Systems and methods for scanning signatures in a string field. In one implementation, the invention provides a method for signature scanning. The method includes receiving a particular string field, scanning the particular string field for a plurality of signatures using a larger scan step size, scanning the particular string field for the remaining signatures that are shorter than what can be scanned by the larger scan step size separately either using the same scanning method but a smaller scan step size or using a different scan method and the same or a smaller scan step size, and outputting any identified signatures in the particular string field.