## 1 Introduction
[37] proposed a hybrid key-distribution protocol combining PQC and QKD to ensure security even if one scheme fails, focusing on theoretical key security models and vulnerability metrics. [PERSON] et al. [38] designed a QKD-enabled authentication framework for Internet of Vehicles by integrating BB84-based key exchange with lattice-based digital signatures, emphasizing mutual authentication and resistance to quantum attacks. [PERSON] et al. [39] presented a blockchain-based service-orchestration platform that secures network-management logs using PQC-enhanced digital signatures and evaluates the performance of Blockchain Network (BCN) operations under quantum-safe computations. [PERSON] et al. [40] proposed a concrete FPGA implementation of a 3-key combiner that integrates keys from pre-quantum, post-quantum, and QKD sources using a dual-PRF construction. [PERSON] et al. [41] experimentally verified using a PQC-based digital signature to authenticate the classical channel in a QKD network, solving the key-management problem for large-scale networks. [PERSON] et al. [42] proposed a prototype QKD system that employs sequential encryption, first with a QKD key and then with AES-256, to ensure security even if one of the primitives fails. Although it does not explicitly adopt PQC algorithms, AES-256 is used as a quantum-resilient encryption method, providing post-quantum level security against quantum attacks. Our study distinguishes itself from previous studies by combining classical and quantum cryptographic techniques into a unified, distributed file encryption. While earlier approaches have primarily focused on secure key exchange or communication protocols, we implement a practical encryption scheme that integrates PQC, QKD, and AES to protect large-scale files. Our proposed scheme decouples key management from encryption by assigning centralized PQC-based key encapsulation and QKD-based key masking to the master node, while enabling parallel AES encryption at slave nodes through an offset-aware partitioning method. Overlapped encryption and transmission pipelines reduce latency, and parallel decryption and reassembly at the master improve scalability and throughput across the cluster. Additionally, our scheme addresses the growing demand for secure and efficient encryption of large-scale files in distributed cloud systems, where conventional methods struggle with scalability and quantum resilience. By decoupling key management from data encryption and leveraging parallel processing, it ensures that large-scale files can be securely handled without compromising performance or long-term security. In this paper, we propose a secure, scalable, and quantum-resilient encryption scheme designed for large-scale file protection in a cluster. The goal of our scheme is (1) to enable efficient encryption of the target file through offset-aware partitioning and parallel processing, (2) to ensure long-term security by integrating both PQC and QKD, and (3) to reduce latency and system overhead by overlapping encryption and transmission. To achieve this, the target file is divided into fixed-size subsets and distributed to slave nodes, where each subset is independently encrypted using an AES key that has been encapsulated via Kyber-based PQC. The encapsulated PQC secret key is then masked using a QKD-derived key transmitted. The encrypted subsets are asynchronously returned to the master node, where decryption is performed by decapsulating the AES key and unmasking it using the QKD key. Our evaluation results using real-world datasets confirm that, even with the added complexity of multi-layered key protection combining PQC and QKD, our scheme