Paper 2026/1413

Optimizing ARIA-GCM on GPUs

Abstract

This paper proposes an optimized GPU implementation of the ARIA-GCM authenticated-encryption pipeline (CTR keystream, GHASH authentication, and their AEAD composition): ARIA-CTR uses a packed 32-bit S-box staged in shared memory, GHASH is optimized separately with a fixed-key 4-bit Shoup lookup table, the two stages are integrated as both a two-kernel and a fused single-kernel AEAD, and the same aria_gcm.cu source is tuned for Ampere and Pascal through compile-time parameters. For ARIA-CTR, the four distinct S-box tables are merged into one 1 KiB shared-memory table (R=1 staging) and each thread encrypts CTR_IPT counter blocks in parallel to fill the ALU-bound diffusion layer. For GHASH, each thread owns one segment of sblk blocks, applies W-way Horner interleaving with precomputed powers of H, and keeps the reduction table in shared memory. Experiments on an RTX 3090 and a GTX 1080 Ti show that packed S-box staging improves naive ARIA-CTR by 14.5×, the Shoup LUT improves bit-serial GHASH by 21.5×, and the tuned pipeline reaches 924 Gb/s (CTR), 2,865 Gb/s (GHASH), and 622 Gb/s (fused AEAD) on the RTX 3090. Using a simple sequential-composition model, we show that the GHASH optimization is what shifts the AEAD bottleneck onto ARIA-CTR: without it the pipeline would be GHASH-bound near 120 Gb/s, whereas the tuned GHASH makes CTR account for about three quarters of the per-byte cost. We back the analysis with Nsight Compute measurements of register usage, achieved occupancy, shared-memory bank conflicts, and DRAM traffic.