Securing the Agents: A2A & MCP with RBAC Access Control

Role-Based Access Control (RBAC) is crucial for agents in an Agent-to-Agent (A2A) as well as MCP based architecture because it ensures that only authorized agents can access or invoke certain resources, methods, or data. In multi-agent systems, especially those interacting with sensitive services like databases, file systems, or user data, unrestricted access can lead to security breaches or misuse. RBAC allows fine-grained control by assigning specific roles (like "reader", "writer", "admin") to agents and mapping those roles to permitted actions. This ensures agents can only perform actions appropriate to their role, enabling secure, scalable collaboration in dynamic environments.

The a2ajava framework implements RBAC by using Java Spring annotations such as @PreAuthorize, which allow developers to declaratively define access control rules for each agent method. It integrates with Spring Security to enforce these rules at runtime. When an agent sends a request, a2ajava validates the agent's identity and roles (using tokens, headers, or context), and ensures the requested operation is permitted for that role. This RBAC enforcement within the A2A protocol layer provides both security and interoperability, allowing safe and trusted interactions between multiple agents in a distributed AI system.

🌐 Live Demo: https://vishalmysore-a2amcpdemo.hf.space/index.html

What I Built 🏗️

I created a security integration layer that enables:

1. Single agent serving both A2A and MCP protocols
2. Role-based access control using Spring Security
3. Dynamic capability exposure based on user roles
4. Unified security context across protocols

How I Built It 🛠️

1. Core Architecture

   • Built on Spring Boot framework
   • Integrated Spring Security for authentication
   • Implemented A2A protocol handlers
   • Added MCP support for AI model interactions

2. Security Implementation
   

   @Agent(groupName = "car booking")
   public class CarBookingAgent {
       @PreAuthorize("hasRole('USER')")
       @Action(description = "Book a car")
       public String bookCar(/*...*/) { /*...*/ }

       @PreAuthorize("hasRole('ADMIN')")
       @Action(description = "Cancel a booking")
       public String cancelCarBooking(/*...*/) { /*...*/ }

       // Public action - no role required
       @Action(description = "Check status")
       public String getBookingStatus(/*...*/) { /*...*/ }
   }

1. Protocol Integration
   • Created protocol-specific adapters
   • Implemented shared authentication handlers
   • Added security context propagation

See It In Action 👀

Here's how it works with our car booking demo:

@Agent(groupName = "car booking")
public class CarBookingAgent {
    @PreAuthorize("hasRole('USER')")
    @Action(description = "Book a car")
    public String bookCar(/*...*/) { /*...*/ }

    @PreAuthorize("hasRole('ADMIN')")
    @Action(description = "Cancel a booking")
    public String cancelCarBooking(/*...*/) { /*...*/ }

    // Public action - no role required
    @Action(description = "Check status")
    public String getBookingStatus(/*...*/) { /*...*/ }
}

Challenges Faced 🎯

1. Protocol Synchronization

   • Challenge: Maintaining consistent security context across A2A and MCP
   • Solution: Implemented a shared security context provider
   • Impact: Seamless security across protocols

2. Authentication Flow

   • Challenge: Different authentication mechanisms for A2A and MCP
   • Solution: Created an abstraction layer for authentication
   • Impact: Unified authentication handling

3. Role-Based Access

   • Challenge: Dynamic capability exposure based on roles
   • Solution: Implemented smart agent card generation
   • Impact: Users see only their allowed actions

4. Client Integration

   • Challenge: Supporting both Python and Java clients
   • Solution: Created protocol-specific adapters
   • Impact: Smooth integration for all clients

Lessons Learned 📚

1. Architecture Insights

   • Spring Security is highly adaptable for custom protocols
   • Protocol-agnostic security design is essential
   • Role-based access control should be decided at design time
   • Caching security context improves performance

2. Best Practices

   • Use annotation-based security consistently
   • Implement security at the protocol level
   • Keep authentication mechanism pluggable
   • Test with different client implementations

3. Integration Lessons

   • Start with clear role definitions
   • Plan for future protocol additions
   • Consider performance implications
   • Document security boundaries clearly

Tips for Others 💡

1. Getting Started

   # Test basic setup with user role
   curl -u user:password https://vishalmysore-a2amcpdemo.hf.space/.well-known/agent.json

   # Check admin capabilities
   curl -u admin:admin https://vishalmysore-a2amcpdemo.hf.space/.well-known/agent.json

1. Implementation Tips

   • Start with clear role definitions
   • Use Spring Security's built-in capabilities
   • Test security context persistence
   • Plan for scalability

2. Common Pitfalls to Avoid

   • Don't mix security contexts between protocols
   • Avoid hardcoding roles in business logic
   • Don't expose sensitive data in public endpoints
   • Remember to test with different client types

Real-World Impact 🌍

This implementation solves several common challenges:

1. Cross-Protocol Security

   • No more duplicate security logic
   • Consistent behavior everywhere
   • Simplified maintenance

2. Role Management

   • Clear capability boundaries
   • Easy to add new roles
   • Granular access control

3. Client Integration

   • Clean API for both protocols
   • Predictable behavior
   • Easy to implement

Try It Yourself! 🛠️

Want to see it in action? Check out the full implementation.

What's Next? 🎯

I'm planning to add:

• OAuth2/JWT support
• Enhanced audit logging
• More granular permissions
• Additional protocol bridges

Looking for Feedback! 💭

I'd love to hear:

1. How do you handle security across different protocols?
2. What features would make this more useful for your use case?
3. Any suggestions for improvements?

Let's discuss in the comments!

A2AJava #MCP #SpringSecurity #AIAgents #SecurityImplementation