Purposize

Purposize is a sequelize plugin to help with technically enforcing purpose limitation.

The European General Data Protection Regulation (GDPR) forces the "controller" to explicitly specify purposes for collecting, processing and storing personal data. This tool is designed to technically implement the concept of purpose limitation (GDPR Art. 5(1b)) and to help with provable compliance.

PURPOSIZE IS STILL WORK IN PROGRESS

Getting started

1. Install purposize using npm i purposize
2. Extend sequelize instance using purposize.init(sequelize)
3. Define your own models
4. Use isPersonalData: true to mark data fields as personal data
5. Sync your models to the DB using sequelize.sync()
6. Load purposes specification from .yml file using purposize.loadPurposes(filePath)

const Sequelize = require('sequelize')
const purposize = require('purposize')

const sequelize = new Sequelize(...)
purposize.init(sequelize)

const Customers = sequelize.define('customers', {
  eMail: {
    type: Sequelize.STRING,
    isPersonalData: true
  },
  postalAddress: {
    type: Sequelize.STRING,
    isPersonalData: true
  },
  unfulfilledOrders: {
    type: Sequelize.INTEGER
  }
})
await sequelize.sync()
await purposize.loadPurposes('./purposes.yml')

Creating instances

When creating instances that should contain personal data you must specify a purpose within the options object using the purpose key. The purpose may either be a string or an array of strings.

The personal data fields that you want to store must match with the relevant fields from your yaml specification.

When specifying only non-personal attributes the purpose field can be omitted.

const alice = await Customers.create({
  eMail: "alice@email.com",
  postalAddress: "1234 Shoppington",
}, {
  purpose: 'ORDER'
  // purpose: ['ORDER', 'NEWSLETTER']
})

const bob = await Customers.create({
  unfulfilledOrders: 2
})
// No purpose needed since unfulfilledOrders is a non-personal attribute

Querying instances

Querying work as usual with the exeception that you have to provide a purpose when wanting to retrieve personal data. When adding personal data fields to the attributes array (SELECT statement) or where object (WHERE statement) you must provide a purpose that legitimizes the access of those personal data fields. The purpose in queries is specified using the for key and must be of type string.

The returned result may contain instances that have been stored for exactly the specified purpose but also compatible purposes. Every instance only contains all non-personal attributes together with the legitimized personal attributes. All other personal attributes that are not legitimized by the specified purpose are stripped out and are not returned.

When no purpose is specified, the query result only contains non-personal data.

const result = await Customers.findAll({
  attributes: [ ... ]
  where: { ... },
  for: 'NEWSLETTER'
})

// Result contains instances that have been stored for the purpose NEWSLETTER or other compatible purposes.
// Every instance contains all non-personal attributes (in this example: unfulfilledOrders) together with the legitimized personal data attributes (in this example: eMail).

Updating instances

When updating already existing attributes you can simply call the save method with no further options.

When wanting to add a new personal data field to an instance you must again specify a purpose that legitimizes the storage. It works the same as creating an instance. You need to set the purpose key within the options object.

// Adding no personal data fields
const alice = await Customers.find({ 
  where: {
    eMail: "alice@email.com"
  },
  for: 'ORDER'
})

alice.eMail = "alison@mail.de"
alice.postalAddress = "9876 Cheapcity"
await alice.save()

// Adding new personal data fields
const bob = await Customers.find({ 
  where: {
    unfulfilledOrders: 2
  }
})

bob.eMail = "bob@email.com"
await alice.save({
  purpose: 'NEWSLETTER'
})

Purpose specification

Explanation of keys

Logging Levels

We have specified the following logging levels

Example

# purposes.yml

purposes:
- name: NEWSLETTER
  relevantFields:
    customers:
      - eMail
  loggingLevel: CHANGE
- name: ORDER
  relevantFields:
    customers:
      - eMail
      - postalAddress
  retentionPeriod: 60 
  loggingLevel: ACCESS
  compatibleWith:
    - MONTHLY_DELIVERY
- name: FULFILLMENT
  relevantFields:
    customers:
      - postalAddress
  compatibleWith:
    - ORDER
- name: MONTHLY_DELIVERY
  relevantFields:
    customers:
      - eMail
      - postalAddress
  loggingLevel: CHANGE

Modified Methods

Sequelize Instance

• sequelize.define
• sequelize.sync

TableDAO

• tableDAO.findAll

Instance

• instance.save
• instance.removePurpose