15. A non-transitory computer-readable-storage medium comprising one or more computer-executable instructions that, when executed by at least one processor of a computing device, cause the computing device to: identify a file; determine that the file has been digitally signed; identify a signer responsible for digitally signing the file; identify a reputation of the signer, the signer's reputation being based at least in part on the determined trustworthiness of at least one additional file that was previously signed by the signer; determine whether the signer's reputation satisfies a predetermined threshold; only perform an independent evaluation of the trustworthiness of the file if the signer's reputation fails to satisfy the predetermined threshold.
15. A non-transitory computer-readable-storage medium comprising one or more computer-executable instructions that, when executed by at least one processor of a computing device, cause the computing device to: identify a file; determine that the file has been digitally signed; identify a signer responsible for digitally signing the file; identify a reputation of the signer, the signer's reputation being based at least in part on the determined trustworthiness of at least one additional file that was previously signed by the signer; determine whether the signer's reputation satisfies a predetermined threshold; only perform an independent evaluation of the trustworthiness of the file if the signer's reputation fails to satisfy the predetermined threshold. 16. The computer-readable-storage medium of claim 15 , wherein the computing device identifies the signer's reputation by obtaining the signer's reputation from a reputation server.