This release adds:

1. Support for certificate authentication for AAD apps
2. More flexibility around AAD authentication, reducing strong coupling to password-based authentication and laying the foundation to easily support any of the AAD client credential flows down the line.

Details

C# SDK 4.5.3 release enables cert-based authentication of AAD apps. Currently we only support app id + password, but AAD also supports multiple client credential flows, such as using certificates.

This is the small first step towards using AppCredentials for AAD verifications, which currently supports Certs or Password, but as-is can simply be extended to support any of the 7 ADAL client flows.

The default paths still use ICredentialProvider and we are enabling AppCredentials for new scenarios. A second iteration will make AppCredentials be the default, but we want to stage that transition to minimize risk.