Secure PIN Storage through Multi-Digit Embedding in Hash Table Cells

Abstract

Personal Identification Number (PIN) systems typically store or process digits individually, making them vulnerable to memory extraction, side channel attacks, reverse engineering, and structural pattern analysis. This paper introduces a novel PIN obfuscation mechanism based on multi-digit embedding inside hash table buckets. Instead of storing each PIN digit in an isolated position, this approach stores a set of digits per cell, where the real digit is hidden among randomly generated noise digits. Only a predefined selection rule such as position-based retrieval or key-driven indexing reveals the actual PIN. This increases confusion, reduces predictability, and adds an additional cryptographic layer without modifying user experience. The proposed technique can be integrated into ATM authentication, mobile banking systems, and secure PIN pads. Experimental results demonstrate that the approach increases resistance to brute-force reconstruction and memory forensics while maintaining minimal computational overhead.