Verify signed Agent Cards

You can verify that a signed Agent Card has a valid cryptographic signature and matches the expected signer identity.

Before you begin

  • You have installed rh-sigstore-a2a.
  • You have a signed Agent Card JSON file.
  • You know the expected signer’s identity and OIDC issuer.

Procedure

  1. Verify the signed Agent Card: 
    $ rh-sigstore-a2a verify <signed_card_file> \
  --identity <identity> \
  --identity_provider <provider_url>

    where:

    <signed_card_file>
    Your signed Agent Card JSON file
    <identity>
    Expected signer identity (email or URI)
    <provider_url>

    OIDC provider URL

    Verification checks that the cryptographic signature is valid, that the signing certificate was issued by a trusted certificate authority, that the signature is displayed in the transparency log, and that the signer’s identity matches your expectations.

    On success, the tool prints the verified Agent Card details (name, version, URL, provider) and exits with code 0. On failure, the tool prints error details and exits with a non-zero code.

  2. Optional: Use verbose output to see certificate details and identity claims: 
    $ rh-sigstore-a2a --verbose verify <signed_card_file> \
  --identity <identity> \
  --identity_provider <provider_url>

    where:

    <signed_card_file>
    Your signed Agent Card JSON file
    <identity>
    Expected signer identity (email or URI)
    <provider_url>

    OIDC provider URL

    Verbose output includes:

    • Agent Card name, version, and URL
    • Signing identity claims (issuer, subject, email or URI)
    • GitHub-specific metadata (repository, workflow name, commit SHA, trigger event, workflow ref)
    • Certificate validity period (not valid before/after)
    • Certificate subject