SIMD in Go — Cryptographic XOR Benchmark

Demonstrates Go 1.26's simd/archsimd package applied to the core operation behind stream ciphers (AES-CTR, ChaCha20, OTP): XOR of a plaintext buffer with a keystream.

What's benchmarked

Implementation	Strategy	Instructions
XORScalar	Byte-by-byte loop	XOR r8, r8
XORSimd256	32 bytes/iteration via AVX2	VPXOR ymm, ymm, ymm
XORSimd256Unrolled	128 bytes/iteration (4× unrolled)	4× VPXOR ymm per iter

Run (macOS with Docker)

./run.sh

Expected speedup

On x86_64 (emulated via Docker on Apple Silicon, real numbers will be higher on native):

• Small payloads (256B): ~5-10× faster with SIMD
• Large payloads (1MB+): ~15-25× faster with SIMD (memory-bandwidth limited)

On native x86 hardware (e.g. Emerald Rapids Xeon), expect even better numbers since VPXOR has 1-cycle latency and can retire 3 per cycle on ports p0/p1/p5.

uops.info reference

For the presentation, show the Emerald Rapids measurements for:

• VPXOR (YMM, YMM, YMM) — the instruction behind Uint8x32.Xor() - link
• VAESENC (XMM, XMM, XMM) — hardware AES round (for context on crypto acceleration)

Filter: select "Emerald Rapids" architecture, then filter by "AES" or "AVX2" extension.

Relevance to Netis

Functions that does sha256.Sum256(...) — SHA-256 internally uses the same class of bitwise operations (XOR, AND, rotate, shift) that SIMD accelerates. Go's crypto/sha256 already uses hardware SHA extensions when available, but understanding the SIMD primitives shows why it's fast.