CT: Certificate Transparency logs log creation and revocation events.

The Google/trillian database which supports Google's CT logs uses Merkle trees but stores the records in a centralized data store - meaning there's at least one SPOF Single Point of Failure - which one party has root on and sole backup privileges for.

Keybase, for example, stores their root keys - at least - in a distributed, redundantly-backed-up blockchain that nobody has root on; and key creation and revocation events are publicly logged similarly to now-called "CT logs".

You can link your Keybase identity with your other online identities by proving control by posting a cryptographic proof; thus adding an edge to a WoT Web of Trust.

While you can add DNS record types like CERT, OPENPGPKEY, SSHFP, CAA, RRSIG, NSEC3; DNSSEC and DoH/DoT/DoQ cannot be considered to be universally deployed across all TLDs. Should/do e.g. ACME DNS challenges fail when a TLD doesn't support DNSSEC, or hasn't secured root nameservers to a sufficient baseline, or? DNS is not a trustless system.

EDNS (Ethereum DNS) is a trustless system. Reading EDNS records does not cost EDNS clients any gas/particles/opcodes/ops/money.

Blockcerts is designed to issue any sort of credential, and allow for signing of any RDF graph like JSON-LD.

List_of_DNS_record_types:
https://en.wikipedia.org/wiki/List_of_DNS_record_types

Blockcerts: https://www.blockcerts.org/ https://github.com/blockchain-certificates :

> Blockcerts is an open standard for creating, issuing, viewing, and verifying blockchain-based certificates

W3C VC-DATA-MODEL: https://w3c.github.io/vc-data-model/ :

> Credentials are a part of our daily lives; driver's licenses are used to assert that we are capable of operating a motor vehicle, university degrees can be used to assert our level of education, and government-issued passports enable us to travel between countries. This specification provides a mechanism to express these sorts of credentials on the Web in a way that is cryptographically secure, privacy respecting, and machine-verifiable

W3C VC-DATA-INTEGRITY: "Verifiable Credential Data Integrity 1.0"
https://w3c.github.io/vc-data-integrity/#introduction :

> This specification describes mechanisms for ensuring the authenticity and integrity of Verifiable Credentials and similar types of constrained digital documents using cryptography, especially through the use of digital signatures and related mathematical proofs. Cryptographic proofs enable functionality that is useful to implementors of distributed systems. For example, proofs can be used to: Make statements that can be shared without loss of trust,

W3C TR DID (Decentralized Identifiers) https://www.w3.org/TR/did-core/ :

> Decentralized identifiers (DIDs) are a new type of identifier that enables verifiable, decentralized digital identity. A DID refers to any subject (e.g., a person, organization, thing, data model, abstract entity, etc.) as determined by the controller of the DID. In contrast to typical, federated identifiers, DIDs have been designed so that they may be decoupled from centralized registries, identity providers, and certificate authorities. Specifically, while other parties might be used to help enable the discovery of information related to a DID, the design enables the controller of a DID to prove control over it without requiring permission from any other party. DIDs are URIs that associate a DID subject with a DID document allowing trustable interactions associated with that subject.

> Each DID document can express cryptographic material, verification methods, or services, which provide a set of mechanisms enabling a DID controller to prove control of the DID. Services enable trusted interactions associated with the DID subject. A DID might provide the means to return the DID subject itself, if the DID subject is an information resource such as a data model.