Performance Comparison of Post-Quantum Signature Algorithms Through An Android Email Application Plug-in

Public key cryptography and signature schemes are essential for reliable digital communication. Asymmetric encryption has been achieved through complex algorithms, such as RSA and Diffie-Hellman, but recent advancements in quantum computing pose threats to the security of these algorithms in the near future as a quantum computer may solve the problems these algorithms are based on. Therefore, Post-Quantum Cryptography (PQC) algorithms have been proposed and investigated by an international community of scientists, especially through the NIST PQC competition ongoing since 2016. They have gathered and classified four different key exchange algorithms and three signature schemes. This paper focuses on implementing the signature schemes inside a popular open-source Android email application as a plug-in and comparing their performances based on this app plug-in utilization. We have used a library, liboqs, from the Open Quantum Safe project as the starting point, which ensures regularity in our results. We also compare the current standard candidate signature schemes with the currently used standard RSA-4096. Our results show that Dilithium has noticeably faster key generation, signing, and verification with the relatively affordable key and signature size. Also, to the best of our knowledge, our study provides the first practical Android email application plug-in supporting PQ-based signatures.