# Security and Privacy in Physical-Digital Environments: Trends and Opportunities
## 3 Security, Privacy, and Confidentiality
### Threats and Countermeasures
#### 3.6.2 Countermeasures  
To mitigate the risks associated with digital threats, users can take several measures, such as the ones in Figure 8, to protect their online presence.  
One of the most pivotal measures is carefully managing their digital footprint. Managing one's digital footprint involves being conscious of the information collected, stored, and shared online, including personal data such as name, address, date of birth, and credit card details. Users should be mindful of the websites and platforms they interact with and take steps to limit the amount of personal information they share. Users should also use strong passwords and two-factor authentication to safeguard their online presence, helping prevent unauthorized access to accounts and sensitive information. Two-factor authentication provides an additional layer of security by requiring users to enter a unique code sent to their mobile device or email.  
In addition to these measures, it is also essential to renew consent permissions periodically, ensuring users' awareness of the data collected and their usage. By regularly reviewing and updating consent permissions, users can better control their digital footprint and mitigate the risks associated with cyber threats.  
Figure 8: Comparison of countermeasures for MR privacy risks.  
To mitigate MR threats, MR systems require strong security protocols. One fruitful approach is edge computing, which allows data to be processed locally on the device rather than transmitted to remote servers, reducing data exposure and latency [32]. By keeping sensitive data on the local device, edge computing minimizes the risks of interception and unauthorized access. This approach is particularly useful for processing biometric data, such as eye tracking and facial recognition, directly on MR headsets without sending it to external cloud servers, thereby enhancing privacy and security.  
Furthermore, context-aware privacy controls enable users to adjust the level of data sharing based on their environment or activity [33]. These controls allow MR devices to dynamically modify privacy settings depending on the user's location, interaction context, or personal preferences. For instance, users in private spaces might set their MR devices to a high-privacy mode, limiting data collection to only essential functions, while in public settings, data-sharing permissions could be more flexible. Another example is the adaptive permission model, where MR applications request access to specific data only when necessary, rather than maintaining continuous access to personal or spatial information.  
Another countermeasure is the implementation of field-of-view restrictions, where the device blurs or limits data capture outside of specific focal points. This technique helps prevent the collection of unnecessary spatial information [34]. In MR, data sanitization before rendering may also reduce privacy risks. For instance, SafeAR [35, 36] automatically identifies instances of sensitive data and applies obfuscation techniques to image streams before rendering. In [37], the authors evaluate qualitative and quantitative methodologies for applying different obfuscation strategies to protect private data in MR applications. The authors collected opinions from tens of users through a specific questionnaire. They conclude that factors like age and occupation influence the users' concerns about privacy-maintenance methods and preferences regarding obfuscation. Overall, the participants identified blurring as the obfuscation method that provides the best aesthetic appeal.  
By integrating edge computing and context-aware privacy controls with existing security measures, MR environments can offer improved user privacy protections while maintaining seamless interactions and performance. Future work in this area should explore adaptive privacy mechanisms that provide greater user control while ensuring data security in dynamic MR settings.