- From: Manu Sporny <msporny@digitalbazaar.com>
- Date: Tue, 17 Sep 2024 10:11:41 -0400
- To: Will Abramson <will@legreq.com>
- Cc: W3C Credentials CG <public-credentials@w3.org>
On Tue, Sep 17, 2024 at 9:29 AM Will Abramson <will@legreq.com> wrote: > This looks like great work. Thanks Will, much appreciated. :) > I only had a quick scan, but I have a question. Are these flows only focused on VC presentation? You can do issuance. Anything that you can do w/ VC API Workflows and Exchanges can (technically) be done over NFC and Bluetooth. >I can't see any use cases or examples that focus on issuance of credentials over NFC at first glance. Is there a reason for this? The examples are just not in there right now because the spec is very draft-y at present. We wanted to get this out there sooner than later to get feedback from the community before doing the next big revision. We know others are working in the space, and we've been working with some of you for a while now. We also want to respect the timeline on which those partners might want to come forward. A few learnings as we've worked on this technology: Most implementations of NFC today are slow. You're lucky if you get 1 KB/s, so what you can do over that connection is limited. That's why the "Non-interactive NFC Presentation" portion of the specification focuses on using CBOR-LD to compress the JSON-LD VCs down to around 400-600 bytes; you need to get that small to get to a "transit card" or "credit card tap"-like experience. https://digitalbazaar.github.io/vc-wireless/#non-interactive-nfc-presentation Now, we have transmitted many multiples of KBs over NFC, and it does work, but the experience isn't great (or, at least, you need to let the individual know that they need to hold their phone over the other NFC device for a couple of seconds). The better route there is Bluetooth. That is why the first NFC message provides protocol upgrades if both sides can do them. If your VC is more than 1KB in size (and most of them are), and you MUST issue over a short range wireless protocol, WiFi Aware, Bluetooth, or LTE tend to be your only options. If you choose Bluetooth (which is broadly available), you can do VCs that are many hundreds of KBs in size with a reasonable UX. That said, what we've found most useful is to just pick up your VC when you're online (e.g., in your web wallet while you're using a web browser -- fast), and then use the NFC presentation portion on your mobile phone (whose web wallet is automatically sync'd to the VCs you just picked up) as you need to use the NFC portion in the physical world. -- manu -- Manu Sporny - https://www.linkedin.com/in/manusporny/ Founder/CEO - Digital Bazaar, Inc. https://www.digitalbazaar.com/
Received on Tuesday, 17 September 2024 14:12:22 UTC