PDF Documents encrypted using the FileOpen software can be opened in a number of viewers other than Adobe Acrobat/Reader. These vendors have incorporated modules from FileOpen that enable the same controls as the ones implemented in the Adobe products. However, FileOpen does not mandate support for all supported features, so there is some inconsistency in the capabilities of different products. Some of these products do not support features that are required by particular publishers, so there may be cases where a PDF will open in Adobe Acrobat/Reader but not in one of the alternative viewers. In this case the only workaround is to use Adobe Acrobat/Reader.
Foxit™ Reader and Foxit Phantom support FileOpen-encrypted PDFs.
Nuance™ PDF Converter Pro and Nuance Reader support FileOpen-encrypted PDFs.
Nitro™ PDF Reader and Nitro Pro support FileOpen-encrypted PDFs.
Tracker™ PDF-XChange Editor supports FileOpen-encrypted PDF files.
Bluebeam™ PDF Revu supports FileOpen-encrypted PDF files.