Data hiding in homomorphically encrypted medical images for verifying their reliability in both encrypted and spatial domains.

In this paper, we propose a new scheme of data hiding of encrypted images for the purpose of verifying the reliability of an image into both encrypted and spatial domains. This scheme couples the Quantization Index Modulation (QIM) and the Paillier cryptosystem. It relies on the insertion into the image, before its encryption, of a predefined watermark, a "pre-watermark". Message insertion (resp. extraction) is conducted into (resp. from) the encrypted image using a modified version of QIM. It is the impact of this insertion process onto the "pre-watermark" that gives access to the message in the spatial domain, i.e. after the image has been decrypted. With our scheme, encryption/decryption processes are completely independent from message embedding/extraction. One does not need to know the encryption/decryption key for hiding a message into the encrypted image. Experiments conducted on ultrasound medical images show that the image distortion is very low while offering a high capacity that can support different watermarking based security objectives.

Secure Teleassistance towards endless medical litigations: identification of liabilities through a protocol using Joint Watermarking-Encryption Evidences.

Teleassistance is defined by the help provided through a telemedicine network by a medical practitioner to one other medical practitioner faced to a difficult case. One of the main limiting factors of its development is the fear of the practitioners to be involved in a litigation. In such a situation, the main issue is to determine as quick and as certain as possible if the damage is in relation with the tort of negligence and the liabilities of each involved physician. After a brief summary of the legal context, we present a protocol combining joint watermarking-encryption and a third party to enforce exchange traceability and therefore to bring valuable electronic evidence in case of teleassistance litigations.

Combination of watermarking and joint watermarking-decryption for 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 images and tracing them, i.e. identifying the person at the origin of an illegal distribution. 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 proof of traceability, is embedded during the decryption process. The scheme we propose makes interoperate such a combination of 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 physician at the origin of a disclosure even if the image has been modified.

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.