Understanding SC 3.3.8:Accessible Authentication (Level AA)

Intent

The purpose of this Success Criterion is to ensure there is an accessible, easy-to-use, and secure method to log in. Most Web sites rely on usernames and passwords for logging in. Memorizing or transcribing a username, password, or one-time-code places a very high or impossible burden upon people with certain cognitive disabilities.

While Web sites can use the recognition of objects or of non-text content provided by the user to meet this SC, such techniques do not fully support the cognitive accessibility community and should be avoided if possible. Refer to Accessible Authentication (Enhanced) for guidance to be more inclusive and accessible.

Remembering a site-specific password is a cognitive function test. Such tests are known to be problematic for many people with cognitive disabilities. Whether it is remembering random strings of characters, or a pattern gesture to perform on a touch screen, cognitive function tests will exclude some people. When a cognitive function test is used, at least one other authentication method must be available which is not a cognitive function test.

If there is more than one step in the authentication process, such as with multi-factor authentication, all steps need to comply with this Success Criterion to pass. There needs to be a path through authentication that does not rely on cognitive function tests.

Being able to recover or change the email and password is an important part of authentication. If the user is authenticating with alternative information in order to recover their account, there needs to be a method that is not a cognitive function test.

Many organizations are required to use 2-factor authentication that combines independent sources to confirm a user's identity. These sources can consist of combining authentication through:

• knowledge (e.g., password, letters in a passphrase or memorized swipe path);
• possession (e.g., through receipt of a one time password generated, or received on a device, or scanning of a QR code on an external device);
• biometrics (e.g., fingerprint scanning, facial recognition or keystroke dynamics).

Most knowledge-based authentication methods rely on a cognitive function test so mechanisms to assist users must be available. When authentication relies on performing an action on a separate device, it should be possible to complete the action without the need to transcribe information. It may not be possible to know what device-based authentication methods are available to a user; offering a choice of methods can allow them to choose the path that most suits them.

Web sites can employ username (or email) and password inputs as an authentication method if it enables the user agent (browsers and third-party password managers) to fill in the fields automatically. Generally, if the login form meets Success Criterion 1.3.5 Input Purpose, and the form controls have an appropriate accessible name in accordance with Success Criterion 4.1.2 Name, Role, Value, the user agent should be able to reliably recognize the fields and automatically fill them in. However, if the user agent is actively blocked from filling in the fields (for instance, by a script), then the page would not pass this criterion because it prevents the mechanism from working.

Copy and paste can be relied on to avoid transcription. Users can copy their login credentials from a local source (such as a standalone third-party password manager) and paste it into the username and password fields on a login form, or into a web-based command line interfaces asking for a password. Blocking people from pasting into authentication fields, or using a different format between the copied text and the input field (for example, "Enter the 3rd, 4th, and 6th character of your password"), would force the user to transcribe information and therefore fail this criterion, unless another method is available.

Beyond usernames and passwords, some sites may use two-factor authentication, asking the user to enter a temporary code or One-Time Password (OTP). A service that requires manual transcription of a 2FA code (for instance, from one device to another) is not compliant. As with usernames and passwords, it must be possible for a user to at least use copy and paste to enter the code or OTP from a local source (such as a standalone third-party password manager, text message application, or software-based security key), or to allow user agents to fill in the fields automatically.

Note that two-factor systems that do not rely on codes - including hardware authentication devices (such as YubiKey), applications on a secondary device that expect the user to confirm that it is indeed them who are trying to log in on their other device, and authentication methods provided by the user's operating system (such as Windows Hello, or Touch ID/Face ID on macOS and iOS) - are not cognitive function test.

If the copy and paste requires the user to have and use multiple devices (e.g., copy code from phone, email to yourself, open on laptop) copying multiple times, then it would still be considered a Cognitive Function Test and fail this criterion. Some systems do allow for simple copy and paste across devices (e.g., tap code on phone, paste on laptop), which do not involve copying multiple times. HOwever, you would need all users to have easy access to that for it to be considered accessibility supported.

If a CAPTCHA is used as part of an authentication process, there must be a method that does not include a cognitive function test, unless it meets the exception. If the test is based on something the website has set such as remembering or transcribing a word, or recognizing a picture the website provided, that would be a cognitive functional test. Recognizing objects, or a picture the user has provided is a cognitive function test; however, it is excepted at the AA level.

An object in this context means the general English definition ("a material thing that can be seen and touched") and can include vehicles and animals. If the test goes beyond recognition (e.g. multiply the number cats by the number of dogs), that does not meet the exception.

Some forms of object recognition may require an understanding of a particular culture. For example, taxis can appear differently in different locales. This is an issue for many people, including people with disabilities, but it is not considered an accessibility-specific issue.

Some CAPTCHAs and cognitive function tests used for authentication may only appear in certain situations, such as when ad blockers are present, or after repeated incorrect password entry. This criterion applies when these tests are used regardless of whether they are used every time or only triggered by specific scenarios.

There are a number of technologies that can be employed to prevent scripted abuse of the authentication process.

• 1.1.1. Rate-limited Access
• 1.1.2. Client Geo-Location
• 1.1.3. Private Client Authentication

None of these systems are 100% effective. However, they may reduce the likelihood of a CAPTCHA being displayed.

Another factor that can contribute to cognitive load is hiding characters when typing. Although this criterion requires that users do not have to type in (transcribe) a password, there are scenarios where that is necessary such as creating a password to be saved by a password manager. Providing a feature to optionally show a password can improve the chance of success for some people with cognitive disabilities or those who have difficulties with accurately typing.

Personal content is sometimes used as a second factor for authentication. For example, as part of account creation the user would upload a picture, and when logging in they would be asked to select that picture from several possible alternatives. Care must be taken to provide adequate security in this case, since non-legitimate users might be able to guess the correct personal content when presented with a choice.

Text-based personal content does not qualify for this exception as it relies on recall (rather than recognition), and transcription (rather than selecting an item). Whilst picture-based personal content will still be a barrier for some people, text based versions tend to be a much larger barrier.

Another factor that can contribute to cognitive load is hiding characters when typing. Although this criterion requires that users do not have to type in (transcribe) a password, there are non-authentication scenarios where that is necessary. For example, creating a password to be saved by a password manager. Providing a feature to toggle the visibility of password can improve the chance of success for some people with cognitive disabilities or those who have difficulties with accurately typing.

Benefits

People with cognitive issues relating to memory, reading (for example, dyslexia), numbers (for example, dyscalculia), or perception-processing limitations will be able to authenticate irrespective of the level of their cognitive abilities.

Examples

• A web site uses a properly marked up username (or email) and password fields as the login authentication (meeting Success Criterion 1.3.5 Input Purpose and Success Criterion 4.1.2: Name, Role, Value). The user's browser or integrated third-party password manager extension can identify the purpose of the inputs and automatically fill in the username and password.
• A web site does not block paste functionality. The user is able to use a third-party password manager to store credentials, copy them, and paste them directly into a login form.
• A web site uses WebAuthn so the user can authenticate with their device instead of username/password. The user's device could use any available modality. Common methods on laptops and phones are facial-scan, fingerprint, and PIN (Personal Identification Number). The web site is not enforcing any particular use, it is assumed a user will setup a method that suits them.
• A web site offers the ability to login with a third-party provider using the OAuth method.
• A web site that requires two-factor authentication allows for multiple options for the 2nd factor, including a USB-based method where the user simply presses a button to enter a time-based token.
• A web site that requires two-factor authentication displays a QR code which can be scanned by an app on a user's device to confirm identity.
• A web site that requires two-factor authentication sends a notification to a user's device. The user must use their device's authentication mechanism (for example, user-defined PIN, fingerprint, facial recognition) to confirm identity.

Related Resources

Resources are for information purposes only, no endorsement implied.

• Security and Privacy Technologies issue paper from the Cognitive Task Force.
• WebAuthN specification.
• Web Authentication API on MDN.
• WebAuthN Demo site.
• OAuth on Wikipedia.
• "Let them paste passwords", from the UK's National Cyber Security Centre

Techniques

Each numbered item in this section represents a technique or combination of techniques that the WCAG Working Group deems sufficient for meeting this Success Criterion. However, it is not necessary to use these particular techniques. For information on using other techniques, see Understanding Techniques for WCAG Success Criteria, particularly the "Other Techniques" section.