Abstract: An authentication system and method may use a generative AI (Gen AI) engine to automatically select one of multiple user electronic devices and which authentication method to use to authenticate a user and authorize an electronic transaction. The transaction may be an international transaction between a user and a third party that may be performed online. The system and method may leverage Gen AI-based Retrieval-augmented Fine-Tuning Authentication (RAFTA) technology to generate a personalized user pathway to authentication. A RAFTA Gen AI engine may use a combination of a retrieval-augmented based model with fine-tuning to optimize authentication processes and enhance security. The retrieval augmentation may include retrieval of transaction histories, security protocols, and user interaction patterns.