  OAuth 2.0 is a popular authorization framework that allows third-party
clients such as websites and mobile apps to request limited access to a user's
account on another application. The specification classifies clients into
different types based on their ability to keep client credentials confidential.
It also describes different grant types for obtaining access to the protected
resources, with the authorization code and implicit grants being the most
commonly used. Each client type and associated grant type have their unique
security and usability considerations. In this paper, we propose a new approach
for OAuth ecosystem that combines different client and grant types into a
unified singular protocol flow for OAuth (USPFO), which can be used by both
confidential and public clients. This approach aims to reduce the
vulnerabilities associated with implementing and configuring different client
types and grant types. Additionally, it provides built-in protections against
known OAuth 2.0 vulnerabilities such as client impersonation, token (or code)
thefts and replay attacks through integrity, authenticity, and audience
binding. The proposed USPFO is largely compatible with existing Internet
Engineering Task Force (IETF) Proposed Standard Request for Comments (RFCs),
OAuth 2.0 extensions and active internet drafts.
