blake3.wasm/README.md

# blake3-wasm-rs

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**blake3-wasm-rs** is a WebAssembly port of the BLAKE3 cryptographic hash function written in **Rust**. It enables fast and secure hashing right inside **browsers** and **Node.js**.

## build

```sh
# lets build it!

# normal
make build

# clean
make
```

## Usage

```ts
import * as blake3 from 'blake3-wasm-rs';

const data = new TextEncoder().encode('hello world');
const key = new Uint8Array(32).fill(1);

// One-shot hashing
blake3.hash(data);
blake3.hashXof(data, 64);        // variable output length
blake3.keyedHash(data, key);     // key must be exactly 32 bytes
blake3.deriveKey('my context', key);

// Conctruct for Streaming
{
    using h = new blake3.Hasher();
    h.update(data.slice(0, 5));
    h.update(data.slice(5));
    h.finalize();
    h.finalizeXof(64);
    h.reset();
}

// Streaming
// Keyed (MAC mode)
{
    using mac = blake3.Hasher.newKeyed(key);
    mac.update(data);
    mac.finalize();
}

// Streaming
// Key derivation mode
{
    using kdf = blake3.Hasher.newDeriveKey('my app v1 :: subkey');
    kdf.update(key);
    kdf.finalize();
}

// Batch hashing without re-allocating
{
    using h = new blake3.Hasher();
    h.update(chunk1);
    const first = h.finalizeAndReset();
    h.update(chunk2);
    const second = h.finalizeAndReset();
}
```

#### Named imports

```ts
import { hash, hashXof, keyedHash, deriveKey, Hasher } from 'blake3-wasm-rs';

const data = new TextEncoder().encode('hello world');
const key = new Uint8Array(32).fill(1);

// One-shot hashing
hash(data);
hashXof(data, 64);          // variable output length
keyedHash(data, key);       // key must be exactly 32 bytes
deriveKey('my context', key);

// Streaming
{
    using h = new Hasher();
    h.update(data.slice(0, 5));
    h.update(data.slice(5));
    h.finalize();
    h.finalizeXof(64);
    h.reset();
}

// Keyed (MAC mode)
{
    using mac = Hasher.newKeyed(key);
    mac.update(data);
    mac.finalize();
}

// Key derivation mode
{
    using kdf = Hasher.newDeriveKey('my app v1 :: subkey');
    kdf.update(key);
    kdf.finalize();
}

// Batch hashing without re-allocating
{
    using h = new Hasher();
    h.update(chunk1);
    const first = h.finalizeAndReset();
    h.update(chunk2);
    const second = h.finalizeAndReset();
}
```

## API

### Functions

| Function                          | Returns      | Description                                     |
|-----------------------------------|--------------|-------------------------------------------------|
| `hash(data)`                      | `Uint8Array` | One-shot 32-byte BLAKE3 digest                  |
| `hashXof(data, outLen)`           | `Uint8Array` | Variable-length digest (XOF mode)               |
| `keyedHash(data, key)`            | `Uint8Array` | Keyed hash / MAC (key must be exactly 32 bytes) |
| `deriveKey(context, keyMaterial)` | `Uint8Array` | Derive a 32-byte subkey                         |

### Hasher class

| Method                         | Returns      | Description                                               |
|--------------------------------|--------------|-----------------------------------------------------------|
| `new Hasher()`                 | `Hasher`     | Streaming hasher, unkeyed                                 |
| `Hasher.newKeyed(key)`         | `Hasher`     | Streaming hasher, MAC mode (key must be exactly 32 bytes) |
| `Hasher.newDeriveKey(context)` | `Hasher`     | Streaming hasher, KDF mode                                |
| `.update(data)`                | `void`       | Feed data, can be called multiple times                   |
| `.finalize()`                  | `Uint8Array` | 32-byte digest, non-destructive                           |
| `.finalizeXof(outLen)`         | `Uint8Array` | Variable-length digest, non-destructive                   |
| `.finalizeAndReset()`          | `Uint8Array` | Finalize then reset (useful for batch hashing)            |
| `.reset()`                     | `void`       | Reset to initial state, preserves mode                    |
| `.free()`                      | `void`       | Release WASM memory manually (prefer `using` instead)     |

> **Memory management:** In all modern browsers (and wasm-bindgen ≥ 0.2.91), WASM memory is freed automatically via the TC39 weak references proposal when the JS object goes out of scope.
> 
> In practice, you often don't need to think about this. For deterministic cleanup or environments without weak reference support (older browsers, some Node.js setups), use `using` (TypeScript 5.2+ / ES2026) or call `.free()` manually. 
> 
> Never call `.free()` on a `using`-managed instance otherwise it will double-free.

## Benchmarks

Tested on **Apple M4**, Node.js v24.

| Size  | @noble/hashes | awasm-noble | awasm-noble (threads) | blake3-wasm |
|-------|---------------|-------------|-----------------------|-------------|
| 32 B  | 28 MB/s       | 105 MB/s    | 94 MB/s               | 129 MB/s    |
| 1 KB  | 105 MB/s      | 843 MB/s    | 819 MB/s              | 568 MB/s    |
| 64 KB | 102 MB/s      | 1,898 MB/s  | 1,855 MB/s            | 2,004 MB/s  |
| 1 MB  | 101 MB/s      | 1,943 MB/s  | 4,711 MB/s            | 1,893 MB/s  |
| 10 MB | 101 MB/s      | 1,911 MB/s  | 6,456 MB/s            | 2,185 MB/s  |

Tested on **Ryzen 7 5800X**, Node.js v24.

| Size  | @noble/hashes | awasm-noble | awasm-noble (threads) | blake3-wasm |
|-------|---------------|-------------|-----------------------|-------------|
| 32 B  | 11 MB/s       | 34 MB/s     | 45 MB/s               | 86 MB/s     |
| 1 KB  | 56 MB/s       | 499 MB/s    | 526 MB/s              | 919 MB/s    |
| 64 KB | 52 MB/s       | 1,729 MB/s  | 1,684 MB/s            | 2,067 MB/s  |
| 1 MB  | 51 MB/s       | 1,550 MB/s  | 4,036 MB/s            | 1,848 MB/s  |
| 10 MB | 50 MB/s       | 1,497 MB/s  | 4,946 MB/s            | 1,776 MB/s  |

## Security

The underlying `blake3` Rust crate targets algorithmic constant time. However, the JavaScript boundary (via napi-rs or WASM) introduces non-determinism from the V8 runtime that is outside our control. For absolute security, use the `blake3` Rust crate directly in a Rust program.

## See also

- [@noble/hashes](https://github.com/paulmillr/noble-hashes) | pure JS implementation
- [awasm-noble](https://github.com/paulmillr/awasm-noble) | auditable WASM implementation
- [blake3-napi](https://github.com/UneBaguette/blake3-napi)  | native Node.js addon, faster for large inputs