Azure Entra ID Certificate Based Authentication

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Prerequisites

• A Microsoft Entra ID application registered in your Azure tenant
• Azure OpenAI or Azure AI Foundry resource deployed
• An X.509 certificate (or OpenSSL to generate one)

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Azure Configuration

1

Get Application Details from Entra ID

Navigate to Azure Portal > Microsoft Entra ID > App registrations and select your application.From the Overview page, note the following values:

• Application (client) ID
• Directory (tenant) ID

2

Prepare a Certificate

You can use an existing certificate or generate a new self-signed certificate.

Generate a new certificate using OpenSSL

# Generate private key and certificate
openssl req -x509 -newkey rsa:2048 \
  -keyout private-key.pem -out certificate.crt \
  -days 365 -nodes \
  -subj "/CN=TrueFoundry-Azure-Integration"

This creates:

• private-key.pem - Keep this secure, you’ll provide it to TrueFoundry
• certificate.crt - Upload this to Azure

If using an existing certificate, ensure you have:

• The private key in PEM format
• The public certificate to upload to Azure

3

Upload Certificate to App Registration

In your app registration, navigate to Certificates & secrets > Certificates > Upload certificate.Upload certificate.crt and note the Thumbprint value displayed after upload.

4

Assign RBAC Role to App Registration

Navigate to your Azure resource > Access control (IAM) > Add role assignment.

• Azure OpenAI
• Azure AI Foundry

Assign Cognitive Services OpenAI User role to your app registration.Learn more about Azure OpenAI RBAC

Assign Azure AI User role to your app registration.Learn more about Azure AI Foundry RBAC

Role assignments may take a few minutes to propagate.

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TrueFoundry Configuration

1

Add Model Account with Certificate Authentication

Navigate to AI Gateway > Models and select your provider (Azure OpenAI or Azure AI Foundry).Click Add Account and select Entra certificate based auth. Fill in the following:

Field	Description
Tenant ID	Directory (tenant) ID from app registration overview
Client ID	Application (client) ID from app registration overview
Certificate	Contents of the private key in PEM format. You can also use a TrueFoundry Secret here.
Certificate Thumbprint	Thumbprint shown after uploading certificate to Azure

For Azure AI Foundry, certificate authentication is configured at the model level, not the account level.

2

Add Models and Test

Add your models as described in the Azure OpenAI or Azure AI Foundry documentation.Test the connection using the Playground to verify authentication works.

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Reference Links

• Register an Entra ID application
• Certificate credentials for application authentication
• Azure OpenAI RBAC
• Azure AI Foundry RBAC