AUTHORIZED WATERMARKING AND
ENCRYPTION SYSTEM BASED ON WAVELET
TRANSFORM FOR TELERADIOLOGY
SECURITY ISSUES
S.NANDHINI Dr.S.KAVITHA M.E.,Ph.d PG SCHOLAR PROFESSOR & DEAN ECE NandhaEngg. College NandhaEngg. College
Erode, Tamilnadu, India. Erode, Tamilnadu, India.
ABSTRACT:Teleradiology is the transmission of radiographic images from one location to another for interpretation by a radiologist. It is most often used to allow rapid interpretation of emergency room, ICU and other emergent examinations after hours of usual operation, at night and one weekend. Such remote transmission raises various ethical and legal issues. In the existing methods, dual watermarking system is used for embedding the encrypted patient details and their fingerprint features independently to reduce the maintenance of multiple records. In this method initial level security is not improved and some process is done repeatedly and hence this increases complexity. In the proposed method, fingerprint authentication of patient is to be done at the initial level which gives the access on their records. Then watermarking based on DWT is to be done for embedding the encrypted patient details and hospital identification. This will increase the security
and there is no process repetition. The software tool to be used is MATLAB.
Keywords:Teleradiology, DWT Authentication.
I. INTRODUCTION
Teleradiology is the e-health service to maintain andtransmit medical transcriptions online for the sake of patientsto provide efficient clinical interpretationwithout carryingthe document for diagnosis purpose. But at present, security andprivacy protection has been a critical issue for the patientssuch as image retention and fraud, privacy, malpractice, liability, licensing and contracts for radiology information system, picture archiving and communication system. Another major issue is multiple document maintenancefor a single patient such as digital X-ray image, personnel details,and diagnosis results aremaintained and transmitted onlineseparately which needs
more time to process. It can be avoidedby merging the multiple documents of a single person to a singledocument using watermarking. Teleradiology needs confidentiality,availability, and reliability which means only an authorizeduser can access patient data, guarantee access to medicalinformation in normal scheduled conditions, proves that informationhas not been altered by unauthorized persons, and informationorigins of its attachment relate to one patient. To provideall these aspects, Teleradiology requires watermarking for efficientmaintenance and transmission of medical data remotely.
In the paper, both cryptography and watermarking techniques are applied on patient details and medical image for the purpose of secured transmission. The security is improved at the initial level by authenticating the patient fingerprint to access patient reports. The cryptography technique used to encrypt the patient details. Text encryption is achieved by Advanced Encryption Standard (AES). Dual watermarking is done for embedding the hospital identification and for encrypted patient details. The watermarking is achieved by Discrete Wavelet Transform (DWT) technique. The efficiency of output image at the receiver side is analyzed using various parameters like Power Signal to Noise Ratio (PSNR), Entropyand Mean Square Error (MSE).
In personnel information system, the confidentiality is usually achieved by fingerprint recognition system which is a widely used biometric system for personnel authentication.
At the sender side, the security is improved at the initial level by authenticating the fingerprint of the patient. The fingerprint verification system restricts access of patient data without authentication. The cryptographic system is mainly used in information systems to ensure services like non repudiation, confidentiality, and integrity. To maintain the privacy of the information, symmetric key cryptographic system is used to secure the data. The encryption of the patient details is achieved by AES algorithm. Watermarking improves the security of medical images by modifying or modulating image pixels with a message in an imperceptible way. Dual watermarking is achieved with encrypted patient details and hospital identification based on DWT. Finally the entire watermarked image is encrypted and transmitted to receiver.
At the receiver side decryption and dewatermarking is done to obtain the original image and patient details without any loss. Quality of image obtained at the receiver side is verified by various validations like Entropy, MSE, and PSNR.
Sender side design involves three different procedures,
A.FINGERPRINT AUTHENTICATION
Fingerprint recognition system is a widely used biometric system for personnel authentication.Among all biometric traits, fingerprints have one of the highest levels of reliability and have been extensively used by forensic experts in criminal investigations.
A fingerprint refers to the flow of ridge patterns in the tip of the finger.The ridge flow exhibits anomalies in local regions of the fingertip and it is the position and orientation of these anomalies that are used to represent and match fingerprints is shown in Figure 1.
Figure 1: Fingerprint
Block diagram of fingerprint authentication system is shown in Figure 2,
Figure 2: Fingerprint Authentication system.
B. DUAL WATERMARKING In order to improve the security of Teleradiology in terms of confidentiality, availability and reliability dual watermarking approach is done. Dual watermarking is embedding two different data’s in the radiology image. One data is hospital identification and the other is encrypted patient details. To improve the security, watermarking is done with a secret key shared with sender and receiver. The two dimensional DWT method is used for watermarking the hospital identification and encrypted patient details. The watermark achieved here is an invisible watermark.
Wavelet domain is a promising domain for watermark embedding. Wavelet refers to small waves. Discrete Wavelet Transform is based on small waves of
limited duration and varying frequency. This is a frequency domain technique in which firstly cover image is transformed into frequency domain and then its frequency coefficients are modified in accordance with the transformed coefficients of the watermark and watermarked image is obtained which is very much robust. DWT decomposes image hierarchically, providing both spatial and frequency description of the image. It decompose an image in basically three spatial directions i.e., horizontal, vertical and diagonal in result separating the image into four different components namely LL, LH, HL and HH. First letter refers to applying either low pass frequency operation or high pass frequency operations to the rows and the second letter refers to the filter applied to the columns of the cover image.Two level DWT is shown in
Figure 3,
Figure 3:Two level DWT
Algorithm for carrying out DWT
1. Original image is decomposed in various sub-bands using DWT, in this paper two- level DWT is use.
2. Sub-band suitable for embedding watermark is chosen.
3. Wavelet coefficients of the selected sub-band are modified according to the watermark image.
4. After embedding watermark watermarked image is obtained.
C. ENCRYPTION
This paper merges a digital watermarking algorithm and an encryption algorithm which is a block cipher algorithm (AES).
Advanced Encryption Standard (AES) is a very powerful standard block cipher algorithm compared to the data encryption standard (DES) algorithm. The AES is a block cipher, meaning that it operates on an input block of data of a known size and outputs a block of data which is the same size. An input key is also required as input to the AES algorithm. A mode of operation is selected which selects a specific implementation of the AES algorithm. The input blocks and output block data are each a fixed length size of 128 bits.
The AES encryption algorithm involved four stages,these are as follows,
2. Shift rows 3. Mix Columns
4. Add Round Key
General flow diagram of sender is given in Figure 4,
Figure 4: Sender Flow diagram
III. DESIGN FOR RECEIVER
The reverse procedure of sender is done at the receiver side. i.edewatermarking and decryption is done.
The general flow diagram of receiver is given in Figure 5,
Figure 5: Receiver Flow diagram
IV. AUTHORIZED WATERMARKING AND ENCRYPTION SYSTEM
A. GUI OF FINGERPRINT AUTHENTICATION:
Output of fingerprint authentication is shown in Figure 6 gives access for authorized person on patient records.
Figure 6: GUI for authorized person Output of fingerprint authentication is shown in Figure 7 restricts access for unauthorized person on patient records
Figure 7: GUI for unauthorized person
B.GUI OF SENDER:
Output of sender is shown in Figure 8 provides the application of watermark and encryption on radiology images.
Figure 8: GUI for sender
C. GUI OF RECEIVER:
Output of Receiver is shown in Figure 9 provides the application of Dewatermark and Decryption to obtain original radiology images.
Figure 9: GUI for Receiver
Original patient details and its encrypted form is shown in Figure 10,
Figure 10: Text and its Encrypted form
V. RESULTS AND DISCUSSION
Finally on comparing the original image and the decrypted output image obtained at the receiver the image quality is verified in order to evaluate the system efficiency. The image quality metrics obtained is shown in Table 1,
Table 1: Image Quality Metrics
S.NO METRICS IMAGE1 IMAGE2 FUSED IMAGE 1 ENTROPY 4.1834 3.6899 1.162 2 SF 40.81 40.821 40.81 3 RMSE 4.0667 4.0596 4.068 4 MAE 34.510 34.479 34.49 5 MEAN 42.941 42.730 42.83 PSNR: 31.8127
PSNR > 30.0 (this corresponds to RMSE <8.6) is commonly considered as good
VI. CONCLUSION
In this paper, a authorized watermarking and encryption system has been proposed, which guarantees an, a priori and a posteriori protection of medical images. It merges the digital watermarking and block cipher algorithm. This system gives access to verify the image
confidentiality, integrity and reliability even though it is encrypted. A simulation result shows the secured transmission of image and data with processing time was low. On the other hand, the execution time for image decryption is not impacted. Finally,Image quality obtained at receiver is good.
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