A signature is a data pattern of interest in a large data file or set of large data files. Such signatures that need to be found arise in applications such as DNA sequence analysis, network intrusion detection, biometrics, large scientific experiments, speech recognition and sensor networks. Related to this is string matching. More specifically we envision a problem where long linear data files (i.e., flat files) contain multiple signatures that are to be found using a multiplicity of processors (parallel processor). This paper evaluates the performance of finding signatures in files residing in the nodes of parallel processors configured as trees, two dimensional meshes and hypercubes. We assume various combinations of sequential and parallel searching. A unique feature of this work is that it is assumed that data is pre-loaded onto processors, as may occur in practice, thus load distribution time need not be accounted for. Elegant expressions are found for average signature searching time and speedup, and graphical results are provided.