rpgmasd-wasm

WebAssembly bindings for rpgm-asset-decrypter-lib, generated via wasm-bindgen. A thin wrapper around the Rust reference implementation - useful when you want behavior guaranteed identical to the Rust crate without a second, hand-maintained implementation.

Install

npm install rpgmasd-wasm

API

The Decrypter class mirrors the Rust API directly (see src/lib.rs for full doc comments):

class Decrypter {
    constructor();
    key(): string | undefined;
    setKeyFromStr(key: string): void;
    setKeyFromFile(fileContent: Uint8Array, fileType: FileType): string;
    decrypt(fileContent: Uint8Array, fileType: FileType): Uint8Array;
    decryptInPlace(fileContent: Uint8Array, fileType: FileType): void;
    encrypt(fileContent: Uint8Array): Uint8Array;
    encryptInPlace(fileContent: Uint8Array): void;
}

plus the FileType enum (Png, Ogg, M4a) and free-function equivalents of the Rust crate's convenience wrappers - decryptAsset, decryptAssetInPlace, encryptAsset, encryptAssetInPlace - each spinning up a throwaway Decrypter internally, for one-shot calls that don't need to hold onto a key.

The *InPlace methods take a Uint8Array and mutate it: wasm-bindgen copies the array's bytes into WASM memory, runs the call, and copies the (possibly mutated) bytes back out afterward - so the mutation is visible on your own Uint8Array once the call returns, same as the reference in-place methods.

Usage

import init, { Decrypter, FileType } from "rpgmasd-wasm";

await init(); // instantiates the wasm module - do this once, before first use

const fileContent = new Uint8Array(await Deno.readFile("./image.rpgmvp"));

const decrypter = new Decrypter();
const decrypted = decrypter.decrypt(fileContent, FileType.Png); // key is auto-derived from the file

The free-function form is shorter when you don't need to reuse the derived key across multiple files:

import init, { decryptAsset, FileType } from "rpgmasd-wasm";

await init();
const decrypted = decryptAsset(fileContent, FileType.Png);

Under Node/Bun, init()'s default fetch()-based loading doesn't apply - pass the .wasm bytes explicitly instead:

import { readFile } from "node:fs/promises";
import init, { Decrypter } from "rpgmasd-wasm";

await init(
  await readFile(new URL("./rpgmasd_wasm_bg.wasm", import.meta.resolve("rpgmasd-wasm"))),
);

Building

wasm-pack build --release --target web

Requires the wasm32-unknown-unknown rustup target (rustup target add wasm32-unknown-unknown) and wasm-pack (cargo binstall wasm-pack). Output goes to pkg/ (gitignored): the compiled .wasm, a JS glue module, a .d.ts, and the package.json this crate publishes to npm from.