How does Calibre's handle epubs with encrypted fonts?
Adobe's Epub best practices guide contains encrypted fonts. Only the fonts are encrypted - not the text/images. If I add it to Calibre & click view it opens in the internal reader just fine.
But double clicking on the file (which opens Calibre's reader), or trying to open it directly from Calibre's reader, generates the "This book is protected by DRM." message.