Search

In the system security technology, the information hiding field is developed as technologies for embedding information into digital content as media. The proposed technique is a technical steganography technique which uses a technique of information hiding through physical / statistical change of signal of contents. In the digital watermarking or steganography technology, the embedding process is frequently performed in the frequency domain in order to increase the latent capacity and to improve the image quality. However, these methods have a disadvantage that the computation complexity is high and the constraint condition becomes complicated. In the contrast, there have been various studies based on histogram shifting technology in reversible information hiding. Assume it selects multiple peaks on the histogram shifting, the capacity of data concealment gradually increased by applying multiple peak histogram method. The steganography technique using histogram shifting doesn't show any significant improvement for the hiding capacity and image quality in the early methods. In this paper, we analyze the effect of information hiding technology in terms of adopting the histogram shift method including skipping. In addition, we propose 2n divergence data hiding as a complimentary technique to improve hiding capacity. The proposed method has been proven through an example using mathematical expressions, and further improvement measures could be derived. [ABSTRACT FROM AUTHOR]

ABSTRACT Most of broadcast encryption schemes do not provide source authentication property. This allows an adversary to launch impersonating attacks. Therefore, broadcast encryption scheme without source authentication is not applicable in our real life as it is. In this paper, we propose two source-authenticated broadcast encryption schemes that achieve both confidentiality and authenticity simultaneously. Ciphertexts in both schemes are of constant size, independent of the size of the receiver set. The first scheme is particularly efficient in case of pre-computation, whereas the overall performance of the second scheme is better than that of Selvi et al.'s scheme. Copyright © 2013 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

ABSTRACT Key revocation is one of the most challenging and open issues in attribute-based encryption (ABE). The previous revocable ABE schemes feature a mechanism that revokes the attribute key periodically without any consideration of the user membership associated with the attribute. Thus, non-revoked users are enforced to access the key authority periodically to receive keying materials in order to update the current key. This is due to the fact that the revocation is done only on the attribute level, which results in security and scalability problems. In this paper, we propose a fine-grained user revocation scheme without affecting any non-revoked users who share the same attributes in ciphertext-policy ABE; it does not require the users to access the key authority and to update keys periodically. The proposed scheme improves the efficiency compared with previous revocable schemes and enhances the security in terms of the backward/forward secrecy on any membership changes in the ciphertext-policy ABE system. Copyright © 2011 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Abstract: Attribute-based encryption (ABE) is a promising cryptographic primitive for fine-grained access control of distributed data. In ciphertext policy attribute-based encryption (CP-ABE), each user is associated with a set of attributes and data are encrypted with access policies on attributes. A user is able to decrypt a ciphertext if and only if his attributes satisfy the access policy embedded in the ciphertext. However, key escrow is inherent in ABE systems. A curious key generation center in that construction has the power to decrypt every ciphertext. We found that most of the existing ABE schemes depending on a single key authority suffer from the key escrow problem. In this study, we propose a novel CP-ABE key issuing architecture that solves the key escrow problem. The proposed scheme separates the power of issuing user keys into two parties: the key generation center and the attribute authority. In the proposed construction, the key generation center and the attribute authority issue different parts of secret key components to users through a secure two-party computation protocol such that none of them can determine the whole set of keys of users individually. We demonstrate how the proposed key issuing protocol can be applied in the existing CP-ABE scheme and resolve the key escrow problem. [Copyright &y& Elsevier]