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Re: Requirements for PDF as container for VC's

From: Leonard Rosenthol <lrosenth@adobe.com>
Date: Sun, 8 Nov 2020 15:07:16 +0000
To: Bill Claxton <williamc@itr8.com>, "public-credentials@w3.org" <public-credentials@w3.org>
Message-ID: <51EE0FAD-5C81-46BF-931D-839DCED2D711@adobe.com>
Bill, thanks for sharing.  I read your evaluation link and there is a lot of good stuff there.   However, I am surprised that your concerns about PDF are around layout and rendering – since in that case, PDF is a better solution since the layout is defined by the issuer and the renderer simply follows the rules of ISO 32000.  So there is never a question about the rendering not matching what the issuer desires.

However, I think you have an item later on that is more relevant and we should consider the importance of:
> How do you assure that what’s in the layout matches the JSON data?

Although I would change that to not be the layout (since the layout, or what I would call presentation) but instead be the data presented.

Leonard

From: Bill Claxton <williamc@itr8.com>
Date: Sunday, November 8, 2020 at 8:35 AM
To: "public-credentials@w3.org" <public-credentials@w3.org>
Subject: Re: Requirements for PDF as container for VC's
Resent-From: <public-credentials@w3.org>
Resent-Date: Sunday, November 8, 2020 at 8:32 AM

Kostas, hi -

We spoke recently about this and I'm following the thread to see what the community thinks.  Happy that you're getting lots of input.

I thought you may want to review my recent article "Evaluating Decentralised Identity Projects<https://nam04.safelinks.protection.outlook.com/?url=https%3A%2F%2Fwmclaxton.medium.com%2F&data=04%7C01%7Clrosenth%40adobe.com%7C8b191c01f36c46a0247108d883eb1dab%7Cfa7b1b5a7b34438794aed2c178decee1%7C0%7C1%7C637404393127925177%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000&sdata=JhI7Zxcn924hZ8imOQmWM1pzKvA5mmaADJxwJ5TDy8A%3D&reserved=0>".  It's a sort of reviewer's guide for decentralised identity apps.  In particular, I would draw your attention to the point: "Have you separated layout from the rendering application, so that 3rd-parties (including verifiers) can render your certs?"  I intend to write a follow up about presentation layer and mention PDF encapsulation as an alternative, but one I am not much in favor of, for the reasons we discussed.

PS - For anyone else reading this thread, I was a PDF evangelist back in the early days of v4 and v5.  I am familiar with the encapsulation methods and indeed used them for a National Archives project in Singapore.
Regards, Bill Claxton (williamc@itr8.com<mailto:williamc@itr8.com>)
Facebook, Skype, MSN, Yahoo, Twitter, Flickr or Gmail: wmclaxton
Voice, Text or Whatsapp: +65-9012-4327
On 11/8/2020 5:17 PM, Kostas Karasavvas wrote:
Hi Leonard,

Thanks for initiating this. I have been thinking of this as well.

On Sun, Nov 8, 2020 at 3:23 AM Leonard Rosenthol <lrosenth@adobe.com<mailto:lrosenth@adobe.com>> wrote:
Kicking off some discussions here – I’d like to start by putting down what I think are some “primary” requirements for the use of PDF in this context.  Am I missing anything?  Do you disagree with any of these?   Feedback welcome!!

## Requirements

- Shall store the VC in native JSON-LD (w/optional compression)
- VC should be in an easily accessible location (for both reading & writing)

Agree. And JSON-LD is what we intend to use. There could also be a 'serialization/type' option to specify the serialization to accommodate other use cases (XML? CBOR-LD?), if need be.

- Should require no language changes to PDF (except "metadata"-like values)
    - implies compatibility with both PDF 1.7 and 2.0

Agree. I assume that PDF 1.7 implies compatibility with older versions as well?

- Shall be usable in conjunction with standard PDF Signing/Certification

Makes sense. I have questions here wrt the PDF spec and how signing is happening (the 'hole' in the file approach) but these are for later.

Regards,
Kostas



Leonard


--
Konstantinos A. Karasavvas
Software Architect, Blockchain Engineer, Researcher, Educator
https://twitter.com/kkarasavvas<https://nam04.safelinks.protection.outlook.com/?url=https%3A%2F%2Ftwitter.com%2Fkkarasavvas&data=04%7C01%7Clrosenth%40adobe.com%7C8b191c01f36c46a0247108d883eb1dab%7Cfa7b1b5a7b34438794aed2c178decee1%7C0%7C1%7C637404393127935172%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000&sdata=osHV0RiHUGkEebCgZia1URKwp6I%2FntL0IdN0EgeWQMk%3D&reserved=0>


Received on Sunday, 8 November 2020 15:07:32 UTC

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