The Remotely Keyed Encryption Schemes (RKESs) are greatly useful in solving the vital problem of how to do bulk encryption/decryption for high-bandwidth applications (like multimedia data encryption) in a way that takes advantage of both the superior power of the host and the superior security of the smart card. Accordingly, we propose two novel RKESs, a Length Preserving (LP) RKES and a Length Increasing (LI) RKES. The proposed LPRKES is based on a general view of the well known Feistel-Network (FN) in which we only use two rounds in an efficient and secure way, employing data-dependent cipher-keys. In the LIRKES, an extra ciphertext block is used, encrypting the one-time random cipher-key based on a signature of the whole ciphertext. The security of the presented schemes are theoretically proven and, compared to the state-of-the-art RKESs, the savings in the required computational complexity, run-time, bandwidth, and storage space are emphasized.

In this paper, a self-recovery image authentication technique is proposed using randomly-sized blocks. To dived an image into randomly-sized blocks, it undergoes recursive arbitrarily-asymmetric quad tree partitioning. Multiple description coding (MDC) that enhances reliability of altered block recovery, is utilized to generate two block descriptions. We propose the use of a chain with multiple links for embedding several signature copies and two descriptions per block in arbitrarily distant blocks. The experimental results deposit that the proposed technique successfully both localizes and compensates the alterations. Furthermore, it is robust against the vector quantization (VQ) attack.

In this paper, a secure variable-size block-based image authentication technique is proposed that can not only localize the alteration detection but also recover the missing data. An image undergoes recursive arbitrarily-asymmetric binary tree partitioning to obtain randomly-sized blocks spanning the entire image. To enhance reliability of altered block recovery, multiple description coding (MDC) is utilized to generate two block descriptions. Block signature copies and the two block descriptions are embedded into two relatively-distant blocks making a doubly linked chain. The experimental results deposit that the proposed technique successfully both localizes and compensates the alterations. Furthermore, it is robust against the vector quantization (VQ) attack.

The foremost issues with most of the existing selective encryption (SE) schemes of images are vulnerability to cryptographic and application specific attacks, reduction in the compression performance, insubstantial computational savings relative to full encryption, and lack of bit stream compliance. This paper is the first one that proposes effective schemes for joint vector quantization (VQ) based image compression and SE. We introduce an image adaptive VQ index compression algorithm suitable for SE, effectively combining remapping of indices, entropy, predictive, differential, and search order coding. We then present SE through codebook pseudorandom shuffling and block ciphering of the VQ index image bit-planes, index usage map, prediction information tables and full indices. Experimentally, the results demonstrate the improved performance and effectiveness of the proposed schemes.

Digital images are vulnerable to various malicious manipulations. So, effective techniques are demanded for assuring the integrity of image contents. In this paper, a public key self-embedding image authentication technique is proposed which can detect and localize alterations of the image contents and can restore the distorted regions. A doubly linked chain is used to embed block signature copies and two block codes into relatively distant blocks. Each block code can not only approximately rebuild a distorted block but also can, combined with another block code, rebuild the block with high quality. Moreover, the proposed technique uses a public key in the verification process that enables verification of the image authenticity without knowing the private key used in the embedding process. The experimental results show that the proposed technique is sensitive to pixel changes and provides secure embedding of the blockwise image signatures. Furthermore, it thwarts many attacks, specially the collage (also called vector quantization, blind copy, or pattern matching) attacks and can successively recover the image attacked areas.

We propose a novel application adaptive (multi-mode) headway-based broadcasting protocol that is most appropriate for public-safety applications in VANETs. Being headway-based, the proposed protocol possesses unique robustness at different speeds and traffic volumes. Moreover, it addresses application differences with a new multi-mode feature. The logic behind the new concepts/approaches adopted in the protocol and their merits are highlighted, supported with analysis and simulation.

A new algorithm is presented for the design of fixed point finite impulse response (FIR) digital filters that can be realized using a minimal number of adders while satisfying both the desired hardware implementation constraints and the frequency domain design constraints. The proposed algorithm makes use of a two-stage search method with a new soft-switching optimization criterion, minimizing the Chebyshev error norm in a discrete canonic signed digit (CSD) space. The proposed design method is implemented as a Matlab-based software package (CSDFIR) that allows the design of both Chebyshev optimal floating point and fixed point CSD FIR filters.

In this paper, a novel morphological reversible contour representation of discrete binary images is proposed. A binary image is represented by a set of nonoverlapping multilevel contours and a residual image. In this proposed representation, the total number of pixels representing an image is far less than the total number of pixels obtained by the seed-based morphological contour-skeleton lossless representation. The proposed contour representation is simple, unique, and general without restrictions on the binary image to be represented. The resulting multicontour image component is robust to noise. An efficient differential chain contour coding scheme is employed to further compress the represented image. The proposed method yields very low bit rates compared to the existing morphological techniques. An automatic filling procedure, which properly fills a proper multicontour image according to its topological structure without need of seed points, is proposed.

This paper presents a morphological technique for text extraction from images. The proposed morphological technique is insensitive to noise, skew and text orientation. It is also free from artifacts that are usually introduced by both fixed/optimal global thresholding and fixed-size block-based local thresholding. Examples are presented to illustrate the performance of the proposed method.