The Agent2Agent (A2A) protocol moves tasks between agents, and its Signed Agent Card lets a client check that a domain owner issued a card. The card does not bound the authority a delegating agent passes on, establish what code a peer runs, keep a task payload from the peer's host, or leave an offline record of who delegated what to whom. This technical report describes cA2A (Confidential A2A), a trust profile layered on A2A rather than a new transport. It composes four mechanisms: signed delegation credentials whose scope can only narrow at each hop, appraisal of a peer's attestation evidence before a task is sent, a payload sealed to the channel key that evidence vouches for, and a signed per-hop provenance record linked to its parent. Attenuated delegation and provenance binding are covered by prior capability-token work and IETF drafts; the contribution here is their composition on A2A with an open implementation. We state six properties and report software experiments rerun against ca2a 0.3.1: attenuation checks over 5,400 generated chains, rejection of in-chain replay and cross-chain splicing, intersection of delegated scope with local policy, sealed-payload behavior at the cryptographic layer, structural checks on linked provenance records, and a cross-operator attestation protocol exercised with synthetic evidence. Chain verification cost about 0.22 ms per hop in this environment. These results do not show that a peer's key is confined to attested code or that attestation works across independent operators. Recorded hardware runs cover one-directional appraisal of an Intel TDX peer by an AMD SEV-SNP peer in another cloud and a same-operator mutual SEV-SNP diagnostic; mutual attestation between independent operators has not been demonstrated.
A trust profile on A2A composing narrowing delegation credentials, peer attestation appraisal, sealed payloads and linked per-hop provenance records.
The source package preserves the recorded inputs and results. The software experiments were rerun against ca2a 0.3.1 for this edition; no hardware run was repeated. No independent replication is claimed.
@@ -82,6 +83,7 @@The Agent2Agent (A2A) protocol moves tasks between agents, and its Signed Agent Card lets a client check that a domain owner issued a card. The card does not bound the authority a delegating agent passes on, establish what code a peer runs, keep a task payload from the peer's host, or leave an offline record of who delegated what to whom. This technical report describes cA2A (Confidential A2A), a trust profile layered on A2A rather than a new transport. It composes four mechanisms: signed delegation credentials whose scope can only narrow at each hop, appraisal of a peer's attestation evidence before a task is sent, a payload sealed to the channel key that evidence vouches for, and a signed per-hop provenance record linked to its parent. Attenuated delegation and provenance binding are covered by prior capability-token work and IETF drafts; the contribution here is their composition on A2A with an open implementation. We state six properties and report software experiments rerun against ca2a 0.3.1: attenuation checks over 5,400 generated chains, rejection of in-chain replay and cross-chain splicing, intersection of delegated scope with local policy, sealed-payload behavior at the cryptographic layer, structural checks on linked provenance records, and a cross-operator attestation protocol exercised with synthetic evidence. Chain verification cost about 0.22 ms per hop in this environment. These results do not show that a peer's key is confined to attested code or that attestation works across independent operators. Recorded hardware runs cover one-directional appraisal of an Intel TDX peer by an AMD SEV-SNP peer in another cloud and a same-operator mutual SEV-SNP diagnostic; mutual attestation between independent operators has not been demonstrated.
A trust profile on A2A composing narrowing delegation credentials, peer attestation appraisal, sealed payloads and linked per-hop provenance records.
The source package preserves the recorded inputs and results. The software experiments were rerun against ca2a 0.3.1 for this edition; no hardware run was repeated. No independent replication is claimed.
@@ -82,6 +83,7 @@