A better understanding

Safety versus Security

The author

Stéphane POTIER Technology Marketing Manager

B&R Automation

stephane.potier@br-automation.com

Perfection in Automation www.br-automation.com

Safety

Safety is freedom from unacceptable risk of physical injury or of

damage to the health of people, either directly, or indirectly as a

result of damage to property or to the environment.

Safety is an attribute of Dependability.

Definition

Dependability

Dependability of a system is the ability to deliver service that can

justifiably be trusted.

Dependability is a measure of a system's availability, reliability,

safety, integrity and its maintainabilty

Definition

Security

Security is the prevention of illegal or unwanted penetration,

intentional or unintentional interference with the proper and intended

operation, or inappropriate access to confidential information in

industrial automation and control systems.

Security is a composite of availability, confidentiality and integrity.

Definition

Dependability & Security attributes

• Availability - readiness for correct service (usually expressed as a

percentage of uptime in a given year)

• Reliability - continuity of correct service (typically expressed as a

probability of failure-free system operation over a specified time)

• Safety - absence of catastrophic consequences or severe injuries

on the users and the environment

• Confidentiality: absence of unauthorized disclosure of information

• Integrity - absence of improper system alteration

• Maintainability - ability for a process to undergo modifications and

repairs

Definition

Dependability attributes

Relationship

Dependability

Availability

Reliability

Safety

Confidentiality

Integrity

Maintainability

Security attributes

Relationship

Security

Availability

Reliability

Safety

Confidentiality

Integrity

Maintainability

Functional Safety

Functional safety is part of the overall safety that depends on a

system or equipment operating correctly in response to its inputs.

including the safe management of likely operator errors, hardware

failures and environmental changes.

IEC 61508 is intended to be a basic functional safety standard

applicable to all kinds of industry.

Definition

Translation

• Dependability = Sûreté de fonctionnement

• Reliability = Fiabilité

• Availability = Disponibilité

• Maintainability = Maintenabilité

• Safety = Sécurité/Sûreté (1)

• Security = Sécurité (1)

• Integrity = Intégrité

(1) The French word « Sécurité » is used to translate

both « Safety » and « Security ». In some industries, the

word « Sûreté » is used to translate « Safety ».

French

Translation

• Dependability = Verlässlichkeit

• Reliability = Zuverlässigkeit

• Availability = Verfügbarkeit

• Maintainability = Instandhaltbarkeit

• Safety = Sicherheit (2)

• Security= Sicherheit (2)

• Integrity = Integrität

(2) The German word « Sicherheit » is used to translate

both « Safety » and « Security ». For this reason the

English terms are usually preferred.

German

References

[1] http://en.wikipedia.org/wiki/Dependability

[2] http://www.iec.ch/functionalsafety

[3] IEC/TS 62443-1-1 Industrial communication networks – Network

and system security – Part 1-1: Terminology, concepts and models

[4] A. Avizienis, J.-C. Laprie and B. Randell: Fundamental Concepts

of Dependability. Research Report No 1145, LAAS-CNRS, April

2001

[5] http://www.open-safety.org

YOUR GLOBAL PARTNER FOR

AUTOMATION EXCELLENCE