bitwise.wasm

Bitwise operations for WebAssembly

npm i @hazae41/bitwise.wasm

Node Package 📦

Features

Reproducible building
Pre-bundled and streamed
Zero-copy memory slices

Algorithms

Bits pack and unpack
Bits xormod

Usage

Concat bits with bytes

import { BitwiseWasm, Memory, bitwise_unpack, bitwise_pack_right } from "@hazae41/bitwise.wasm";

// Wait for WASM to load
await BitwiseWasm.initBundled();

// Create a header of bits
const head_bits = new Uint8Array([0x00, 0x01, 0x00, 0x01])

// Create a body of bytes
const body_bytes = new Uint8Array(256)
crypto.getRandomValues(body_bytes)

// Pass it to WASM
using body_bytes_memory = new Memory(body_bytes)

// Unpack it
using body_bits_memory = bitwise_unpack(body_bytes_memory)

// Pass it to JS
const body_bits = body_bits_memory.bytes

// Concat both bits arrays
const full_bits = new Uint8Array(head_bits.length + body_bits.length)
full_bits.set(head_bits, 0)
full_bits.set(body_bits, head_bits.length)

// Pass it to WASM
using full_bits_memory = new Memory(full_bits)

// Pack it adding 0-padding to the right
using full_bytes_memory = bitwise_pack_right(fullBits)

// Pass it to JS
const full_bytes = full_bytes_memory.bytes

Xoring with mask

import { BitwiseWasm, Memory, bitwise_xor_mod } from "@hazae41/bitwise.wasm";

// Wait for WASM to load
await BitwiseWasm.initBundled();

const bytes = new Uint8Array(1024)
crypto.getRandomValues(bytes)

using bytes_memory = new Memory(bytes)

const mask = new Uint8Array(4)
crypto.getRandomValues(mask)

using mask_memory = new Memory(mask)

using xored_memory = bitwise_xor_mod(bytes_memory, mask_memory)
const xored = xored_memory.bytes

using unxored_memory = bitwise_xor_mod(xored_memory, mask_memory)
const unxored = unxored_memory.bytes

Building

Unreproducible building

You need to install Rust

Then, install wasm-pack

cargo install wasm-pack

Finally, do a clean install and build

npm ci && npm run build

Reproducible building

You can build the exact same bytecode using Docker, just be sure you're on a linux/amd64 host

docker compose up --build

Then check that all the files are the same using npm diff

npm diff

If the output is empty then the bytecode is the same as the one I commited

Automated checks

Each time I release a new version on GitHub, the GitHub's CI clones the GitHub repository, reproduces the build, and throws an error if the NPM release is different. If a version is present on NPM but not on GitHub, do not use it!