Password Based Authentication System

I am looking for a simple Desktop Application or program for a Password-Based Authentication System that requires Basic security. I prefer the programming language to be Python but I'm fine if it is in C++. The ideal candidate for this job should have experience in developing Desktop Applications using Python. There will be some rules on the user name and the password, where the user name should be chosen from this set [a-zA-Z0-9_] and the system should check for swear words, and the password should use the latest NIST password guidelines to set rules for passwords. the passwords should be stored in a shadow file.