CN101394553A - Image ciphering, deciphering method and device - Google Patents
Image ciphering, deciphering method and device Download PDFInfo
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- CN101394553A CN101394553A CNA2008101688530A CN200810168853A CN101394553A CN 101394553 A CN101394553 A CN 101394553A CN A2008101688530 A CNA2008101688530 A CN A2008101688530A CN 200810168853 A CN200810168853 A CN 200810168853A CN 101394553 A CN101394553 A CN 101394553A
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Abstract
The embodiment of the invention discloses an image encryption method, which comprises the following steps: low-frequency coefficients of an image are obtained; the low-frequency coefficients are divided into at least two groups of coefficients; at least a group of coefficients are selected from at least two groups of coefficients, and the encryption of at least one group of selected coefficients is carried out. The embodiment of the invention further discloses an image decryption method, which comprises the following steps: the encrypted image is received; the low-frequency coefficients of the image are obtained; the low-frequency coefficients are divided into at least two groups of coefficients; at least one group of coefficients are selected from at least two groups of coefficients, and the decryption of the selected at least one group of coefficients is carried out. The proposal can overcome the problem of poor confidentiality caused by fixed and open encrypted coefficients in the prior art by dividing the low-frequency coefficients of the image into at least two groups and selecting at least one group of coefficients for carrying out the encryption. The embodiment of the invention further correspondingly discloses an image encryption device and an image decryption device.
Description
Technical field
The present invention relates to the figure multimedia technology field, relate in particular to method, the device of image deciphering, deciphering.
Background technology
Along with image in network quick transmission and be extensive use of.The user has higher requirement to the copyright authentication and the safe transmission of image information.To the authentication of image copyright, can adopt digital watermark technology, copyright information is hidden in the image, reach the ownership of identifying works and follow the trail of the illegally purpose in infringement source; To the safe transmission of image information, can adopt the image encryption technology, the real information of hidden image itself, the safe transmission of guarantee information in channel.
In order to satisfy to the copyright authentication of image information and the requirement of safe transmission, the method that has proposed a cover watermark and encrypted the Combined Protection image.This method comprises: the image block that image division is become the 8*8 pixel, each image block is carried out DCT (Discrete Cosine Transform, discrete cosine transform) conversion, obtain the coefficient matrix of the dct transform of 8*8, wherein the direct current system of each coefficient matrix is used for encrypting, and AC system is used for watermarked.Through Network Transmission, the user obtains encrypting and watermarked image, obtains watermarked image by legal secret key decryption.
In realizing process of the present invention, the inventor finds to have following problem in the prior art at least: coefficient watermarked and that encrypt is fixed as ac coefficient and DC coefficient in the coefficient matrix respectively in the said method, promptly the zone of Jia Miing is fixed, encrypt easy victim and crack, fail safe is not high.
Summary of the invention
The embodiment of the invention provides image encryption, decryption method and device, encrypts the zone and does not fix, and has improved fail safe.
A kind of image decryption method comprises:
Obtain the low frequency coefficient of image;
Described low frequency coefficient is divided at least two group coefficients;
From described at least two group coefficients, choose at least one group of coefficient, the described at least one group of coefficient of choosing encrypted.
A kind of image decryption method comprises:
Receive the image of encrypting;
Obtain the low frequency coefficient of described image;
Described low frequency coefficient is divided at least two group coefficients;
From described at least two group coefficients, choose at least one group of coefficient, the described at least one group of coefficient of choosing is decrypted.
A kind of image encrypting apparatus comprises:
The coefficient acquisition module is used to obtain the low frequency coefficient of image;
The coefficient grouping module is used for described low frequency coefficient is divided at least two group coefficients;
Encrypting module is used for choosing at least one group of coefficient from described at least two group coefficients, and the described at least one group of coefficient of choosing encrypted.
A kind of image place decryption device comprises:
The image receiver module is used to receive the image of encryption;
The coefficient acquisition module is used to obtain the low frequency coefficient of described image;
The coefficient grouping module is used for described low frequency coefficient is divided at least two group coefficients;
Deciphering module is used for choosing at least one group of coefficient from described at least two group coefficients, and the described at least one group of coefficient of choosing is decrypted.
The image processing method that the embodiment of the invention provides, device are divided at least two groups by the low frequency coefficient with image, choose at least one group of coefficient and encrypt, and overcome in the prior art because of the coefficient of encrypting to fix and open, cause the problem of confidentiality difference.
Description of drawings
In order to be illustrated more clearly in the embodiment of the invention or technical scheme of the prior art, to do to introduce simply to the accompanying drawing of required use in embodiment or the description of the Prior Art below, apparently, accompanying drawing in describing below only is some embodiments of the present invention, for those of ordinary skills, under the prerequisite of not paying creative work, can also obtain other accompanying drawing according to these accompanying drawings.
Fig. 1 is the schematic flow sheet of embodiment of the invention image encryption method;
Fig. 2 is the schematic flow sheet of step 102 among Fig. 1;
Fig. 3 is the schematic flow sheet of step 104 among Fig. 1;
Fig. 4 is the schematic flow sheet of embodiment of the invention image decryption method;
Fig. 5 is the schematic flow sheet of step 403 among Fig. 4;
Fig. 6 is the flow chart of step 405 among Fig. 4;
Fig. 7 is the structural representation of embodiment of the invention image encrypting apparatus;
Fig. 8 is the structure schematic diagram of embodiment of the invention image decrypting device knot;
Fig. 9 is an embodiment of the invention wavelet low frequency coefficient grouping schematic diagram;
Coefficient quantization principle schematic when Figure 10 embeds for embodiment of the invention watermark;
Figure 11 embeds schematic diagram for embodiment of the invention repetitive watermark;
Figure 12 (a) is original Lena image;
Figure 12 (b) encrypts and watermarked Lena image;
Figure 12 (c) is deciphering and the Lena image that contains watermark;
Figure 13 (a) is original cameraman image;
Figure 13 (b) encrypts and watermarked cameraman image;
Figure 13 (c) is deciphering and the cameraman image that contains watermark.
Embodiment
Below in conjunction with the accompanying drawing in the embodiment of the invention, the technical scheme in the embodiment of the invention is clearly and completely described, obviously, described embodiment only is the present invention's part embodiment, rather than whole embodiment.Based on the embodiment among the present invention, those of ordinary skills belong to the scope of protection of the invention not making the every other embodiment that is obtained under the creative work prerequisite.
Below a kind of image processing method in the embodiment of the invention is described in detail, referring to Fig. 1, method comprises:
101, obtain the low frequency coefficient of image
In this example, equity image to be sent carries out 3 grades of wavelet transformations, obtains the low frequency coefficient { a of image wavelet transform
1, a
2, a
3, a
4, a
5, a
6... .a
n.
102, described low frequency coefficient is divided at least two group coefficients:
Described low frequency coefficient is divided at least two group coefficients by certain rule, and as shown in Figure 2, this step comprises:
201, produce binary number at random by key
In this example, key produces and the identical binary number of described low frequency coefficient number at random
202, described low frequency coefficient and described binary number are compared
In this example, the binary number of described low frequency coefficient and correspondence position is made comparisons:
a
1?a
2?a
3?a
4?a
5?a
6......?a
n
0 1 0 1 1 0......?1
203, according to the pairing low frequency coefficient in position of described binary number " 0 " and " 1 ", described low frequency coefficient is divided into coefficient " 0 " group, coefficient " 1 " group
In this example, a
1, a
3, a
6The binary number of correspondence position is " 0 ", then a
1, a
3, a
6Be assigned to coefficient " 0 " group;
a
2, a
4, a
5A
nThe binary number of correspondence position is " 1 ", then a
2, a
4, a
5A
nBe assigned to coefficient " 1 " group.
204, coefficient " 0 " group is first group of coefficient, and coefficient " 1 " group is second group of coefficient
In this example, making coefficient " 0 " group is first group of coefficient, and coefficient " 1 " group is second group of coefficient, and then first group of coefficient is { a
1, a
3, a
6; Second group of coefficient is { a
2, a
4, a
5A
n.
103, choosing at least one group of coefficient encrypts;
Image there are following two kinds of processing modes, are respectively
(1) watermarked and encrypted image
Choose at least one group of coefficient, encrypt also watermarked at least one group of selected coefficient; Or
Choose at least one group of coefficient, at least one group of selected coefficient encrypted, choose other at least one group of coefficient simultaneously, watermarked at least one group of coefficient of choosing.
(2) encrypted image
At least one group of coefficient of picked at random encrypted at least one group of selected coefficient.
In this example, be first kind of mode to the treatment of picture mode.To first group of coefficient { a
1, a
3, a
6Watermarked, to second group of coefficient { a
2, a
4, a
5Carry out DES (Data Encryption Standard, data encryption standard) and encrypt.
To coefficient { a
1, a
3, a
6Watermarked after, coefficient becomes
To coefficient { a
2, a
4, a
5A
nAfter the encryption, coefficient becomes
104, obtain image after the encryption, detailed process is referring to Fig. 3:
301, after encryption is finished,, merge described first group of coefficient and second group of coefficient, the low frequency coefficient after obtaining merging according to " 0 " of described binary number and the position of " 1 ";
In this example, the position according to " 0 " of described binary number reverts to original position with first group of coefficient; Position according to " 1 " of described binary number reverts to original position with second group of coefficient.Low frequency coefficient after obtaining merging.
According to binary number
The position of " 0 ", with first group of coefficient be
Revert to original position, according to described binary number
The position of " 1 ", with second group of coefficient be
Revert to original position, the low frequency coefficient after obtaining merging is
302, the low frequency coefficient after the described merging is carried out wavelet inverse transformation, the image after obtaining encrypting.
In this example, to described low frequency coefficient
Carry out wavelet inverse transformation, the image after obtaining encrypting.If among the top embodiment, encipher only not, also selected one group of coefficient watermarked, then step 301 and 302 correspondingly, be after encrypting and the watermark embedding finishes dealing with, according to " 0 " of described binary number and the position of " 1 ", merge described first group of coefficient and second group of coefficient, the low frequency coefficient after obtaining merging; Low frequency coefficient after the described merging is carried out wavelet inverse transformation, obtain encrypting and watermarked after image.
The method that the embodiment of the invention provides is got low frequency coefficient subregion at random based on wavelet transformation, and a part is used for encrypting, a part is used for watermarked, algorithm security is higher, and the main energy of image in the wavelet low frequency subband set is encrypted low frequency sub-band and can be reached better scramble effect simultaneously.
Below image decryption method in the embodiment of the invention is described in detail, as shown in Figure 4, comprising:
401, receive the image of encrypting;
402, the image of encrypting is carried out 3 grades of wavelet transformations;
In this example, receiving terminal carries out 3 grades of wavelet transformations to image watermarked and that encrypt, obtains low frequency coefficient
403, described low frequency coefficient is divided at least two group coefficients, detailed process is referring to Fig. 5:
Use with identical rule described low frequency coefficient is divided at least two group coefficients.
As shown in Figure 5, step 403 comprises:
501, produce binary number at random by key
In this example, receiving terminal produces and the identical binary number of described low frequency coefficient number at random by using the key identical with transmitting terminal
502, described low frequency coefficient and described binary number are compared
In this example, the binary number of described low frequency coefficient and correspondence position is made comparisons:
0 1 0 1 1 0...... 1
503, according to the pairing low frequency coefficient in position of described binary number " 0 " and " 1 ", described low frequency coefficient is divided into coefficient " 0 " group, coefficient " 1 " group
In this example,
The binary number of correspondence position is " 0 ", then
Be assigned to coefficient " 0 " group;
The binary number of correspondence position is " 1 ", then
Be assigned to coefficient " 1 " group.
504, coefficient " 0 " group is the 3rd a group of coefficient, and coefficient " 1 " group is the 4th a group of coefficient
In this example, making coefficient " 0 " group is the 3rd group of coefficient, and coefficient " 1 " group is the 4th a group of coefficient, and then the 3rd group of coefficient is
The 4th group of coefficient is
404, choosing at least one group of coefficient respectively is decrypted.
According to the difference of image in the transmitting terminal processing mode, receiving terminal can be divided into two classes to the image processing mode, be respectively:
The first kind: receive image watermarked and that encrypt
1) decrypted image
Choosing at least one group of coefficient that is used to encrypt is decrypted;
2) from image, extract watermark
Choose and be used at least one group of watermarked coefficient and extract watermark;
3) deciphering and extraction watermark
Choose that at least one group of being used for encrypting is decrypted and be used at least one group of watermarked coefficient and extract watermark from choosing.
Second class: receive the encipher only image
1) deciphering;
Choosing at least one group of coefficient that is used to encrypt is decrypted;
2) the encryption coefficient of choosing is decrypted after, choose at least one group of coefficient, watermarked in selected at least one group of coefficient, at least one group of selected coefficient can with the deciphering after coefficient identical, also can with the deciphering after coefficient different.
The zone of watermark and encryption is independent of each other.Image encryption, watermark embeds, the image deciphering, watermark extracting, these four processes are configurable.For the user provides multiple choices, satisfy the different needs of user.Be that transmitting terminal can be selected: 1) image encryption and watermark are embedded, obtain encrypting and watermarked image 2) only image is encrypted, obtain encrypted image.Receiving terminal can be selected: 1) watermarked image carries out image deciphering and watermark extracting to encrypting also, obtain decrypted image and watermark with watermark, 2) watermarked image only carries out the image deciphering to encrypting also, obtain decrypted image with watermark, 3) to encrypting and watermarked image only carries out the extraction of watermark, obtain watermark, 4) transmitting terminal has only been carried out the image deciphering of encrypting and added watermark, obtain decrypted image with watermark.5) it is watermarked transmitting terminal only have been carried out the image encrypted, obtains encrypting and watermarked image.
In this example, receiving image watermarked and that encrypt, is the third mode of the first kind to the mode of described image processing.From first group of coefficient
Middle extraction watermark is to second group of coefficient
Carry out the DES deciphering.
From coefficient
After extracting watermark, coefficient becomes
To coefficient
After the deciphering, coefficient becomes
405, obtain image after the deciphering, detailed process is referring to Fig. 6:
601, after deciphering, extracting watermark processing,, merge described the 3rd group of coefficient and the 4th group of coefficient, the low frequency coefficient after obtaining merging according to " 0 " of described binary number and the position of " 1 ";
In this example, the position according to " 0 " of described binary number reverts to original position with the 3rd group of coefficient; Position according to " 1 " of described binary number reverts to original position with the 4th group of coefficient.Low frequency coefficient after obtaining merging.
According to binary number be
The position of " 0 ", be { a with the 3rd group of coefficient
1, a
3, a
6, revert to original position, according to described binary number
The position of " 1 ", be { a with the 4th group of coefficient
2, a
4, a
5A
nReverting to original position, the low frequency coefficient after obtaining merging is { a
1, a
2, a
3, a
4, a
5, a
6... .a
n.
602, the low frequency coefficient after the described merging is carried out wavelet inverse transformation, deciphered and extract the image after the watermark.
In this example, to described low frequency coefficient { a
1, a
2, a
3... .a
nCarry out wavelet inverse transformation, obtain having the decrypted image of watermark.
The method that the embodiment of the invention provides by the low frequency coefficient Random assignment of key with image after, can be deciphered and be had the image of watermark, image display effect and former figure no significant difference have reached the purpose of protection copyright simultaneously.
One of ordinary skill in the art will appreciate that all or part of flow process that realizes in the foregoing description method, be to instruct relevant hardware to finish by computer program, described program can be stored in the computer read/write memory medium, this program can comprise the flow process as the embodiment of above-mentioned each side method when carrying out.Wherein, described storage medium can be magnetic disc, CD, read-only storage memory body (Read-Only Memory, ROM) or at random store memory body (Random Access Memory, RAM) etc.
A kind of image processing apparatus that the embodiment of the invention is provided describes in detail below, and described device is applicable to image encryption or encrypts and watermarked, referring to Figure 10:
A kind of device of image encryption comprises:
Encrypting module 703 is used for choosing at least one group of coefficient from described at least two group coefficients, and the described at least one group of coefficient of choosing encrypted.
Described image processing apparatus also comprises:
Described coefficient grouping module 702 may further include:
Binary number acquiring unit 706 is used for producing binary number at random by key;
Comparing unit 707 is used for described low frequency coefficient and described binary number are compared;
Grouped element 708 is used for the pairing low frequency coefficient in position according to described binary number " 0 " and " 1 ", and described low frequency coefficient is divided into coefficient " 0 " group, coefficient " 1 " group.
Described coefficient acquisition module is used for described image is carried out wavelet transformation, the low frequency coefficient behind the acquisition wavelet transformation, and described device also comprises:
Coefficient merges module 709, is used for according to " 0 " of described binary number and the position of " 1 " merge coefficient " 0 " group, coefficient " 1 " group, the low frequency coefficient after obtaining merging;
The image image device that the embodiment of the invention is provided describes in detail below, and described device is applicable to image deciphering or deciphering and extracts watermark, referring to Figure 11:
Image receiver module 801 is used to receive the image of encryption;
Coefficient acquisition module 802 is used to obtain the low frequency coefficient of described image;
Coefficient grouping module 803 is used for described low frequency coefficient is divided at least two group coefficients;
Deciphering module 804 is used for choosing at least one group of coefficient from described at least two group coefficients, and the described at least one group of coefficient of choosing is decrypted.
Described image processing apparatus also comprises:
Extract watermark module 806, be used for choosing at least one group of coefficient, in the described at least one group of coefficient of choosing, extract watermark from described at least two group coefficients.
Described coefficient grouping module 803 may further include:
Binary number acquiring unit 807 is used for producing binary number at random by key;
Comparing unit 808 is used for described low frequency coefficient and described binary number are compared;
Grouped element 809 is used for the pairing low frequency coefficient in position according to described binary number " 0 " and " 1 ", and described low frequency coefficient is divided into coefficient " 0 " group, coefficient " 1 " group.
Described coefficient acquisition module 802 is used for described image is carried out wavelet transformation, the low frequency coefficient behind the acquisition wavelet transformation, and described device also comprises:
Coefficient merges module 810, is used for according to " 0 " of described binary number and the position of " 1 ", merges described coefficient " 0 " group, coefficient " 1 " group, the low frequency coefficient after obtaining merging;
Inverse transform module 811 is used for described low frequency coefficient is carried out wavelet inverse transformation, the image after obtaining deciphering.
The image encrypting apparatus that the embodiment of the invention provides is divided at least two groups by the low frequency coefficient with image, selects wherein at least one group to be used for encrypting, and makes that encrypting the zone does not fix, and has improved the image safety of transmission; Can also promptly encrypt simultaneously image, select again at least one group watermarked, be about to encrypt and watermark is united and made image obtain transmitting duplicate protection with copyright.Can be decrypted and or extraction watermark by the image deciphering.
Introduce process watermarked and the extraction watermark with application example below.
Transmitting terminal obtain encrypting and the concrete steps of watermarked image as follows: 1) (x y) carries out 3 grades of 2-D DWT (Discrete Wavelet Transform), extracts DWT low frequency sub-band coefficient to original image f; 2) randomly low frequency coefficient is divided into incoherent two parts S1 and S2 by key K ey0; 3) wherein the S1 zone is used for watermarked W, generates S1 ', and the S2 zone is used for des encryption, generates S2 '; 4) S1 ' and S2 ' is synthetic, by wavelet inverse transformation obtain encrypting and watermarked image f ' (x, y);
Obtain with the step of the decrypted image of watermark and watermark as follows at receiving terminal: 1) (x y) carries out 3 grades of 2-D DWT (Discrete Wavelet Transform), extracts DWT low frequency sub-band coefficient to pending image f '; 2) randomly low frequency coefficient is divided into incoherent two parts S1 ' and S2 ' by key K ey0; 3) wherein S1 ' zone is used to extract watermark W, and S2 ' zone is used for the DES deciphering, generates S2; 4) S1 ' and S2 is synthetic, obtain decrypted image f by wavelet inverse transformation with watermark " (x, y).Below wavelet coefficient grouping, watermark embedding and watermark extracting are described in detail:
A, the grouping of wavelet low frequency coefficient
Be that the original-gray image of 256*256 is carried out three layers of orthogonal wavelet and decomposed at first to size.If LL
3Be low frequency sub-band, HL
i, LH
i, HH
i(i=1,2,3) are respectively its level, vertical and diagonal angle medium-high frequency subband.Produce random binary array A, size and LL by key K ey0
3Identical.By with low frequency coefficient LL
3Relatively, be ' 1 ' position at the A array element value, with LL
3The value of middle correspondence position is taken out the district as S1; At the A array element value is ' 0 ' position, with LL
3The value of middle correspondence position is taken out the district as S2.As shown in Figure 9:
B, watermark embed process
S1 zone coefficient to be embedded is E, is E1 after embedding; Watermarked is W; Quantization step is Q, gets Q=20.
Figure 10 is a quantization principles figure schematic diagram:
1) by quantizing step-length Q reference axis is divided into interval collection of the M shown in the last figure and the interval collection of N.
2) actual value of reference axis has been represented the numerical value of coefficient E to be embedded, and the interval collection of M is all represented binary system watermark ' 1 ' on the reference axis simultaneously, and the interval collection of reference axis N has all been represented binary system watermark ' 0 '.
3) treat quantization parameter E round numbers merchant and get remainder operation:
Rem=E-fix*Q
4) according to collection and watermark W between coefficient E location to be quantified, E is carried out quantification treatment: when W=1, make quantized result E1 be and the interval middle coordinate value of concentrating of the immediate M of E; When W=0, make E1 be and the interval middle coordinate value of concentrating of the immediate N of E.
The processing procedure that quantizes can be expressed as follows:
(1) E1=Q/2 when fix=0 and W=1
(2) E1=3Q/2 when fix=0 and W=0
(3) when fix ≠ 0 and W=1
(4) when fix ≠ 0 and W=0
(5) repetitive watermark embeds: continuous three bits among the corresponding E of a bit among the watermarked W, as shown in figure 11, if current watermark bit to be embedded is " 1 ", then actual watermarked be " 111 "; If current watermark bit to be embedded is " 0 ", then actual watermarked be " 000 ".
Present embodiment is that the gray level image of 256*256 is an example with the size, produces the random binary array through key K ey0 and chooses, and the size of area E is about 500 bits, so can watermarked 166 bits.
C, watermark extraction process
Watermarked gray level image carries out three layers of orthogonal wavelets decomposition to encrypting also, and LL3 is a low frequency sub-band.Still produce random binary array A, size and LL by key K ey0
3' identical.By with low frequency coefficient LL
3' relatively, be ' 1 ' position at the A array element value, with LL
3The value of ' middle correspondence position is taken out the district as S1 '; At the A array element value is ' 0 ' position, with LL
3The value of ' middle correspondence position is taken out the district as S2 '.
Take out S1 ' zone, watermark information is by judging that its range value E1 ' decides, if belong to the M zone, then extract binary system watermark ' 1 ' that if belong to the n-quadrant, then extract binary system watermark ' 0 ', expression formula is as follows:
Repeat to embed because this method has also adopted, can determine complete watermark, improved the probability of correct extraction watermark significantly through election process.
Now provide these two representative images of lena and cameraman and do the test result of experiment.
Figure 12 shows result watermarked to image Lena with embodiment of the invention method and that encrypt.Figure 15 (a) is original Lena image, Figure 15 (b) encrypts and watermarked Lena image, as seen from the figure, encrypted image and former figure visually have good scramble effect, Figure 15 (c) is deciphering and the Lena image that contains watermark, still contains the image and the original image no significant difference of watermark as seen from the figure after the deciphering.
Figure 13 shows result watermarked to image cameraman with the inventive method and that encrypt.Figure 16 (a) is original cameraman image, Figure 16 (b) encrypts and watermarked cameraman image, as seen from the figure, encrypted image and former figure visually have good scramble effect, Figure 16 (c) is deciphering and the cameraman image that contains watermark, still contains the image and the original image no significant difference of watermark as seen from the figure after the deciphering.
In embodiments of the present invention, be that example is introduced with the wavelet transformation, in fact the present invention can also be applicable to other conversion, for example dct transform etc.With the dct transform is example, image is through behind the dct transform, obtain DC coefficient and ac coefficient respectively, DC coefficient belongs to low frequency coefficient, comprise high frequency coefficient and low frequency coefficient in the ac coefficient, adopt method of the present invention, all low frequency coefficients can be divided at least two groups, same determines that wherein two groups are respectively watermark embedding zone and encrypt the zone, are respectively applied for watermarked and encryption.After object is carried out watermarked or encryption, at the image that carries out after anti-dct transform obtains to handle.At receiving terminal, it is similar that processing method and front embodiment describe, and repeats no more.Simultaneously, thought of the present invention can be used for audio frequency, video field equally.
The above; only be the specific embodiment of the present invention, but protection scope of the present invention is not limited thereto, anyly is familiar with those skilled in the art in the technical scope that the present invention discloses; can expect easily changing or replacing, all should be encompassed within protection scope of the present invention.Therefore, protection scope of the present invention should be as the criterion by described protection range with claim.
Claims (16)
1, a kind of image encryption method is characterized in that, comprising:
Obtain the low frequency coefficient of image;
Described low frequency coefficient is divided at least two group coefficients;
From described at least two group coefficients, choose at least one group of coefficient, the described at least one group of coefficient of choosing encrypted.
2, the method for claim 1 is characterized in that, also comprises:
From described at least two group coefficients, choose at least one group of coefficient, watermarked in the described at least one group of coefficient of choosing.
3, method as claimed in claim 1 or 2 is characterized in that, described low frequency coefficient is divided at least two group coefficients, comprising:
Produce binary number at random by key;
Described low frequency coefficient and described binary number are compared;
According to the pairing low frequency coefficient in position of described binary number " 0 " and " 1 ", described low frequency coefficient is divided into coefficient " 0 " group, coefficient " 1 " group.
4, the method for claim 1 is characterized in that, the described low frequency coefficient that obtains image comprises:
Described image is carried out wavelet transformation, the low frequency coefficient behind the acquisition wavelet transformation;
Described method also comprises:
After encryption is finished,, merge described coefficient " 0 " group, coefficient " 1 " group, the low frequency coefficient after obtaining merging according to " 0 " of described binary number and the position of " 1 ";
Low frequency coefficient after the described merging is carried out wavelet inverse transformation, the image after obtaining encrypting.
5, a kind of image decryption method is characterized in that, comprising:
Receive the image of encrypting;
Obtain the low frequency coefficient of described image;
Described low frequency coefficient is divided at least two group coefficients;
From described at least two group coefficients, choose at least one group of coefficient, the described at least one group of coefficient of choosing is decrypted.
6, method as claimed in claim 5 is characterized in that, also comprises:
From described at least two group coefficients, choose at least one group of coefficient, in the described at least one group of coefficient of choosing, extract watermark.
7, as the method for claim 5 or 6, it is characterized in that, described low frequency coefficient be divided at least two group coefficients comprise:
Produce binary number at random by key;
Described low frequency coefficient and described binary number are compared;
According to the pairing low frequency coefficient in position of described binary number " 0 " and " 1 ", described low frequency coefficient is divided into coefficient " 0 " group, coefficient " 1 " group.
8, method as claimed in claim 7 is characterized in that, the described low frequency coefficient that obtains described image comprises:
Described image is carried out wavelet transformation, the low frequency coefficient behind the acquisition wavelet transformation;
Described method also comprises:
After decryption processing is finished,, merge described coefficient " 0 " group, coefficient " 1 " group, the low frequency coefficient after obtaining merging according to " 0 " of described binary number and the position of " 1 ";
Low frequency coefficient after the described merging is carried out wavelet inverse transformation, the image after obtaining deciphering.
9, a kind of image encrypting apparatus is characterized in that, comprising:
The coefficient acquisition module is used to obtain the low frequency coefficient of image;
The coefficient grouping module is used for described low frequency coefficient is divided at least two group coefficients;
Encrypting module is used for choosing at least one group of coefficient from described at least two group coefficients, and the described at least one group of coefficient of choosing encrypted.
10, device as claimed in claim 9 is characterized in that, also comprises:
Watermarked module is used for choosing at least one group of coefficient from described at least two group coefficients, and is watermarked in the described at least one group of coefficient of choosing.
11, device as claimed in claim 9 is characterized in that, described coefficient grouping module comprises:
The binary number acquiring unit is used for producing binary number at random by key;
Comparing unit is used for described low frequency coefficient and described binary number are compared;
Grouped element is used for the pairing low frequency coefficient in position according to described binary number " 0 " and " 1 ", and described low frequency coefficient is divided into coefficient " 0 " group, coefficient " 1 " group.
12, device as claimed in claim 9 is characterized in that, described coefficient acquisition module is used for described image is carried out wavelet transformation, the low frequency coefficient behind the acquisition wavelet transformation, and described device also comprises:
Coefficient merges module, is used for according to " 0 " of described binary number and the position of " 1 " merge coefficient " 0 " group, coefficient " 1 " group, the low frequency coefficient after obtaining merging;
Inverse transform module is used for the low frequency coefficient after the described merging is carried out wavelet inverse transformation, the image after obtaining encrypting.
13, a kind of image decrypting device is characterized in that, comprising:
The image receiver module is used to receive the image of encryption;
The coefficient acquisition module is used to obtain the low frequency coefficient of described image;
The coefficient grouping module is used for described low frequency coefficient is divided at least two group coefficients;
Deciphering module is used for choosing at least one group of coefficient from described at least two group coefficients, and the described at least one group of coefficient of choosing is decrypted.
14, device as claimed in claim 13 is characterized in that, also comprises:
Extract the watermark module, be used for choosing at least one group of coefficient, in the described at least one group of coefficient of choosing, extract watermark from described at least two group coefficients.
15, device as claimed in claim 13 is characterized in that, described coefficient grouping module comprises:
The binary number acquiring unit is used for producing binary number at random by key;
Comparing unit is used for described low frequency coefficient and described binary number are compared;
Grouped element is used for the pairing low frequency coefficient in position according to described binary number " 0 " and " 1 ", and described low frequency coefficient is divided into coefficient " 0 " group, coefficient " 1 " group.
16, device as claimed in claim 13 is characterized in that, described coefficient acquisition module is used for described image is carried out wavelet transformation, the low frequency coefficient behind the acquisition wavelet transformation, and described device also comprises:
Coefficient merges module, is used for according to " 0 " of described binary number and the position of " 1 ", merges described coefficient " 0 " group, coefficient " 1 " group, the low frequency coefficient after obtaining merging;
Inverse transform module is used for described low frequency coefficient is carried out wavelet inverse transformation, the image after obtaining deciphering.
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| CN2008101688530A CN101394553B (en) | 2008-09-28 | 2008-09-28 | Image ciphering, deciphering method and device |
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103618599A (en) * | 2013-12-04 | 2014-03-05 | 重庆大学 | Method for processing data set before encryption |
| CN102415087B (en) * | 2009-05-11 | 2014-09-03 | 富士通株式会社 | Image encryption/decoding device, method, and program |
| CN107146192A (en) * | 2017-05-02 | 2017-09-08 | 湖北工程学院 | A kind of safety of image guard method and device |
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2008
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Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102415087B (en) * | 2009-05-11 | 2014-09-03 | 富士通株式会社 | Image encryption/decoding device, method, and program |
| US8935536B2 (en) | 2009-05-11 | 2015-01-13 | Fujitsu Limited | Image encryption/decryption device, method, and storage medium storing a program |
| CN103618599A (en) * | 2013-12-04 | 2014-03-05 | 重庆大学 | Method for processing data set before encryption |
| CN103618599B (en) * | 2013-12-04 | 2016-09-14 | 重庆大学 | Data set encryption pre-treating method |
| CN107146192A (en) * | 2017-05-02 | 2017-09-08 | 湖北工程学院 | A kind of safety of image guard method and device |
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| Publication number | Publication date |
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| CN101394553B (en) | 2010-12-08 |
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