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ODTTF

ODTTF (Obfuscated OpenType) is an embedded font file type used in Microsoft's Open XML Paper Specification (XPS) and Office Open XML formats. The file type refers to an obfuscated subsetted font based on the fonts used in the original document. Its MIME type is . The files can be extracted from the DOCX file by changing the filename extension to , so the archive can be browsed and extracted. The MIME type is Microsoft's own invention and has not been submitted to the IANA registry. According to the source code of Okular (see function parseGUID() and method XpsFile::loadFontByName()), the first 32 bytes of the font file are obfuscated by XOR using the font file name (a GUID). The rest of the file is normal OpenType. The byte order of the GUID representation is reversed from the formatted form as used in the filename and does not coincide with the internal byte order of the representation in the .NET Framework.

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Article summary

ODTTF (Obfuscated OpenType) is an embedded font file type used in Microsoft's Open XML Paper Specification (XPS) and Office Open XML formats. The file type refers to an obfuscated subsetted font based on the fonts used in the original document. Its MIME type is . The files can be extracted from the DOCX file by changing the filename extension to , so the archive can be browsed and extracted. The MIME type is Microsoft's own invention and has not been submitted to the IANA registry. According to the source code of Okular (see function parseGUID() and method XpsFile::loadFontByName()), the first 32 bytes of the font file are obfuscated by XOR using the font file name (a GUID). The rest of the file is normal OpenType. The byte order of the GUID representation is reversed from the formatted form as used in the filename and does not coincide with the internal byte order of the representation in the .NET Framework.

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Discussion questions

  1. Summarise the article in your own words. Which single claim would you verify first, and why?
  2. Which claim in this article is most likely to be revised as the sources update? How would you check its current status?
  3. If two sources disagreed about one of these facts, what would you need in order to trust one over the other?

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Key claims and bibliography are generated from the same tracked claims and sources as the article page.