Cryptographic Accelerators for Digital Signature Based on Ed25519

This article presents highly optimized implementations of the Ed25519 digital signature algorithm [Edwards curve digital signature algorithm (EdDSA)]. This algorithm significantly improves the execution time without sacrificing security, compared to exiting digital signature algorithms. Although EdDSA is employed in many widely used protocols, such as TLS and SSH, there appear to be extremely few hardware implementations that focus only on EdDSA. Hence, we propose two different field-programmable gate array (FPGA)-based EdDSA implementations, i.e., efficient and high-performance Ed25519 architectures applicable for a security level comparable to AES-128. Our proposed efficient Ed25519 scheme achieves an improvement of more than 84% compared to the best previous work by reducing the required area. It also incorporates more than 8x speedup. Furthermore, our proposed high-performance architecture shows a 21x speedup with more than 6200 digital signature algorithms per second, showing a significant improvement in terms of utilized area x time on a Xilinx Zynq-7020 FPGA. Finally, the effective side-channel countermeasures are embedded in our proposed designs, which also outperform the previous works.