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Graded Quiz: Cryptography: Principles and Techniques :Penetration Testing, Threat Hunting, and Cryptography (IBM Cybersecurity Analyst Professional Certificate) Answers 2025

1. Question 1 — Symmetric Encryption Characteristic

  • Uses the same key for both encryption and decryption

  • ❌ Slower than asymmetric

  • ❌ Requires certificate

  • ❌ Uses two keys

Explanation:
Symmetric encryption always uses one shared key.


2. Question 2 — Why asymmetric is secure for key distribution

  • ❌ Single key

  • Uses separate public and private keys

  • ❌ Faster

  • ❌ No keys required

Explanation:
The public key can be openly shared without risking decryption.


3. Question 3 — RSA security foundation

  • ❌ Speed

  • ❌ Single key

  • Difficulty of factoring large composite numbers

  • ❌ Use of prime numbers

Explanation:
RSA security relies on the fact that factoring huge composite numbers is computationally infeasible.


4. Question 4 — Attack trying all key combinations

  • ❌ Chosen ciphertext

  • ❌ MitM

  • Brute-force attack

  • ❌ Dictionary attack

Explanation:
Brute-force = exhaustively testing every possible key.


5. Question 5 — Dictionary attack weakness

  • ❌ Only works with symmetric

  • It only works if the password is a common word

  • ❌ Slower than brute-force

  • ❌ Requires real-time access

Explanation:
Dictionary attacks rely on lists of common passwords.


6. Question 6 — Why MitM attacks are dangerous

  • Attackers can intercept and alter communication

  • ❌ Require brute force

  • ❌ Require physical access

  • ❌ Impossible to detect

Explanation:
MitM attackers can read AND modify messages secretly.


7. Question 7 — Pattern detection in ciphertext

  • ❌ Known plaintext

  • Linear cryptanalysis

  • ❌ Differential cryptanalysis

  • ❌ Timing attacks

Explanation:
Linear cryptanalysis studies linear patterns in encrypted data.


8. Question 8 — Good key management practice

  • ❌ Store keys in plain text

  • ❌ Reuse same key for many apps

  • Implement access controls for key retrieval

  • ❌ Share keys via email

Explanation:
Keys must be securely stored and access-controlled.


9. Question 9 — What hash function does

  • ❌ Encrypts

  • Generates fixed-size output from input data

  • ❌ Compresses

  • ❌ Stores data

Explanation:
Hashing is a one-way function producing a fixed-length digest.


10. Question 10 — Digital signature purpose

  • Verify authenticity and integrity

  • ❌ Compress data

  • ❌ Encrypt whole message

  • ❌ Generate random keys

Explanation:
Digital signatures confirm who sent the message and that it wasn’t altered.


🧾 Summary Table

Q Correct Answer Key Concept
1 Same key for enc/dec Symmetric encryption
2 Public/private keys Asymmetric distribution
3 Factoring difficulty RSA security
4 Brute-force attack Try all keys
5 Common words only Dictionary attack weakness
6 Intercept & alter MitM danger
7 Linear cryptanalysis Pattern analysis
8 Access controls Key management
9 Fixed-size hash Hash function
10 Auth + integrity Digital signatures