Hussein Muhaisen introduces Kaitai Struct, a tool for declarative binary parsing, which streamlines the development of parsers for various binary formats. By creating a dummy binary file format called KAISTDE, he demonstrates how to approach reverse engineering with a clear specification. The format includes a 16-byte header with a magic string, version, flags, entry count, and reserved bytes. Each entry contains a type byte, key length, value length, key, and binary value. The type byte is used to identify the kind of data, with examples like PNG and JPG. The article details the structure of the KAISTDE format through a header file, kaistde.h, that defines the in-memory representation of the file. Muhaisen provides the serialization function, kaistde_write, which converts the in-memory structure into a binary file format and writes it to disk. He also includes a main function that builds the KAISTDE file, showcasing how to populate it with entries. The entire project is available on GitHub for further exploration. After building the KAISTDE file, Muhaisen explains how to inspect it using a hex editor, revealing the underlying data structure and confirming its integrity. He emphasizes that reverse engineering often requires a black box approach, where users describe the unknown format while generating a parser simultaneously. The article concludes with a suggestion to write a parser, highlighting the challenges and time investment involved, and hints at using Python for this task.