From Client Secrets to Certificate-Based Authentication: Building a Secure Integration with Azure Key Vault and Azure Functions
Summary Enterprise API integrations require more than simply obtaining an access token. The authentication model must provide a reliable way for an application to establish its identity while protecting the credentials used to do so. In this implementation, we explored a certificate-based authentication architecture using Microsoft Entra ID, an X.509 self-signed certificate, Azure Key Vault, Azure Functions, Managed Identity, and Microsoft Authentication Library (MSAL). The objective was to replace dependency on an expiring client secret with a certificate-backed application identity, while keeping the private certificate protected within Azure infrastructure. This article walks through the complete implementation — from creating the certificate and registering its pu...