GDS advise that teams do not build login systems.

Building a login system is no easy task. While there are numerous open source libraries that make it trivial to add login functionality to your service, the moment you add that feature you’re:

  • significantly increasing your user support overhead (people forget how to sign in, lose their passwords etc)
  • gathering personal data that you’ll need to constantly review and protect
  • adding a relatively complex interaction for users to complete

Find alternatives

Many features that often come with using a login system can be completed in other (and potentially more useful) ways.

Saving search results, for example, doesn’t require a login but just a way of helping users remember a specific URL. Instead of having users log in, you could:

  • provide a tool to help send the URL to an email address
  • have instructions on creating a bookmark in their browser
  • take their email address and let them know if the search results change

The exact details will vary according to what users need from your service, but if there’s an alternative to a login system – use it.

When there isn’t an alternative

If, after careful review and design work, there’s no option but to build a login system, you’ll need to consider:

  • who you’re providing a login service for – a small number of agents (administrative users, accredited partners etc) or for a broad range of citizens or businesses?
  • if you have enough user data – enough to build trust with users or will you need to match them against other services (online or offline)?

It’s probably safe to carry on if you’re building a service for a small number of clearly identified agents. Make sure that any authentication and authorisation code written for your system is carefully separated from the application so that you can:

  • specifically monitor use of the system for attempts to gain access, like
    • unusually high numbers of failed login attempts over a short period of time
    • a sequence of failed logins on a given account over a long period of time
  • separate user data from other data you hold to avoid collecting a large amount of identifiable information
  • swap to a new identity system, like the GOV.UK Verify scheme, without invasive changes to the rest of your codebase

Read the advice published by the GOV.UK Verify if you need to:

  • build a system for a broad range of citizens and businesses
  • do sophisticated matching with other systems so you can build confidence in the identity of your users

Credentials

You should help your users to pick strong, secure passwords or phrases and consider whether it’s appropriate to require 2-factor authentication for extra security.

As a minimum passphrases should be eight characters long and include a mix of letters, numbers and symbols, but ideally they’ll be longer than that. We refer to passphrases as a phrase is usually easier to remember but harder to guess than a short collection of symbols or a single word.

For some admin systems on GOV.UK we use the zxcvbn library that measures how hard it would be for a computer to crack a passphrase using brute-force methods. That library is used to validate new passphrases and insist on strong passphrases. It’s only one measure, but it increases our confidence that our users are picking good passphrases.

All new government services should be served over HTTPS to ensure the communication between the user and the service is encrypted. This is especially important when logging in.

Lower usage rates

The Electronic License Management System (ELMS) license application system on Business Link required a login to complete an application. In building a new version of the system for GOV.UK we removed that requirement and usage rates have increased considerably. There’s still a login system for approved users in local authorities who need to process those applications.

Also see