This disclosure describes systems and method for preventing the transfer of ‘user-identifiable information’ from a client device while collecting telemetry data that is relevant to features of an operating system or computing application. In various examples, telemetry data is gathered to monitor the performance or use of an operating system or computing application. The process of collecting telemetry data can involve capturing data associated with files that are not directly associated with the operating system or computing application that is being monitored. This disclosure presents techniques that use a cryptographic hash function to prevent user identifiable information from being revealed in file attributes during the process of collecting telemetry data. A user's privacy is protected by the computational impracticability of recreating the original filename from the hash value.