1. A computer data system, comprising: a database storing a plurality of signature strings; a memory storing computer instructions; a processor configured to execute the computer instructions to perform the operations of: assigning values to characters in the signature strings; calculating differences between the assigned values of the characters in the signature strings; identifying common features of the signature strings using the calculated differences; grouping the signature strings into signature groups according to the common features; receiving an input string into the memory; detecting predetermined features of the input string; comparing the predetermined features of the input string with the common features of one or more of the signature groups; and comparing the input string with one or more individual signature strings in one of the signature groups if the predetermined features of the input string match the common features of the one of the signature groups.