1. The document discusses several standards related to avionics safety and security, including DO-178B for software development processes, safety case analysis, and the Common Criteria for security evaluation. 2. DO-178B defines 5 design assurance levels (DALs) from A to E based on the level of risk. It also requires objective-based development, requirements traceability, and verification and validation plans. 3. Safety cases evaluate the safety argument and risk reduction measures through a structured report. The Common Criteria provides a framework for defining and evaluating security requirements and components through protection profiles, classes, and assurance levels.

1. Standards in Safety and
Security for Avionics
Alessandro Bruni, 08/11/2012

2. A Plethora of Standards
Concerning either:
1. Security
2. Safety
w.r.t.
3. Item development/evaluation
4. System development/evaluation

5. What we'll see here
1. DO-178B: SW development process
2. Safety Case Analysis
3. Common Criteria for Security

6. DO-178B
Objective Based:
"Objectives and activities that must be met or performed to
earn certification for the software product."
5 Design Assurance Levels (DALs):
A. Catastrophic
B. Hazardous/Severe-Major
C. Major
D. Minor
E. No Effect
From: Verification of Safety-Critical Software by B. Scott Andersen And George Romanski, Oct 2011

7. Assurance Levels and Risk

8. Software Engineering 101
"Most accidents are not the result of unknown scientific
principles but rather of a failure to apply well-known,
standard engineering practices."
How to apply good practices?
1. PSAC (Plan for Software Aspects of Certification)
2. SDP (Software Development Plan)
3. SVP (Software Verification Plan)
4. SCMP (Software Configuration Management Plan)
5. SQAP (Software Quality Assurance Plan)

9. No Surprises
Safe:
identification of the potential hazards, their likelihood and the effectiveness
of the countermeasures
Strong requirements:
multiple levels of requirements at different abstraction levels
No unintended function:
only what is specified should be present, no dead code, no hidden features
Traceable:
requirements and other project artifacts (eg. source code) are mapped
through a navigable relationship between two or more items

10. Requirements
Must have:
1. Requirement ID
2. Version ID
3. Author
4. Reviewer A Good Requirement:
a. compliance with system requirements,
b. accuracy and consistency,
c. compatibility with the target computer,
d. verifiability,
e. conformance to standards,
f. traceability, and
g. algorithmic aspects

11. Development Process
1. No prescribed SW life-cyclenot necessarily
waterfall to be successful
2. Reverse engineeringmay be applied to produce
necessary documentation
3. Reviews and independenceseparation of
responsibilities
(DO-178B does not specify how reviews must be done)

12. Validation and Verification
Validation "Are we building the right product?"
design error, comment error, documentation error,error-handling
problems, test errors, structural coverage problems,
modified functionality, requirements errors, code errors
Verification "Are we building the product right?"
1. requirements based tests
2. analysis (delivers document providing the evidence of correctness)
3. formal methods
4. exhaustive input testing (for small models)
5. structural coverage analysis (dead code vs. deactivated code)

13. Obtaining a Certificate
In the U.S. the certification authority is the FAA, but the FAA delegates its
responsibilities to a system of DERs (designated engineering representatives).
DER's Stages of Involvement:
o SOI-1:
o to ensure that there is a plan for certification everyone agrees on
o SOI-2:
o reviews any open issues from the first meeting
o done at 50% of the project
o SOI-3:
o takes place when 50% of the verification is complete
o SOI-4:
o to assess the readiness of the package for certification
o done when all certification evidence has been produced

14. Thoughts from the DO-178C Committee
D. Daniels, Verocel Ltd.
DO-178B: represented consensus of the avionics
community as of 1992
DO-178C: a series of addenda addressing formal methods,
object-oriented technology, model based design and
verification, tool qualification.
Formal methods don't have certification credit yet.
Goal based standard: avoids checklist mentality
Not an aspirational standard!
Does not try to advance the state of engineering practices, rather tries to reach
an agreement between current practices.

15. The Safety Case
Safety case: a clear, comprehensive and defensible
argument that a system is acceptably safe to operate in a
particular context.
Important aspects:
1. argument
2. clarity
3. system level
4. acceptable
5. context
From: A systematic approach to Safety Case Management, Tim Kelly, University of York, 2003

16. Safety Case Report
1. Scope
2. System Description
3. System Hazards
4. Safety Requirements
5. Risk Assessment
} product safety argument
6. Hazard Control / Risk Reduction Measures
7. Safety Analysis / Test } process safety argument
8. Safety Management System
9. Development Process Justification
10.Conclusions

17. Goal Structuring Notation

18. Lifecycle
Evolving Safety Arguments, during the whole software development lifecycle

19. Common Criteria
for IT Security Evaluation
1. Huge collection of security criteria
2. Useful for:
a. software developers
b. testers
c. evaluators
3. Highly customizable

20. Part 1: Introduction and General Model
Assets and Countermeasures

21. Evaluation

22. Security Requirements
Library of template requirements, better
specified by:
1. Iteration
2. Assignment
3. Selection
4. Refinement

23. Part 2: Security Functional Components
Classes:
Organized in
Families:
Components:
Protection Profiles:
Sets of families tailored for certain software
products (e.g. firewalls)

24. Classes
FAU: Security Audit
FCO: Communication
FCS: Cryptographic support
FDP: User Data Protection
FIA: Identification and Authentication
FMT: Security Management
FPR: Privacy
FPT: Protection of the TSF
FRU: Resource Utilization
FTA: TOE Access
FTP: Trusted Path/Channels

25. Part 3 : Security Assurance Components
Families, components and levels
Assurance levels:
Packages!

26. Classes
..instantiated:
EAL1: Functionally tested
EAL2: Structurally tested
EAL3: Methodically tested and
checked
EAL4: Methodically designed, tested
and reviewed
EAL5: Semiformally designed and
tested
EAL6: Semiformally verified design and
tested
EAL7: Formally verified design and
tested

27. Composed Assurance Packages
CAP A: Structurally composed
Only requires cooperation of the developer of the
independent component.

28. Composed Assurance Packages
CAP A: Structurally composed
Only requires cooperation of the developer ofthe
independent component.
CAP C: Methodically composed, tested,
reviewed
Max assurance from rigorous analysis of
interaction without full access to evaluation
evidence of base components

29. Composed Assurance Packages
CAP A: Structurally composed
Only requires cooperation of the developer of the
independent component.
CAP C: Methodically composed, tested,
reviewed
Max assurance from rigorous analysis of
interaction without full access to evaluation
evidence of base components
CAP B: Methodically composed
Developer gains max assurance under interaction
between components, minimising involvment of
component developer

30. Thanks for the attention :)