ATAR — Agent Trust & Attribution Root

The free, decentralized trust layer for AI agents — the SSL/CA of the agent era. No servers. No blockchain. No cost.

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ATAR gives every AI agent a self-sovereign cryptographic identity (did:agent:) and lets agents vouch for one another with signed, tamper-evident attestations. Think of it as a passport + word-of-mouth trust network for software agents: anyone can verify who an agent is and who vouches for it — offline, for $0.

This is the still-unclaimed top layer of the AI era: transport (MCP/A2A) is solved, but trust & attribution is not. ATAR is the open protocol for it.

Contents

• Why it matters
• Install
• Quickstart
• How it works
• CLI reference
• Visual identity
• Project status
• Honest constraints
• Contributing

Why it matters (the "top layer" thesis)

• Transport is solved. MCP (tools) and A2A (agent-to-agent) are now consolidated under the Linux Foundation. You cannot reinvent HTTP.
• Trust is not. No free, decentralized, serverless "who is this agent and who vouches for it" layer exists in 2026. Central registries reintroduce a server; blockchains cost gas and are empirically hollow (ERC-8004: 59–90% Sybil reviewers).
• ATAR is the gap. Identity + vouching with zero infrastructure. The protocol itself captures no value (a public good, like HTTP) — value accrues to the applications built on top (directories, "Know Your Agent" analytics), exactly as Google built on top of a free HTTP.

Install

ATAR is not yet on PyPI. For now, install from source:

git clone https://github.com/Dominik-8/ATAR.git
cd atar
pip install -e ".[dev]"

PyPI release (pip install atar) coming soon.

Quickstart

# 1. create two agent identities
atar keygen --name alice
atar keygen --name bob

# 2. alice vouches for bob's competence in "coding"
atar vouch --from alice --for "did:agent:..." --score 0.95 --scope coding \
    --out bob-vouch.json

# 3. anyone verifies the vouch offline (no server, no internet)
atar verify bob-vouch.json          # -> VALID

# 4. build an agent card (DID + name + vouches) to present on contact
atar card --name bob --out card.json

# 5. render the Know-Your-Agent dashboard from a local trust graph
atar dashboard --seed "did:agent:..." --scope coding --out dash.html

Real vs demo network. agents.toml holds only real running agents (seed_agent seed + reporting_agent cron). The larger graph in demo.toml is an illustration — those agents are not real processes and are never in the default bootstrap. ATAR's value is a trust layer over real agents; demo nodes exist only to show the shape of a bigger graph.

atar bootstrap --config agents.toml   # real agents only
atar bootstrap --config demo.toml     # demo illustration, not real

How it works

1. Identity — Ed25519 keypair; did:agent: derived from the public key. Self-resolving, offline-verifiable, $0.
2. Vouch — a signed attestation: issuer vouches subject for scope@score. Tamper-evident (any change invalidates the signature).
3. ATC Carrier — vouches encoded as header-safe tokens + an "agent card" JSON, presented inline over HTTP/A2A/MCP. ATAR rides on top of existing transports; it replaces nothing.
4. Transparency graph — vouches are content-addressed (sha256 of their bytes), so they can be gossiped with no operator. Each agent computes transitive trust locally from a seed of trusted roots.
5. Revocation + Freshness + Rotation — trust can be actively killed (revoke), passively expired (TTL), or recovered via key rotation. See SPEC.md §6–§10.

See SPEC.md for the full wire format and algorithms.

CLI reference

Visual identity (ATAR-style)

ATAR has its own dark, corporate look - consistent and standalone.

The canonical tokens live in atar/theme.css — reuse them for any ATAR UI, web page, or digest so the design stays consistent.

Project status

All phases implemented and tested (122 tests, CI green). See SPEC.md for the authoritative protocol specification.

Next: wider real-agent adoption; formal RFC publication (this spec is the draft for it).

Honest constraints

• Sybil resistance is partial. Free, serverless identity means anyone can mint unlimited agents. ATAR provides the mechanism (signed vouches); meaningful reputation emerges from the web-of-trust, not from the protocol. We do not promise Sybil-proofing — that is mathematically incompatible with "free + decentralized + zero-server".
• Bootstrap needs a seed. Adoption is the real risk. We seed ATAR by forcing our own agents (your primary agent) to use it, riding MCP/A2A as carriers rather than competing with them.

Contributing

See CONTRIBUTING.md. Security issues: SECURITY.md.

License

MIT — see LICENSE.