Signing and Verifying Example

Signed agent used as an example for AgentCard signing and verifying.

Read more about signing and verifying AgentCards here: Agent Card Signing.

Getting started

1. Start the server

   uv run .
   

2. Run the test client

   uv run test_client.py
   

Build Container Image

Agent can also be built using a container file.

1. Navigate to the directory samples/python/agents/signing_and_verifying directory:

cd samples/python/agents/signing_and_verifying

2. Build the container file

   podman build . -t signing_and_verifying-a2a-server
   

[!Tip]
Podman is a drop-in replacement for docker which can also be used in these commands.

3. Run your container

   podman run -p 9999:9999 signing_and_verifying-a2a-server
   

Validate

To validate in a separate terminal, run the A2A client:

cd samples/python/hosts/cli
uv run . --agent http://localhost:9999

Disclaimer

Important: The sample code provided is for demonstration purposes and illustrates the mechanics of the Agent-to-Agent (A2A) protocol. When building production applications, it is critical to treat any agent operating outside of your direct control as a potentially untrusted entity.

All data received from an external agent—including but not limited to its AgentCard, messages, artifacts, and task statuses—should be handled as untrusted input. For example, a malicious agent could provide an AgentCard containing crafted data in its fields (e.g., description, name, skills.description). If this data is used without sanitization to construct prompts for a Large Language Model (LLM), it could expose your application to prompt injection attacks. Failure to properly validate and sanitize this data before use can introduce security vulnerabilities into your application.

Developers are responsible for implementing appropriate security measures, such as input validation and secure handling of credentials to protect their systems and users.