Scenario: All Azure Functions must centralize management and distribution of configuration data for different environments and geographies, encrypted by using a company-provided RSA-HSM key.
Microsoft Azure Key Vault is a cloud-hosted management service that allows users to encrypt keys and small secrets by using keys that are protected by hardware security modules (HSMs).
You need to create a managed identity for your application.
Reference:
https://docs.microsoft.com/en-us/azure/app-service/app-service-key-vault-references