Master Cryptography: Secure Your Code in Theory of Computation

Question 1

Which characteristic is essential for a robust cryptographic hash function?

Accepted Answer

Consistent hash values for identical inputs

Answer

Ease of inverting the hash function

Answer

Variable-length hash outputs

Answer

Vulnerability to collision attacks

Question 2

Which symmetric-key encryption algorithm operates with a fixed block size and a variable key size?

Accepted Answer

AES

Answer

RSA

Answer

SHA-256

Answer

ECC

Question 3

Which symmetric-key encryption algorithm is renowned for its high performance, enabling rapid encryption and decryption processes?

Accepted Answer

AES

Answer

RSA

Answer

DES

Answer

ECC

Question 4

What is the purpose of a digital signature?

Accepted Answer

To verify the origin and integrity of a message, ensuring that it comes from a trusted source and has not been tampered with.

Answer

To encrypt a message, making it unreadable to unauthorized parties.

Answer

To decrypt a message, converting it back to its original form.

Answer

To compress a message, reducing its file size for efficient storage or transmission.

Question 5

What is the difference between a block cipher and a stream cipher?

Accepted Answer

Block ciphers encrypt fixed-length blocks of data at a time, while stream ciphers encrypt individual bits or bytes in a continuous stream.

Answer

Stream ciphers are faster than block ciphers because they do not require padding.

Answer

Block ciphers are more secure than stream ciphers because they are not susceptible to certain types of attacks.

Answer

There is no fundamental difference between block ciphers and stream ciphers.

Question 6

What is the role of a hash function in cryptography?

Accepted Answer

To generate a unique fingerprint of a message that can be used for verification and data integrity.

Answer

To encrypt a message, making it unreadable to unauthorized parties.

Answer

To decrypt a message, converting it back to its original form.

Answer

To generate a random number that can be used for cryptographic purposes.

Question 7

What is the concept of a public-key infrastructure (PKI)?

Accepted Answer

A system for issuing, managing, and revoking digital certificates that bind digital identities to public keys.

Answer

A network of interconnected cryptographic devices that provide secure communication channels.

Answer

A set of algorithms used for encryption and decryption, particularly for asymmetric cryptography.

Answer

A type of firewall that protects against cyber attacks by inspecting incoming and outgoing network traffic.

Question 8

Which of the following is not a cryptographic hash function?

Accepted Answer

AES

Answer

MD5

Answer

SHA-256

Answer

HMAC

Question 9

Which of the following algorithms is specifically designed for symmetric-key encryption?

Accepted Answer

AES

Answer

RSA

Answer

SHA-256

Answer

ECC

Question 10

Which cipher mode encrypts each block with a unique initialization vector, ensuring that identical plaintext blocks result in distinct ciphertext blocks?

Accepted Answer

Cipher Block Chaining Mode (CBC)

Answer

Electronic Codebook Mode (ECB)

Answer

Cipher Feedback Mode (CFB)

Answer

Output Feedback Mode (OFB)

Question 11

What is the key size used in AES in its 256-bit mode?

Accepted Answer

256 bits

Answer

128 bits

Answer

192 bits

Answer

384 bits

Question 12

Which of the following cryptosystems utilizes the same key for both encryption and decryption?

Accepted Answer

DES

Answer

RSA

Answer

ECC

Answer

DSA

Question 13

What is the primary purpose of a digital signature in the context of cryptography?

Accepted Answer

To authenticate the origin and integrity of a message, ensuring it has not been tampered with

Answer

To encrypt a message and ensure its confidentiality

Answer

To compress a message, reducing its size for efficient transmission

Answer

To provide non-repudiation, preventing the sender from denying their involvement in sending the message

Question 14

Which of the following protocols is used for establishing a secure communication channel by exchanging cryptographic keys?

Accepted Answer

Diffie-Hellman

Answer

MD5

Answer

AES

Answer

SHA-256

Question 15

Which of the following describes a cryptanalytic attack that attempts to exploit physical characteristics of the encryption device or implementation?

Accepted Answer

Side-channel attack

Answer

Brute-force attack

Answer

Linear cryptanalysis

Answer

Differential cryptanalysis

Question 16

Which of the following is a function that takes an arbitrarily long input and produces a fixed-size output, often used for data integrity verification?

Accepted Answer

MD5

Answer

AES

Answer

RSA

Answer

Diffie-Hellman

Question 17

Which of the following is not a fundamental principle of cryptography?

Accepted Answer

Availability

Answer

Confidentiality

Answer

Integrity

Answer

Non-repudiation

Question 18

Which of the following is NOT a fundamental property of a robust cipher?

Accepted Answer

Availability: Guaranteeing that data is accessible to authorized parties when needed.

Answer

Confidentiality: Ensuring that only authorized parties can access sensitive information.

Answer

Integrity: Protecting data from unauthorized modification or corruption.

Answer

Non-repudiation: Preventing individuals from denying their involvement in creating or sending a message.

Question 19

Which encryption technique employs the same key for both encryption and decryption?

Accepted Answer

DES (Data Encryption Standard)

Answer

RSA (Rivest-Shamir-Adleman)

Answer

ECC (Elliptic Curve Cryptography)

Answer

SHA-256 (Secure Hash Algorithm 256)

Question 20

Differentiate between block ciphers and stream ciphers.

Accepted Answer

Block ciphers process data in fixed-size blocks, while stream ciphers handle data in a continuous stream, encrypting each bit or byte individually.

Answer

Stream ciphers are inherently more efficient than block ciphers.

Answer

Block ciphers offer superior security compared to stream ciphers.

Answer

Block ciphers and stream ciphers share no fundamental distinctions.

Question 21

State the primary purpose of a digital signature.

Accepted Answer

Verifying the authenticity and integrity of electronic messages.

Answer

Concealing the contents of a message from unauthorized parties.

Answer

Generating random numbers for cryptographic applications.

Answer

Reducing the size of a message for efficient transmission.

Question 22

Identify the option that is NOT a cryptographic hash function.

Accepted Answer

DES (Data Encryption Standard)

Answer

MD5 (Message Digest 5)

Answer

SHA-256 (Secure Hash Algorithm 256)

Answer

HMAC (Hash-based Message Authentication Code)

Question 23

What is the ultimate objective of cryptanalysis?

Accepted Answer

Breaking existing encryption algorithms to expose their vulnerabilities.

Answer

Developing new encryption algorithms with enhanced security.

Answer

Analyzing the theoretical foundations of encryption algorithms.

Answer

Implementing encryption algorithms in hardware and software systems.

Question 24

Which algorithm belongs to the category of symmetric-key algorithms?

Accepted Answer

AES

Answer

RSA

Answer

DSA

Answer

SHA-256

Question 25

Which of the following is NOT a type of symmetric-key encryption algorithm?

Accepted Answer

RSA

Answer

AES

Answer

DES

Answer

RC4

Question 26

Which of the following is NOT a type of symmetric-key encryption algorithm?

Accepted Answer

ElGamal

Answer

Blowfish

Answer

AES

Answer

DES

Question 27

In asymmetric encryption, what is the key difference between a private key and a public key?

Accepted Answer

A private key is used for decryption, while a public key is used for encryption.

Answer

Both keys can be used for encryption and decryption.

Answer

A private key is used for encryption, while a public key is used for decryption.

Question 28

What is the primary purpose of a digital signature in cryptography?

Accepted Answer

To verify both the origin and integrity of a message.

Answer

To encrypt the content of a message.

Answer

To ensure anonymity for the sender of a message.

Question 29

Which protocol is widely used to establish secure communication channels over insecure networks?

Accepted Answer

TLS/SSL

Answer

IMAP

Answer

HTTP

Answer

FTP

Question 30

What is the primary advantage of utilizing hash functions in cryptography?

Accepted Answer

Producing a fixed-size output that can be used to efficiently verify data integrity.

Answer

Encrypting data to protect it from unauthorized access.

Answer

Generating random numbers for encryption algorithms.

Question 31

Which common method is employed to protect passwords from being compromised?

Accepted Answer

Hashing

Answer

Permutation

Answer

Diffusion

Answer

Substitution

Question 32

What is the main purpose of employing a block cipher in cryptography?

Accepted Answer

Efficient encryption of large amounts of data.

Answer

Efficient encryption of small amounts of data.

Answer

Generating secure random numbers.

Answer

Authentication of users.

Question 33

Which of the following best describes a common steganography technique?

Accepted Answer

Concealing data within images.

Answer

Employing encryption to secure data.

Answer

Generating random numbers for cryptographic use.

Answer

Using hash functions to verify data integrity.

Question 34

What is the overarching goal of cryptography?

Accepted Answer

Protecting data against unauthorized access, use, or modification.

Answer

Enhancing data transmission speed.

Answer

Reducing data size through compression.

Question 35

Which of the following algorithms is used in the RSA cryptosystem?

Accepted Answer

Asymmetric cryptography

Answer

Symmetric cryptography

Answer

Digital signature

Answer

Hashing algorithm

Question 36

What is the main purpose of a digital certificate?

Accepted Answer

To establish trust and verify the identity of a user or device

Answer

To encrypt data

Answer

To hash data

Answer

To decrypt data

Question 37

Which of the following is a common attack technique used against hash functions?

Accepted Answer

Collision attack

Answer

Replay attack

Answer

Man-in-the-middle attack

Answer

Brute force attack

Question 38

Which of the following is an example of a symmetric-key algorithm?

Accepted Answer

AES

Answer

ECC

Answer

RSA

Answer

SHA-256

Question 39

What is the main reason for using a salt when hashing passwords?

Accepted Answer

To increase the difficulty of cracking passwords using pre-computed tables (rainbow tables)

Answer

To generate a random key for encryption

Answer

To encrypt the password

Question 40

Which of the following is a characteristic of a keyless hash function?

Accepted Answer

It does not require a key for the hashing process

Answer

It generates a variable-length output

Answer

It is vulnerable to collision attacks

Answer

It is used for asymmetric encryption

Question 41

What is the purpose of a digital envelope in cryptography?

Accepted Answer

To combine symmetric and asymmetric encryption for secure data transmission

Answer

To hash data using a symmetric key

Answer

To generate a random key for encryption

Question 42

Which encryption algorithm employs a block cipher and processes 128-bit blocks?

Accepted Answer

AES

Answer

RSA

Answer

DES

Question 43

Which cryptanalytic attack aims to recover plaintext without knowledge of the key?

Accepted Answer

Ciphertext-only attack

Answer

Chosen-ciphertext attack

Answer

Chosen-plaintext attack

Answer

Known-plaintext attack

Question 44

Which cryptographic hash function produces a 256-bit digest?

Accepted Answer

SHA-256

Answer

RIPEMD-160

Answer

MD5

Answer

SHA-512

Question 45

Which type of digital signature is based on asymmetric cryptography?

Accepted Answer

RSA signature

Answer

SHA-256 hash

Answer

HMAC

Answer

MD5 checksum

Question 46

Which steganography technique conceals secret data within audio files?

Accepted Answer

Audio steganography

Answer

Text steganography

Answer

Image steganography

Answer

Video steganography

Question 47

Which vulnerability is commonly exploited in cryptographic implementations?

Accepted Answer

Timing attack

Answer

Cross-site scripting

Answer

SQL injection

Answer

Buffer overflow

Question 48

Which of the following is NOT a fundamental cryptographic technique?

Accepted Answer

Factorization

Answer

Substitution

Answer

Block cipher

Answer

Transposition

Question 49

What is the primary function of a digital signature?

Accepted Answer

Guarantee message authenticity and integrity

Answer

Compress a message

Answer

Decrypt a message

Answer

Encrypt a message

Question 50

Which of the following represents a common vulnerability in cryptographic systems?

Accepted Answer

Man-in-the-middle attack

Answer

Buffer overflow

Answer

SQL injection

Answer

Cross-site scripting

Question 51

What is the primary role of a hash function in cryptography?

Accepted Answer

Create a fixed-size digest from a message

Answer

Encrypt a message

Answer

Decrypt a message

Answer

Generate a random key

Question 52

Which of the following is classified as a public-key cryptosystem?

Accepted Answer

RSA

Answer

MD5

Answer

AES

Answer

DES

Question 53

What is the central objective of cryptanalysis?

Accepted Answer

Compromise or weaken a cryptosystem

Answer

Educate about cryptography

Answer

Design a new cryptosystem

Answer

Implement a cryptosystem

Question 54

Which of the following represents a common application of cryptography in real-world scenarios?

Accepted Answer

Secure online banking

Answer

Compressing large files

Answer

Processing images

Answer

Generating random numbers