Implementation and Reliability Evaluation of a ChaCha20 Stream Cipher Hardware Accelerator

Cryptography is fundamental to ensuring the security and privacy of space communications, enabling the reliable exchange of sensitive data between spacecraft, ground stations, and other components of space infrastructure. However, using encryption can be computationally costly, resulting in lower throughput or higher latencies. One strategy to mitigate the costs imposed by cryptography is using accelerators. In addition, these systems that operate in space are susceptible to faults due to adverse conditions and require the implementation of protection techniques to mitigate these faults and ensure correct operation. In this context, this paper presents a fault-tolerant and high-performance encryption accelerator for the ChaCha20 stream cipher. We present a low-cost optimized implementation and a fault-tolerant version using Hamming Error Correction Code (ECC) and Triple Modular Redundancy (TMR). Results show that the optimized and hardened versions accelerated the application by 23 × and 17 × compared to the software solution. The optimized solution can process 281.25 MB/s, presenting a higher throughput than state-of-the-art works that rely on FPGA implementation. The hardened solution can process 187.50 MB/s, leading to an overhead of 1.52× more Look-Up Tables (LUTs) and 1.03× more Flip-Flops (FFs) compared to the optimized solution of this work.