OpeningFiles, File Structures, and File FormatsFile ExtensionsChanging a File’s Extension to Evade DetectionFiles and the HEX EditorFile SignatureASCII is not Text or HEXValue of File SignaturesComplex Files: Compound, Compressed, and Encrypted FilesWhy do Compound Files Exist?Compressed FilesForensics and Encrypted FilesThe Structure of CiphersSummaryNotesAppendix 4A: Common File ExtensionsAppendix 4B: File Signature DatabaseAppendix 4C: Magic Number DefinitionAppendix 4D: Compound Document Header