About this Study Set
This study set covers Cryptography through
20 practice questions.
A collection of factual questions covering the history, principles, and applications of cryptographic systems. Every question includes the correct answer so you can learn as you go — pick any format above to get started.
Questions & Answers
Browse all 20 questions from the
Fundamentals of Cryptography study set below.
Each question shows the correct answer — select a study format above to practice interactively.
1
Which classical cipher works by shifting each letter of the plaintext by a fixed number of positions down the alphabet?
-
A
Vigenere cipher
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B
Caesar cipher
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C
Playfair cipher
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D
Rail fence cipher
2
What does the acronym AES stand for in modern symmetric encryption?
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A
Advanced Encryption Standard
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B
Automated Encoding System
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C
Applied Electronic Security
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D
Algorithmic Encryption Suite
3
In public-key cryptography, which key is typically made available to the public to encrypt messages?
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A
Private key
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B
Secret key
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C
Public key
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D
Session key
4
Who are the three individuals associated with the invention of the RSA algorithm?
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A
Diffie, Hellman, and Merkle
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B
Rivest, Shamir, and Adleman
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C
Shannon, Turing, and Von Neumann
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D
Kahn, Massey, and Knudsen
5
What is the primary purpose of a cryptographic hash function?
-
A
To encrypt sensitive data
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B
To verify data integrity
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C
To compress large files
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D
To generate random numbers
6
Which of the following is considered a symmetric-key encryption algorithm?
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A
RSA
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B
ECC
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C
DES
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D
Diffie-Hellman
7
The Enigma machine, used extensively during World War II, was primarily employed by which military force?
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A
United States Navy
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B
Imperial Japanese Army
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C
Nazi Germany
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D
Royal Air Force
8
What is the term for the process of converting ciphertext back into plaintext?
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A
Encoding
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B
Decryption
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C
Hashing
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D
Obfuscation
9
Which mathematical problem forms the basis of the security for the RSA algorithm?
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A
Discrete logarithm problem
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B
Integer factorization
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C
Elliptic curve mapping
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D
Knapsack problem
10
What does a digital signature primarily provide to a recipient?
-
A
Message encryption
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B
Data compression
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C
Authenticity and integrity
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D
Anonymity
11
The Vigenere cipher is categorized as what type of cipher?
-
A
Transposition cipher
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B
Polyalphabetic substitution cipher
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C
Monoalphabetic substitution cipher
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D
Stream cipher
12
Which protocol is widely used to provide secure communication over a computer network, such as the internet?
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A
TLS
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B
FTP
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C
HTTP
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D
SMTP
13
What is the name of the 'one-time pad' property that makes it theoretically unbreakable if used correctly?
-
A
Computational hardness
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B
Perfect secrecy
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C
Prime factorization
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D
Substitution parity
14
In cryptography, what is 'salt' used for?
-
A
To encrypt the main key
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B
To prevent rainbow table attacks on hashes
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C
To increase the length of a password
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D
To hide the algorithm type
15
Which of these is a widely used elliptic curve standard?
-
A
Curve25519
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B
RSA-4096
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C
DES-CBC
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D
SHA-3
16
What is the definition of a 'brute-force attack'?
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A
Exploiting a software vulnerability
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B
Guessing every possible key until the correct one is found
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C
Intercepting data in transit
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D
Modifying the plaintext directly
17
Which organization is responsible for publishing many of the standards used in modern cryptography, such as FIPS?
-
A
NIST
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B
IEEE
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C
ISO
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D
W3C
18
What is the function of a 'Nonce' in cryptographic protocols?
-
A
To identify the user
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B
To provide a unique value for a single communication session
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C
To compress the message
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D
To provide long-term key storage
19
Which of these is a stream cipher?
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A
AES
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B
ChaCha20
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C
RSA
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D
Twofish
20
What does 'Diffie-Hellman' allow two parties to achieve over an insecure channel?
-
A
Data encryption
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B
Shared secret key exchange
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C
Digital document signing
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D
Message authentication
