key auth implementation

Hello! I need help implementing key authentication for my program. I'm looking for an experienced programmer who can get the job done quickly and precisely. The desired programming language/framework for this project is Java. Additionally, API integration will be necessary for completion, as I am looking for an authentication system for multiple users. If you think you have what it takes to make this key authentication implementation a reality, then please reach out and let's get started. Thanks for your time!