Privacy-Preserving Credit Card Approval Using Homomorphic SVM: Toward Secure Inference in FinTech Applications
In sensitive financial technology applications—such as credit card approval—the high computational overhead of fully homomorphic encryption (FHE) hinders practical deployment, making it challenging to simultaneously achieve strong privacy guarantees and computational efficiency. Method: This paper proposes the first CKKS-based homomorphic encryption framework for soft-margin support vector machines (SVMs). It innovatively incorporates a hybrid kernel function to model nonlinear credit features in ciphertext space and introduces a ciphertext-domain adaptive thresholding mechanism to enhance classification robustness. Contribution/Results: Evaluated on the Credit Card Approval dataset, the method achieves accuracy comparable to plaintext SVM (within ±0.3%), while reducing inference latency by 42%. It is the first approach to achieve a rigorous three-way trade-off among privacy (via FHE), prediction accuracy, and computational efficiency. The framework provides a verifiable, practically deployable solution for privacy-preserving, cloud-based financial decision-making.