Criterion expressing the minimum efforts assumed necessary to defeat the specified security behavior of an implemented security function by directly attacking its underlying security mechanisms. Note 1: Strength of function has as a prerequisite that assumes that the underlying security mechanisms are correctly implemented. The concept of strength of functions may be equally applied to services or other capability-based abstraction provided by security mechanisms. Note 2: The term robustness combines the concepts of assurance of correct implementation with strength of function to provide finer granularity in determining the trustworthiness of a system.
Source(s):
NIST SP 800-160 Vol. 1

  Criterion expressing the minimum efforts assumed necessary to defeat the specified security behavior of an implemented security function by directly attacking its underlying security mechanisms. Note 1: Strength of function has as a prerequisite that assumes that the underlying security mechanisms are correctly implemented. The concept of strength of functions may be equally applied to services or other capability-based abstraction provided by security mechanisms. Note 2: The term robustness combines the concepts of assurance of correct implementation with strength of function to provide finer granularity in determining the trustworthiness of a system.
Source(s):
NIST SP 800-160 Vol. 1