A 16-bit on-chip embedded encryption system built upon eFUSE, cipher, hash functions, and ECCs for optical nerve stimulation is discussed. The foundry-provided eFUSE architecture is modified with a one-shot block that mitigates the supply voltage drop problem during sensing and subsequent resetting. Novel logic gate-based auxiliary circuit facilitates the different testing and programming mode operation in eFUSE. A 128-bit cipher is reduced to 16 bits with cascade structure using the proposed divide-and-conquer algorithm but keeping the cipher strength constant. The developed dedicated resource sharing technique improves power-performance-area (PPA) by decreasing the cipher area and power consumption 2.7 times and 5.1 times, respectively. The system is fabricated with 0.18μm BCDlite process consisting of 1.8 V and 5 V devices.