1. A system, comprising: an interface configured to receive a file; a processor configured to: select a size for a Hilbert curve based at least in part on a determination of a threshold amount of negative space to be included in the Hilbert curve; transform file contents using the Hilbert curve; down-sample the transformed file contents; and perform a hashing operation on the down-sampled result; and a memory coupled to the processor and configured to provide the processor with instructions.