The importance of hardware security increases significantly to protect the vast amounts of private data stored on edge devices. Physical unclonable functions (PUFs) are gaining prominence as hardware security primitives due to their ability to generate true random digital keys by exploiting the inherent randomness of the physical devices. Traditional approaches, however, require significant data movement between memory units and PUF generation circuits to perform encryption, presenting considerable energy efficiency and security challenges. This study introduces an innovative approach where PUF key generation and encryption are accomplished in the same vertically integrated resistive random access memory (V-RRAM), alleviating the data movement issue. The proposed V-RRAM encryption machine offers concealable PUFs, high area efficiency, and multi-thread data handling using parallel XOR logic operations. The encryption machine is compared with other machines, demonstrating the highest spatiotemporal cost-effectiveness.