At IEEE Security & Privacy 2015, Bos, Costello, Naehrig, and Stebila proposed an instantiation of Peikert's ring-learning-with-errors--based (Ring-LWE) key-exchange protocol (PQCrypto 2014), together with an implementation integrated into OpenSSL, with the affirmed goal of providing post-quantum security for TLS. In this work we revisit their instantiation and stand-alone implementation. Specifically, we propose new parameters and a better suited error distribution, analyze the scheme's hardness against attacks by quantum computers in a conservative way, introduce a new and more efficient error-reconciliation mechanism, and propose a defense against backdoors and all-for-the-price-of-one attacks. By these measures and for the same lattice dimension, we more than double the security parameter, halve the communication overhead, and speed up computation by more than a factor of 8 in a portable C implementation and by more than a factor of 27 in an optimized implementation targeting current Intel CPUs. These speedups are achieved with comprehensive protection against timing attacks.
Additional Metadata
Keywords Public-key cryptography / Post-quantum key exchange, Ring-LWE, high-speed software, vectorization
THEME Information (theme 2)
Stakeholder Infineon Technologies AG, Munich, Germany
Conference USENIX Security Symposium
Citation
Alkin, E, Ducas, L, Pöppelmann, T, & Schwabe, P. (2016). Post-Quantum Key Exchange -- A new hope.