In no particular order, there are a number of blockchain PKI (and DNS (!)) proposals and proofs of concept.
"CertLedger: A New PKI Model with Certificate Transparency Based on Blockchain" (2018) https://arxiv.org/pdf/1806.03914 https://scholar.google.com/scholar?q=related:LF9PMeqNOLsJ:sc...
"TABLE 1: Security comparison of Log Based Approaches to Certificate Management" (p.12) lists a number of criteria for blockchain-based PKI implementations:
- Resilient to split-world/MITM attack
- Provides revocation transparency
- Eliminates client certificate validation process
- Eliminates trusted key management
- Preserves client privacy
- Require external auditing
- Monitoring promptness
... These papers also clarify why a highly-replicated decentralized trustless datastore — such as a blockchain — is advantageous for PKI. WoT is not mentioned.
"Blockchain-based Certificate Transparency and Revocation Transparency" (2018) https://fc18.ifca.ai/bitcoin/papers/bitcoin18-final29.pdf
Who can update and revoke which records in a permissioned blockchain (or a plain old database, for that matter)?
Letsencrypt has a model for proving domain control with ACME; which AFAIU depends upon DNS, too.
TLA references "Certificate Transparency Using Blockchain" (2018)
Running a permissioned blockchain is nontrivial. "Just fork XYZ and call it a day" doesn't quite describe the amount of work involved. There's read latency at scale. There's merging things to maintain vendor strings,
> but its integration with current solutions
- Verify issuee identity
- Update (domain/CN/subjectAltName, date) index
- Update cached cert and CRL bundles
- Propagate changes to all clients
> and avoiding centralized middleware services that will weaken the schema described in the documents.
Eventually, a CDN will look desireable. IPFS may fit the bill, IDK?
You are right. It's needed a relevant BFT protocol, a lot of work with masternodes community and smart economic system inside. You can look at an example of a such protocol:
> Trillian is an implementation of the concepts described in the Verifiable Data Structures white paper, which in turn is an extension and generalisation of the ideas which underpin Certificate Transparency.
> Trillian implements a Merkle tree whose contents are served from a data storage layer, to allow scalability to extremely large trees.