Does anyone know where I can find details about the patent concerning the compression logic for Roshal archives?

RAR archives are somewhat common nowadays and I would like to read up on the exact legal patent that cover their format. A patent number would be helpful, to that end.

If there are multiple patents covering that format, then the latter the patent is, the better.

A link to an official web source that covers it would be even better.


  • You can go to google patents or The Lens or Free Patents on Line or Espacenet or PatentScope or even the USPTO patent search portal and type in some keywords.
    – George White
    Nov 12 '21 at 6:11
  • Please understand that later patents are likely narrower than earlier patents so you shouldn’t just focus on them.
    – Eric S
    Nov 12 '21 at 16:29

Wikipedia has an article on the RAR file format. I did a patent search for patents with Eugene Roshal and just Roshal listed as the inventor and found none. The file format was developed in 1993 so one would assume that even if there were patents they would be likely expired by now. The Wikipedia article states there is copyright protection on the software and libraries. Copyright protection is off topic for this site.

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