Attributes

AvailabilityReliabilitySafetyConfidentialityIntegrityMaintainability

Dependability Means

Fault PreventionFault ToleranceFault RemovalFault Forecasting

ThreatsFaultsErrorsFailures

ability to deliver service that can justifiably be trusted

Risk definition and expression

Negligible Marginal Critical Catastrophic

Frequent

Probable

Occasional

Remote

Improbable

Pro

bab

ility

of

occ

urr

ence

Mishap severity

High

MediumLow

Serious

Probabilities of occurrence and mishap severity

Appliocation domains (transportation, energy production, telecommunications,

banking, etc.)

IEC 61508 (1998) – Combination of the probability of a damage and of its severity

MIL-STD-882D (Février 2000) – An expression of the impact and possibility of a mishap in terms of potential mishap severity and probability of occurrence

Risk assessment Practices vary according to countries

France: ‘globally at least as relevant’ (GAMAB) UK: ‘As low as reasonably possible’ (ALARP) Germany: ‘Minimum endogenous mortality’ (MEM)

Risk management Current situation: Risk level strength of

verification and validation activities Software considerations in airborne systems

and equipment certification, DO-178-B Common Criteria for Information Technology

Security Evaluation, ISO/IEC Standard 15408

Means for dependability

Fault PreventionFault ToleranceFault RemovalFault Forecasting

Verificationand Validation

Addressed faults (e.g., accidental, malicious)Coverage

Demonstration, analytical and experimentalDiversity