Updates to obfuscation

[mattgarrish]

This PR makes the following changes:

• creates a new "Limitations" section to separate the obfuscation introduction from the discussion of its drawbacks. Also extends the discussion a bit as per Obfuscation #1873
• adds a caution box to rs spec about potential legal ramifications to match the caution in the core spec
• reduces the requirement to deobfuscate to recommendation
• harmonizes spelling of deobfuscation

Addresses #1873

• Reading Systems preview
• Reading Systems diff

---

Preview | Diff

[dauwhe]

I think this is good, in that it identifies the motivations for this as well as the limitations.

[iherman]

We may want to ask Nick to review these changes, to see if this can be good enough to close #1873.

[dauwhe]

@npdoty does this look acceptable to you?

[iherman]

The issue was discussed in a meeting on 2022-02-03

List of resolutions:

• Resolution No. 2: Remove the legal reference from PR 1980, and merge 1980.

View the transcript

2. Updates to Obfuscation.

See github pull request epub-specs#1980.

See github issue epub-specs#1873.

Dave Cramer: this is the PR. There's a lot of discussion in the related issue..
… we've made a bunch of fixes to this.
… npd asked if we could explain harms of font obfuscation techniques, i.e., interop issues, opacity for end users inspecting what they are reading.
… but i've never had to inspect font file of epub i'm reading, so i'm not on board with that.
… could create liability for RS.
… but i'm not aware of legal issues, or threat of legal issues.

Brady Duga: i'm skeptical of even mentioning legal issues without explicit guidance from lawyers.
… even the caution that we're currently proposing, not sure what legal implications we are hinting at with that.
… if I was concerned about legal issues, I would consult my legal team rather than getting it from a spec.

Dave Cramer: i share this concern.

Matt Garrish: yeah, i struggled to come up with a caution that was meaningful.
… there was talk about DMCA.
… there are probably legal issues all over the place, so why pick just one.
… i'm not strongly in favor of this, so I would be okay with removal.
… stuff on content side is a little less controversial.

Dave Cramer: and some of the other limitations are legitimate.
… there can be real interop problems, etc..

Wendy Reid: +1 to general caution.

Brady Duga: i'm fine with the general caution.

Dave Cramer: mgarrish can you just remove the legal reference?.

Matt Garrish: yes.

Brady Duga: one other language issue about "designed to break the obfuscation".
… you're not breaking the obfuscation because its a well defined algorithm.

Wendy Reid: "deobfuscate".

Brady Duga: "intentionally make available"?.

Matt Garrish: agree.
… on the RS side, do we leave it as SHOULD, or should be go back to MUST support deobfuscation?.

Brady Duga: fine with having it as SHOULD support deobfuscation.

Dave Cramer: fine with leaving it at SHOULD, this is not a core feature.

Proposed resolution: Remove the legal reference from PR 1980, and merge 1980. (Wendy Reid)

Shinya Takami (高見真也): +1.

Wendy Reid: +1.

Toshiaki Koike: +1.

Matthew Chan: +1.

Brady Duga: +1.

Masakazu Kitahara: +1.

Dave Cramer: +1.

Resolution #2: Remove the legal reference from PR 1980, and merge 1980.