This knowledge base article describes why encrypted text files cannot be previewed on a Mac that is using application based encryption mode.
The following sections are covered:
Applies to the following Sophos products and versions Sophos SafeGuard File Encryption for Mac 8.1Sophos SafeGuard File Encryption for Mac 8.2
The behaviour is expected.
The Finder process reads the text file, and since Finder is not an in-application, the content is not decrypted while it is being read. A general rule is that preview works if Finder starts a separate process to read the file content, which is most likely the case for more complex files like Office files.
Finder is a predefined out-application and cannot be configured as an in-application. For an application based encryption, access to encrypted files is restricted to selected processes like Office applications. Because the Finder implements so many different operations on the file (preview, copy, share, Finder extensions,...), and it is not possible to distinguish the operation on the file system level, access to the encrypted files is therefore not allowed for the whole process.
This also ensures that encrypted files which have been copied using Finder keep their encryption state. To prevent any unwanted and untested side effects, Finder is a predefined out-application and cannot be configured as an in-application. This is the same on Windows for the Explorer process.
Sign up to the Sophos Support SMS Notification Service to get the latest product release information and critical issues.
If you've spotted an error or would like to provide feedback on this article, please use the section below to rate and comment on the article. This is invaluable for us to ensure that we continually strive to give our customers the best information possible.
Every comment submitted here is read (by a human) but we do not reply to specific technical questions. For technical support post a question to the community. Or click here for new feature/product improvements. Alternatively for paid/licensed products open a support ticket.