Re: Rendering Verifiable Credentials @ RWoT11

Replying a bit late to the party,

Blockcerts has had the visual layer since its inception and we continue to make it one of the main “selling point” of the solution.

At this stage in Blockcerts v3 we do support HTML (with inline CSS), base64 pdf and base64 images (png, jpeg, gif and bmp). With HTML, we do run the code through an XSS sanitizer before rendering to mitigate the risk of attacks. The name of the property is `display` and it is an object with 3 subproperties, `content`, `contentMediaType` and `contentEncoding` (see https://www.blockcerts.org/schema/3.1/context.json).

We have a webcomponent for rendering, but we do expect at this point the HTML to be display ready, meaning that we don’t necessarily check the quality of the HTML in terms of accessibility before rendering and trust the issuer to have done their part. I doubt however the component itself is super a11y compatible, but I have never had it tested for that purpose.

We also have a `metadata` property which allows the issuer to provide more information that does not necessarily need to be part of the display, but is rendered by the webcomponent in a separate section.

I will try to get a budget to attend RWOT and would be happy to work on the question if I do. I think a standardized way of rendering VCs is important for the whole ecosystem.

Best

Julien

From: Leonard Rosenthol <lrosenth@adobe.com>
Date: Tuesday, 19 July 2022 at 14:04
To: Manu Sporny <msporny@digitalbazaar.com>, public-credentials@w3.org <public-credentials@w3.org>
Subject: [EXTERNAL] [jfraichot@learningmachine.com] Re: Rendering Verifiable Credentials @ RWoT11
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SVG (the standard profile) supports JS and CSS, so all the same issues you have with HTML you have with SVG.  There are profiles of SVG that don’t allow JS or CSS, such as SVG Tiny or SVG Basic…

I will note, however, that the IETF tried using a reduced functionality profile for allowing SVG in RFC’s and ran into a lot of issues with lack of tool support…so they ended up having to write their own “SVG cleaner” application…

Leonard

From: Manu Sporny <msporny@digitalbazaar.com>
Date: Monday, July 18, 2022 at 7:48 PM
To: public-credentials@w3.org <public-credentials@w3.org>
Subject: Re: Rendering Verifiable Credentials @ RWoT11
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On 7/18/22 12:27 AM, Bill Claxton, NextID Founder & Operations Director wrote:
> This is why we use HTML and CSS to create responsive layouts and why the
> NextCert Issuer supports uploading of layouts using zip packages.

Bill, feel free to add links to any relevant work here as  PR:

https://nam04.safelinks.protection.outlook.com/?url=https%3A%2F%2Fgithub.com%2FWebOfTrustInfo%2Frwot11-the-hague%2Fblob%2Fmaster%2Fadvance-readings%2Frendering-verifiable-credentials.md&amp;data=05%7C01%7Clrosenth%40adobe.com%7C71063fa04f7f49c182fe08da69180df5%7Cfa7b1b5a7b34438794aed2c178decee1%7C0%7C0%7C637937849283179812%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000%7C%7C%7C&amp;sdata=skFf2H2BaPSVCEIKAb5zBbPv3GMx3DC92%2BHtTPEZfAQ%3D&amp;reserved=0

We had considered HTML/CSS and had backed off a bit given the possibility of
all sorts of tracking/JS injection attacks. That said, it's a natural desire
to use what's already out there and deployed broadly... and there might be
hope in sandboxing components via Web Components:

https://nam04.safelinks.protection.outlook.com/?url=https%3A%2F%2Fdev.to%2Femileperron%2Fweb-components-in-2021-the-good-the-bad-and-the-ugly-3kg&amp;data=05%7C01%7Clrosenth%40adobe.com%7C71063fa04f7f49c182fe08da69180df5%7Cfa7b1b5a7b34438794aed2c178decee1%7C0%7C0%7C637937849283179812%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000%7C%7C%7C&amp;sdata=crjvzxXPzCwVaKZqVX9khecRajkV66v82hz23fZAk04%3D&amp;reserved=0

Has anyone out there tried to use a Web Component as a rendering layer for VCs?

-- manu

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Founder/CEO - Digital Bazaar, Inc.
News: Digital Bazaar Announces New Case Studies (2021)
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