Dalel Bouslimi

A Joint Encryption/Watermarking System for Verifying the Reliability of Medical Images

In this paper, we propose a joint encryption/water-marking system for the purpose of protecting medical images. This system is based on an approach which combines a substitutive watermarking algorithm, the quantization index modulation, with an encryption algorithm: a stream cipher algorithm (e.g., the RC4) or a block cipher algorithm (e.g., the AES in cipher block chaining (CBC) mode of operation). Our objective is to give access to the outcomes of the image integrity and of its origin even though the image is stored encrypted. If watermarking and encryption are conducted jointly at the protection stage, watermark extraction and decryption can be applied independently. The security analysis of our scheme and experimental results achieved on 8-bit depth ultrasound images as well as on 16-bit encoded positron emission tomography images demonstrate the capability of our system to securely make available security attributes in both spatial and encrypted domains while minimizing image distortion. Furthermore, by making use of the AES block cipher in CBC mode, the proposed system is compliant with or transparent to the DICOM standard.

A joint encryption/watermarking algorithm for verifying the reliability of medical images: Application to echographic images

In this paper we propose a joint encryption/watermarking algorithm for the purpose of protecting medical images. The proposed solution gives access to the outcomes of the image integrity and of its origins as its attachment to one patient even if the image is stored encrypted. In this study, the given solution combines the RC4 stream cipher and two substitutive watermarking modulations: the Least Significant Bit Method and the Quantization Index Modulation. If watermarking and encryption are conducted jointly at the protection stage, watermark extraction and decryption can be applied independently. Experimental results achieved on 8 bits encoded echographic images illustrate the overall performances of the proposed scheme. At least, a capacity rate of 1 and 0.5 bits of message per pixel of image can be embedded in the spatial and the encrypted domains respectively, with a peak signal to noise ratio greater than 49 dB.

Content-based image retrieval in homomorphic encryption domain

In this paper, we propose a secure implementation of a content-based image retrieval (CBIR) method that makes possible diagnosis aid systems to work in externalized environment and with outsourced data as in cloud computing. This one works with homomorphic encrypted images from which it extracts wavelet based image features next used for subsequent image comparison. By doing so, our system allows a physician to retrieve the most similar images to a query image in an outsourced database while preserving data confidentiality. Our Secure CBIR is the first one that proposes to work with global image features extracted from encrypted images and does not induce extra communications in-between the client and the server. Experimental results show it achieves retrieval performance as good as if images were processed non-encrypted.

A joint watermarking/encryption algorithm for verifying medical image integrity and authenticity in both encrypted and spatial domains

In this paper, we propose a new joint watermarking/encryption algorithm for the purpose of verifying the reliability of medical images in both encrypted and spatial domains. It combines a substitutive watermarking algorithm, the quantization index modulation (QIM), with a block cipher algorithm, the Advanced Encryption Standard (AES), in CBC mode of operation. The proposed solution gives access to the outcomes of the image integrity and of its origins even though the image is stored encrypted. Experimental results achieved on 8 bits encoded Ultrasound images illustrate the overall performances of the proposed scheme. By making use of the AES block cipher in CBC mode, the proposed solution is compliant with or transparent to the DICOM standard.

A telemedicine protocol based on watermarking evidence for identification of liabilities in case of litigation

In case of litigation in telemedicine applications, one main issue is to determine liabilities of each physician involved in the data exchange. To achieve this goal, we propose an efficient watermarking based telemedicine protocol. Its objective is not only to ensure the security of data but also to provide evidence that an exchange took place. We show how watermarking in combination with cryptographic mechanisms and a third party can enforce data and exchange traceability. The efficiency of our solution is demonstrated by means of a security analysis.

An end to end secure CBIR over encrypted medical database

In this paper, we propose a new secure content based image retrieval (SCBIR) system adapted to the cloud framework. This solution allows a physician to retrieve images of similar content within an outsourced and encrypted image database, without decrypting them. Contrarily to actual CBIR approaches in the encrypted domain, the originality of the proposed scheme stands on the fact that the features extracted from the encrypted images are themselves encrypted. This is achieved by means of homomorphic encryption and two non-colluding servers, we however both consider as honest but curious. In that way an end to end secure CBIR process is ensured. Experimental results carried out on a diabetic retinopathy database encrypted with the Paillier cryptosystem indicate that our SCBIR achieves retrieval performance as good as if images were processed in their non-encrypted form.

A crypto-watermarking system for ensuring reliability control and traceability of medical images

In this paper, we propose a novel crypto-watermarking system for the purpose of verifying the reliability of medical images and tracing them, i.e. identifying the person at the origin of an illegal disclosure. This system couples a common watermarking method, based on Quantization Index Modulation (QIM), and a joint watermarking-decryption (JWD) approach. At the emitter side, it allows the insertion of a watermark as a proof of reliability of the image before sending it encrypted; at the reception, another watermark, a traceability proof, is embedded during the decryption process. The scheme we propose makes interoperate these two watermarking approaches taking into account risks of interferences between embedded watermarks, allowing the access to both reliability and traceability proofs. Experimental results confirm the efficiency of our system, and demonstrate it can be used to identify the origin of a disclosure even if the image has been altered. We provide a system for ensuring medical image reliability and traceability.The proposed system relies on the insertion of two watermarks.Interferences in-between watermarks have been studied.The overall performances of the proposed system have been evaluated and discussed.

An a Priori and a Posteriori Protection by Means of Data Hiding of Encrypted Images: Application to Ultrasound Images

In this paper, we propose a novel scheme which allows embedding a message, a set of security attributes, into encrypted images. This message can be accessed whether the image is encrypted or not for the purpose of verifying the reliability of images. The proposed solution relies on the insertion into the image of a predefined watermark, a “pre-watermark”, before the encryption process. Message insertion and extraction are then conducted into the encrypted image. It is the impact of this data hiding process onto the “pre-watermark” that gives us access to the message after the image has been decrypted. The proposed scheme has been implemented considering the RC4 stream cipher algorithm and the Least Significant Bit substitution watermarking method. Experimental results achieved on 8 bit depth ultrasound images demonstrate the capability of our system to make available security attributes in both spatial and encrypted domains while minimizing image distortion.

Joint watermarking and lossless JPEG-LS compression for medical image security

In this paper, we present a new joint watermarking-compression scheme the originality of which stands in the combination of the lossless compression standard JPEG-LS with the bit substitution watermarking modulation. This scheme allows the access to watermarking-based security services without decompressing the image. It becomes possible to trace images or to verify their authenticity directly from their compressed bitstream. Performance of our scheme, expressed in terms of embedding capacity and distortion, are evaluated on ultrasound images. They show that the watermarked images do not perceptually differ from their original counterparts while offering a capacity large enough to support various security services.

Joint Watermarking and Lossless JPEG-LS Compression for Medical Image Security

Abstract In this paper, we present a new joint watermarking-compression scheme the originality of which stands on the combination of the lossless compression standard JPEG-LS with the bit substitution watermarking modulation. This scheme allows the access to watermarking-based security services without decompressing the image. It becomes possible to trace images or to verify their authenticity directly from their compressed bitstream. Performance of our scheme, expressed in terms of embedding capacity and distortion, are evaluated on ultrasound images. They show that the watermarked images do not perceptually differ from their original counterparts while offering a capacity large enough to support various security services. We further illustrate how our scheme can be used for verifying the image integrity and authenticity.