Building an Identity-Aware Proxy with OpenSSL

An Identity-Aware Proxy (IAP) does exactly that—it defends applications by verifying user identity before letting traffic through. When paired with OpenSSL, it adds strong, proven encryption to the identity check, ensuring that both authentication and transport security are uncompromised. This combination is becoming the standard for protecting backend APIs, internal tools, and cloud-hosted workloads.

At its core, an IAP sits between the client and the target service. Every request passes through it. The proxy uses identity data—such as OAuth tokens, mutual TLS certificates, or SSO—before allowing a connection. With OpenSSL, you can implement TLS handshakes, certificate validation, and encrypted tunnels directly inside the proxy layer. This prevents plaintext traffic and stops unauthorized actors even if they reach the proxy endpoint.

Key steps to building an Identity-Aware Proxy with OpenSSL:

1. Certificate Management – Generate and sign certificates using openssl req and openssl ca. Store them securely.
2. Mutual TLS Setup – Configure the proxy to require client certificates. Use OpenSSL’s verification functions to reject invalid or expired certs.
3. Integration with Authentication Providers – Fetch identity claims from OAuth2 or OIDC after the TLS handshake, binding the cryptographic identity to the application-level identity.
4. Policy Enforcement – Apply allow/deny rules in the proxy based on user groups, roles, and device trust, coupled with TLS session data.
5. Logging and Auditing – Capture both authentication events and OpenSSL session details for compliance and forensic analysis.

When done correctly, the proxy never forwards a single byte until it knows exactly who is asking and encrypts every response before sending it back. Deploy it near your services, whether as a standalone reverse proxy or integrated into service mesh ingress. The synergy between OpenSSL’s transport security and IAP’s access control closes two of the biggest attack surfaces: identity spoofing and data interception.

If speed matters, use hardware TLS acceleration with OpenSSL for lower latency. If scale matters, use a horizontally-scalable proxy architecture with centralized certificate distribution. Always update OpenSSL to patch known vulnerabilities, and rotate certificates before expiry to maintain trust.

Strong authentication. Strong encryption. Minimal surface area. That’s the blueprint.

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