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B.Tech Cyber Security Cybersecurity — practice by topic

Browse 90 questions across 4 Cybersecurity topics. Choose what you want to revise, then open a question to check its answer and worked solution.

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Cybersecurity topics

Network Security (40)Cryptography (38)Cybersecurity Framework Core (6)Incident Response Life Cycle (6)

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SYMMETRIC encryption usesRead the answer and worked solution →ASYMMETRIC (public-key) cryptography usesRead the answer and worked solution →AES isRead the answer and worked solution →RSA security relies on the difficulty ofRead the answer and worked solution →

Worked practice questions

SYMMETRIC encryption uses

  1. two different keys: public for encrypt, private for decrypt
  2. no keys (steganography)
  3. the SAME secret key for both encryption and decryption
  4. biometric data only
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Correct answer: C. the SAME secret key for both encryption and decryption

1. SYMMETRIC encryption: a single shared secret key encrypts and decrypts. 2. Examples: AES, DES, 3DES, ChaCha20. 3. ADVANTAGE: very fast — used for bulk data encryption (file storage, disk encryption, TLS data channel). 4. DISADVANTAGE: key distribution — how do two parties agree on the secret without a pre-existing secure channel? 5. Option A is asymmetric. Options B, D are not encryption types. _Source: Boneh & Shoup, "A Graduate Course in Applied Cryptography", §2 (Symmetric encryption)._

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ASYMMETRIC (public-key) cryptography uses

  1. two linked keys: public + private
  2. the same key for both parties
  3. a one-way hash only
  4. no encryption at all
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Correct answer: A. two linked keys: public + private

1. ASYMMETRIC crypto: a key PAIR — anyone can encrypt to your public key, only your private key can decrypt. 2. Examples: RSA, ECC (Elliptic Curve), DSA, ElGamal. 3. SOLVES key distribution: you can publish your public key openly; secrecy of the private key is all that matters. 4. TRADE-OFF: much slower than symmetric (1000s of times). In practice: use asymmetric to exchange a session key, then symmetric for the actual data (HYBRID scheme). 5. Other options describe other cryptographic primitives. _Source: Boneh & Shoup, "A Graduate Course in Applied Cryptography", §10 (Public-key encryption)._

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AES is

  1. an asymmetric encryption algorithm
  2. a key-exchange protocol
  3. a hashing algorithm
  4. the Advanced Encryption Standard — a block cipher
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Correct answer: D. the Advanced Encryption Standard — a block cipher

1. AES (Advanced Encryption Standard): a SYMMETRIC BLOCK CIPHER, standardised by NIST in 2001 (FIPS 197). 2. Operates on 128-bit blocks; key sizes 128, 192, or 256 bits. 3. Internally uses substitution-permutation rounds (10/12/14 rounds for the three key sizes). 4. UNIVERSALLY ADOPTED: hardware-accelerated on virtually every modern CPU (AES-NI), used in TLS, full-disk encryption, WPA2/3, etc. 5. Other options misidentify AES. _Source: Boneh & Shoup, "A Graduate Course in Applied Cryptography", §4 (Block ciphers + AES)._

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