path: root/docs/api/hashing.md

{% callout %}

Bun implements the `createHash` and `createHmac` functions from [`node:crypto`](https://nodejs.org/api/crypto.html) in addition to the Bun-native APIs documented below.

{% /callout %}

## `Bun.password`

`Bun.password` is a collection of utility functions for hashing and verifying passwords with various cryptographically secure algorithms.

```ts
const password = "super-secure-pa$$word";

const hash = await Bun.password.hash(password);
// => $argon2id$v=19$m=65536,t=2,p=1$tFq+9AVr1bfPxQdh6E8DQRhEXg/M/SqYCNu6gVdRRNs$GzJ8PuBi+K+BVojzPfS5mjnC8OpLGtv8KJqF99eP6a4

const isMatch = await Bun.password.verify(password, hash);
// => true
```

The second argument to `Bun.password.hash` accepts a params object that lets you pick and configure the hashing algorithm.

```ts
const password = "super-secure-pa$$word";

// use argon2 (default)
const argonHash = await Bun.password.hash(password, {
  algorithm: "argon2id", // "argon2id" | "argon2i" | "argon2d"
  memoryCost: 4, // memory usage in kibibytes
  timeCost: 3, // the number of iterations
});

// use bcrypt
const bcryptHash = await Bun.password.hash(password, {
  algorithm: "bcrypt",
  cost: 4, // number between 4-31
});
```

The algorithm used to create the hash is stored in the hash itself. When using `bcrypt`, the returned hash is encoded in [Modular Crypt Format](https://passlib.readthedocs.io/en/stable/modular_crypt_format.html) for compatibility with most existing `bcrypt` implementations; with `argon2` the result is encoded in the newer [PHC format](https://github.com/P-H-C/phc-string-format/blob/master/phc-sf-spec.md).

The `verify` function automatically detects the algorithm based on the input hash and use the correct verification method. It can correctly infer the algorithm from both PHC- or MCF-encoded hashes.

```ts
const password = "super-secure-pa$$word";

const hash = await Bun.password.hash(password, {
  /* config */
});

const isMatch = await Bun.password.verify(password, hash);
// => true
```

Synchronous versions of all functions are also available. Keep in mind that these functions are computationally expensive, so using a blocking API may degrade application performance.

```ts
const password = "super-secure-pa$$word";

const hash = Bun.password.hashSync(password, {
  /* config */
});

const isMatch = Bun.password.verifySync(password, hash);
// => true
```

## `Bun.hash`

`Bun.hash` is a collection of utilities for _non-cryptographic_ hashing. Non-cryptographic hashing algorithms are optimized for speed of computation over collision-resistance or security.

The standard `Bun.hash` functions uses [Wyhash](https://github.com/wangyi-fudan/wyhash) to generate a 64-bit hash from an input of arbitrary size.

```ts
Bun.hash("some data here");
// 11562320457524636935n
```

The input can be a string, `TypedArray`, `DataView`, `ArrayBuffer`, or `SharedArrayBuffer`.

```ts
const arr = new Uint8Array([1, 2, 3, 4]);

Bun.hash("some data here");
Bun.hash(arr);
Bun.hash(arr.buffer);
Bun.hash(new DataView(arr.buffer));
```

Optionally, an integer seed can be specified as the second parameter. For 64-bit hashes seeds above `Number.MAX_SAFE_INTEGER` should be given as BigInt to avoid loss of precision.

```ts
Bun.hash("some data here", 1234);
// 15724820720172937558n
```

Additional hashing algorithms are available as properties on `Bun.hash`. The API is the same for each, only changing the return type from number for 32-bit hashes to bigint for 64-bit hashes.

```ts
Bun.hash.wyhash("data", 1234); // equivalent to Bun.hash()
Bun.hash.crc32("data", 1234);
Bun.hash.adler32("data", 1234);
Bun.hash.cityHash32("data", 1234);
Bun.hash.cityHash64("data", 1234);
Bun.hash.murmur32v3("data", 1234);
Bun.hash.murmur32v2("data", 1234);
Bun.hash.murmur64v2("data", 1234);
```

## `Bun.CryptoHasher`

`Bun.CryptoHasher` is a general-purpose utility class that lets you incrementally compute a hash of string or binary data using a range of cryptographic hash algorithms. The following algorithms are supported:

- `"blake2b256"`
- `"md4"`
- `"md5"`
- `"ripemd160"`
- `"sha1"`
- `"sha224"`
- `"sha256"`
- `"sha384"`
- `"sha512"`
- `"sha512-256"`

```ts
const hasher = new Bun.CryptoHasher("sha256");
hasher.update("hello world");
hasher.digest();
// Uint8Array(32) [ <byte>, <byte>, ... ]
```

Once initialized, data can be incrementally fed to to the hasher using `.update()`. This method accepts `string`, `TypedArray`, and `ArrayBuffer`.

```ts
const hasher = new Bun.CryptoHasher("sha256");

hasher.update("hello world");
hasher.update(new Uint8Array([1, 2, 3]));
hasher.update(new ArrayBuffer(10));
```

If a `string` is passed, an optional second parameter can be used to specify the encoding (default `'utf-8'`). The following encodings are supported:

{% table %}

---

- Binary encodings
- `"base64"` `"base64url"` `"hex"` `"binary"`

---

- Character encodings
- `"utf8"` `"utf-8"` `"utf16le"` `"latin1"`

---

- Legacy character encodings
- `"ascii"` `"binary"` `"ucs2"` `"ucs-2"`

{% /table %}

```ts
hasher.update("hello world"); // defaults to utf8
hasher.update("hello world", "hex");
hasher.update("hello world", "base64");
hasher.update("hello world", "latin1");
```

After the data has been feed into the hasher, a final hash can be computed using `.digest()`. By default, this method returns a `Uint8Array` containing the hash.

```ts
const hasher = new Bun.CryptoHasher("sha256");
hasher.update("hello world");

hasher.digest();
// => Uint8Array(32) [ 185, 77, 39, 185, 147, ... ]
```

The `.digest()` method can optionally return the hash as a string. To do so, specify an encoding:

```ts
hasher.digest("base64");
// => "uU0nuZNNPgilLlLX2n2r+sSE7+N6U4DukIj3rOLvzek="

hasher.digest("hex");
// => "b94d27b9934d3e08a52e52d7da7dabfac484efe37a5380ee9088f7ace2efcde9"
```

Alternatively, the method can write the hash into a pre-existing `TypedArray` instance. This may be desirable in some performance-sensitive applications.

```ts
const arr = new Uint8Array(32);

hasher.digest(arr);

console.log(arr);
// => Uint8Array(32) [ 185, 77, 39, 185, 147, ... ]
```

<!-- Bun.sha; -->