File Format Identification

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File Format Identification is the process of figuring out the format of a sequence of bytes. Operating systems typically do this by file extension or by embedded MIME information. Forensic applications need to identify file types by content.



  • Written in C.
  • Rules in /usr/share/file/magic and compiled at runtime.
  • Powers the Unix “file” command, but you can also call the library directly from a C program.

Digital Preservation Efforts

PRONOM is a project of the National Archives of the United Kingdom to develop a registry of file types. A similar project was started by JSTOR and Harvard as the JSTOR/Harvard Object Validation Environment. Attempts are now underway to merge these two efforts in the Global Digital Format Registry and the Universal Digital Format Registry.

The UK National Archives developed the Digital Record Object Identification (DROID) tool, an "automatic file format identification tool." This tool is written in Java and can be downloaded from SourgeForge.



Forensic Innovations File Investigator TOOLS

  • Proprietary, but free trial available.
  • Available as consumer applications and OEM API.
  • Identifies 3,000+ file types, using multiple methods to maintain high accuracy.
  • Extracts metadata for many of the supported file types.

Stellent/Oracle Outside-In

Forensic Assistant

  • Proprietary.
  • Provides detection of password protected archives, some files of cryptographic programs, Pinch/Zeus binary reports, etc.

Data Sets

If you are working in the field of file format identification, please consider reporting the results of your algorithm with one of these publicly available data sets:


Current research papers on the file format identification problem. Most of these papers concern themselves with identifying file format of a few file sectors, rather than an entire file. Please note that this bibliography is in chronological order!

  • Fileprints: identifying file types by n-gram analysis, LiWei-Jen, Wang Ke, Stolfo SJ, Herzog B.., IProceeding of the 2005 IEEE workshop on information assurance, 2005. (Presentation Slides) (PDF)
  • Douglas J. Hickok, Daine Richard Lesniak, Michael C. Rowe, File Type Detection Technology, 2005 Midwest Instruction and Computing Symposium.(PDF)
  • Gregory A. Hall, Sliding Window Measurement for File Type Identification, Computer Forensics and Intrusion Analysis Group, ManTech Security and Mission Assurance, 2006. (PDF)
  • FORSIGS; Forensic Signature Analysis of the Hard Drive for Multimedia File Fingerprints, John Haggerty and Mark Taylor, IFIP TC11 International Information Security Conference, 2006, Sandton, South Africa.
  • Martin Karresand , Nahid Shahmehri, "Oscar -- Using Byte Pairs to Find File Type and Camera Make of Data Fragments," Annual Workshop on Digital Forensics and Incident Analysis, Pontypridd, Wales, UK, pp.85-94, Springer-Verlag, 2006.
  • Robert F. Erbacher and John Mulholland, "Identification and Localization of Data Types within Large-Scale File Systems," Proceedings of the 2nd International Workshop on Systematic Approaches to Digital Forensic Engineering, Seattle, WA, April 2007.
  • Ryan M. Harris, "Using Artificial Neural Networks for Forensic File Type Identification," Master's Thesis, Purdue University, May 2007. (PDF)
  • Predicting the Types of File Fragments, William Calhoun, Drue Coles, DFRWS 2008. (Presentation Slides) (PDF)
  • Roussev, Vassil, and Garfinkel, Simson, "File Classification Fragment-The Case for Specialized Approaches," Systematic Approaches to Digital Forensics Engineering (IEEE/SADFE 2009), Oakland, California. (PDF)
  • Irfan Ahmed, Kyung-suk Lhee, Hyunjung Shin and ManPyo Hong, Fast File-type Identification, Proceedings of the 25th ACM Symposium on Applied Computing (ACM SAC 2010), ACM, Sierre, Switzerland, March 2010.