Re: SFRs - Requirement Specification or Implementation Description?

[Tom Benkart <tom.benkart@consulting-cc.com>]

I agree with your view - this has been an accepted position in multiple
evaluations that I've been involved with.

If starting/stopping the TOE is equivalent to starting/stopping the audit
function and an audit is generated for those events, then the requirement
is satisfied.  There is no requirement that a separate management
operation for starting/stopping the audit function be available.

If an explicitly stated variant of FAU_GEN is used, another possible
issue is introduced - is the dependency on FAU_GEN from other SFRs
satisfied?  

Tom

At 01:54 PM 11/29/2006, you wrote:
> What is the purpose
> of Security Functional Requirements (SFRs) in a Security Target? Are they
> intended to specify what security functionality is to be provided by the
> TOE, or to specify the security functionality the TOE implements?
>  
> This question is raised as the result of a recent validator comment. The
> ST claims FAU_GEN.1 and the TSS explains that the TOE satisfies the
> aspect of the requirement to audit startup and shutdown of the audit
> function because auditing is always enabled – when the TOE starts up, an
> audit record of TOE startup is generated, which indicates the startup of
> the audit function (and, similarly, the TOE generates an audit record
> that it is shutting down, indicating shutdown of the audit function). To
> my knowledge, and in my own experience, this reasoning has always been
> acceptable for justifying that a TOE satisfies this aspect of FAU_GEN.1.
> The validator, however, insists that the ST must explicitly state its
> audit requirement because it clearly does not audit startup and shutdown
> of the audit function (because the TOE does not provide a capability to
> turn the audit function on and off).
>  
> I am interested in other people’s views about this.
>  
> Anthony J. Apted
> Lead Evaluator/Senior System Security Engineer
> SAIC CCTL
> Ph: (410) 953-6837
> Fx: (410) 953-7001
>  
>

Tom Benkart
Common Criteria Consulting LLC
work: 301-570-9308
cell: 240-401-1173
tom.benkart@consulting-cc.com