From ch...@hexforge.co.uk on November 08, 2012 18:26:33

PROBLEM: If fonts are obfuscated using the IDPF method, a warning appears during validation:

Epubcheck Version 3.0-RC-1

Validating against EPUB version 2.0
WARNING: ../encrypted_sample.epub: resource OEBPS/Fonts/Avenir-Roman.otf cannot be decrypted

Check finished with warnings or errors METHOD: 1. Create an epub containing at least one IDPF-obfuscated font, with the appropriate META-INF/encryption.xml file
2. Validate with 3.0RC1 or 3.0b5, and observe the warning above.
3. Validate with 3.0b4, and no warning appears RESULT: An unexpected warning occurs EXPECTED: I expected the epub to validate without warnings. PLATFORM: The incorrect warning appears in 3.0b5 and 3.0RC1. It works correctly in 3.0b4.
Running on MacOS 10.7.5 ADDITIONAL INFO: I downloaded the source for RC1 and stepped through the encryption validation. It appears that com.adobe.epubcheck.ocf.EncryptionHandler constructs IDPFFontManglingFilter with a null parameter. This causes the filter to always return False from canDecrypt, resulting in the warning.

The attached example epub demonstrates the problem - it validates cleanly with 3.0b4, but fails with the decryption warning in 3.0b5 and 3.0RC1. For licensing reasons, the OTF file included is not a real font, but since epubcheck doesn't actually examine the font data, I believe it's valid for the purposes of reproducing the issue.

Attachment: encrypted_sample.epub

Original issue: http://code.google.com/p/epubcheck/issues/detail?id=220