The trust reputation of the combination of an installation package and installer, as a pair, and the combination of a file and an installer, as a pair, is used to store the identity of a file in a persistent cache. An entry in the persistent cache indicates the trust worthiness of a file that does not contain malware thereby avoiding a scan of the file for malware. The trust worthiness of a file may be determined from known trust reputations of the installation package, installer, and file from a network of computing resources. By relying on the known trust reputation of the combination of the installation package and installer and the combination of the file and installer, the identity of the file may be stored in persistent cache quickly.