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USABLE SECURITY
References
Cranor & Garfinkel, Security and Usability, O’Reilly
Sasse & Flechais, “Usable Security: Why Do We Need It? How Do We Get It?”
McCracken & Wolfe, User Centered Website Development: a Human-Computer Interaction Approach, Prentice Hall.
Theofanos & Pfleeger, “Shouldn’t All Security be Usable”, IEEE Security & Privacy
People
People are the “weakest link in the chain” of system security.
Even a very usable security mechanism is likely to create extra work from the users’ point of view. It is human nature to look for shortcuts and workarounds, especially when they do not understand why their behavior compromises security.
Usability and Security
Usability and security are often seen as competing design goals.
Security mechanisms have to be usable to be effective.
Mechanisms that are not employed in practice or that are used incorrectly, provide little or no protection.
Human Computer Interaction Many website, applications, and
devices have complicated and confusing interfaces.
HCI goal is to improve usability.
Why HCI?
Competitive advantage. Reduce maintenance cost. Improve productivity. Reduce support cost.
How?
User-centered design methodology. User testing early and often. Interdisciplinary
Psychology Graphic Design Technical Writing
Highly Iterative
DESIGN
PROTOTYPE
EVALUATE
READY TO IMPLEMENT
MEET USER SPECIFICATIONS?
NO YES
User Analysis
Type of users Users are probably not like us. Not
computer professionals. Design the product with user in mind. Determine who the users are may not be
a trivial task. Understand user goals
Design the product the user wants and will use.
Organization
Content Organization User terminology How users group information
Visual Organization Proximity Alignment Consistency Contrast
Organization
Navigation How can users effectively find what they
need or do their task.
User Testing
High fidelity Low fidelity
Computer prototype Paper prototype Paper Prototyping: A How-To Video
User Testing with prototype Give the user a task Have them think out loud Do not coach Record whether the user was
successful or got confuse Redesign prototype and test on other
users.
Usable Security
Do user testing of security mechanisms.
Look at the usability of security messages.
Incorporate usable design principles into security mechanisms.
Problem #5
Incorporating usability and security into the software design process.
Software Development
Often and security and usability are added at the end of the software development process.
Human Problem
Current security mechanisms are too complex for many users.
Users may not behave in a way for the security mechanisms to be effective.
Example: Medical staff remained logged in
throughout the day. Circumventing security controls allows efficient patient care.
Usability Design Goal
Reduce the mental workload to make a security decision.
Is this easier said than done? Example:
Password policies Long passwords More complex passwords Change passwords frequently
Mental Workload
We do not recall our passwords 100% of the time. We mistype our passwords.
Given a large number of attempts, most users log in successfully.
When the number of allowed attempts was increased from 3 to 9, the percentage of successful logins was increased from 53% t0 93%.
Awkward Behaviors
Policy “User should lock their computers
screens when they are away from their desks.”
Many users in shared offices do not comply with this policy.
Why? Will my colleagues think that I do not
trust them? Most users prefer to have a trusting
relationship with their colleagues.
Handheld fingerprint ID Device for Law Enforcement
Shouldn’t All Security Be Usable – page 12
Social Behavior
People that follow security policies to the letter are described as “paranoid” and “anal” by their peers.
If secure systems require users to behave in a manner that conflicts with their norms, values , or self-image, most users will not comply.
Where a positive culture is in place, compliance can be a shared value and a source of pride.
Users and security
Do users have to be security experts to use systems securely?
Users must believe that their assets are under threat and that the security mechanism provides effective protection against the threat.
Security is too challenging Security makes unreasonable
demands on users, system administrators and developers.
Users cannot always tell legitimate email from phishing.
Security devices are difficult for system administrators to configure.
Building secure applications is difficult for developers
Problem #6
E-Mail Fraud Hides Behind Friendly Face
Status of Security Today
The security perimeter has expanded Mobile workforce
Laptops Smart phones
We cannot depend upon technology to protect us Firewalls & IPS are limited Hackers are attacking users rather than
network vulnerabilities
Users’ Goals
Security is not the primary goal of users.
Security must be designed to support production tasks.
Security regulations should not interfere with getting your job done.
Mental Models for Security Psychological acceptability relies on
mental models for computer constructs, such as a computer “file system” with files stored in folders.
We need similar effective mental models for the user perception of security, trust, and risk.
Complexity and Usability
As the security mechanisms grow more complex, they become harder to configure, to manage, to maintain, and to implement correctly.
Complexity has the greatest potential to weaken not only usability but also security.
Empowering the user
We need to make it easier for the user to do the right thing, hard to do the wrong thing, and easy to recover when the wrong thing happens anyway.
Security Messages
http://msdn.microsoft.com/en-us/library/ms995351.aspx
Problem #8
Error messages
