# E-SAWM: A Semantic Analysis-Based ODF Watermarking Algorithm for Edge Cloud Scenarios
## 3 Model and Algorithm  
### Dynamic Watermarking Implementation  
In compliance with regulatory requirements, data users in open banking must possess data traceability capabilities to effectively trace and determine data leakage incidents. Watermarking is a widely used technical approach to trace and assign responsibility in such scenarios. Based on the aforementioned service architecture, an effective approach for tracking data and mitigating the risk of data leakage involves leveraging the data proximity processing capabilities of the edge cloud, which requires the utilization of the edge cloud's computing power to implement data leakage tracking technology. Furthermore, it is essential to employ a highly efficient and flexible watermarking algorithm on the edge cloud side to support the tracking of financially sensitive data. Specifically, in the context of OFD file applications, the edge cloud watermarking service facilitates the dynamic addition of timely watermarks after file processing on the edge cloud to ensure effective tracking in the event of data leakage. Data watermarking in the financial industry encompasses two main approaches: static watermarking and dynamic watermarking. Static watermarking involves adding a large number of watermarks to the data during the pre-preparation phase, which is done once and remains unchanged. On the other hand, dynamic watermarking is performed in real time during the data access process, including data querying, accessing, real-time exchange,  
Figure 4: OFD annotation file contents for watermarking. Figure 5: Illustration of OFD page with added explicit watermark. and dynamic release. This approach ensures that the watermarks are dynamic and updated in real time. Unlike static watermarking, which can be pre-processed in batches on the central cloud without real-time requirements, dynamic watermarking is primarily deployed in the edge cloud to meet the demands of real-time data processing. Specifically, in financial business scenarios, where sensitive data need to be accessed by various platforms via API interfaces, the bank's data documents are appended with a unified static watermark before being shared. Upon reaching the third-party application, a dynamic watermark is added by the \"regulatory outpost\" based on the application's information and document content. Subsequently, the watermark information is dynamically replaced at each stage of data usage, ensuring accurate tracking of any potential data file leakage. The following examples provide a step-by-step illustration of the watermarking process:  
1. Adding watermarks during data reception by the application-side database, as depicted in Figure 6. As the application side receives open banking data from a bank, a dynamic watermark is added, either explicitly or implicitly, while the data traverses a supervisory outpost situated in the edge cloud. This watermarking enables traceability in the event of an open banking data breach, allowing for identification of the breaching application side. The standard format typically follows: \"Received Data from XXX Bank by XX Organization on xx/xx/xxxx (date). Purpose: XXX\". ;
2. Adding watermarks during the download of data from the database by application-side employees, as shown in Figure 7. Whenever an application-side employee retrieves data from the application-side database, a dynamic watermark, typically implicit in nature, is embedded. This watermark serves the purpose of identifying the individual responsible for any data leakage when tracing its origin in the context of open banking. The format commonly follows \"On xx/xx/xxxx (date), employee xxx downloaded open banking data from the database. Purpose: XXX\". Remarkably, the newly added watermark can coexist with the original watermark;
3. Adding watermarks when sharing data with external entities on the application side, as shown in Figure 8. In some cases, the application side needs to desensitize the open banking data, then share it with a partner, such as in the need for business cooperation.