The S.F.U (Security. Functionality. Usability/Ease of Use) is a security triad widely used.
In any implementation of security controls, all three factors – Security, Functionality, and Ease of Use, have to be considered carefully, searched for the balanced trade-off for all stakeholders.
Using the S.F.U Security Triads
Simply focusing on any one individual factor will severely impaired the others.
- Increased in Security will impair Functionality and Usability
- Increased in Functionality will cause vitiation of Security and Usability
- Increased in Usability reduce Security and Functionality
Security are usually the one being undermine by many corporations. Simply because it is not something that generate income for the organization. Although not included in the S.F.U security triad, an increase in Functionality and Usability means increase in work efficiency.
Adversaries would love to see companies heading towards that direction. Undermining security concerns, they could exploit the huge of pool of vulnerabilities opened to them.
Other Write-up on S.F.U Security Triads
 Andrew Waite. InfoSec Triads: Security/Functionality/Ease-of-Use. June 12, 2010.