Gce Model Questions Vol1 2021 Computer Studies Question 32

Practice objective / multiple choice question 32 from the 2021 Gce Model Questions Vol1 Computer Studies examination.

Gce Model Questions Vol1 2021 Computer Studies Objective / Multiple Choice Medium Difficulty
Question 32 GCE_MODEL_QUESTIONS_VOL1 • 2021 • COMPUTER_STUDIES • objective

A secure system requires passwords of exactly eight characters. Each character may be an uppercase letter (26 choices), a lowercase letter (26 choices), a digit (10 choices) or one of eight special symbols. The policy also demands that every password contain **at least one digit** and **at least one special symbol**.\n\n(a) How many different passwords satisfy the policy? Give your answer in scientific notation (to two significant figures).\n(b) If an attacker can test \(10^{6}\) passwords per second, estimate the minimum time (in years, to one decimal place) required to try half of the possible passwords.\n(c) Briefly discuss whether storing passwords using reversible encryption is ethically acceptable.

Answer Options

Correct Answer A. Total possible passwords ≈ 1.9 × 10¹⁴. Half the space ≈ 9.6 × 10¹³ attempts, which at 10⁶ attempts s⁻¹ takes about 3.1 years. Using reversible encryption to store passwords is unethical; passwords should be stored with one‑way salted hashes.
B. Total possible passwords ≈ 3.0 × 10¹⁴. Half the space ≈ 1.5 × 10¹⁴ attempts, which at 10⁶ attempts s⁻¹ takes about 5.0 years. Using reversible encryption to store passwords is unethical; passwords should be stored with one‑way salted hashes.
C. Total possible passwords ≈ 2.5 × 10¹⁴. Half the space ≈ 1.3 × 10¹⁴ attempts, which at 10⁶ attempts s⁻¹ takes about 4.2 years. Using reversible encryption to store passwords is unethical; passwords should be stored with one‑way salted hashes.
D. Total possible passwords ≈ 1.2 × 10¹⁴. Half the space ≈ 6.0 × 10¹³ attempts, which at 10⁶ attempts s⁻¹ takes about 1.9 years. Using reversible encryption to store passwords is unethical; passwords should be stored with one‑way salted hashes.
Correct Answer
A
Correct Option:
Total possible passwords ≈ 1.9 × 10¹⁴. Half the space ≈ 9.6 × 10¹³ attempts, which at 10⁶ attempts s⁻¹ takes about 3.1 years. Using reversible encryption to store passwords is unethical; passwords should be stored with one‑way salted hashes.

About This Question

This is Gce Model Questions Vol1 2021 Computer Studies Question 32. It is one of the objective questions from the 2021 Gce Model Questions Vol1 Computer Studies examination.

Difficulty level: Medium .

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