|
+8.1.1 Common Usability Considerations for Authenticators |
8.1.1 Common Usability Considerations for AuthenticatorsWhen selecting and implementing an authentication system, consider usability across the entire lifetime of the selected authenticators (e.g., their typical use and intermittent events) while being mindful of users, their goals, and their contexts of use. A single authenticator type does not usually suffice for the entire user population. Therefore, whenever possible and based on AAL requirements, CSPs should support alternative authenticator types and allow users to choose the type that best meets their needs. Task immediacy, perceived cost-benefit trade-offs, and unfamiliarity with certain authenticators often impact choices. Users tend to choose options that incur the least burden or cost at that moment. For example, if a task requires immediate access to an information system, a user may prefer to create a new subscriber account and password rather than select an authenticator that requires more steps. Alternatively, users may choose a federated identity option that is approved at the appropriate IAL, AAL, and federation assurance level (FAL) if they already have a subscriber account with an identity provider. Users may understand some authenticators better than others and have different levels of trust based on their understanding and experience. Positive user authentication experiences are integral to achieving desired business outcomes. Therefore, organizations should strive to consider authenticators from the users’ perspective. The overarching authentication usability goal is to minimize user burden and authentication friction (e.g., the number of times a user has to authenticate, the steps involved, the amount of information they have to track). Single sign-on (SSO) exemplifies one such minimization strategy. Usability considerations that are applicable to most authenticators include the following: Provide information on the use and maintenance of the authenticator (e.g., what to do if the authenticator is lost or stolen) and instructions for use, especially if there are different requirements for first-time use or initialization. Users will need to remember to have their authenticator readily available. Consider the need for alternative authentication options to protect against loss, damage, or other negative impacts on the original authenticator and the potential loss of battery power, if applicable. Alternative authentication options based on AAL requirements allow users to choose an authenticator based on their context, goals, and tasks (e.g., the frequency and immediacy of the task). Alternative authentication options also help address availability issues that may occur with a particular authenticator. Consider the characteristics of user-facing text:
Write user-facing text (e.g., instructions, prompts, notifications, error messages) in plain language for the intended audience. Avoid technical jargon, and write for the audience’s expected literacy level.
Consider the legibility of user-facing and user-entered text, including font style, size, color, and contrast with the surrounding background. Illegible text contributes to user entry errors. To enhance legibility, consider the use of:
High contrast (i.e., black on white)
Sans serif fonts for electronic displays and serif fonts for printed materials
Fonts that clearly distinguish between characters that are easily confused (e.g., the capital letter “O” and the number zero “0”)
A minimum font size of 12 points as long as the text fits for display on the device
Avoid using icons (e.g., padlocks or shields) that might be confused with security indicators in browsers.
Consider user experience during authenticator entry:
Offer the option to display text during entry, as masked text entry is error-prone. Once a given character is displayed long enough for the user to see, it can be hidden. Consider the device when determining masking delay time, as it takes longer to enter passwords on mobile devices (e.g., tablets and smartphones) than on traditional desktop computers. Ensure that masking delay durations are consistent with user needs.
Ensure that the time allowed for text entry is adequate (i.e., the entry screen does not time out prematurely). Ensure that the allowed text entry times are consistent with user needs.
Provide clear, meaningful, and actionable feedback on entry errors to reduce user confusion and frustration. Significant usability implications arise when users have no way of knowing that they have entered text incorrectly.
Allow at least 10 entry attempts for authenticators that require the entry of the authenticator output by the user. The longer and more complex the entry text, the greater the likelihood of user entry errors.
Provide clear, meaningful feedback on the number of remaining allowed attempts. For rate limiting (i.e., throttling), inform users how long they have to wait until the next attempt.
Minimize the impact of form-factor constraints, such as limited touch and display areas on mobile devices:
Larger touch areas improve usability for text entry since typing on small devices is significantly more error-prone and time-consuming than typing on a full-size keyboard due to the size of the input mechanism (e.g., a finger) relative to the size of the on-screen target.
Follow good user interface and information design for small displays.
Usability considerations for intermittent events (e.g., reauthentication, subscriber account lockout, expiration, revocation, damage, loss, theft, non-functional software) across authenticator types include the following: Prompt users to perform some activity just before (e.g., two minutes before) an inactivity timeout would otherwise occur. Prompt users to save their work before a fixed reauthentication timeout occurs, regardless of user activity. Clearly communicate how and where to acquire technical assistance (e.g., provide users with a link to an online self-service feature, chat sessions, or a phone number for help desk support). Ideally, sufficient information can be provided to enable users to recover from intermittent events on their own without outside intervention. Provide an accessible means for the subscriber to end their session (i.e., logoff). Subsequent sections describe usability considerations specific to a particular authenticator. 1. Visão geral
1.1 Referências1.2 Requisitos identificados1.3 Regulamentos relacionados2. Requisitos identificados
3. Regulamentos relacionados
|