2.3.1

Defensive Design

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Defensive Design

Defensive design is an approach to software development that aims to produce robust and reliable programs.

Defensive design

Defensive design

Defensive design considerations include:
- Anticipating misuse of the program.
- Writing maintainable code.
- Testing the program.

Robust and reliable

Robust and reliable

Robust programs can handle unexpected inputs and data without crashing and without being tricked into malicious action.
- Thus, preventing an unauthorised user from performing a certain action when they do not have the correct access rights.
Reliable programs will work as intended under many different conditions or situations.
- The way a program has been created and is intended to work is often very different to how users will actually use it.

Anticipating misuse

Anticipating misuse

There are a number of ways that a system could be misused:
- Malicious inputs.
- Attempts to remotely connect.
- Attempts to alter access rights.
- Brute force attacks.

1

Computer Systems

1.1

Systems Architecture

1.1.1Fetch-Execute Cycle 1.1.2Common CPU Components & Their Function 1.1.3Von Neumann Architecture 1.1.4Factors Affecting CPU Performance 1.1.5Embedded Systems 1.1.6Exam-Style Questions - Von Neumann Architecture 1.1.7Diagnostic Misconceptions - Embedded vs General

1.2

Memory & Storage

1.2.1Types of Memory 1.2.2Flash Memory 1.2.3Properties of Flash Memory 1.2.4Running Out of Memory 1.2.5Virtual Memory 1.2.6Units of Capacity 1.2.7Calculating Capacity Requirements 1.2.8Solid State Storage 1.2.9Properties of Solid State Media 1.2.10Magnetic Storage 1.2.11Properties of Magnetic Media 1.2.12Examples of Magnetic Storage 1.2.13Optical Storage 1.2.14Properties of Optical Media 1.2.15Examples of Optical Storage 1.2.16Types of Optical Disk 1.2.17Number Bases 1.2.18Converting Number Bases 1.2.19Hexadecimal 1.2.20Using Hexadecimal 1.2.21Converting Denary & Hexadecimal 1.2.22Binary Addition 1.2.23Binary Shifts 1.2.24Representing Text 1.2.25ASCII & Unicode 1.2.26Representing Images 1.2.27Converting Binary & Images 1.2.28Representing Sound 1.2.29Data Compression 1.2.30Grade 9 - Storage 1.2.31Exam-Style Questions - Primary Memory 1.2.32Exam-Style Questions - Storage 1.2.33Exam-Style Questions - Data Conversions 1.2.34Diagnostic Misconceptions - RAM vs ROM 1.2.35Diagnostic Misconceptions - Bits, Nibbles & Bytes 1.2.36Diagnostic Misconceptions - Bits Required to Store 1.2.37End of Topic Test - Computer Systems 1.2.38End of Topic Test - Representation

1.3

Computer Networks, Connections & Protocols

1.4

Network Security

1.4.1Forms of Attack 1.4.2Penetration Testing 1.4.3Malware 1.4.4How Malware Spreads 1.4.5Social Engineering 1.4.6Phishing 1.4.7Cracking Passwords 1.4.8Denial of Service Attacks 1.4.9Data Interception 1.4.10Methods of Data Interception 1.4.11SQL Injection 1.4.12Network Administration 1.4.13Network Forensics 1.4.14Protecting Against Malware 1.4.15Firewalls 1.4.16User Access Levels 1.4.17Passwords 1.4.18Encryption 1.4.19End of Topic Test - Networks

1.5

Systems Software

1.5.1System Software 1.5.2Utility Software 1.5.3Operating Systems 1.5.4User Interfaces 1.5.5Memory & Process Management 1.5.6File Management 1.5.7Device Management 1.5.8User Management 1.5.9Encryption Software 1.5.10Defragmentation Software 1.5.11Data Compression Software 1.5.12Backup Software

1.6

Ethical, Legal, Cultural & Environmental Concern

2

Computational Thinking, Algorithms & Programming

2.1

Algorithms

2.1.1Computational Thinking - Abstraction 2.1.2Computational Thinking - Decomposition 2.1.3Algorithmic Thinking 2.1.4Pseudocode 2.1.5Flowchart Diagrams 2.1.6Interpreting Algorithms 2.1.7Correcting Algorithms 2.1.8Completing Algorithms 2.1.9Search Algorithms 2.1.10Binary Search 2.1.11Linear Search 2.1.12Overview of Sort Algorithms 2.1.13Bubble Sort 2.1.14Merge Sort 2.1.15Insertion Sort 2.1.16Exam-Style Questions - Sorting Algorithms

2.2

Programming Fundamentals

2.3

Producing Robust Programs

2.3.1Defensive Design 2.3.2Validation & Sanitisation 2.3.3Authentication & Contingencies 2.3.4Maintainability 2.3.5Purpose of Testing 2.3.6Types of Testing 2.3.7Test Plans 2.3.8Types of Errors 2.3.9End of Topic Test - Programming 2.3.10Exam-Style Questions - Testing

2.4

Boolean Logic

2.4.1Binary Systems 2.4.2Logic Circuits 2.4.3Boolean Logic 2.4.4Boolean Operators 2.4.5Grade 9 - Logic

2.5

Programming Languages & IDEs

2.5.1High-Level vs Low-Level Languages 2.5.2Translation - Compliers & Interpreter 2.5.3Translation - Assemblers 2.5.4Integrated Development Environments 2.5.5Exam-Style Questions - Translation

Jump to other topics

1

Computer Systems

1.1

Systems Architecture

1.1.1Fetch-Execute Cycle 1.1.2Common CPU Components & Their Function 1.1.3Von Neumann Architecture 1.1.4Factors Affecting CPU Performance 1.1.5Embedded Systems 1.1.6Exam-Style Questions - Von Neumann Architecture 1.1.7Diagnostic Misconceptions - Embedded vs General

1.2

Memory & Storage

1.2.1Types of Memory 1.2.2Flash Memory 1.2.3Properties of Flash Memory 1.2.4Running Out of Memory 1.2.5Virtual Memory 1.2.6Units of Capacity 1.2.7Calculating Capacity Requirements 1.2.8Solid State Storage 1.2.9Properties of Solid State Media 1.2.10Magnetic Storage 1.2.11Properties of Magnetic Media 1.2.12Examples of Magnetic Storage 1.2.13Optical Storage 1.2.14Properties of Optical Media 1.2.15Examples of Optical Storage 1.2.16Types of Optical Disk 1.2.17Number Bases 1.2.18Converting Number Bases 1.2.19Hexadecimal 1.2.20Using Hexadecimal 1.2.21Converting Denary & Hexadecimal 1.2.22Binary Addition 1.2.23Binary Shifts 1.2.24Representing Text 1.2.25ASCII & Unicode 1.2.26Representing Images 1.2.27Converting Binary & Images 1.2.28Representing Sound 1.2.29Data Compression 1.2.30Grade 9 - Storage 1.2.31Exam-Style Questions - Primary Memory 1.2.32Exam-Style Questions - Storage 1.2.33Exam-Style Questions - Data Conversions 1.2.34Diagnostic Misconceptions - RAM vs ROM 1.2.35Diagnostic Misconceptions - Bits, Nibbles & Bytes 1.2.36Diagnostic Misconceptions - Bits Required to Store 1.2.37End of Topic Test - Computer Systems 1.2.38End of Topic Test - Representation

1.3

Computer Networks, Connections & Protocols

1.4

Network Security

1.4.1Forms of Attack 1.4.2Penetration Testing 1.4.3Malware 1.4.4How Malware Spreads 1.4.5Social Engineering 1.4.6Phishing 1.4.7Cracking Passwords 1.4.8Denial of Service Attacks 1.4.9Data Interception 1.4.10Methods of Data Interception 1.4.11SQL Injection 1.4.12Network Administration 1.4.13Network Forensics 1.4.14Protecting Against Malware 1.4.15Firewalls 1.4.16User Access Levels 1.4.17Passwords 1.4.18Encryption 1.4.19End of Topic Test - Networks

1.5

Systems Software

1.5.1System Software 1.5.2Utility Software 1.5.3Operating Systems 1.5.4User Interfaces 1.5.5Memory & Process Management 1.5.6File Management 1.5.7Device Management 1.5.8User Management 1.5.9Encryption Software 1.5.10Defragmentation Software 1.5.11Data Compression Software 1.5.12Backup Software

1.6

Ethical, Legal, Cultural & Environmental Concern

2

Computational Thinking, Algorithms & Programming

2.1

Algorithms

2.1.1Computational Thinking - Abstraction 2.1.2Computational Thinking - Decomposition 2.1.3Algorithmic Thinking 2.1.4Pseudocode 2.1.5Flowchart Diagrams 2.1.6Interpreting Algorithms 2.1.7Correcting Algorithms 2.1.8Completing Algorithms 2.1.9Search Algorithms 2.1.10Binary Search 2.1.11Linear Search 2.1.12Overview of Sort Algorithms 2.1.13Bubble Sort 2.1.14Merge Sort 2.1.15Insertion Sort 2.1.16Exam-Style Questions - Sorting Algorithms

2.2

Programming Fundamentals

2.3

Producing Robust Programs

2.3.1Defensive Design 2.3.2Validation & Sanitisation 2.3.3Authentication & Contingencies 2.3.4Maintainability 2.3.5Purpose of Testing 2.3.6Types of Testing 2.3.7Test Plans 2.3.8Types of Errors 2.3.9End of Topic Test - Programming 2.3.10Exam-Style Questions - Testing

2.4

Boolean Logic

2.4.1Binary Systems 2.4.2Logic Circuits 2.4.3Boolean Logic 2.4.4Boolean Operators 2.4.5Grade 9 - Logic

2.5

Programming Languages & IDEs

2.5.1High-Level vs Low-Level Languages 2.5.2Translation - Compliers & Interpreter 2.5.3Translation - Assemblers 2.5.4Integrated Development Environments 2.5.5Exam-Style Questions - Translation

Practice questions on Defensive Design

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1
How might a system be misused?Fill in the list
2
What does it mean for a program to be robust?Multiple choice
3
What is the purpose of a check digit?Multiple choice
4
What is the purpose of terminal testing?Multiple choice
5
Which of the following best describes the purpose of a presence check?Multiple choice

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Diagnostic Misconceptions - Array Index

Validation & Sanitisation