In one disclosed method, a computing system receives a first request to download a first file to a client device. The computing system further sends, based at least in part on the first request, a first digest of the first file to the client device to enable the client device to compare the first digest with at least a second digest of a second file stored locally at the client device. The computing system further receives, after sending the first digest to the client device, a second request to refrain from downloading the first file to the client device.