feature: Strict CardSignature Checking

[usize]

Feature Description

Introduce a --require-a2a-signature flag to enforce verification of A2A AgentCard signatures before allowing agent-to-agent communication.

When enabled:

• The gateway controller verifies incoming AgentCards against a set of trusted public keys stored in Kubernetes Secrets (PEM or JWKS).

• If a signature is missing or cannot be verified, the peer connection is blocked.

• Enforcement can be implemented via ingress/egress NetworkPolicies or mesh AuthorizationPolicies.

Goal:

To ensure that only agents with authenticated, signed AgentCards can be discovered or connected to, preventing spoofed or unverified peers.

Proposed Solution

• New --require-a2a-signature CLI flag available on kagenti controller.

• Trusted key material loaded via an A2ACardSignatureProvider which may be kubernetes secrets or a service which implements an veryAgentSignature method -- which takes in a CardSignature and returns verified/unverified.

• Verification performed per A2A spec https://a2a-protocol.org/latest/specification/#556-agentcardsignature-object

• Unverified peers blocked via network or gateway policy.

• Audit mode and metrics for verification results.

Want to contribute?

• I would like to work on this issue.

Additional Context

Related to: rossoctl/rossoctl#303

[usize]

We should add an A2ASignatureVerificationProvider interface so that we can support e.g. a JWKS server, secrets or other ways of vouching that a signature is correct.

https://auth0.com/docs/secure/tokens/json-web-tokens/json-web-key-sets

[kevincogan]

Hi @usize, I’ve implemented something similar in the past and would love to work on this issue. Can I be assigned to this issue/feature?

[kevincogan]

@usize I believe this issue is now complete and ready to be closed. Thanks!

[pdettori]

closing as it is complete - feel free to reopen if there is still a need