sorry for the late answer. I had in between contact with the Adobe engineers.
To answer the questions first:
- Yes, the fonts were encrypted. InDesign does this by default. You can't embed fonts with InDesign that are not encrypted, mangled and not substituted (CS5.5 uses the Adobe mangling algorithm, CS6 uses the mangling algorithm of the IDPF).
- The fonts were in TTF, OTF format. SVG fonts aren't supported by InDesign.
- And yes, the "com.apple.ibooks.display-options.xml" includes the specified-fonts to true.
However, deleting the encryption.xml was not bringing a new result, except that now all other reader apps do not show the fonts anymore (what happens deleting this file, but was a nice try).
The Adobe engineers told the following:
So we do mangle, but additionally we also encrypt the fonts (which is why there is an encryption.xml file running around there).
Mangling is not the same of encryption but I could see there could be some confusion here.
Thats also the reason why ePub Check 3.05b shows a Warning Message, on fonts embedded with InDesign. Example:
WARNING: resource OEBPS/font/DINPro-Light.OTF cannot be decrypted
The font encryption (not the mangling) used by Adobe is not compatible with iBooks neither with ePub Check.
My personal opinion is that both Adobe and Apple should work better together for ePub. Somehow, Apple does not (want to) support the Adobe encryption. Adobe does not respect the standards of the IDPF completely using their own encryption.
But who has the force to order this?