2.3.3

Authentication & Contingencies

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Authentication and Contingencies

Two very important elements of defensive design are authentication and contingency planning.

Authentication

Authentication

Authentication is the process of checking that a person or system is authorised to use a system.
The most common form of authentication is to require users to enter a username and password.
Once a user has authenticated themselves, they should be able to see data relevant to themselves and no one else.

Contingency planning

Contingency planning

It is impossible to predict all possible cases of misuse, but there are ways to help reduce errors. For example:
- Providing helpful prompt messages.
- Providing error-recovery routes (e.g. an undo feature).
- Preventing access from certain parts of the system.
- Using exception handling.

Exceptions

Rather than leaving the program to crash when an error happens, exceptions give us a chance to handle the error more gracefully.

Exceptions

Exceptions

When an error arises in a program, the program is said to 'throw' an exception.
An exception is a description of the error that arose.
Exceptions can be 'caught' or handled rather than allowing the program to crash.

Handling exceptions

Handling exceptions

If an exception can be dealt with internally, then we can catch the exception and continue with the program.
This is done using a structure as below:
- try: ---
- except: ---
The code within the try block will be executed.
- If an exception is thrown inside the try block, then the except block will be run to 'clean up' after the exception.

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 Authentication & Contingencies

Can you answer these? Test yourself with free interactive practice on Seneca — used by over 10 million students.

1
The most common form of authentication requires what data from the user?Fill in the list
2
Once a user is authenticated, what should they see?Multiple choice
3
Which of these is a common error-recovery route?Multiple choice
4
What is it called when an error arises in a program?Multiple choice
5
What is the purpose of the 'except' block of a try-except structure?Multiple choice

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Validation & Sanitisation

Maintainability