Anti-Spam Techniques Based on Artificial Immune System Anti-Spam Techniques Based on Artificial Immune System YING TAN CRC Press Taylor & Francis Group 6000 Broken Sound Parkway NW, Suite 300 Boca Raton, FL 33487-2742 © 2016 by Taylor & Francis Group, LLC CRC Press is an imprint of Taylor & Francis Group, an Informa business No claim to original U.S. Government works Version Date: 20151013 International Standard Book Number-13: 978-1-4987-2519-4 (eBook - PDF) This book contains information obtained from authentic and highly regarded sources. Reasonable efforts have been made to publish reliable data and information, but the author and publisher cannot assume responsibility for the validity of all materials or the consequences of their use. The authors and publishers have attempted to trace the copyright holders of all material reproduced in this publication and apologize to copyright holders if permission to publish in this form has not been obtained. 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Visit the Taylor & Francis Web site at http://www.taylorandfrancis.com and the CRC Press Web site at http://www.crcpress.com Contents ListofFigures....................................................................xi ListofTables.................................................................... xv ListofSymbols ................................................................ xix Preface.......................................................................... xxi Acknowledgments .............................................................xxv Author........................................................................ xxvii 1 Anti-SpamTechnologies..................................................... 1 1.1 SpamProblem............................................................. 1 1.1.1 DefinitionofSpam................................................ 1 1.1.2 ScaleandInfluenceofSpam...................................... 2 1.2 PrevalentAnti-SpamTechnologies........................................ 3 1.2.1 LegalMeans....................................................... 3 1.2.2 E-MailProtocolMethods......................................... 4 1.2.3 SimpleTechniques................................................ 5 1.2.3.1 AddressProtection...................................... 5 1.2.3.2 KeywordsFiltering...................................... 5 1.2.3.3 BlackListandWhite-List............................... 6 1.2.3.4 GrayListandChallenge-Response...................... 6 1.2.4 IntelligentSpamDetectionApproaches.......................... 7 1.3 E-MailFeatureExtractionApproaches................................... 7 1.3.1 TermSelectionStrategies.......................................... 8 1.3.2 Text-BasedFeatureExtractionApproaches....................... 9 1.3.3 Image-BasedFeatureExtractionApproaches.................... 11 1.3.3.1 PropertyFeaturesofImage............................ 11 1.3.3.2 ColorandTextureFeaturesofImage.................. 11 1.3.3.3 CharacterEdgeFeatures............................... 12 1.3.3.4 OCR-BasedFeatures................................... 13 1.3.4 Behavior-BasedFeatureExtractionApproaches................. 13 1.3.4.1 BehaviorFeaturesofSpammers........................ 14 1.3.4.2 NetworkBehaviorFeaturesofSpam................... 15 v vi ■ Contents 1.3.4.3 SocialNetwork–BasedBehaviorFeatures.............. 15 1.3.4.4 Immune-BasedBehaviorFeatureExtraction Approaches............................................. 16 1.4 E-MailClassificationTechniques........................................ 17 1.5 PerformanceEvaluationandStandardCorpora......................... 19 1.5.1 PerformanceMeasurements...................................... 19 1.5.2 StandardCorpora................................................ 20 1.6 Summary................................................................. 21 2 ArtificialImmuneSystem.................................................. 23 2.1 Introduction............................................................. 23 2.2 BiologicalImmuneSystem.............................................. 24 2.2.1 Overview......................................................... 24 2.2.2 AdaptiveImmuneProcess....................................... 25 2.2.3 CharacteristicsofBIS............................................ 26 2.3 ArtificialImmuneSystem............................................... 28 2.3.1 Overview......................................................... 28 2.3.2 AISModelsandAlgorithms..................................... 29 2.3.2.1 NegativeSelectionAlgorithm.......................... 30 2.3.2.2 ClonalSelectionAlgorithm............................ 31 2.3.2.3 ImmuneNetworkModel.............................. 33 2.3.2.4 DangerTheoryModel................................. 34 2.3.2.5 ImmuneConcentration................................ 35 2.3.2.6 OtherModelsandAlgorithms......................... 37 2.3.3 CharacteristicsofAIS............................................ 37 2.3.4 ApplicationFieldsofAIS........................................ 38 2.4 ApplicationsofAISinAnti-Spam....................................... 40 2.4.1 HeuristicMethods............................................... 40 2.4.2 NegativeSelection............................................... 41 2.4.3 ImmuneNetwork................................................ 42 2.4.4 DynamicAlgorithms............................................. 42 2.4.5 HybridModels................................................... 43 2.5 Summary................................................................. 44 3 TermSpacePartition-BasedFeatureConstructionApproach............ 45 3.1 Motivation............................................................... 45 3.2 PrinciplesoftheTSPApproach......................................... 47 3.3 ImplementationoftheTSPApproach.................................. 49 3.3.1 Preprocessing..................................................... 49 3.3.2 TermSpacePartition............................................. 49 3.3.3 FeatureConstruction............................................ 51 3.4 Experiments.............................................................. 53 Contents ■ vii 3.4.1 InvestigationofParameters...................................... 53 3.4.2 PerformancewithDifferentFeatureSelectionMetrics.......... 55 3.4.3 ComparisonwithCurrentApproaches.......................... 56 3.5 Summary................................................................. 58 4 ImmuneConcentration-BasedFeatureConstructionApproach......... 59 4.1 Introduction............................................................. 59 4.2 DiversityofDetectorRepresentationinAIS............................ 60 4.3 MotivationofConcentration-BasedFeature ConstructionApproach.................................................. 61 4.4 OverviewofConcentration-BasedFeature ConstructionApproach.................................................. 62 4.5 GeneLibraryGeneration................................................ 62 4.6 ConcentrationVectorConstruction..................................... 63 4.7 RelationtoOtherMethods.............................................. 65 4.8 ComplexityAnalysis..................................................... 66 4.9 ExperimentalValidation................................................. 66 4.9.1 ExperimentsonDifferentConcentrations...................... 68 4.9.2 ExperimentswithTwo-ElementConcentrationVector......... 70 4.9.3 ExperimentswithMiddleConcentration....................... 72 4.10 Discussion............................................................... 74 4.11 Summary................................................................. 78 5 LocalConcentration-BasedFeatureExtractionApproach ............... 83 5.1 Introduction............................................................. 83 5.2 StructureofLocalConcentrationModel................................ 84 5.3 TermSelectionandDetectorSetsGeneration........................... 85 5.4 ConstructionofLocalConcentration–BasedFeatureVectors.......... 87 5.5 StrategiesforDefiningLocalAreas...................................... 88 5.5.1 UsingaSlidingWindowwithFixedLength..................... 88 5.5.2 UsingaSlidingWindowwithVariableLength.................. 89 5.6 AnalysisofLocalConcentrationModel................................. 89 5.7 ExperimentalValidation................................................. 90 5.7.1 SelectionofaProperTendencyThreshold...................... 91 5.7.2 SelectionofProperFeatureDimensionality..................... 91 5.7.3 SelectionofaProperSlidingWindowSize...................... 92 5.7.4 SelectionofOptimalTermsPercentage......................... 93 5.7.5 ExperimentsoftheModelwithThreeTerm SelectionMethods............................................... 93 5.7.6 ComparisonbetweentheLCModeland CurrentApproaches.............................................. 94 5.7.7 Discussion........................................................ 97 5.8 Summary................................................................. 99 viii ■ Contents 6 Multi-ResolutionConcentration-BasedFeatureConstruction Approach.................................................................. 101 6.1 Introduction............................................................ 101 6.2 StructureofMulti-ResolutionConcentrationModel.................. 102 6.2.1 DetectorSetsConstruction.................................... 103 6.2.2 CalculationofMulti-ResolutionConcentrations.............. 103 6.3 Multi-ResolutionConcentration-BasedFeatureConstruction Approach............................................................... 103 6.4 WeightedMulti-ResolutionConcentration-BasedFeature ConstructionApproach................................................ 105 6.5 ExperimentalValidation................................................ 106 6.5.1 InvestigationofParameters..................................... 107 6.5.2 ComparisonwiththePrevalentApproaches................... 108 6.5.3 PerformancewithOtherClassificationMethods.............. 111 6.6 Summary............................................................... 111 7 AdaptiveConcentrationSelectionModel................................ 115 7.1 OverviewofAdaptiveConcentrationSelectionModel................ 115 7.2 SetupofGeneLibraries................................................ 116 7.3 ConstructionofFeatureVectorsBasedon ImmuneConcentration................................................ 116 7.4 ImplementationofAdaptiveConcentrationSelectionModel......... 118 7.5 ExperimentalValidation................................................ 119 7.5.1 ExperimentalSetup............................................. 119 7.5.2 ParameterSelection............................................. 120 7.5.3 ExperimentsofProposedModel............................... 122 7.5.4 Discussion...................................................... 123 7.6 Summary............................................................... 124 8 VariableLengthConcentration-BasedFeature ConstructionMethod..................................................... 125 8.1 Introduction............................................................ 125 8.2 StructureofVariableLengthConcentrationModel................... 126 8.2.1 ConstructionofVariableLengthFeatureVectors.............. 126 8.2.2 RecurrentNeuralNetworks.................................... 127 8.3 ExperimentalParametersandSetup.................................... 129 8.3.1 ProportionofTermsSelection.................................. 129 8.3.2 DimensionofFeatureVectors.................................. 129 8.3.3 SelectionofSizeofSlidingWindow........................... 129 8.3.4 ParametersofRNN............................................ 130 8.4 ExperimentalResultsontheVLCApproach.......................... 131 8.5 Discussion.............................................................. 133 8.6 Summary............................................................... 134
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