NEON crypto

Abstract

NEON is a vector instruction set included in a large fraction of new ARM-based tablets and smartphones. This paper shows that NEON supports high-security cryptography at surprisingly high speeds; normally data arrives at lower speeds, giving the CPU time to handle tasks other than cryptography. In particular, this paper explains how to use a single 800MHz Cortex A8 core to compute the existing NaCl suite of high-security cryptographic primitives at the following speeds: 5.60 cycles per byte (1.14 Gbps) to encrypt using a shared secret key, 2.30 cycles per byte (2.78 Gbps) to authenticate using a shared secret key, 527102 cycles (1517/second) to compute a shared secret key for a new public key, 624846 cycles (1280/second) to verify a signature, and 244655 cycles (3269/second) to sign a message. These speeds make no use of secret branches and no use of secret memory addresses. Keywords: vectorization-friendly cryptographic primitives – efficient software implementations – smartphones – tablets – there be dragon