A network environment is described for securely storing data for anonymized contact tracing while an application is executing in a background state. An application can receive a message containing data while the application is executing in a background state. The data is encrypted using a public key. Next, the application can store the encrypted data in an alternate data store. Subsequently, and upon user authentication, the application can decrypt a secure data store decrypt the encrypted data. The application can then store the decrypted data in the decrypted secure data store. The application can receive user input indicating a positive test result for a communicable disease with an incubation period, and anonymously upload the data stripped of any uniquely identifying information.