基于哈希的二维工程CAD图拓扑关系认证技术

Topology Authentication of 2D Engineering CAD Drawings Based on Hashing

针对二维工程CAD图拓扑关系完整性认证问题,提出一种基于哈希的拓扑完整性认证算法。该算法首先提取图纸的拓扑关系生成拓扑图;其次对图中的组件进行编码,并提出一种局部拓扑量化模式(LTQP),实现各组件拓扑特征的量化;然后将组件按照其编码分成5类,基于各组件的LTQP值,利用离散余弦变换生成每类组件的哈希序列;最后将每类组件的哈希序列进行合并,得到完整的图纸哈希序列。实验结果表明,该算法对旋转、缩放和平移等非恶意操作具有鲁棒性,同时对恶意拓扑攻击具有脆弱性,采用将组件分类来生成哈希序列的方式,能够对受到拓扑攻击的组件的种类进行定位。

Since it's difficult to authenticate the topological relation in the2-dimensional engineering CAD drawing,a topological integrity authentication algorithm is proposed based on Hashing in thispaper.Firstly,the algorithm extracts the topological relations of the drawings to generate the topology graph.Secondly,the components in the engineering CAD drawing are encoded,and the local topological quantization pattern(LTQP)is proposed to quantize the topological features of each component.Then,the components are divided into five categories according to their coding,and a Hash sequence is generated by discrete cosine transform based on the LTQP values.Finally,the Hash sequence of each category is combined to obtain the complete Hash sequence of the drawing.The experimental results show that the algorithmis robust to rotation,scaling and translation in engineering CAD drawings,and is vulnerable to the change of topological connection.By classifying the components to generate a Hash sequence,the algorithm can locate the type of components which is subjected to the topology attack.