Securing AI agent identity with X.509 PKI on AWS
Learn how to secure multi-agent AI systems with cryptographic identity using Keyfactor EJBCA and AWS services. This reference architecture combines signed request envelopes, user-signed delegation assertions, RFC 8693 audience-scoped tokens, and real-time OCSP revocation to prove agent identity and prevent request forgery across agent-to-agent and MCP tool calls.
When AI agents interact with databases, APIs, and other sensitive systems, it becomes critical to establish cryptographic identity through X.509 public key infrastructure (PKI). The main challenge is proving which agent initiated a request, preventing forgery between agents, and confirming that each agent only acts on behalf of authorized users. Traditional methods like sharing API keys or passing OAuth tokens are insufficient for enterprise environments requiring a zero-trust approach.
Modern multi-agent AI frameworks often utilize the Model Context Protocol (MCP) to connect LLM-powered agents to external tools and data sources. However, MCP has no built-in authentication standard and is transport-agnostic, creating a significant security gap. Without proper identity mechanisms in place, malicious components could impersonate agents, replay intercepted credentials, or invoke unprotected tools.
To address this issue, Keyfactor EJBCA can be integrated with various AWS services. EJBCA is a PKI platform offering high-availability deployment, REST API automation, and Online Certificate Status Protocol (OCSP) validation. The architecture employs four complementary security mechanisms: signed request envelopes for cryptographic proof of possession, user-signed delegation assertions for credential-free authorization, RFC 8693 audience-scoped tokens to limit token exposure, and real-time OCSP revocation checking to immediately propagate credential changes across all agents.
The solution leverages Amazon Bedrock for LLM inference via the AWS Strands Agents SDK. While demonstrated using a database as the protected resource, the authentication pattern applies to any MCP-compatible tool server. All example code is available in the accompanying GitHub repository.
Keyfactor EJBCA is a widely adopted machine identity management platform used by over 1,500 enterprise customers across various industries. Keyfactor provides certificate lifecycle management, PKI operations, and machine identity governance to establish and maintain cryptographic trust.
The partnership between AWS and Keyfactor combines AWS managed services (Amazon Bedrock, AWS Secrets Manager, Amazon RDS) with PKI infrastructure for certificate lifecycle management, automated enrollment, and real-time revocation. This joint reference architecture demonstrates how to integrate these technologies to secure AI agent deployments.
The three authentication layers and their corresponding trust boundaries are outlined in the accompanying figures, illustrating how credentials flow between users, agents, and the MCP tool server.
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