Patent ID: 8331404
Filing Date: 2012-12-11
Classification: H04L

Abstract:
1. A method of detecting digital signatures in a character stream including header characters and payload characters of addressed data packets, comprising: applying the header characters to a first deterministic finite automata having an initial state, intermediate states and at least one header match state, there being at least one state for every character position within the header of the packet, and organised to detect by entry into said match state a header match of a string of header characters with a header rule which specifies the locations within the header of predetermined characters; applying said payload characters to a second deterministic finite automata having an initial state, intermediate states and at least one content match state and organised by means of entry into said content match state to detect a content match between a character set in said payload characters and at least one content rule specifying the occurrence of a predetermined sequence of characters; and linking said header match and said content match in a rule-defining deterministic finite automata which indicates the occurrence of both the header match and the content match.