Third, the invention
Aiming at the existing palm vein identification process, the invention aims to provide a palm vein intelligent lock based on a DWT-DCT (discrete wavelet transform-discrete cosine transform) encryption algorithm, which has good safety in the identification process, can still accurately identify a palm vein image after being attacked by different attacks by adopting the DWT-DCT encryption algorithm, solves the defects of the prior art, and provides a palm vein identification technology with high safety and high robustness.
The technical scheme for realizing the purpose of the invention is as follows:
a palm vein intelligent lock based on DWT-DCT transform encryption algorithm comprises a lock body, a lock handle, a palm vein identity recognition module and other identity recognition modules;
the palm vein authentication module is installed on the lock body, the built-in palm vein acquisition module acquires palm vein images of a user in a non-contact mode, and the safety of the palm vein authentication module can be improved in a non-contact mode.
The lock body is internally provided with a central processing unit which comprises a palm vein image preprocessing unit, a palm vein image encryption unit, a palm vein feature extraction unit and a palm vein matching decision identification and judgment unit, wherein:
the palm vein image preprocessing unit performs maximum ROI cutting on an original palm image acquired by acquisition equipment, performs image enhancement and suppresses noise by limiting contrast adaptive histogram equalization (CLAHE).
The palm vein image encryption unit performs Discrete Wavelet Transform (DWT) and Discrete Cosine Transform (DCT) on the preprocessed palm vein image, and the specific flow is as follows:
s1: performing two-stage decomposition on the preprocessed palm vein image by using Discrete Wavelet Transform (DWT), and decomposing an image F (i, j) into four parts: a clearer low-frequency sub-image LL (i, j) and three high-frequency fuzzy sub-images are respectively LH (i, j), HL (i, j) and HH (i, j);
s2: performing Discrete Cosine Transform (DCT) on the four subband graphs LL (i, j), LH (i, j), HL (i, j) and HH (i, j) respectively to obtain subband coefficient matrixes which are respectively expressed as DLL (i, j), DLH (i, j), DHL (i, j) and DHH (i, j);
s3: generating a chaotic sequence H (i, j) through a Logistic Map chaotic system, and then carrying out binarization processing on the chaotic sequence H (i, j) according to the size of the palm vein image to obtain a binary matrix HB (i, j);
s4: HB (i, j) and subband diagram coefficient matrixes DLL (i, j), DLH (i, j), DHL (i, j) and DHH (i, j) are subjected to dot multiplication operation respectively to obtain encrypted image subgraphs EDLL (i, j), EDLH (i, j), EDHL (i, j) and EDHH (i, j);
s5: carrying out Inverse Discrete Cosine Transform (IDCT) on the encrypted image sub-graphs EDLL (i, j), EDLH (i, j), EDHL (i, j) and EDHH (i, j) to obtain encrypted sub-graph graphs ELL (i, j), ELH (i, j), EHL (i, j) and EHH (i, j);
s6: and performing Inverse Discrete Wavelet Transform (IDWT) on the encrypted sub-band diagrams ELL (i, j), ELH (i, j), EHL (i, j) and EHH (i, j) to obtain an encrypted palm vein image E (i, j).
The palm vein feature extraction unit firstly adopts a self-adaptive Gabor filtering method to extract palm vein features, divides a palm vein image into a plurality of sub-regions, determines a main direction of the sub-regions, calculates a standard variance for each sub-region and determines a center frequency; and secondly, carrying out VennCode coding on the palm vein features, wherein the obtained feature matrix can be used for identity recognition.
The palm vein matching decision identification and judgment unit calculates the image characteristic value after characteristic extraction and the characteristic value in the image characteristic value database by adopting a Hamming distance algorithm, sets a threshold value, if the value is smaller than the threshold value, the identity authentication is successful, otherwise, the user does not exist.
The other identity recognition modules are used for unlocking the intelligent lock and have the function of unlocking the intelligent lock together with the palm vein recognition module.
The principle of the palm vein intelligent lock based on the DWT-DCT transform encryption algorithm is as follows: the palm vein intelligent lock has other identification and palm vein identification modes to unlock. When the user adopts other identification modes, the operation can be carried out according to the authentication mode. For example: if the key is used, the key is inserted into the key hole and rotated to be opened; if the fingerprint is used for unlocking, the registered finger is placed at the finger print identification designated position of the intelligent lock; if the IC card identification is used, the IC card is placed at the IC card identification position of the intelligent lock; and so on. When a user selects a palm vein identification mode to unlock the lock, firstly, a palm of registered information is placed at the position about 8cm in front of a palm vein acquisition module, a near-infrared camera acquires a palm vein image of the user, then, the image is subjected to maximum ROI cutting, image enhancement is carried out through limiting contrast self-adaptive histogram equalization (CLAHE), a preprocessed image is obtained, then, an encryption algorithm is carried out on the image, feature extraction is carried out on the image, and finally, matching decision is carried out on a feature value to be compared and a feature value stored in the device. If the matching is successful and the identity authentication is correct, the lock can be automatically opened, otherwise, no matching item is displayed.
The palm vein intelligent lock based on the DWT-DCT transform encryption algorithm has the following advantages by adopting vein identification: the palm vein has good universality and uniqueness. The palm vein texture is different from person to person, even from the left hand and the right hand of the same person. The palm vein is positioned in the skin, and compared with biological characteristics such as fingerprints and palm prints, the palm vein anti-fake method has the characteristics of being not easy to damage and steal and the like, and compared with biological characteristics such as irises and human faces, the palm vein anti-fake method has the advantages of being high in information confidentiality, large in fake difficulty, low in manufacturing cost of acquisition equipment, easy to apply in a large scale and the like.
The invention has the beneficial effects that:
(1) compared with the traditional palm vein recognition intelligent lock, the invention provides the palm vein recognition method based on the DWT-DCT (discrete wavelet transform-discrete cosine transform) encrypted image. The method combines the feature vector of the palm vein image with the encryption technology, realizes that the palm vein image can be accurately identified after being attacked by different kinds, solves the defects of the prior art, and provides the palm vein identification technology with high safety and high robustness.
(2) The database established by the invention is an image characteristic value database, palm vein images are encrypted through a DWT-DCT (discrete wavelet transform-discrete cosine transform) algorithm to form an encrypted image database, and then the characteristics of the encrypted images in the database are extracted, so that the image characteristic database is established. The established image characteristic database can greatly reduce the storage space and form a light palm vein identification system.
(3) In the identification process, the encryption protection is carried out when the characteristic database is established, and the palm vein image to be identified is encrypted in the user identification process, so that the double encryption mode improves the higher safety of the whole palm vein identity identification system.
Fifth, detailed description of the invention
Preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings.
The conventional palm vein image identification process is shown in fig. 1, and each step plays an irreplaceable role in the whole palm vein identification system. Image acquisition: and shooting a palm vein image of the user by adopting a near-infrared camera. Image preprocessing: and performing maximum ROI cutting on the acquired original palm image, and performing image enhancement through limiting contrast adaptive histogram equalization (CLAHE) to obtain clearer palm vein information. Image feature extraction: and extracting the palm vein characteristics by using a self-adaptive Gabor filtering method. Image feature matching: and after the characteristic values are coded, matching and identifying by utilizing the Hamming distance.
As shown in fig. 2, the palm vein image recognition process is encrypted, first, the palm vein image to be recognized is subjected to preprocessing, then the preprocessed palm vein image is encrypted, then the encrypted palm vein image is subjected to feature extraction, finally, the distance between the feature value and the feature value in the encrypted feature database is calculated through a hamming distance algorithm, a threshold value a is set, if the distance is smaller than a, the user identity authentication is successful, otherwise, the user does not exist. Therefore, the palm vein recognition result is obtained, and the palm vein intelligent lock can be opened immediately after the user identity authentication is successful.
As shown in fig. 3, the palm vein image is encrypted, and the specific process is as follows:
s1: performing two-stage decomposition on the preprocessed palm vein image by using Discrete Wavelet Transform (DWT), and decomposing an image F (i, j) into four parts: a clearer low-frequency sub-image LL (i, j) and three high-frequency fuzzy sub-images are respectively LH (i, j), HL (i, j) and HH (i, j);
s2: performing Discrete Cosine Transform (DCT) on the four subband graphs LL (i, j), LH (i, j), HL (i, j) and HH (i, j) respectively to obtain subband coefficient matrixes which are respectively expressed as DLL (i, j), DLH (i, j), DHL (i, j) and DHH (i, j);
s3: generating a chaotic sequence H (i, j) through a Logistic Map chaotic system, and then carrying out binarization processing on the chaotic sequence H (i, j) according to the size of the palm vein image to obtain a binary matrix HB (i, j);
s4: HB (i, j) and subband diagram coefficient matrixes DLL (i, j), DLH (i, j), DHL (i, j) and DHH (i, j) are subjected to dot multiplication operation respectively to obtain encrypted image subgraphs EDLL (i, j), EDLH (i, j), EDHL (i, j) and EDHH (i, j);
s5: carrying out Inverse Discrete Cosine Transform (IDCT) on the encrypted image sub-graphs EDLL (i, j), EDLH (i, j), EDHL (i, j) and EDHH (i, j) to obtain encrypted sub-graph graphs ELL (i, j), ELH (i, j), EHL (i, j) and EHH (i, j);
s6: and performing Inverse Discrete Wavelet Transform (IDWT) on the encrypted sub-band diagrams ELL (i, j), ELH (i, j), EHL (i, j) and EHH (i, j) to obtain an encrypted palm vein image E (i, j).
As shown in fig. 4, the establishing of the palm vein image Feature Database is to encrypt the palm vein image through DWT-DCT transform to form an encrypted image Database DWTDCT _ Database, and then perform Feature extraction on the encrypted image in the Database, thereby establishing an image Feature Database DWTDCT _ Feature. The established image characteristic database can greatly reduce the storage space and form a light palm vein identification system.
Because the technical scheme of the invention is sufficient, the DWT-DCT transformation algorithm is well applied to the field of palm vein intelligent locks, and the encryption processing is carried out only in the palm vein identification process by adopting the DWT-DCT transformation algorithm, the palm vein identification method has the advantages that the palm vein image identification can still be accurately carried out after the identification system is attacked by different attacks, the defects of the prior art are overcome, and the palm vein identification technology with high safety and high robustness is provided. In addition, the established image feature database can greatly reduce the storage space, and a light palm vein identification system is formed.
Finally, it should be noted that the above embodiments are only used for illustrating the technical solutions of the present invention, and not for limiting the protection scope of the present invention, although the present invention is described in detail with reference to the preferred embodiments, it should be understood by those skilled in the art that modifications or equivalent substitutions can be made on the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention.