1.
Betty receives a cipher text message from her colleague Tim. What type of function does Betty need to use to read the plaintext message?
Correct Answer
C. Decryption
Explanation
Betty needs to use the decryption function to read the plaintext message. Encryption is the process of converting plaintext into cipher text, while decryption is the reverse process of converting cipher text back into plaintext. Hashing is a one-way function that cannot be reversed, so it is not applicable in this scenario. Validation is the process of checking the integrity or correctness of data, but it does not involve deciphering a cipher text message. Therefore, the correct answer is decryption.
2.
Alice and Bob would like to communicate with each other using a session key but they do not already have a shared secret key. Which algorithm can they use to exchange a secret key?
Correct Answer
D. Diffie-Hellman
Explanation
Alice and Bob can use the Diffie-Hellman algorithm to exchange a secret key. Diffie-Hellman is a key exchange algorithm that allows two parties to establish a shared secret key over an insecure channel. It works by each party generating a public-private key pair, exchanging their public keys, and then using their own private keys and the received public key to compute a shared secret key. This shared secret key can then be used for secure communication between Alice and Bob.
3.
Gary is sending a message to Patricia. He wants to ensure that nobody tampers with the message while it is in transit. What goal of cryptography is Gary attempting to achieve?
Correct Answer
B. Integrity
Explanation
Gary is attempting to achieve the goal of integrity in cryptography. Integrity ensures that the message remains unchanged and unaltered during transit. It verifies that the message has not been tampered with by any unauthorized party. By focusing on integrity, Gary wants to guarantee the authenticity and reliability of the message, ensuring that it has not been modified or corrupted in any way.
4.
When Patricia receives a message from Gary, she wants to be able to demonstrate to Sue that the message actually came from Gary. What goal of cryptography is Patricia attempting to achieve?
Correct Answer
D. Nonrepudiation
Explanation
Patricia is attempting to achieve the goal of nonrepudiation. Nonrepudiation ensures that the sender of a message cannot deny sending it, providing proof of the message's origin. In this case, Patricia wants to be able to demonstrate to Sue that the message came from Gary, preventing Gary from denying his involvement.
5.
Which information security objective allows trusted entities to endorse information?
Correct Answer
C. Certification
Explanation
Certification is the information security objective that allows trusted entities to endorse information. Certification involves a formal process where an independent third party assesses and verifies the security controls and measures implemented by an organization. This endorsement provides assurance to other entities that the information and systems are secure and can be trusted. Certification is important for establishing trust and credibility in the information security field.
6.
Which approach to cryptography provides the strongest theoretical protection?
Correct Answer
A. Quantum cryptography
Explanation
Quantum cryptography provides the strongest theoretical protection because it is based on the principles of quantum mechanics, which offers unique properties such as the ability to detect any unauthorized interception or eavesdropping on the communication channel. It uses quantum key distribution to securely exchange encryption keys, making it highly resistant to attacks from quantum computers or any other advanced computational methods. Asymmetric cryptography and elliptic curve cryptography also offer strong protection, but quantum cryptography is considered to be even more secure. Classic cryptography, on the other hand, is based on older, less secure algorithms and is therefore not as strong as the other options.
7.
Which type of cipher works by rearranging the characters in a message?
Correct Answer
C. Transposition
Explanation
Transposition ciphers work by rearranging the characters in a message. Instead of replacing each character with another, as in substitution ciphers, transposition ciphers change the order of the characters. This can be done by shifting the positions of the characters, reversing the order, or using a specific pattern to rearrange them. The goal of a transposition cipher is to make the message more difficult to understand by changing the order of the characters, rather than replacing them with different ones.
8.
Which set of characteristics describes the Caesar cipher accurately?
Correct Answer
C. Symmetric, stream, substitution
Explanation
The Caesar cipher is a symmetric encryption method, meaning that the same key is used for both encryption and decryption. It is a stream cipher, where each letter is encrypted individually. Additionally, it uses a substitution technique, where each letter is replaced with another letter according to a fixed rule. Therefore, the correct answer is "Symmetric, stream, substitution".
9.
What is the only unbreakable cipher when it is used properly?
Correct Answer
B. Vernam
Explanation
The Vernam cipher is considered the only unbreakable cipher when used properly because it is based on the principle of a one-time pad. This means that each character in the plaintext is encrypted using a random key that is as long as the message itself and is never reused. As a result, the ciphertext produced by the Vernam cipher is statistically random and provides perfect secrecy, making it impossible for an attacker to decipher the original message without the correct key.
10.
Which cryptographic attack offers cryptanalysts the most information about how an encryption algorithm works?
Correct Answer
A. Chosen plaintext
Explanation
Chosen plaintext attack offers cryptanalysts the most information about how an encryption algorithm works. In this attack, the attacker can choose specific plaintexts and observe the corresponding ciphertexts generated by the encryption algorithm. By analyzing the relationship between the chosen plaintexts and the resulting ciphertexts, the attacker can gain insights into the inner workings of the encryption algorithm, such as its key generation process or any vulnerabilities it may have. This attack is considered powerful because it provides the attacker with the ability to actively manipulate and control the input to the encryption algorithm.