421 research outputs found
On the Design of Perceptual MPEG-Video Encryption Algorithms
In this paper, some existing perceptual encryption algorithms of MPEG videos
are reviewed and some problems, especially security defects of two recently
proposed MPEG-video perceptual encryption schemes, are pointed out. Then, a
simpler and more effective design is suggested, which selectively encrypts
fixed-length codewords (FLC) in MPEG-video bitstreams under the control of
three perceptibility factors. The proposed design is actually an encryption
configuration that can work with any stream cipher or block cipher. Compared
with the previously-proposed schemes, the new design provides more useful
features, such as strict size-preservation, on-the-fly encryption and multiple
perceptibility, which make it possible to support more applications with
different requirements. In addition, four different measures are suggested to
provide better security against known/chosen-plaintext attacks.Comment: 10 pages, 5 figures, IEEEtran.cl
JPEG Image Encryption Using Combined Reversed And Normal Direction-Distorted Dc Permutation With Key Scheduling Algorithm-Based Permutation
This thesis work studied on digital image encryption algorithms performed towards JPEG images. With image encryption algorithms, JPEG images can be securely scrambled or encrypted prior to distribution. The intended recipient will be given a decryption key in which only with this key the receiver can received and decrypt the media for viewing. The proposed approach uses a frequency domain combinational framework of coefficients scrambling with Key Scheduling Algorithm based (KSA-based) permutation. This novel algorithm applies coefficients scrambling using Combined-Reverse-and-Normal-Direction (CRND) scanning together with Distorted DC permutation (DDP). This encryption algorithm involved the manipulation of JPEG zigzag scanning table according to 10 different scanning tables which was derived by reversing the existing zigzag scanning directions. With the same compression properties, this encryption algorithm was shown to be able to produce average file size smaller than baseline JPEG and other encryption. It was also shown that the average decoding speed for this technique outperform most of other existing techniques and the same time able to maintain image quality (PSNR) as other techniques. It terms of security, with the combination of Distorted DC permutation (DDP), it was considered to be having medium security based on some basic attack analysis that was carried out. It is also shown that this technique is fully format compliance as most of other techniques do. Based on the simple nature of CRND, this technique is easy to be implemented on existing system and thus should be able reduce the cost of implementing a new encryption system
Recovering Sign Bits of DCT Coefficients in Digital Images as an Optimization Problem
Recovering unknown, missing, damaged, distorted or lost information in DCT
coefficients is a common task in multiple applications of digital image
processing, including image compression, selective image encryption, and image
communications. This paper investigates recovery of a special type of
information in DCT coefficients of digital images: sign bits. This problem can
be modelled as a mixed integer linear programming (MILP) problem, which is
NP-hard in general. To efficiently solve the problem, we propose two
approximation methods: 1) a relaxation-based method that convert the MILP
problem to a linear programming (LP) problem; 2) a divide-and-conquer method
which splits the target image into sufficiently small regions, each of which
can be more efficiently solved as an MILP problem, and then conducts a global
optimization phase as a smaller MILP problem or an LP problem to maximize
smoothness across different regions. To the best of our knowledge, we are the
first who considered how to use global optimization to recover sign bits of DCT
coefficients. We considered how the proposed methods can be applied to
JPEG-encoded images and conducted extensive experiments to validate the
performances of our proposed methods. The experimental results showed that the
proposed methods worked well, especially when the number of unknown sign bits
per DCT block is not too large. Compared with other existing methods, which are
all based on simple error-concealment strategies, our proposed methods
outperformed them with a substantial margin, both according to objective
quality metrics (PSNR and SSIM) and also our subjective evaluation. Our work
has a number of profound implications, e.g., more sign bits can be discarded to
develop more efficient image compression methods, and image encryption methods
based on sign bit encryption can be less secure than we previously understood.Comment: 13 pages, 8 figure
A digital signature and watermarking based authentication system for JPEG2000 images
In this thesis, digital signature based authentication system was introduced, which is able to protect JPEG2000 images in different flavors, including fragile authentication and semi-fragile authentication. The fragile authentication is to protect the image at code-stream level, and the semi-fragile is to protect the image at the content level.
The semi-fragile can be further classified into lossy and lossless authentication. With lossless authentication, the original image can be recovered after verification. The lossless authentication and the new image compression standard, JPEG2000 is mainly discussed in this thesis
Safe Transfert of Medical Images by Conjoined Coding : Selective Encryption by AES Using the Stream Cipher Mode OFB and JPEG Compression
The traffic of digital images has increased rapidly in the wide networks. The protection of this kind of data becomes
important for many reasons such as confidentiality, obscurity and security. Nowadays, the most important engine to
provide confidentiality is encryption. Therefore, the classical and modern ciphers are not suitable for such huge
quantity of data in real-time environment. Selective encryption (SE) is an approach to encode a portion of the data in
order to reduce computational requirements and to provide a proportional privacy. This paper presents a new method
of partial or selective encryption for JPEG images. It is based on encoding of some Huffman bitstream with AES cipher.
The proposed method results in a significant reduction in encrypting and decrypting processing time, provides a
constant bit rate and keeps the JPEG bitstream compliance.Le trafic des images numériques augmente rapidement sur les réseaux. La protection des données
numériques, et en particulier les images médicales, devient importante pour de nombreuses raisons telles
que la confidentialité et l'intégrité. Actuellement, la façon la plus répandue de répondre au problème de la
confidentialité est le cryptage. Cependant, les algorithmes classiques et modernes de chiffrement ne sont
pas capables de chiffrer une énorme quantité de données dans un environnement en temps réel. Le cryptage
sélectif (CS) est une approche qui ne chiffre qu'une partie des données afin de diminuer le temps de calcul
tout en assurant une certaine sécurité. Cet article présente une nouvelle méthode de cryptage sélectif pour
des images médicales comprimées au format JPEG. Cette méthode est basée sur le cryptage par flot avec
AES d'une partie du flux binaire issue du codage par Huffman. Les résultats de la méthode proposée
présentent un gain de temps de calcul significatif tout en conservant le taux de compression et le format
initial de JPEG
WG1N5315 - Response to Call for AIC evaluation methodologies and compression technologies for medical images: LAR Codec
This document presents the LAR image codec as a response to Call for AIC evaluation methodologies and compression technologies for medical images.This document describes the IETR response to the specific call for contributions of medical imaging technologies to be considered for AIC. The philosophy behind our coder is not to outperform JPEG2000 in compression; our goal is to propose an open source, royalty free, alternative image coder with integrated services. While keeping the compression performances in the same range as JPEG2000 but with lower complexity, our coder also provides services such as scalability, cryptography, data hiding, lossy to lossless compression, region of interest, free region representation and coding
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