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Authentication

FoundationHigherAQA

Understand Authentication for GCSE Computer Science with this free worksheet and full mark scheme — Foundation and Higher exam-style questions with worked answers for AQA GCSE Computer Science (8525). Authentication confirms a user's identity, most commonly using a username and password.

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These worksheets and mark schemes are original, written for Virtus Academy and checked against the current AQA specification. Every worksheet comes with a full mark scheme.

Foundation

WorksheetFoundation · PDFMark SchemeFoundation · PDF

Higher

WorksheetHigher · PDFMark SchemeHigher · PDF

Topic overview

Authentication confirms that a user is who they claim to be, before granting access to a system.

The most common method is a username and password. A strong password is long, mixes upper and lower case letters, numbers and symbols, and is not a dictionary word or personal detail. Length matters more than complexity, because each extra character multiplies the number of possible combinations.

Stronger systems add more. Two-factor authentication requires a second piece of evidence, such as a code sent to a phone, so a stolen password alone is not enough. Biometrics use a fingerprint or face. CAPTCHA distinguishes humans from automated programs attempting to guess passwords at speed.

Revision notes

Passwords

A strong password is long, mixes character types, and avoids dictionary words and personal details.

Length matters most, because each additional character multiplies the number of possible combinations an attacker must try.

Two-factor authentication

A second piece of evidence is required alongside the password, such as a code sent to a phone.

This means a stolen password alone is not enough to gain access, which greatly reduces the value of a leaked password database.

Other methods

Biometrics use a physical characteristic such as a fingerprint or face.

CAPTCHA distinguishes humans from automated programs, preventing software from attempting thousands of password guesses per second.

Key points

  • Authentication confirms a user's identity.
  • Strong passwords are long and mix character types.
  • Length matters more than complexity.
  • Two-factor requires a second piece of evidence.
  • A stolen password alone is then insufficient.
  • CAPTCHA distinguishes humans from programs.

Worked examples

Example 1

State two features of a strong password. [2 marks]

Working

It is long, ideally twelve characters or moregive the first feature
It mixes upper and lower case letters, numbers and symbols, and is not a dictionary wordgive the second feature

Example 2

Explain how two-factor authentication improves security. [2 marks]

Working

It requires a second piece of evidence in addition to the password, such as a code sent to a phonestate what it requires
so an attacker who has stolen the password still cannot gain access without the second factorexplain the benefit

Example 3

Explain the purpose of CAPTCHA. [2 marks]

Working

It distinguishes a human user from an automated programstate its purpose
preventing software from attempting thousands of password guesses per secondexplain why that matters

Common mistakes

  • Saying complexity matters more than length.

    Each extra character multiplies the combinations, so length matters most.

  • Confusing authentication with authorisation.

    Authentication confirms who you are; authorisation determines what you may do.

  • Saying two-factor uses two passwords.

    The second factor is a different kind of evidence.

  • Giving only one password feature.

    Several are examinable.

Exam tips

  • Emphasise length when describing strong passwords.
  • Explain two-factor through the stolen-password scenario.
  • Distinguish authentication from authorisation.
  • Learn several authentication methods.

Key terms

Authentication
Confirming a user is who they claim to be.
Two-factor authentication
Requiring a second piece of evidence.
Biometrics
Authentication using a physical characteristic.
CAPTCHA
A test distinguishing humans from automated programs.

Related topics

Written and reviewed against the current AQA specification. Spotted an error? Let us know.