Overview of Symmetric Key Cryptography Answers 1. What primary advantage does the CTR stream encryption method provide? A. It is slower compared to other methods. B. It is efficient and can operate in parallel. C. It does not require a key for encryption. D. It can only encrypt data sequentially. Answer: It is efficient and can operate in parallel. (B) CTR is known for its speed and ability to be parallelized, making it efficient for encryption tasks. 2. What is the primary purpose of key rotation in symmetric-key cryptography? A. To eliminate the need for a secure key exchange. B. To increase the lifetime of a single key. C. To simplify the key management process. D. To increase security and reduce impact from key compromise. Answer: To increase security and reduce impact from key compromise. (D) Regular key rotation helps in minimizing the risk associated with key compromise and enhances overall security. 3. Which method is often used to initiate secure key exchanges in symmetric-key cryptography? A. Asymmetric cryptography for initial key exchange. B. Direct sharing of the secret key. C. Using a single trustless entity. D. Data encryption with a symmetric key. Answer: Asymmetric cryptography for initial key exchange. (A) Asymmetric cryptography is frequently employed for the initial secure exchange of symmetric keys. 4. How does encrypting sensitive files relate to the concept of confidentiality? A. It eliminates all encryption vulnerabilities. B. It allows unauthorized access to sensitive content. C. It provides persistence in data storage. D. It ensures that only authorized users can access the information. Answer: It ensures that only authorized users can access the information. (D) Encrypting files protects their confidentiality by ensuring that only authorized users can read the data. 5. Which of the following is NOT a common application of encryption? A. Network Traffic Monitoring B. Database Security C. File Encryption D. Data Transmission Answer: Network Traffic Monitoring (A) While encryption is prevalent for securing various applications, network traffic monitoring is not typically categorized as an encryption application. 6. What is a distinguishing feature of symmetric-key cryptography? A. Encryption and decryption require separate algorithms. B. It utilizes a single shared secret key for both encryption and decryption. C. It is inherently more secure compared to asymmetric-key cryptography. D. Different keys are used for encryption and decryption. Answer: It utilizes a single shared secret key for both encryption and decryption. (B) Symmetric-key cryptography uses the same key for both encryption and decryption. 7. Which of the following statements accurately describes a vulnerability in symmetric-key cryptography? A. The algorithms used are too complex and slow. B. The system is vulnerable if the shared key is compromised. C. There is no efficient way to share the key among parties. D. The encryption and decryption processes require two separate keys. Answer: The system is vulnerable if the shared key is compromised. (B) The security of symmetric-key cryptography relies on the secrecy of the shared key. 8. Which of the following symmetric key algorithms is considered to be highly secure and efficient? A. Data Encryption Standard (DES) B. Blowfish C. Advanced Encryption Standard (AES) D. Triple DES (3DES) Answer: Advanced Encryption Standard (AES) (C) AES is widely used due to its high security and efficiency. 9. Which mode of operation is known to be the simplest but is also considered vulnerable? A. Cipher Block Chaining (CBC) B. Electronic Codebook (ECB) C. Cipher Feedback (CFB) D. Output Feedback (OFB) Answer: Electronic Codebook (ECB) (B) ECB is the simplest mode of operation but is vulnerable to patterns in the plaintext. 10. Why is symmetric-key cryptography generally faster than asymmetric-key cryptography? A. Due to the longer key lengths used in symmetric-key algorithms. B. Because it utilizes multiple keys for encryption. C. It encrypts data in a parallel fashion. D. Because symmetric-key algorithms are simpler and less computationally intensive. Answer: Because symmetric-key algorithms are simpler and less computationally intensive. (D) Symmetric-key cryptography is faster due to the simplicity of its algorithms. 11. What does Cipher Block Chaining (CBC) require for its first block of encryption? A. No additional input is required. B. An initialization vector (IV). C. A secondary encryption algorithm. D. A unique key. Answer: An initialization vector (IV). (B) CBC requires an initialization vector for encrypting the first block. 12. What is a drawback of the RC4 stream cipher? A. It requires a complex key management system. B. It does not support large amounts of data. C. It is vulnerable to certain types of attacks if implemented poorly. D. It is highly secure and widely accepted. Answer: It is vulnerable to certain types of attacks if implemented poorly. (C) RC4 is vulnerable to attacks if it is not implemented correctly. 13. In which mode of operation does encryption of each block depend on the previous block's ciphertext? A. Cipher Feedback (CFB) B. Electronic Codebook (ECB) C. Cipher Block Chaining (CBC) D. Output Feedback (OFB) Answer: Cipher Block Chaining (CBC) (C) In CBC, each block's encryption is based on the ciphertext from the previous block.