Re: [PROPOSED WORK ITEM] Cryptographic Event Log

I fully support this work item. I think a general purpose hashed event log
would be very useful (and I hope the group takes as input the format and
lessons learned while developing the did:webvh method event log, and
similar prior art).


On Sun, Jul 13, 2025 at 10:19 AM Manu Sporny <msporny@digitalbazaar.com>
wrote:

> This is a proposal for a new CCG work item; the cryptographic event log.
>
> The Cryptographic Event Log specification defines a data model for an
> author to express changes to data, such as a DID Document, over time
> and the means for a verifier to cryptographically verify those
> changes. This data model helps you create decentralized,
> mini-blockchains for data without the need for a big/expensive
> consensus network. It is a useful technology tool for building DID
> Methods, social media feeds, content provenance logs, and other data
> objects that change over time, and where you need to be able to prove
> when and how they changed over time.
>
> ## Link to Draft
>
> https://digitalbazaar.github.io/cel-spec/
>
> ## Owners
>
> Manu Sporny (@msporny), Markus Sabadello (@peacekeeper)
>
> ## Work Item Questions
>
> > Please note if this work item supports the Silicon Valley Innovation
> program or another government or private sector project.
>
> It is meant to support the "decentralized DID Method" class of DID
> Methods, as an input document, in the upcoming DID Methods WG Charter
> at W3C. It would be better for it to serve as an input document by
> being a CCG work item.
>
> > 1. Explain what you are trying to do using no jargon or acronyms.
>
> We are trying to define the most minimal data model for an author to
> express changes to data over time and the means for a verifier to
> cryptographically verify those changes. You can think of it as a
> mini-blockchain data structure that is useful for things like DID
> Documents, Social Media conversations, and changes to creative works
> (books, photos, videos) over time.
>
> > 2. How is it done today, and what are the limits of the current practice?
>
> Today, there is no standardized data structure for a cryptographic
> event log. Instead, entire systems are usually developed (Bitcoin,
> Ethereum, etc.) and then standardization is attempted on them (with
> limited success). The limitations of the current practice is that
> these systems become an "all or nothing" endeavor -- either you trust
> the network, and it's data, or you don't -- either you store all
> objects/references in this network, or you don't. Cryptographic event
> logs today are often tightly coupled to their consensus networks.
>
> > 3. What is new in your approach and why do you think it will be
> successful?
>
> By separating the cryptographic event log data structure from the
> cryptographic proof or consensus network, you can have data that is
> protected through diverse proof systems or consensus networks where
> one can distrust some of the proof systems/networks while trusting
> alternate sets. Ultimately, people can philosophically agree to
> disagree on all but one of the proof systems in the cryptographic
> event log and still trust that the log is legitimate. Buying into the
> changes on a piece of data is no longer and all-or-nothing decision.
>
> > 4. How are you involving participants from multiple skill sets and
> global locations in this work item? (Skill sets: technical, design,
> product, marketing, anthropological, and UX. Global locations: the
> Americas, APAC, Europe, Middle East.)
>
> The work is highly technical and so input from product, marketing,
> anthropological, and UX doesn't make sense at this moment as those are
> more focused at the application layer (in a specification that would
> use this specification). We are performing the work in the CCG, which
> is global and diverse in perspective, including people from around the
> world, multiple decentralized projects, and multiple philosophical
> positions.
>
> > 5. What actions are you taking to make this work item accessible to a
> non-technical audience?
>
> We are attempting to include examples in the specification that show
> how the technology would work for DIDs, social media messages, and
> other things of that nature. We are also using AI to try to convey the
> concepts in the specification to a more general audience through the
> mapping of technical concepts to general concepts that are more
> familiar to people such as using social media, or figuring out if they
> should trust if a set of historical events happened in the order that
> they are being presented.
>
> If you would like to support this work, please express your support in
> this email thread, or go to the following location and provide your
> support via a comment on this Github issue:
>
> https://github.com/w3c-ccg/community/issues/252
>
> -- manu
>
> --
> Manu Sporny - https://www.linkedin.com/in/manusporny/
> Founder/CEO - Digital Bazaar, Inc.
> https://www.digitalbazaar.com/
>
>