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A Difference Expansion Based Reversible Data Hiding Algorithm Using Edge-Oriented Prediction
Wen-Chao Yang,Ling-Hwei Chen,Chang-Hsing Lee 보안공학연구지원센터 2014 International Journal of Security and Its Applicat Vol.8 No.6
In this paper, a difference expansion based reversible data hiding approach which achieves the low distortion requirement under the same embedding capacity is proposed. An edge-oriented prediction method and a modified overflow/underflow prevention method are proposed to achieve the requirement. For each pixel, the prediction method uses edge information to get a better predicted value in an attempt to reduce the image distortion. Experimental results have demonstrated that the proposed reversible data hiding method yields lower distortion than several well-known expansion-based reversible data hiding methods.
A Cryptographic Key Assignment Scheme with Adaptable Time-token Constraint in a Hierarchy
Hsing-Chung Chen,Shiuh-Jeng Wang,Jyh-Horng Wen 보안공학연구지원센터 2008 International Journal of Multimedia and Ubiquitous Vol.3 No.4
A scheme, which uses flexible cryptographic key management upon adaptable time-token constraint for a user hierarchy access control (UHAC) scheme, is proposed in this paper. For adapting the changeability in a UHAC system, we propose a technique of assigning independent time-token which is distributed by a trusted agency server to reply an authorized user for once secure access request. The key feature of the technique is to adapt some secure parameters in distributed time-token for responding to each legal access request. Further, all class keys will be updated proactively by the concept of proactive key management, which makes the advantage that is proven and free from the scenario of the collusive attack example which proposed by Yi et al. in [18]. This cryptographic key assignment scheme based on the difficulty in solving a discrete logarithm, with adaptable time-token constraint, can achieve better security and more efficient management, than the conventional UHAC scheme. Besides, our scheme provides a flexible manner and dynamic key management to increase the availability of user access in UHAC structure.