10. A machine-implemented grammar inference engine for intrusion masquerade detection, comprising: a pre-processing device that receives one or more sets of user input content data and outputs filtered data; a grammar generating device that is coupled to the pre-processing device and that is configured (1) to generate a set of user grammars by applying a compression algorithm to the filtered data and (2) to form at least one model for the set of user grammars using characteristics of the set of user grammars the characteristics including a first estimated algorithmic minimum sufficient statistic for the set of user grammars; and a grammar applying device that is coupled to a classifier that compares the first algorithmic minimum sufficient statistic for the set of user grammars generated by the grammar generating device to a second estimated algorithmic sufficient statistic for at least one target block of other input content data, calculated using the compression algorithm, and that determines a distance between the at least one target block of the other input content data and the at least model for the set of user grammars, the classifier being coupled to the grammar applying device and to a post-processor, the classifier receiving (1) distance values representing determined distances from the grammar applying device and (2) decision criteria from the post-processor, the classifier being configured to calculate a likelihood of fit between the at least one target block of the other input content data and the at least one model for the set of user grammars based on the comparison provided by the grammar applying device as an indication of an intrusion masquerade.
10. A machine-implemented grammar inference engine for intrusion masquerade detection, comprising: a pre-processing device that receives one or more sets of user input content data and outputs filtered data; a grammar generating device that is coupled to the pre-processing device and that is configured (1) to generate a set of user grammars by applying a compression algorithm to the filtered data and (2) to form at least one model for the set of user grammars using characteristics of the set of user grammars the characteristics including a first estimated algorithmic minimum sufficient statistic for the set of user grammars; and a grammar applying device that is coupled to a classifier that compares the first algorithmic minimum sufficient statistic for the set of user grammars generated by the grammar generating device to a second estimated algorithmic sufficient statistic for at least one target block of other input content data, calculated using the compression algorithm, and that determines a distance between the at least one target block of the other input content data and the at least model for the set of user grammars, the classifier being coupled to the grammar applying device and to a post-processor, the classifier receiving (1) distance values representing determined distances from the grammar applying device and (2) decision criteria from the post-processor, the classifier being configured to calculate a likelihood of fit between the at least one target block of the other input content data and the at least one model for the set of user grammars based on the comparison provided by the grammar applying device as an indication of an intrusion masquerade. 11. The machine-implemented grammar inference engine of claim 10 , further comprising a grammar database coupled to the grammar applying device and to the grammar generating device that stores the at least one model for the set of user grammars.