CTS 1120 Final
Comprehensive Resource To Help You Ace 2026-2027 Exams
Includes Frequently Tested Questions With Elaborated 100%
Correct Complete Solutions
Guaranteed Pass First Attempt!! Current Update!!
1. Betty receives a ciphertext message from her colleague Tim. What type of function does
Betty need to use to read the plaintext message?
A. Encryption
B. Hashing
C. Decryption
D. Validation
Answer: C. Decryption
Rationale: Decryption converts ciphertext back into readable plaintext using the correct key.
Encryption does the reverse, and hashing is a one-way function that cannot be reversed.
2. Alice and Bob would like to communicate using a session key, but they do not already have
a shared secret key. Which algorithm can they use to exchange a secret key?
A. Rivest, Shamir, Adelman (RSA)
B. Message digest algorithm (MD5)
C. Blowfish
D. Diffie-Hellman
Answer: D. Diffie-Hellman
Rationale: Diffie-Hellman is a key exchange algorithm. It lets two parties derive the same secret
key over an insecure channel without ever sending the key. RSA is mainly used for encryption
and signatures, MD5 is a hash, and Blowfish is a symmetric cipher.
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?
A. Confidentiality
,B. Integrity
C. Authentication
D. Nonrepudiation
Answer: B. Integrity
Rationale: Integrity means the data has not been altered. It is usually verified with hashes or
digital signatures. Confidentiality only prevents others from reading the message.
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?
A. Confidentiality
B. Integrity
C. Authentication
D. Nonrepudiation
Answer: D. Nonrepudiation
Rationale: Nonrepudiation provides proof to a third party that a specific sender created the
message, so the sender cannot deny it. Authentication only convinces the recipient. A digital
signature supplies nonrepudiation.
5. Which information security objective allows trusted entities to endorse information?
A. Validation
B. Authorization
C. Certification
D. Witnessing
Answer: C. Certification
Rationale: Certification is the endorsement of information by a trusted entity, such as a
certificate authority vouching for a public key. Authorization concerns permissions, not
endorsement.
6. Which approach to cryptography provides the strongest theoretical protection?
A. Quantum cryptography
B. Asymmetric cryptography
,C. Elliptic curve cryptography
D. Classic cryptography
Answer: A. Quantum cryptography
Rationale: Quantum cryptography relies on the laws of physics. Any eavesdropping disturbs the
quantum state and can be detected, which gives the strongest theoretical protection. The other
approaches depend on computational difficulty.
7. Which type of cipher works by rearranging the characters in a message?
A. Substitution
B. Steganographic
C. Transposition
D. Asymmetric
Answer: C. Transposition
Rationale: A transposition cipher changes the order of characters but leaves the characters
themselves unchanged. A substitution cipher replaces characters with others, and
steganography hides the existence of a message.
8. Which set of characteristics describes the Caesar cipher accurately?
A. Asymmetric, block, substitution
B. Asymmetric, stream, transposition
C. Symmetric, stream, substitution
D. Symmetric, block, transposition
Answer: C. Symmetric, stream, substitution
Rationale: The Caesar cipher uses one shared key (symmetric), works on one character at a time
(stream, per the source), and shifts each letter to another letter (substitution).
9. What is the only unbreakable cipher when it is used properly?
A. Rivest-Shamir-Adelman (RSA)
B. Vernam
C. Elliptic Curve Diffie-Hellman in Ephemeral mode (ECDHE)
D. Blowfish
Answer: B. Vernam
, Rationale: The Vernam cipher (one-time pad) is unbreakable only when the key is truly random,
as long as the message, kept secret, and never reused.
10. Which cryptographic attack offers cryptanalysts the most information about how an
encryption algorithm works?
A. Chosen plaintext
B. Ciphertext only
C. Known plaintext
D. Chosen ciphertext
Answer: A. Chosen plaintext
Rationale: In a chosen-plaintext attack, the attacker selects the plaintext to be encrypted and
studies the resulting ciphertext. This gives the most insight into the algorithm. A ciphertext-only
attack gives the least.
11. What mathematical problem forms the basis of most modern cryptographic algorithms?
A. Factoring large primes
B. Traveling salesman problem
C. Quantum mechanics
D. Birthday problem
Answer: A. Factoring large primes
Rationale: Algorithms such as RSA depend on the fact that multiplying two large primes is easy
but factoring the product is extremely hard. The birthday problem relates to hash collisions, not
to the basis of these algorithms.
12. What is NOT an effective key distribution method for plaintext encryption keys?
A. Paper
B. Unencrypted email
C. CD
D. Smart card
Answer: B. Unencrypted email
Rationale: Unencrypted email sends the key across the network where anyone can intercept it.
Paper, CDs, and smart cards are physical methods that can be controlled and delivered securely.
Comprehensive Resource To Help You Ace 2026-2027 Exams
Includes Frequently Tested Questions With Elaborated 100%
Correct Complete Solutions
Guaranteed Pass First Attempt!! Current Update!!
1. Betty receives a ciphertext message from her colleague Tim. What type of function does
Betty need to use to read the plaintext message?
A. Encryption
B. Hashing
C. Decryption
D. Validation
Answer: C. Decryption
Rationale: Decryption converts ciphertext back into readable plaintext using the correct key.
Encryption does the reverse, and hashing is a one-way function that cannot be reversed.
2. Alice and Bob would like to communicate using a session key, but they do not already have
a shared secret key. Which algorithm can they use to exchange a secret key?
A. Rivest, Shamir, Adelman (RSA)
B. Message digest algorithm (MD5)
C. Blowfish
D. Diffie-Hellman
Answer: D. Diffie-Hellman
Rationale: Diffie-Hellman is a key exchange algorithm. It lets two parties derive the same secret
key over an insecure channel without ever sending the key. RSA is mainly used for encryption
and signatures, MD5 is a hash, and Blowfish is a symmetric cipher.
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?
A. Confidentiality
,B. Integrity
C. Authentication
D. Nonrepudiation
Answer: B. Integrity
Rationale: Integrity means the data has not been altered. It is usually verified with hashes or
digital signatures. Confidentiality only prevents others from reading the message.
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?
A. Confidentiality
B. Integrity
C. Authentication
D. Nonrepudiation
Answer: D. Nonrepudiation
Rationale: Nonrepudiation provides proof to a third party that a specific sender created the
message, so the sender cannot deny it. Authentication only convinces the recipient. A digital
signature supplies nonrepudiation.
5. Which information security objective allows trusted entities to endorse information?
A. Validation
B. Authorization
C. Certification
D. Witnessing
Answer: C. Certification
Rationale: Certification is the endorsement of information by a trusted entity, such as a
certificate authority vouching for a public key. Authorization concerns permissions, not
endorsement.
6. Which approach to cryptography provides the strongest theoretical protection?
A. Quantum cryptography
B. Asymmetric cryptography
,C. Elliptic curve cryptography
D. Classic cryptography
Answer: A. Quantum cryptography
Rationale: Quantum cryptography relies on the laws of physics. Any eavesdropping disturbs the
quantum state and can be detected, which gives the strongest theoretical protection. The other
approaches depend on computational difficulty.
7. Which type of cipher works by rearranging the characters in a message?
A. Substitution
B. Steganographic
C. Transposition
D. Asymmetric
Answer: C. Transposition
Rationale: A transposition cipher changes the order of characters but leaves the characters
themselves unchanged. A substitution cipher replaces characters with others, and
steganography hides the existence of a message.
8. Which set of characteristics describes the Caesar cipher accurately?
A. Asymmetric, block, substitution
B. Asymmetric, stream, transposition
C. Symmetric, stream, substitution
D. Symmetric, block, transposition
Answer: C. Symmetric, stream, substitution
Rationale: The Caesar cipher uses one shared key (symmetric), works on one character at a time
(stream, per the source), and shifts each letter to another letter (substitution).
9. What is the only unbreakable cipher when it is used properly?
A. Rivest-Shamir-Adelman (RSA)
B. Vernam
C. Elliptic Curve Diffie-Hellman in Ephemeral mode (ECDHE)
D. Blowfish
Answer: B. Vernam
, Rationale: The Vernam cipher (one-time pad) is unbreakable only when the key is truly random,
as long as the message, kept secret, and never reused.
10. Which cryptographic attack offers cryptanalysts the most information about how an
encryption algorithm works?
A. Chosen plaintext
B. Ciphertext only
C. Known plaintext
D. Chosen ciphertext
Answer: A. Chosen plaintext
Rationale: In a chosen-plaintext attack, the attacker selects the plaintext to be encrypted and
studies the resulting ciphertext. This gives the most insight into the algorithm. A ciphertext-only
attack gives the least.
11. What mathematical problem forms the basis of most modern cryptographic algorithms?
A. Factoring large primes
B. Traveling salesman problem
C. Quantum mechanics
D. Birthday problem
Answer: A. Factoring large primes
Rationale: Algorithms such as RSA depend on the fact that multiplying two large primes is easy
but factoring the product is extremely hard. The birthday problem relates to hash collisions, not
to the basis of these algorithms.
12. What is NOT an effective key distribution method for plaintext encryption keys?
A. Paper
B. Unencrypted email
C. CD
D. Smart card
Answer: B. Unencrypted email
Rationale: Unencrypted email sends the key across the network where anyone can intercept it.
Paper, CDs, and smart cards are physical methods that can be controlled and delivered securely.
