## 5 Application Domains  
This section summarizes the above discussion by providing a gamut of applications of emerging de-identification research. **Cybersecurity:** Gathering intelligence by surveilling suspects in cyberspace is necessary to maintain a secure internet [111]. Government-authorized agents have been known to survey the social networks, disguising themselves among malicious users. Social behavioral biometrics-based de-identification can aid security agents in the covert observation and anonymous moderation of cyberspaces. **Continuous Authentication:** Continuous authentication refers to a technology that verifies users on an ongoing basis to provide identity confirmation and cybersecurity protection [112]. Social behavioral biometrics (SBB) authenticates users on social networking sites continuously without any active participation of the users. The templates of users' writing patterns and acquaintance networks information must be stored in the database for SBB authentication. Instead of storing the identifying templates directly, SBB-based de-identification techniques can be applied to the templates to ensure account security and user privacy. **Protecting Anonymity:** Authorized officials often publish case studies and written content of cybercrime victims to create public awareness [113]. In such cases, social networking portals and blogs are used as convenient media to disseminate information. Typically, the identities of the victims are kept anonymous. However, the content written by the victim and their social behavioral patterns may still contain identifying information. Therefore, de-identification of these published materials helps protect user anonymity when their identity must be kept confidential. **Multi-Factor Authentication:** Leveraging the discriminative ability of an individual's social data and psychological information, a multi-factor authentication system can be implemented [114]. As a remote and accessible biometric, aesthetic identification can also provide additional security if the primary modality is suspected to be compromised. De-identification in this context would preserve the security of the system when storing a user's preference template. **Video Surveillance:** Anonymization of primary or auxiliary biometric data protects the privacy of the subjects. If the original biometric is perturbed such that primary biometric identification is successful while the auxiliary biometric traits are not easily recognizable, or vice versa, this solution can be integrated with surveillance methods [115]. In such a situation, the de-identification of primary biometric can ensure the data privacy of individuals who appear in the footage but are not persons-of-interest. **Risk Analysis:** The ability to estimate a person's emotional state using the facial biometric or gait analysis finds potential applications in threat-assessment and risk analysis [116]. Analysis of emotional state can be applied in the surveillance of public places in order to estimate the threat posed by an individual based on continuous monitoring of their emotional state. Based on the necessity of data protection, primary biometrics can be obscured while preserving the auxiliary information about emotions. **Health Care:** Individuals can exhibit postural problems which could be diagnosed through static posture and gait analysis [117]. In such a case, primary gait biometric can be readily de-identified while preserving auxiliary biometric traits, such as age, gender, activity, and emotion. **Mental illness:** Many applications predict and identify mental and/or physical illnesses by monitoring user emotions [74]. De-identifying any sensitive patient biometric data using the methods in the applications discussed above would ensure patient privacy, which could increase their willingness to opt-in for such services. **Adaptive Caregiving:** The ability of an intelligent system to analyze user emotion information and exhibit realistic interactions has high potential [74].