of ith pixel point be：By the pixel value of the ith pixel point in current image block and currentElement Value subtract each other after to 256 modulus, the then pixel value using obtained value as the ith pixel point in current image block；Wherein, 1 ≤i≤I_cur, I_curRepresent the total number of pixel included in current image block；

3. _ 1_7, making m=m+1, and j=j+1 is made, next pending image in the encryption area image after scramble will be removed Block, using next element taken out from the 4th random sequence as currentElement, is then back to step as current image block 3. _ 1_6 is continued executing with, until all image blocks in the encryption area image after removing scramble are disposed, image decryption is completed Process, obtain the decryption area image containing secret information；Wherein, "=" in m=m+1 and j=j+1 is assignment；

Second of situation is that receiving terminal only has image watermarking key, only the encryption area image containing secret information is carried out concealed Information extraction, detailed process are：

3. the width and height of _ 2_1, encryption area image containing secret information correspond to W and H, by containing secret information plus Close area image is divided intoThe size of individual non-overlapping copies is g × g image block；Wherein, symbolFor to Under round symbol；

Input parameter using the 3rd key key3 as random () function, random () function is set to produce one the 6th Random sequence；Wherein, the value of each element in the 6th random sequence is 0 or 1；

3. _ 2_2, the m' image block currently pending in the encryption area image containing secret information be defined as currently scheming As block；Wherein, m' is positive integer, and m' initial value is 1,

3. _ 2_3, calculate the respective pixel value of the non-central pixels of g × g-1 and central pixel point in current image block Pixel value difference to the values of 256 modulus, by the pixel value of s-th of non-central pixel in current image block and middle imago The difference of the pixel value of vegetarian refreshments is designated as to the value of 256 modulus Its In, s is positive integer, and s initial value is 1,1≤s≤g × g-1,Represent s-th of non-central picture in current image block The pixel value of vegetarian refreshments,The pixel value of the central pixel point in current image block is represented, if the size of current image block is big Small is 2 × 2, then specifies any one pixel in current image block as central pixel point, and rest of pixels point is as in non- Imago vegetarian refreshments, mod are modulus symbol；

3. _ 2_4, according to step 3. _ 2_3 in g × g-1 value being calculated, determine the secret information of current image block Region is extracted, is designated as Wherein, symbol " ∪ " accords with for union operation Number,

3. _ 2_5, secret information bit extraction is carried out to g × g-1 non-central pixels in current image block, specifically Process is：For s-th of non-central pixel in current image block, if by step 3. _ 2_3 is calculatedIt is full Foot：Then whenDuring equal to 0, the secret information bit for extracting to obtain is " 0 ", WhenDuring equal to 1, the secret information bit for extracting to obtain is " 1 "；If by step 3. _ 2_3 is calculatedMeet：Then whenDuring equal to 0, obtained secret information ratio is extracted Specially for " 0 ", whenDuring equal to 1, the secret information bit for extracting to obtain is " 1 "；

3. _ 2_6, m'=m'+1 is made, then by next pending image block in the encryption area image containing secret information As current image block, return again to step 3. _ 2_3 continues executing with, until from each in the encryption area image containing secret information Secret information bit is extracted in each non-central pixel in image block, extraction obtains secret information；Wherein, m'=m'+1 In "=" be assignment；

It is 3. _ 2_7, hidden to every in the obtained secret information of extraction using the value of each element in the 6th random sequence Secret information bit, which corresponds, carries out XOR decryption, obtains the secret information of XOR decryption, the final secret obtained as extraction Information；

The third situation is that the existing image watermarking key of receiving terminal has encryption key again, first to the encrypted domain containing secret information Image carry out secret information extraction, after to secret information extract after encryption area image be decrypted, detailed process is：

3. the width and height of _ 3_1, encryption area image containing secret information correspond to W and H, by containing secret information plus Close area image is divided intoThe size of individual non-overlapping copies is g × g image block；Wherein, symbolFor to Under round symbol；

3. _ 3_2, the m' image block currently pending in the encryption area image containing secret information be defined as currently scheming As block；Wherein, m' is positive integer, and m' initial value is 1,

3. _ 3_3, calculate the respective pixel value of the non-central pixels of g × g-1 and central pixel point in current image block Pixel value difference to the values of 256 modulus, by the pixel value of s-th of non-central pixel in current image block and middle imago The difference of the pixel value of vegetarian refreshments is designated as to the value of 256 modulus Its In, s is positive integer, and s initial value is 1,1≤s≤g × g-1,Represent s-th of non-central picture in current image block The pixel value of vegetarian refreshments,The pixel value of the central pixel point in current image block is represented, if the size of current image block is big Small is 2 × 2, then specifies any one pixel in current image block as central pixel point, and rest of pixels point is as in non- Imago vegetarian refreshments, mod are modulus symbol；

3. _ 3_4, according to step 3. _ 3_3 in g × g-1 value being calculated, determine the secret information of current image block Region is extracted, is designated as Wherein, symbol " ∪ " accords with for union operation Number,

3. _ 3_5, secret information bit extraction is carried out to g × g-1 non-central pixels in current image block, specifically Process is：For s-th of non-central pixel in current image block, if by step 3. _ 3_3 is calculatedIt is full Foot：Then whenDuring equal to 0, the secret information bit for extracting to obtain is " 0 ", WhenDuring equal to 1, the secret information bit for extracting to obtain is " 1 "；If by step 3. _ 3_3 is calculatedMeet：Then whenDuring equal to 0, obtained secret information ratio is extracted Specially for " 0 ", whenDuring equal to 1, the secret information bit for extracting to obtain is " 1 "；

3. _ 3_6, carrying out recovery operation to g × g-1 non-central pixels in current image block, detailed process is：It is right S-th of non-central pixel in current image block, if by step 3. _ 3_3 is calculatedMeet：Then whenDuring equal to 0, order WhenDuring equal to 1, orderIf by step 3. _ 3_3 count ObtainMeet：Then whenDuring equal to 0, orderWhenDuring equal to 0, order If by step 3. _ 3_3 is calculatedMeet：Then makeIf by step 3. _ 3_3 is calculatedMeet：Then makeWherein, symbolTo round symbol downwards, WithIn "=" be assignment；

3. _ 3_7, m'=m'+1 is made, then by next pending image block in the encryption area image containing secret information As current image block, return again to step 3. _ 3_3 continues executing with, until from each in the encryption area image containing secret information Secret information bit is extracted in each non-central pixel in image block, obtains the encrypted domain figure after secret information extraction Picture, and extract and obtain secret information；Wherein, "=" in m'=m'+1 is assignment；

It is 3. _ 3_8, hidden to every in the obtained secret information of extraction using the value of each element in the 6th random sequence Secret information bit, which corresponds, carries out XOR decryption, obtains the secret information of XOR decryption, the final secret obtained as extraction Information；

3. the width and height of the encryption area image after the extraction of _ 3_9, secret information correspond to W and H, if W × H can Divided exactly by g × g, then the encryption area image after secret information is extracted is divided intoThe size of individual non-overlapping copies is g × g image block；If W × H can not be divided exactly by g × g, the encryption area image after secret information is extracted is divided intoThe size of individual non-overlapping copies is g × g image block, and the encryption area image after secret information is extracted Right and lower section size are not that g × g block also serves as image block, are sharedIndividual image block；Wherein, g value For 2 or 3, symbolTo round symbol, symbol downwardsFor the symbol that rounds up；

3. _ 3_10, the input parameter using the second key key2 as random () function, produce random () function One the 5th random sequence；Wherein, the length of the 5th random sequence is Count, the value of each element in the 5th random sequence For the integer in [0, Count], the value of all elements in the 5th random sequence does not repeat and is in random distribution；

3. _ 3_11, using the 5th random sequence to secret information extract after encryption area image in all sizes Scramble is carried out for g × g image block, obtains the encryption area image after scramble；

3. _ 3_12, the input parameter using first key key1 as random () function, produce random () function One the 4th random sequence；Wherein, the value of each element in the 4th random sequence is the integer in [0,255]；

3. _ 3_13, m-th of image block currently pending in the encryption area image after scramble will be gone to be defined as present image Block, it is currentElement by j-th of the element definition currently taken out from the 4th random sequence；Wherein, m and j is positive integer, m Initial value with j is 1, and 1≤m≤M, M represent to go in the encryption area image after scramble the total number of the image block included, 1≤j ≤ J, J represent the length of the 4th random sequence；

3. _ 3_14, using currentElement each pixel in current image block is decrypted, in current image block The process that is decrypted of ith pixel point be：By the pixel value of the ith pixel point in current image block and currentElement Value subtract each other after to 256 modulus, the then pixel value using obtained value as the ith pixel point in current image block；Wherein, 1 ≤i≤I_cur, I_curRepresent the total number of pixel included in current image block；

3. _ 3_15, making m=m+1, and j=j+1 is made, next pending figure in the encryption area image after scramble will be removed Picture block, using next element taken out from the 4th random sequence as currentElement, is then back to step as current image block Suddenly 3. _ 3_14 is continued executing with, until all image blocks in the encryption area image after removing scramble are disposed, completes image decryption Process, obtain secret information extraction after decryption area image；Wherein, "=" in m=m+1 and j=j+1 is assignment.

Compared with prior art, the advantage of the invention is that：

1) the inventive method uses double-encryption mechanism in image encryption part, i.e., first divides the image into image block, After the pixel value of each pixel in each image block is added with the value of an element in the random sequence for encrypting To 256 modulus；Then line shuffle is entered to all image blocks after encryption, double-encryption enhances the security of the inventive method.

2) the inventive method can be embedded in secret information directly in the image of encryption, even if image watermarking person does not know original Beginning picture material, it is possibility to have effect ground solves the problems, such as picture material safety and privacy leakage, and image encryption person and concealed letter Without complicated agreement between breath insertion person, and embedding capacity is big, and encryption is embedded in data will not also cause the swollen of view data It is swollen.

3) the inventive method is practical, can be directly in ciphertext area image if receiving terminal has image watermarking key The hiding secret information of extraction；If receiving terminal has encryption key, it can directly decrypt and obtain approximate original image；If connect Receiving end has image watermarking key and encryption key simultaneously, then can ensure after the hiding secret information of extraction, can be without distortions Recover original image.

Brief description of the drawings

Fig. 1 a are the schematic diagram that β values are 0 time shift 1；

Fig. 1 b are the schematic diagram that β values are 1 time shift 2；

Fig. 2 realizes block diagram for the totality of image encryption and encryption area image hiding reversible data；

Fig. 3 is that receiving terminal only has encryption key, and only the encryption area image containing secret information is decrypted；And receiving terminal was both There is image watermarking key to have encryption key again, first to containing secret information encryption area image carry out secret information extraction, after to hidden The totality that encryption area image after secret information extraction is decrypted realizes block diagram.

Embodiment

The present invention is described in further detail below in conjunction with accompanying drawing embodiment.

Embodiment one：

A kind of encryption area image reversible data concealing method for double-encryption that the present embodiment proposes, it includes image and added Close, encryption area image hiding reversible data, the extraction of concealed data and original image Distortionless three parts；Wherein,

As shown in Fig. 2 the processing procedure of image encryption part is：

1. the width and height that _ 1, set original image to be encrypted correspond to W and H, if W × H can be whole by g × g Remove, be then divided into original image to be encryptedThe size of individual non-overlapping copies is g × g image block；If W × H can not be divided exactly by g × g, then be divided into original image to be encryptedThe size of individual non-overlapping copies is g × g image block, and the right of original image to be encrypted and lower section size are not also served as into image block for g × g block, It is sharedIndividual image block；Wherein, g value is 2 or 3, symbolTo round symbol, symbol downwardsFor Round up symbol.

1. _ 2, set a first key key1；Then join first key key1 as the input of random () function Number, random () function is set to produce first random sequence；Wherein, first key is a text, the first random sequence Length is more than the total number of image block included in original image to be encrypted, and the value of each element in the first random sequence is [0,255] integer in.

1. m-th of image block currently pending in original image to be encrypted _ 3, is defined as current image block, ought Preceding j-th of the element definition taken out from the first random sequence is currentElement；Wherein, m and j is positive integer, m and j just Initial value is 1, and 1≤m≤M, M represent the total number of the image block included in original image to be encrypted, 1. _ 1 can according to step Know,Or1≤j≤J, J represent the length of the first random sequence, J >=M.

1. _ 4, each pixel in current image block is encrypted using currentElement, in current image block The process that ith pixel point is encrypted is：By the pixel value of ith pixel point and the value of currentElement in current image block To 256 modulus after addition, the then pixel value using obtained value as the ith pixel point in current image block；Wherein, 1≤i ≤I_cur, I_curRepresent the total number of pixel included in current image block, the I if g=2_curValue be 4 or 2 or 1, if g=3 Then I_curValue be 9 or 6 or 4 or 3 or 2 or 1.

1. _ 5, making m=m+1, and make j=j+1, using next pending image block in original image to be encrypted as Current image block, using next element taken out from the first random sequence as currentElement, be then back to step 1. _ 4 after It is continuous to perform, until all image blocks in original image to be encrypted are disposed, obtain one-time pad encryption image；Wherein, m=m+ "=" in 1 and j=j+1 is assignment.

1. _ 6, counting the total number for the image block that the size included in one-time pad encryption image is g × g, it is designated as Count, according to step 1. _ 1 it can be seen from,OrAnd set second key key2；Then the input parameter using the second key key2 as random () function, random () function is made to produce one second Random sequence；Wherein, the second key is the text that another is differed with first key, and the length of the second random sequence is Count, the value of each element in the second random sequence are the integer in [0, Count], all members in the second random sequence The value of element does not repeat and is in random distribution.

1. _ 7, the image block that all sizes in one-time pad encryption image are g × g is carried out using the second random sequence Scramble, the double-encryption process of original image is so far completed, obtain the encryption area image of double-encryption；It is above-mentioned, first key Key1 and the second key key2 is encryption key.

As shown in Fig. 2 the processing procedure of encryption area image hiding reversible data part is：

2. _ 1, the encryption area image of double-encryption is divided intoThe size of individual non-overlapping copies is g × g Image block；Wherein, symbolTo round symbol downwards.

A the 3rd key key3 is set as image watermarking key；Then using the 3rd key key3 as random () letter Several input parameters, random () function is set to produce the 3rd random sequence；Recycle each member in the 3rd random sequence The value of element corresponds to every secret information bit in original secret information and carries out XOR encryption, obtains the hidden of XOR encryption Secret information, as secret information to be embedded；Wherein, the 3rd key differs for another with first key and the second key Text, the length of the 3rd random sequence are more than or equal to the length of original secret information, and each member in the 3rd random sequence The value of element is 0 or 1.

2. _ 3, calculate the respective pixel value of the non-central pixels of g × g-1 in current image block and central pixel point The difference of pixel value is to the values of 256 modulus, by the pixel value and center pixel of s-th of non-central pixel in current image block The difference of the pixel value of point is designated as f to the value of 256 modulus_cur(s), f_cur(s)=(h_cur(s)-h_cur,center)mod 256；Its In, s is positive integer, and s initial value is 1,1≤s≤g × g-1, h_cur(s) s-th of non-central picture in current image block is represented The pixel value of vegetarian refreshments, h_cur,centerThe pixel value of the central pixel point in current image block is represented, if the size of current image block Size is 2 × 2, then specifying any one pixel in current image block, rest of pixels point is as non-as central pixel point Central pixel point, mod are modulus symbol.

2. _ 4, according to step 2. _ 3 in g × g-1 value being calculated, determine the secret information insertion of current image block Region, it is designated as Z_cur, Z_cur=[T_p,T_p+β]∪[T_n-β,T_n]；Wherein, symbol " ∪ " is union operation symbol, T_p=0, T_n= 255, β represent regulatory factor, and β value is the integer more than or equal to 0, and β value is bigger, can lift embedding capacity, but together When can be embedded in image after secret information distortion it is bigger, therefore generally can use β is 0 or 1 or 2.

2. _ 5, for step 2. _ 3 in g × g-1 value being calculated, be handled as follows：2. _ 3 fallen into a trap for step Obtained f_cur(s), if f_cur(s) it is more than T_p+ β, then correct f_cur(s), process is：Make f'_cur(s)=f_cur(s)+(β+1), F is made again_cur(s)=f'_cur(s)；If f_cur(s) it is less than T_n- β, then correct f_cur(s), process is：Make f'_cur(s)=f_cur(s)-(β + 1), then f is made_cur(s)=f'_cur(s)；If f_cur(s)∈Z_cur, then f is kept_cur(s) it is constant；Wherein, f'_cur(s) in be introduced into Between variable, f_cur(s)=f'_cur(s) "=" in is assignment；The actual process for displacement of the step, Fig. 1 a give β and taken It is worth the schematic diagram for 0 time shift 1；Fig. 1 b give the schematic diagram that β values are 1 time shift 2.

2. secret information bit insertion, specific mistake _ 6, are carried out to g × g-1 non-central pixels in current image block Cheng Wei：For s-th of non-central pixel in current image block, if by step 2. _ 5 in g × g-1 value determining S-th of value f_cur(s) meet：f_cur(s)∈[T_n-β,T_n], then when secret information bit to be embedded is " 0 ", make f "_cur(s) =f_cur(s)-(T_n-f_cur(s)), then to h_cur(s) it is modified to complete the insertion of secret information bit, process is：Order h'_cur(s)=(f "_cur(s)+h_cur,center) mod 256, then make h_cur(s)=h'_cur(s)；When secret information bit to be embedded For " 1 " when, make f "_cur(s)=f_cur(s)-(T_n-f_cur(s)) -1, then to h_cur(s) it is modified to complete secret information ratio Special insertion, process are：Make h'_cur(s)=(f "_cur(s)+h_cur,center) mod 256, then make h_cur(s)=h'_cur(s)；If through S-th of value f in the g × g-1 value determined in crossing step 2. _ 5_cur(s) meet：f_cur(s)∈[T_p,T_p+ β], then when to be embedded Secret information bit when being " 0 ", make f "_cur(s)=f_cur(s)+(f_cur(s)-T_p), then to h_cur(s) it is modified with complete Into the insertion of secret information bit, process is：Make h'_cur(s)=(f "_cur(s)+h_cur,center) mod 256, then make h_cur(s)= h'_cur(s)；When secret information bit to be embedded is " 1 ", f "_cur(s)=f_cur(s)+(f_cur(s)-T_p)+1, then to h_cur (s) it is modified to complete the insertion of secret information bit, process is：Make h'_cur(s)=(f "_cur(s)+h_cur,center)mod 256, then make h_cur(s)=h'_cur(s)；Wherein, f "_curAnd h' (s)_cur(s) be introducing intermediate variable, h_cur(s)=h'_cur (s) "=" in is assignment.

2. _ 7, make m'=m'+1, then using double-encryption encryption area image in next pending image block as Current image block, return again to step and 2. _ 3 continue executing with, until in each image block in the encryption area image of double-encryption Each non-central pixel is embedded with secret information bit, obtains the encryption area image containing secret information；Wherein, in m'=m'+1 "=" be assignment.

As shown in figure 3, concealed data extraction and original image Distortionless part, the first situation is that receiving terminal only adds Key, only the encryption area image containing secret information is decrypted, detailed process is：

3. the width and height of _ 1_1, encryption area image containing secret information correspond to W and H, if W × H can by g × G is divided exactly, then is divided into the encryption area image containing secret informationThe size of individual non-overlapping copies is g × g image Block；If W × H can not be divided exactly by g × g, the encryption area image containing secret information is divided intoIt is individual mutually not Overlapping size is g × g image block, and by the right of the encryption area image containing secret information and lower section size not Image block is also served as g × g block, is sharedIndividual image block；Wherein, g value is 2 or 3, symbolFor to Under round symbol, symbolFor the symbol that rounds up.

3. _ 1_2, the input parameter using the second key key2 as random () function, random () function is set to produce one Individual 5th random sequence；Wherein, the length of the 5th random sequence is Count, and the value of each element in the 5th random sequence is Integer in [0, Count], the value of all elements in the 5th random sequence do not repeat and are in random distribution；Due to key phase Together, therefore the 5th random sequence is identical with the second random sequence.

3. _ 1_3, using the 5th random sequence it is g × g to all sizes in the encryption area image containing secret information Image block carry out scramble, obtain the encryption area image after scramble.

3. _ 1_4, the input parameter using first key key1 as random () function, random () function is set to produce one Individual 4th random sequence；Wherein, the length of the 4th random sequence is more than the image block included in the encryption area image after removing scramble Total number, the value of each element in the 4th random sequence is the integer in [0,255]；Because key is identical, therefore the 4th Random sequence is identical with the first random sequence.

3. _ 1_5, m-th of image block currently pending in the encryption area image after scramble will be gone to be defined as present image Block, it is currentElement by j-th of the element definition currently taken out from the 4th random sequence；Wherein, m and j is positive integer, m Initial value with j is 1, and 1≤m≤M, M represent to go in the encryption area image after scramble the total number of the image block included, according to Step 1. _ 1 understand,Or1≤j≤J, J represent the length of the 4th random sequence, J >=M.

3. _ 1_6, using currentElement each pixel in current image block is decrypted, in current image block The process that is decrypted of ith pixel point be：By the pixel value of the ith pixel point in current image block and currentElement Value subtract each other after to 256 modulus, the then pixel value using obtained value as the ith pixel point in current image block；Wherein, 1 ≤i≤I_cur, I_curRepresent the total number of pixel included in current image block, the I if g=2_curValue be 4 or 2 or 1, if g =3 I_curValue be 9 or 6 or 4 or 3 or 2 or 1.

3. _ 1_7, making m=m+1, and j=j+1 is made, next pending image in the encryption area image after scramble will be removed Block, using next element taken out from the 4th random sequence as currentElement, is then back to step as current image block 3. _ 1_6 is continued executing with, until all image blocks in the encryption area image after removing scramble are disposed, image decryption is completed Process, obtain the decryption area image containing secret information；Wherein, "=" in m=m+1 and j=j+1 is assignment.

Embodiment two：

A kind of encryption area image reversible data concealing method for double-encryption that the present embodiment proposes, its image encryption part With image encryption part of the encryption area image hiding reversible data part with embodiment one and encryption area image hiding reversible data Part is identical, the difference is that only concealed data extraction and original image Distortionless part, in the present embodiment receiving terminal Only image watermarking key, only carries out secret information extraction to the encryption area image containing secret information, and detailed process is：

3. the width and height of _ 2_1, encryption area image containing secret information correspond to W and H, by containing secret information plus Close area image is divided intoThe size of individual non-overlapping copies is g × g image block；Wherein, symbolFor to Under round symbol.

Input parameter using the 3rd key key3 as random () function, random () function is set to produce one the 6th Random sequence；Wherein, the value of each element in the 6th random sequence is 0 or 1.

3. _ 2_3, calculate the respective pixel value of the non-central pixels of g × g-1 and central pixel point in current image block Pixel value difference to the values of 256 modulus, by the pixel value of s-th of non-central pixel in current image block and middle imago The difference of the pixel value of vegetarian refreshments is designated as to the value of 256 modulus Its In, s is positive integer, and s initial value is 1,1≤s≤g × g-1,Represent s-th of non-central picture in current image block The pixel value of vegetarian refreshments,The pixel value of the central pixel point in current image block is represented, if the size of current image block is big Small is 2 × 2, then specifies any one pixel in current image block as central pixel point, and rest of pixels point is as in non- Imago vegetarian refreshments, mod are modulus symbol.

3. _ 2_5, secret information bit extraction is carried out to g × g-1 non-central pixels in current image block, specifically Process is：For s-th of non-central pixel in current image block, if by step 3. _ 2_3 is calculatedIt is full Foot：Then whenDuring equal to 0, the secret information bit for extracting to obtain is " 0 ", WhenDuring equal to 1, the secret information bit for extracting to obtain is " 1 "；If by step 3. _ 2_3 is calculatedMeet：Then whenDuring equal to 0, obtained secret information ratio is extracted Specially for " 0 ", whenDuring equal to 1, the secret information bit for extracting to obtain is " 1 ".

3. _ 2_6, m'=m'+1 is made, then by next pending image block in the encryption area image containing secret information As current image block, return again to step 3. _ 2_3 continues executing with, until from each in the encryption area image containing secret information Secret information bit is extracted in each non-central pixel in image block, extraction obtains secret information；Wherein, m'=m'+1 In "=" be assignment.

It is 3. _ 2_7, hidden to every in the obtained secret information of extraction using the value of each element in the 6th random sequence Secret information bit, which corresponds, carries out XOR decryption, obtains the secret information of XOR decryption, the final secret obtained as extraction Information.

Embodiment three：

A kind of encryption area image reversible data concealing method for double-encryption that the present embodiment proposes, its image encryption part Image encryption part and encryption area image with encryption area image hiding reversible data part and embodiment one or embodiment two can Reverse data hidden parts are identical, concealed data extraction and original image Distortionless part the difference is that only, in this implementation In example, as shown in figure 3, the existing image watermarking key of receiving terminal has encryption key, first to the encryption area image containing secret information again Carry out secret information extraction, after to secret information extract after encryption area image be decrypted, detailed process is：

3. the width and height of _ 3_1, encryption area image containing secret information correspond to W and H, by containing secret information plus Close area image is divided intoThe size of individual non-overlapping copies is g × g image block；Wherein, symbolFor to Under round symbol.

3. _ 3_3, calculate the respective pixel value of the non-central pixels of g × g-1 and central pixel point in current image block Pixel value difference to the values of 256 modulus, by the pixel value of s-th of non-central pixel in current image block and middle imago The difference of the pixel value of vegetarian refreshments is designated as to the value of 256 modulus Its In, s is positive integer, and s initial value is 1,1≤s≤g × g-1,Represent s-th of non-central pixel in current image block The pixel value of point,The pixel value of the central pixel point in current image block is represented, if the size of current image block For 2 × 2, then specifying any one pixel in current image block, rest of pixels point is as non-central as central pixel point Pixel, mod are modulus symbol.

3. _ 3_5, secret information bit extraction is carried out to g × g-1 non-central pixels in current image block, specifically Process is：For s-th of non-central pixel in current image block, if by step 3. _ 3_3 is calculatedIt is full Foot：Then whenDuring equal to 0, the secret information bit for extracting to obtain is " 0 ", WhenDuring equal to 1, the secret information bit for extracting to obtain is " 1 "；If by step 3. _ 3_3 is calculatedMeet：Then whenDuring equal to 0, obtained secret information ratio is extracted Specially for " 0 ", whenDuring equal to 1, the secret information bit for extracting to obtain is " 1 ".

3. _ 3_6, carrying out recovery operation to g × g-1 non-central pixels in current image block, detailed process is：It is right S-th of non-central pixel in current image block, if by step 3. _ 3_3 is calculatedMeet：Then whenDuring equal to 0, order WhenDuring equal to 1, orderIf by step 3. _ 3_3 count ObtainMeet：Then whenDuring equal to 0, orderWhenDuring equal to 0, order If by step 3. _ 3_3 is calculatedMeet：Then makeIf by step 3. _ 3_3 is calculatedMeet：Then makeWherein, symbolTo round symbol downwards, WithIn "=" be assignment.

3. _ 3_7, m'=m'+1 is made, then by next pending image block in the encryption area image containing secret information As current image block, return again to step 3. _ 3_3 continues executing with, until from each in the encryption area image containing secret information Secret information bit is extracted in each non-central pixel in image block, obtains the encrypted domain figure after secret information extraction Picture, and extract and obtain secret information；Wherein, "=" in m'=m'+1 is assignment.

It is 3. _ 3_8, hidden to every in the obtained secret information of extraction using the value of each element in the 6th random sequence Secret information bit, which corresponds, carries out XOR decryption, obtains the secret information of XOR decryption, the final secret obtained as extraction Information.

3. the width and height of the encryption area image after the extraction of _ 3_9, secret information correspond to W and H, if W × H can Divided exactly by g × g, then the encryption area image after secret information is extracted is divided intoThe size of individual non-overlapping copies is g × g image block；If W × H can not be divided exactly by g × g, the encryption area image after secret information is extracted is divided intoThe size of individual non-overlapping copies is g × g image block, and the encryption area image after secret information is extracted Right and lower section size are not that g × g block also serves as image block, are sharedIndividual image block；Wherein, g value For 2 or 3, symbolTo round symbol, symbol downwardsFor the symbol that rounds up.

3. _ 3_10, the input parameter using the second key key2 as random () function, produce random () function One the 5th random sequence；Wherein, the length of the 5th random sequence is Count, the value of each element in the 5th random sequence For the integer in [0, Count], the value of all elements in the 5th random sequence does not repeat and is in random distribution；Due to key phase Together, therefore the 5th random sequence is identical with the second random sequence.

3. _ 3_11, using the 5th random sequence to secret information extract after encryption area image in all sizes Scramble is carried out for g × g image block, obtains the encryption area image after scramble.

3. _ 3_12, the input parameter using first key key1 as random () function, produce random () function One the 4th random sequence；Wherein, the value of each element in the 4th random sequence is the integer in [0,255]；Due to key It is identical, therefore the 4th random sequence is identical with the first random sequence.

3. _ 3_13, m-th of image block currently pending in the encryption area image after scramble will be gone to be defined as present image Block, it is currentElement by j-th of the element definition currently taken out from the 4th random sequence；Wherein, m and j is positive integer, m Initial value with j is 1, and 1≤m≤M, M represent to go in the encryption area image after scramble the total number of the image block included,Or1≤j≤J, J represent the length of the 4th random sequence, J >=M.

3. _ 3_14, using currentElement each pixel in current image block is decrypted, in current image block The process that is decrypted of ith pixel point be：By the pixel value of the ith pixel point in current image block and currentElement Value subtract each other after to 256 modulus, the then pixel value using obtained value as the ith pixel point in current image block；Wherein, 1 ≤i≤I_cur, I_curRepresent the total number of pixel included in current image block, the I if g=2_curValue be 4 or 2 or 1, if g =3 I_curValue be 9 or 6 or 4 or 3 or 2 or 1.

Claims

1. the encryption area image reversible data concealing method of a kind of double-encryption, it is characterised in that including image encryption, encrypted domain Image hiding reversible data, the extraction of concealed data and original image Distortionless three parts；Wherein,

The processing procedure of described image encryption part is：

1. the width and height that _ 1, set original image to be encrypted correspond to W and H, if W × H can be divided exactly by g × g, Original image to be encrypted is divided intoThe size of individual non-overlapping copies is g × g image block；If W × H can not It is enough to be divided exactly by g × g, then original image to be encrypted is divided intoThe size of individual non-overlapping copies is g × g's Image block, and the right of original image to be encrypted and lower section size are not also served as into image block for g × g block, shareIndividual image block；Wherein, g value is 2 or 3, symbolTo round symbol, symbol downwardsTo be upward Round symbol；

1. _ 2, set a first key key1；Then the input parameter using first key key1 as random () function, makes Random () function produces first random sequence；Wherein, the length of the first random sequence is more than original image to be encrypted In the total number of image block that includes, the value of each element in the first random sequence is the integer in [0,255]；

1. m-th of image block currently pending in original image to be encrypted _ 3, is defined as current image block, will currently from J-th of the element definition taken out in first random sequence is currentElement；Wherein, m and j is the initial value of positive integer, m and j Be 1,1≤m≤M, M represent the total number of the image block included in original image to be encrypted, 1≤j≤J, J represent first with The length of machine sequence；

1. _ 4, each pixel in current image block is encrypted using currentElement, to i-th in current image block The process that pixel is encrypted is：The pixel value of ith pixel point in current image block is added with the value of currentElement Afterwards to 256 modulus, the then pixel value using obtained value as the ith pixel point in current image block；Wherein, 1≤i≤ I_cur, I_curRepresent the total number of pixel included in current image block；

1. _ 5, making m=m+1, and j=j+1 is made, using next pending image block in original image to be encrypted as current Image block, using next element taken out from the first random sequence as currentElement, it is then back to step and 1. _ 4 continues to hold OK, until all image blocks in original image to be encrypted are disposed, one-time pad encryption image is obtained；Wherein, m=m+1 and j "=" in=j+1 is assignment；

1. _ 6, counting the total number for the image block that the size included in one-time pad encryption image is g × g, Count is designated as；And Set a second key key2；Then the input parameter using the second key key2 as random () function, makes random () Function produces second random sequence；Wherein, the length of the second random sequence is Count, each in the second random sequence The value of element is the integer in [0, Count], and the value of all elements in the second random sequence does not repeat and is in random distribution；

1. _ 7, the image block that all sizes in one-time pad encryption image are g × g is put using the second random sequence Disorderly, the double-encryption process of original image is so far completed, obtains the encryption area image of double-encryption；It is above-mentioned, first key Key1 and the second key key2 is encryption key；

2. _ 1, the encryption area image of double-encryption is divided intoThe size of individual non-overlapping copies is g × g figure As block；Wherein, symbolTo round symbol downwards；

A the 3rd key key3 is set as image watermarking key；Then using the 3rd key key3 as random () function Input parameter, random () function is set to produce the 3rd random sequence；Recycle each element in the 3rd random sequence It is worth to correspond every secret information bit in original secret information and carries out XOR encryption, obtains the concealed letter of XOR encryption Breath, as secret information to be embedded；Wherein, the length of the 3rd random sequence is more than or equal to the length of original secret information, And the value of the 3rd each element in random sequence is 0 or 1；

2. the m' image block currently pending in the encryption area image of double-encryption _ 2, is defined as current image block；Its In, m' is positive integer, and m' initial value is 1,

2. _ 3, calculate the pixel of the respective pixel value of the non-central pixels of g × g-1 and central pixel point in current image block The difference of value is to the values of 256 modulus, by the pixel value of s-th of non-central pixel in current image block and central pixel point The difference of pixel value is designated as f to the value of 256 modulus_cur(s), f_cur(s)=(h_cur(s)-h_cur,center)mod256；Wherein, s is Positive integer, s initial value is 1,1≤s≤g × g-1, h_cur(s) s-th of non-central pixel in current image block is represented Pixel value, h_cur,centerThe pixel value of the central pixel point in current image block is represented, if the size of current image block is 2 × 2, then specifying any one pixel in current image block, rest of pixels point is as non-central pixel as central pixel point Point, mod are modulus symbol；

2. _ 4, according to step 2. _ 3 in g × g-1 value being calculated, determine the secret information insertion region of current image block, It is designated as Z_cur, Z_cur=[T_p,T_p+β]∪[T_n-β,T_n]；Wherein, symbol " ∪ " is union operation symbol, T_p=0, T_n=255, β table Show regulatory factor, β value is the integer more than or equal to 0；

2. _ 5, for step 2. _ 3 in g × g-1 value being calculated, be handled as follows：For step 2. _ 3 in calculate The f arrived_cur(s), if f_cur(s) it is more than T_p+ β, then correct f_cur(s), process is：Make f'_cur(s)=f_cur(s)+(β+1), then make f_cur(s)=f'_cur(s)；If f_cur(s) it is less than T_n- β, then correct f_cur(s), process is：Make f'_cur(s)=f_cur(s)-(β+1), F is made again_cur(s)=f'_cur(s)；If f_cur(s)∈Z_cur, then f is kept_cur(s) it is constant；Wherein, f'_cur(s) the middle anaplasia to be introduced into Amount, f_cur(s)=f'_cur(s) "=" in is assignment；

2. _ 6, carrying out secret information bit insertion to g × g-1 non-central pixels in current image block, detailed process is： For s-th of non-central pixel in current image block, if by step 2. _ 5 in s-th in g × g-1 value determining Value f_cur(s) meet：f_cur(s)∈[T_n-β,T_n], then when secret information bit to be embedded is " 0 ", make f "_cur(s)=f_cur (s)-(T_n-f_cur(s)), then to h_cur(s) it is modified to complete the insertion of secret information bit, process is：Make h'_cur(s) =(f "_cur(s)+h_cur,center) mod256, then make h_cur(s)=h'_cur(s)；When secret information bit to be embedded is " 1 ", Make f "_cur(s)=f_cur(s)-(T_n-f_cur(s)) -1, then to h_cur(s) it is modified to complete the insertion of secret information bit, Process is：Make h'_cur(s)=(f "_cur(s)+h_cur,center) mod256, then make h_cur(s)=h'_cur(s)；If by step 2. _ 5 S-th of value f in g × g-1 value of middle determination_cur(s) meet：f_cur(s)∈[T_p,T_p+ β], then when secret information to be embedded When bit is " 0 ", f " is made_cur(s)=f_cur(s)+(f_cur(s)-T_p), then to h_cur(s) it is modified to complete secret information The insertion of bit, process are：Make h'_cur(s)=(f "_cur(s)+h_cur,center) mod256, then make h_cur(s)=h'_cur(s)；When When secret information bit to be embedded is " 1 ", f "_cur(s)=f_cur(s)+(f_cur(s)-T_p)+1, then to h_cur(s) repaiied Just to complete the insertion of secret information bit, process is：Make h'_cur(s)=(f "_cur(s)+h_cur,center) mod256, then make h_cur (s)=h'_cur(s)；Wherein, f "_curAnd h' (s)_cur(s) be introducing intermediate variable, h_cur(s)=h'_cur(s) "=" in For assignment；

2. m'=m'+1 _ 7, is made, then using next pending image block in the encryption area image of double-encryption as current Image block, return again to step and 2. _ 3 continue executing with, until each in each image block in the encryption area image of double-encryption Non-central pixel is embedded with secret information bit, obtains the encryption area image containing secret information；Wherein, in m'=m'+1 "=" is assignment；

The first situation is that receiving terminal only has encryption key, only the encryption area image containing secret information is decrypted, specific mistake Cheng Wei：

3. the width and height of _ 1_1, encryption area image containing secret information correspond to W and H, if W × H can be whole by g × g Remove, be then divided into the encryption area image containing secret informationThe size of individual non-overlapping copies is g × g image block； If W × H can not be divided exactly by g × g, the encryption area image containing secret information is divided intoIndividual non-overlapping copies Size be g × g image block, and be not g by the right of the encryption area image containing secret information and lower section size × g block also serves as image block, sharesIndividual image block；Wherein, g value is 2 or 3, symbolTo take downwards Integral symbol, symbolFor the symbol that rounds up；

3. _ 1_2, the input parameter using the second key key2 as random () function, random () function is set to produce one the Five random sequences；Wherein, the length of the 5th random sequence is Count, the value of each element in the 5th random sequence for [0, Count] in integer, the value of all elements in the 5th random sequence do not repeat and is in random distribution；

3. _ 1_3, the figure for being g × g to all sizes in the encryption area image containing secret information using the 5th random sequence As block carries out scramble, the encryption area image after scramble is obtained；

3. _ 1_4, the input parameter using first key key1 as random () function, random () function is set to produce one the Four random sequences；Wherein, the length of the 4th random sequence is total more than the image block included in the encryption area image after removing scramble Number, the value of each element in the 4th random sequence is the integer in [0,255]；

3. _ 1_5, m-th of image block currently pending in the encryption area image after scramble will be gone to be defined as current image block, will J-th of the element definition currently taken out from the 4th random sequence is currentElement；Wherein, m and j is positive integer, m and j's Initial value is 1, and 1≤m≤M, M represent to go in the encryption area image after scramble the total number of the image block included, 1≤j≤J, J Represent the length of the 4th random sequence；

3. _ 1_6, using currentElement each pixel in current image block is decrypted, to i-th in current image block The process that individual pixel is decrypted is：By the value phase of the pixel value and currentElement of the ith pixel point in current image block To 256 modulus after subtracting, the then pixel value using obtained value as the ith pixel point in current image block；Wherein, 1≤i≤ I_cur, I_curRepresent the total number of pixel included in current image block；

3. _ 1_7, making m=m+1, and j=j+1 is made, next pending image block in area image of encrypting after scramble will be gone to make For current image block, using next element taken out from the 4th random sequence as currentElement, be then back to step 3. _ 1_ 6 continue executing with, until all image blocks in the encryption area image after removing scramble are disposed, complete the process of image decryption, Obtain the decryption area image containing secret information；Wherein, "=" in m=m+1 and j=j+1 is assignment；

Second of situation is that receiving terminal only has image watermarking key, only carries out secret information to the encryption area image containing secret information Extraction, detailed process are：

3. the width and height of _ 2_1, encryption area image containing secret information correspond to W and H, by the encrypted domain containing secret information Image is divided intoThe size of individual non-overlapping copies is g × g image block；Wherein, symbolTo be downward Round symbol；

Input parameter using the 3rd key key3 as random () function, make random () function produce one it is the 6th random Sequence；Wherein, the value of each element in the 6th random sequence is 0 or 1；

3. _ 2_2, the m' image block currently pending in the encryption area image containing secret information be defined as present image Block；Wherein, m' is positive integer, and m' initial value is 1,

3. _ 2_3, the picture for calculating the respective pixel value of the non-central pixels of g × g-1 and central pixel point in current image block The difference of element value is to the values of 256 modulus, by the pixel value and central pixel point of s-th of non-central pixel in current image block The difference of pixel value the value of 256 modulus is designated as Wherein, s For positive integer, s initial value is 1,1≤s≤g × g-1,Represent s-th of non-central pixel in current image block Pixel value,The pixel value of the central pixel point in current image block is represented, if the size of current image block is 2 × 2, then specifying any one pixel in current image block, rest of pixels point is as non-central pixel as central pixel point Point, mod are modulus symbol；

3. _ 2_4, according to step 3. _ 2_3 in g × g-1 value being calculated, determine the secret information extraction of current image block Region, it is designated as Wherein, symbol " ∪ " is union operation symbol,

3. _ 2_5, secret information bit extraction, detailed process are carried out to g × g-1 non-central pixels in current image block For：For s-th of non-central pixel in current image block, if by step 3. _ 2_3 is calculatedMeet：Then whenDuring equal to 0, the secret information bit for extracting to obtain is " 0 ", whenDuring equal to 1, the secret information bit for extracting to obtain is " 1 "；If by step 3. _ 2_3 is calculatedMeet：Then whenDuring equal to 0, obtained secret information ratio is extracted Specially for " 0 ", whenDuring equal to 1, the secret information bit for extracting to obtain is " 1 "；

3. _ 2_6, make m'=m'+1, then using containing secret information encryption area image in next pending image block as Current image block, return again to step 3. _ 2_3 continues executing with, until from each image in the encryption area image containing secret information Secret information bit is extracted in each non-central pixel in block, extraction obtains secret information；Wherein, in m'=m'+1 "=" is assignment；

3. every secret in _ 2_7, the secret information obtained using the value of each element in the 6th random sequence to extraction is believed Cease bit and correspond progress XOR decryption, obtain the secret information of XOR decryption, the final secret information obtained as extraction；

The third situation is that the existing image watermarking key of receiving terminal has encryption key again, first to the encryption area image containing secret information Carry out secret information extraction, after to secret information extract after encryption area image be decrypted, detailed process is：

3. the width and height of _ 3_1, encryption area image containing secret information correspond to W and H, by the encrypted domain containing secret information Image is divided intoThe size of individual non-overlapping copies is g × g image block；Wherein, symbolTo take downwards Integral symbol；

3. _ 3_2, the m' image block currently pending in the encryption area image containing secret information be defined as present image Block；Wherein, m' is positive integer, and m' initial value is 1,

3. _ 3_3, the picture for calculating the respective pixel value of the non-central pixels of g × g-1 and central pixel point in current image block The difference of element value is to the values of 256 modulus, by the pixel value and central pixel point of s-th of non-central pixel in current image block The difference of pixel value the value of 256 modulus is designated as Wherein, s For positive integer, s initial value is 1,1≤s≤g × g-1,Represent s-th of non-central pixel in current image block Pixel value,The pixel value of the central pixel point in current image block is represented, if the size of current image block is 2 × 2, then specifying any one pixel in current image block, rest of pixels point is as non-central pixel as central pixel point Point, mod are modulus symbol；

3. _ 3_4, according to step 3. _ 3_3 in g × g-1 value being calculated, determine the secret information extraction of current image block Region, it is designated as Wherein, symbol " ∪ " is union operation symbol,

3. _ 3_5, secret information bit extraction, detailed process are carried out to g × g-1 non-central pixels in current image block For：For s-th of non-central pixel in current image block, if by step 3. _ 3_3 is calculatedMeet：Then whenDuring equal to 0, the secret information bit for extracting to obtain is " 0 ", whenDuring equal to 1, the secret information bit for extracting to obtain is " 1 "；If by step 3. _ 3_3 is calculatedMeet：Then whenDuring equal to 0, obtained secret information ratio is extracted Specially for " 0 ", whenDuring equal to 1, the secret information bit for extracting to obtain is " 1 "；

3. _ 3_6, carrying out recovery operation to g × g-1 non-central pixels in current image block, detailed process is：For working as S-th of non-central pixel in preceding image block, if by step 3. _ 3_3 is calculatedMeet：Then whenDuring equal to 0, order WhenDuring equal to 1, orderIf by step 3. _ 3_3 calculates ArriveMeet：Then whenDuring equal to 0, orderWhenDuring equal to 0, order If by step 3. _ 3_3 is calculatedMeet：Then makeIf by step 3. _ 3_3 is calculatedMeet：Then makeWherein, symbolTo round symbol downwards, WithIn "=" be assignment；

3. _ 3_7, make m'=m'+1, then using containing secret information encryption area image in next pending image block as Current image block, return again to step 3. _ 3_3 continues executing with, until from each image in the encryption area image containing secret information Secret information bit is extracted in each non-central pixel in block, obtains the encryption area image after secret information extraction, and Extraction obtains secret information；Wherein, "=" in m'=m'+1 is assignment；

3. every secret in _ 3_8, the secret information obtained using the value of each element in the 6th random sequence to extraction is believed Cease bit and correspond progress XOR decryption, obtain the secret information of XOR decryption, the final secret information obtained as extraction；

3. _ 3_9, secret information extraction after encryption area image width and highly correspond to W and H, if W × H can by g × G is divided exactly, then the encryption area image after secret information is extracted is divided intoThe size of individual non-overlapping copies is g × g's Image block；If W × H can not be divided exactly by g × g, the encryption area image after secret information is extracted is divided intoThe size of individual non-overlapping copies is g × g image block, and the encryption area image after secret information is extracted Right and lower section size are not that g × g block also serves as image block, are sharedIndividual image block；Wherein, g value For 2 or 3, symbolTo round symbol, symbol downwardsFor the symbol that rounds up；

3. _ 3_10, the input parameter using the second key key2 as random () function, random () function is set to produce one 5th random sequence；Wherein, the length of the 5th random sequence is Count, the value of each element in the 5th random sequence for [0, Count] in integer, the value of all elements in the 5th random sequence do not repeat and is in random distribution；

3. _ 3_11, using the 5th random sequence to secret information extract after encryption area image in all sizes for g × G image block carries out scramble, obtains the encryption area image after scramble；

3. _ 3_12, the input parameter using first key key1 as random () function, random () function is set to produce one 4th random sequence；Wherein, the value of each element in the 4th random sequence is the integer in [0,255]；

3. _ 3_13, m-th of image block currently pending in the encryption area image after scramble will be gone to be defined as current image block, It is currentElement by j-th of the element definition currently taken out from the 4th random sequence；Wherein, m and j is positive integer, m and j Initial value be 1,1≤m≤M, M represent to go in the encryption area image after scramble the total number of the image block included, 1≤j≤ J, J represent the length of the 4th random sequence；

3. _ 3_14, using currentElement each pixel in current image block is decrypted, in current image block The process that i pixel is decrypted is：By the value phase of the pixel value and currentElement of the ith pixel point in current image block To 256 modulus after subtracting, the then pixel value using obtained value as the ith pixel point in current image block；Wherein, 1≤i≤ I_cur, I_curRepresent the total number of pixel included in current image block；

3. _ 3_15, making m=m+1, and j=j+1 is made, next pending image block in the encryption area image after scramble will be removed As current image block, using next element taken out from the 4th random sequence as currentElement, be then back to step 3. _ 3_14 is continued executing with, until all image blocks in the encryption area image after removing scramble are disposed, completes the mistake of image decryption Journey, obtain the decryption area image after secret information extraction；Wherein, "=" in m=m+1 and j=j+1 is assignment.