> ## Documentation Index
> Fetch the complete documentation index at: https://docs.qu.ai/llms.txt
> Use this file to discover all available pages before exploring further.

# pbkdf2

```ts theme={null}
function pbkdf2(
   _password, 
   _salt, 
   iterations, 
   keylen, 
   algo): string
```

Return the [PBKDF2](https://en.wikipedia.org/wiki/PBKDF2) for `keylen` bytes for `password` using the `salt` and
using `iterations` of `algo`.

This PBKDF is outdated and should not be used in new projects, but is required to decrypt older files.

## Parameters

| Parameter    | Type                                               | Description                        |
| :----------- | :------------------------------------------------- | :--------------------------------- |
| `_password`  | [`BytesLike`](/sdk/content/type-aliases/BytesLike) | The password to use.               |
| `_salt`      | [`BytesLike`](/sdk/content/type-aliases/BytesLike) | The salt to use.                   |
| `iterations` | `number`                                           | The number of iterations to use.   |
| `keylen`     | `number`                                           | The length of the key to generate. |
| `algo`       | `"sha256"` \| `"sha512"`                           | The algorithm to use.              |

## Returns

`string`

The key derived from the password.

## Example

```ts theme={null}
// The password must be converted to bytes, and it is generally
// best practices to ensure the string has been normalized. Many
// formats explicitly indicate the normalization form to use.
password = 'hello';
passwordBytes = toUtf8Bytes(password, 'NFKC');

salt = id('some-salt');

// Compute the PBKDF2
pbkdf2(passwordBytes, salt, 1024, 16, 'sha256');
```

## Source

[crypto/pbkdf2.ts:55](https://github.com/dominant-strategies/quais.js/blob/c1c12d43f9d34c6baad2b0542bd6d0acd6fefcbf/src/crypto/pbkdf2.ts#L55)