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In a method of hiding data in bit-planes that correspond to a series of digital signals, a single bit is chosen from the bits of each processed signal and then inverted. In a previous work a level transformation that performs the following three functions has been proposed: inverting the chosen bit, minimizing the level change caused by the bit inversion, and yielding random variations in the output level. This paper evaluates the random variations resulting from the transformation and demonstrates its effectiveness in secure data hiding.First, the properties of the level transformation are analyzed. Some theoretical values are also calculated especially to evaluate the increase of level differences caused by the random variations. Next, results of computer simulations of the transformation are presented, and the changes in level distributions are measured. These results indicate that the random variations in output levels reduce effectively the deformation of the level distributions at the expense of a little increase of the level differences.

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In this paper, an assurance case development tool is proposed to derive the argument decomposition structure from generic model definitions. The method solves O-DA issues for assuring business, application, and technology architecture of TOGAF. An example case study using the proposed tool is also shown for the system configuration model of the tool itself. Discussions based on the case study showed the effectiveness and appropriateness of the proposed methods. Future work includes the formalization of assurance case derivation process from ArchiMate, UML, and SysML models.

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