Research On Integrity Authentication Technology Of Engineering CAD Drawings Based On Hashing

Computer aided design is one of the important supporting technologies of modern industry.As an important branch of CAD,engineering CAD is widely used in many fields such as petroleum,construction,chemical engineering,bridge.It is significant to national economic level and modernization development.With the development of industrial design automation and Internet technology,collaborative design in the network environment has become the choice of industry.Online engineering CAD product release has brought convenience to the industry,but it also brought lots of security risks.Detecting whether the engineering CAD was malicious tampering and ensuring the integrity of the content has gradually become an urgent need.At present,most of the content integrity authentication technology was used to verify the mechanical CAD geometric information.The research on the geometric information and topological relations of engineering CAD is lacking.This paper proposed an integrity authentication technology of the engineering CAD drawings based on the hashing.The hashing authentication technology of engineering CAD mainly included three parts:feature extraction,feature processing and hash generation.And the most important part is feature extraction.3D CAD models and 2D CAD drawings have different characteristics.In this paper,we designed different hash algorithms according to their characteristics.1.Topology authentication of 3D engineering CAD models based on local topology quantization patternThe topology graph of 3D engineering CAD models is generated by extracting the topological relation,and then the component is encoded.A local topological quantization pattern(LTQP)is proposed to quantize topological relation of the 3D CAD models.Finally,the discrete cosine transform is used to generate the hash sequence of the model.2.Integrity authentication of 2D engineering CAD drawings based on covariance matrixIn this paper,a method of feature extraction using Zernike moments was proposed for the component geometric information of 2D CAD drawings.Firstly,the geometric features of 2D CAD drawings were extracted by Zernike moments,and the geometric information and topological relations are merged.Finally,we used the measurement matrix to get the Hash sequence of 2D engineering CAD drawings.This paper experimented with process plant CAD,the results show that the proposed hashing algorithm is robust to topology-preserving operations such as rotation,translation,and scaling,and is vulnerable to the change of topological connection.By classifying the components to generate a hash sequence,both algorithms can locate the type of components which is subjected to the topology attack.Moreover,the algorithm proposed in this paper is general and can be widely applied to various fields of engineering CAD drawings.