Fragile Watermarking Algorithm for High Precision Map of OpenDRIVE Format

Objectives: It is not supposed to be ignored that the issue of data integrity protection of high precision map, which is considered as a key data resource in the development of digital transportation. However, hash algorithms applied to file verification did not consider the function of inferring the location of tampered content inside a message based on a single checksum exception in its design. Therefore, an algorithm that can verify the integrity of high-precision map data and accurately locate tampering can not only effectively prevent and resolve network security risks in the field of digital transportation, but also effectively protect the safety of people's lives and property. Focusing on this question, this paper proposed a fragile watermarking algorithm that is suitable for high precision map of OpenDRIVE format. Methods: This algorithm is designed based on Unicode zero-width characters and MD5 hash algorithm. The algorithm proposed use zero-width character sequences to embed watermark information, with XML nodes as units to generate, embed, extract and verify watermarks. The watermark information corresponding to each node is composed of a combination of a tree watermark and a road feature watermark. In order not to affect the normal use of the data, the embedding position of the watermark sequence is selected at the end of the row corresponding to the starting label or unique label of each node. When the data is distributed, the administrator can use this algorithm to generate fragile watermarks and embed them into highprecision map data and verify whether the watermarks are successfully embedded in the file. When the user needs to verify the integrity of the file, this algorithm can be used to extract and verify the watermark. If the two are completely consistent, inform the user that the integrity of the file has passed the inspection, otherwise the algorithm will determine the tampering location for the user based on the abnormal situation. Results: The result show that:(1) Embedding watermarks into high-precision map documents will not cause visible abnormal display phenomena. (2) Embedding watermarks will not cause significant changes in the size of high-precision map documents, and the ratio of increment to original size can be controlled within 5%. (3) Highly sensitive to attacks against nodes and watermarks, and able to accurately locate the location of tampering. When whole element deletion occurs, the geometric information of the deleted element can be inferred. Conclusions: This algorithm is suitable for the integrity protection of high-precision map data, and can also be applied to the integrity protection of other structurally similar data such as HTML and CSS, as long as cancelling some preprocessing requirements, reconfirming the appropriate watermark embedding position and clarifying the definition of features and the sorting rules between features.