Crate base64_turbo 

Base64 Turbo

A SIMD-accelerated Base64 encoder/decoder for Rust, optimized for high-throughput systems.

This crate provides runtime CPU detection to utilize AVX2, SSE4.1, or AVX512 (via feature flag) intrinsics. It includes a highly optimized scalar fallback for non-SIMD targets and supports no_std environments.

Usage

Add this to your Cargo.toml:

[dependencies]
base64-turbo = "0.1"

Basic API (Allocating)

Standard usage for general applications. Requires the std feature (enabled by default).

use base64_turbo::STANDARD;

let data = b"Hello world";

// Encode to String
let encoded = STANDARD.encode(data);
assert_eq!(encoded, "SGVsbG8gd29ybGQ=");

// Decode to Vec<u8>
let decoded = STANDARD.decode(&encoded).unwrap();
assert_eq!(decoded, data);

Zero-Allocation API (Slice-based)

For low-latency scenarios or no_std environments where heap allocation is undesirable. These methods write directly into a user-provided mutable slice.

use base64_turbo::STANDARD;

let input = b"Raw bytes";
let mut output = [0u8; 64]; // Pre-allocated stack buffer

// Returns Result<usize, Error> indicating bytes written
let len = STANDARD.encode_into(input, &mut output).unwrap();

assert_eq!(&output[..len], b"UmF3IGJ5dGVz");

Feature Flags

This crate is highly configurable via Cargo features:

Feature	Default	Description
std	Yes	Enables String and Vec support. Disable this for no_std environments.
simd	Yes	Enables runtime detection for AVX2 and SSE4.1 intrinsics. If disabled or unsupported by hardware, the crate falls back to scalar logic automatic.
parallel	No	Enables Rayon support. Automatically parallelizes processing for payloads larger than 512KB. Recommended only for massive data ingestion tasks.
avx512	No	Enables AVX512 intrinsics.

Safety & Verification

This crate utilizes unsafe code for SIMD intrinsics and pointer arithmetic to achieve maximum performance.

• Formal Verification (Kani): Scalar (Done), SSE4.1 (In Progress), AVX2 (Done), AVX512 (In Progress) code mathematic proven to be UB free and panic free.
• MIRI Tests: Core SIMD logic and scalar fallbacks are verified with MIRI (Undefined Behavior checker) in CI.
• Fuzzing: The codebase is fuzz-tested via cargo-fuzz.
• Fallback: Invalid or unsupported hardware instruction sets are detected at runtime, ensuring safe fallback to scalar code.

Learn More: Details on our threat model and formal verification strategy.

Structs

Engine

A high-performance, stateless Base64 encoder/decoder.

Enums

Error

Errors that can occur during Base64 encoding or decoding operations.

Constants

STANDARD

Standard Base64 (RFC 4648) with padding (=).

STANDARD_NO_PAD

Standard Base64 (RFC 4648) without padding.

URL_SAFE

URL-Safe Base64 with padding.

URL_SAFE_NO_PAD

URL-Safe Base64 without padding.