Crash when reading Adobe-obfuscated font when publication identifier is empty

[olivierkorner]

The Adobe font obfuscation algorithm key is built using the publication identifier.

If it is empty, or just urn:uuid:, the deobfuscation will crash with a "Division by zero" error because the key is empty:
https://github.com/readium/r2-streamer-swift/blob/4067b31f7e88306d66bcef253b5fb538b7b0be68/r2-streamer-swift/Parser/EPUB/Resource%20Transformers/EPUBDeobfuscator.swift#L69

If the key is empty, the deobfuscator should just return the data with transformation.

I have an EPUB to test the issue that I can send privately but not share here.

[mickael-menu]

Thanks Olivier, could you send me the EPUB on Slack?

The toolkit should not crash in this case, but the font won't be deobfuscated. Is it an error in the publication that the font is declared obfuscated, or that the publication identifier is missing?

(Note to self: GEF2016.epub)

[olivierkorner]

The publication identifier is missing (actually, it is set to urn:uuid:). Note that it looks like the font is not obfuscated in the EPUB.