Fast prime field elliptic-curve cryptography with 256-bit primes

This paper studies software optimization of elliptic-curve cryptography with 256-bit prime fields. We propose a constant-time implementation of the NIST and SECG standardized curve P-256, that can be seamlessly integrated into OpenSSL. This accelerates Perfect Forward Secrecy TLS handshakes that use ECDSA and/or ECDHE, and can help in improving the efficiency of TLS servers. We report significant performance improvements for ECDSA and ECDH, on several architectures. For example, on the latest Intel Haswell microarchitecture, our ECDSA sign is 2.33 × faster than OpenSSL’s implementation.