Start learning →

MCA Cyber Security Cryptography — practice questions

Explore 38 free Cryptography questions in MCA Cyber Security Cybersecurity. Open each question or exercise to read its content, reference answers and available explanation.

Practise Cryptography with Quill →

Cryptography questions and exercises with answers

Showing questions 1–30 of 38.

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 →A DIGITAL SIGNATURE provides which security property?Read the answer and worked solution →DIFFIE-HELLMAN key exchange allows two parties toRead the answer and worked solution →Which hash algorithm is considered DEPRECATED / WEAK and should NOT be used for new applications?Read the answer and worked solution →TLS (Transport Layer Security) uses a HYBRID encryption scheme. Why?Read the answer and worked solution →A CERTIFICATE AUTHORITY (CA) in PKI does what?Read the answer and worked solution →FORWARD SECRECY in TLS meansRead the answer and worked solution →A SALT in password hashing isRead the answer and worked solution →RSA encryption with PKCS#1 v1.5 padding is now consideredRead the answer and worked solution →Data that has not been encrypted is called:Read the answer and worked solution →The service that keeps sensitive information from unauthorised entities is:Read the answer and worked solution →A confidentiality service is provided by which cryptographic process?Read the answer and worked solution →The result of applying a hash function is also called a message:Read the answer and worked solution →A public key together with its corresponding private key is called a:Read the answer and worked solution →Turning ciphertext back into plaintext with an algorithm and key is:Read the answer and worked solution →A cryptographic hash function maps a bit string of arbitrary length to one of:Read the answer and worked solution →A message authentication code is described as a cryptographic:Read the answer and worked solution →A MAC uses which kind of key?Read the answer and worked solution →A MAC detects modifications that are intentional and also:Read the answer and worked solution →Providing assurance of the identity of an entity interacting with a system is:Read the answer and worked solution →Providing assurance of where information came from is:Read the answer and worked solution →Which service supports proving to a third party who signed a message?Read the answer and worked solution →Signature generation uses a digital signature algorithm together with a:Read the answer and worked solution →Signature verification uses the digital signature together with a:Read the answer and worked solution →A block cipher algorithm maps bit strings of a fixed length to strings of:Read the answer and worked solution →An algorithm using a block cipher as a primitive to provide a service is a:Read the answer and worked solution →A random bit generator outputs bits that appear statistically independent and:Read 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
Show answer and solution

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)._

Open this question →

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
Show answer and solution

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)._

Open this question →

AES is

  1. an asymmetric encryption algorithm
  2. a key-exchange protocol
  3. a hashing algorithm
  4. the Advanced Encryption Standard — a block cipher
Show answer and solution

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)._

Open this question →

How to practise

  1. Choose a Cryptography question and try to work out your answer.
  2. Open the question to check the correct answer and read its worked solution.
  3. Continue in the app for bite-sized lessons, explanations and review with Quill. You can start without creating an account.

More Cybersecurity topics

Network SecurityCybersecurity Framework CoreIncident Response Life Cycle