Aithos Agent Card Registry

A public, verifiable registry that hosts A2A Agent Cards and lets their owners edit them. Anyone can publish a card; the card is signed by its owner's key; only a holder of an authorized key can change it.

There are no accounts, no passwords and no sessions. The key is the account.

Aithos can also certify ownership of domains on an Agent Card, proved by a record in each domain's own DNS zone.

📖 Documentation — SPEC.md holds the normative rules.

Quickstart with the CLI

brew install aithos-protocol/tap/aithos

aithos key new              # generates your key. Its thumbprint — a 43-character
                            # string, call it <kid> below — is your entry's
                            # permanent address, known before anything is published.

aithos card init            # writes agent-card.json, already valid
$EDITOR agent-card.json     # name, description, endpoints — say what your agent is
aithos publish agent-card.json --key <kid>

aithos whatis <kid>         # read the entry back: status, lineage, who may change it
aithos verify <kid>         # is the served card intact, and which key signed it?

$EDITOR agent-card.json     # edit the card…
aithos publish agent-card.json --key <kid> --bump patch    # …and publish the new version

Then, to certify the domains that entry owns:

aithos certify <kid> --key <kid> --domains acme.com,acme.fr

--domains names the complete set. When a zone has no record yet, the command prints the line to paste into it and sends nothing. DOMAIN-CERTIFICATION.md has the rules.

Commands

Command	What it does
aithos key new	Generate a key. Its thumbprint is the address of any entry it creates, so you know the address before publishing anything.
aithos key ls	List the keys on this machine.
aithos card init	Write a minimal card that already satisfies the strict A2A profile.
aithos card check <file>	Validate a card locally, without publishing it.
aithos publish <file> --key <kid>	Sign a card and publish it. --bump major|minor|patch raises the version; --offline signs without contacting anything; --key repeats to authorize several keys.
aithos certify <kid> --key <kid> --domains <list>	Certify domains: each zone declares the agent, and a key holder signs the request.
aithos whatis <kid>	Look up what the registry holds at an address, the way whois does.
aithos verify <kid|url|file>	Check a published card, or any signed A2A card, against its signatures.
aithos withdraw <kid> --key <kid>	Withdraw an entry. Permanent, and the identifier is never reusable.

There is no rotate command: rotation is the choice of which keys sign. Co-sign one version with the old key and the new one to widen the authorized set, then sign with the survivors alone to narrow it.

Keys live in ~/.config/aithos/keys, mode 0600, encrypted at rest as a JWE (PBES2-HS256+A128KW with A256GCM) unless --no-passphrase says otherwise.

Other ways to install

cargo install aithos                      # from crates.io

# prebuilt, with a provenance attestation — the checkable way in:
gh release download --repo aithos-protocol/registry --pattern '*apple-darwin*'
gh attestation verify aithos-*.tar.gz --repo aithos-protocol/registry

Homebrew is the convenient way in, not the checkable one: the formula is four URLs and four checksums. What proves a binary that will hold your signing keys is gh attestation verify.

The tool talks to https://registry.aithos.world by default; --registry (or AITHOS_REGISTRY) points it anywhere else, registry-dev.aithos.world included. Register a second key before you need it — publish one version signed by both (--key repeats) and either can act alone from then on; there is no operator to restore access to a lost key.