# Scrypt Wrapper

NodeJS's standard library's `crypto` module contains an `scrypt` function,
which uses the Scrypt password-based key derivation function to create a hash
which can be stored to later verify a password's validity. This library is a
thin wrapper around that function which handles salting, serializing and
deserializing hash metadata, and verification. It contains both asynchronous
and synchronous versions of its functions, and is thoroughly tested.

## Usage

```javascript
const { hash, verify } = require('@techworkers/scrypt-wrapper')
const userEnteredPassword = 'some password'
const hashedPassword = await hash(userEnteredPassword)
if (await verify(hashedPassword, userEnteredPassword)) {
    // allowed!
}
```

Or, in a synchronous environment...

```javascript
const { hashSync, verifySync } = require('@techworkers/scrypt-wrapper')
const userEnteredPassword = 'some password'
const hashedPassword = hashSync(userEnteredPassword)
if (verifySync(hashedPassword, userEnteredPassword)) {
    // allowed!
}
```

Async and sync versions can be used together. For example, Sequelize doesn't
offer async setters:

```javascript
const sequelize = require('sequelize')
const { Model } = sequelize
const { hashSync, verify } = require('@techworkers/scrypt-wrapper')
module.exports = (sequelize, DataTypes) => {
  class User extends Model {
    static async authenticated(name, password) {
      const user = await User.findOne({ where: { name } })
      if (!user) return null
      if (await verify(user.password, password)) return user
      else return null
    }
  }
  User.init(
    {
      name: DataTypes.STRING,
      password: {
        type: DataTypes.STRING,
        set(password) {
          this.setDataValue('password', hashSync(password))
          // We need to generate the hash ^^^ value synchronously here
        },
      },
    },
    {
      sequelize,
      tableName: 'Users',
      modelName: 'User',
    },
  )
  return User
}

// Creating a user
const user = await User.create({name: 'user', password: 'monkey'})
// Validating them
const reFetchedUser = await User.authenticated('user', 'monkey')
```

## Tests

Run tests with `yarn test`.