Lesson overview
Explain authentication, authorisation and encryption, including why MFA and secure keys matter.
Focus: Authentication and encryption.
What you will learn
- Define the key GCSE Computer Science terms used in authentication and encryption.
- Explain how authentication works in a practical scenario.
- Compare authorisation with an alternative or related method.
- Apply authentication and encryption accurately in exam-style questions.
Before you start
- Cybersecurity threats.
- Binary/data representation.
- Web protocols.
Authentication scenarios
Use login, file permission and secure-message examples below to separate authentication, authorisation and encryption.
Authentication and encryption infographic
Explanation
Authentication checks identity, such as by password, biometrics, smart card or a one-time code. Authorisation decides what an authenticated user is allowed to access.
Multi-factor authentication combines different evidence types, making an account harder to compromise if one factor is stolen.
Encryption transforms readable data into ciphertext using a key, so intercepted data is not useful without the correct key to decrypt it.
Worked examples
Applying authentication
A teacher logs in with a password and phone code.
They can open their class files but not the headteacher's private folder.
Files sent over the connection are encrypted.
Answer: The password and code authenticate the teacher, permissions authorise access, and encryption protects data in transit.
Quick checks
1. What does authentication check?
- a. The colour of a keyboard
- b. The size of a monitor
- c. That a user or device is who it claims to be
Reveal answer
Answer: c. Correct. Authentication is about proving identity.
Not quite. Focus on authentication in the scenario.
2. Which idea is most closely linked to authentication and encryption?
- a. Encryption
- b. A monitor brightness setting
- c. A random file extension
Reveal answer
Answer: a. Correct. Encryption is part of this topic.
Not quite. Choose the option that belongs to the Computer Science concept.
Practice
1. What is authorisation?
Reveal answer
Answer: Deciding what an authenticated user is allowed to access or do.
Marking: Credit permissions/access rights.
2. Give one example of a second factor.
Reveal answer
Answer: Authenticator app code, hardware token, biometric or SMS code.
Marking: Credit valid factor.
3. Why encrypt data sent over public Wi-Fi?
Reveal answer
Answer: So intercepted data is unreadable without the key.
Marking: Credit protection from interception.
4. What is ciphertext?
Reveal answer
Answer: Encrypted data that is not readable without decryption.
Marking: Credit transformed unreadable data.
Exam practice ladder
- Fluency: recall the key term and use it accurately.
- Application: apply the idea to the scenario rather than giving a generic definition.
- Algorithmic reasoning: show the steps, condition or variable change clearly.
- Evaluation: explain why one method, structure or control is suitable.
Answers and marking guidance
Exact answers and marking guidance are hidden under each question. For this lesson, earn marks by naming the correct Computer Science idea, applying it to the scenario and showing the logic or value change clearly.
Common mistakes
- Confusing authentication with authorisation.
- Saying encryption stops data being intercepted at all.
- Assuming a password alone is always enough.
- Forgetting keys are needed for encryption and decryption.
Extension
Explain how HTTPS uses authentication and encryption to make online banking safer.
Next lesson
Next, continue with Defensive security measures.
Exam-board guidance
Aplailasain is an independent learning resource and is not endorsed by any exam board.
AQA GCSE Computer Science
AQA GCSE Computer Science: this skill supports problem solving, clear algorithms and accurate programming explanations.
OCR GCSE Computer Science
OCR GCSE Computer Science: expect precise algorithm reasoning, trace work and careful use of programming vocabulary.
Pearson Edexcel GCSE Computer Science
Pearson Edexcel GCSE Computer Science: practise explaining the method as well as giving the final answer or code.
Eduqas GCSE Computer Science
Eduqas GCSE Computer Science: secure the transferable idea first, then check how your class applies it in tasks.
WJEC Wales
WJEC Wales: use accurate terminology and show enough working for the examiner to follow your logic.
CCEA
CCEA: connect the idea to your class route and use the same algorithm, programming or systems vocabulary your teacher uses.