**1. What is a cipher that replaces one letter for another, possibly retaining the letter frequency of the original message?**

- brute-force
- cryptanalysis
- nonrepudiation
- substitution
- transposition
- Vigenère

**2. What is a method of cryptanalysis in which an attacker tries every possible key knowing that eventually one of them will work?**

- brute-force
- cryptanalysis
- nonrepudiation
- substitution
- transposition
- Vigenère

**3. What cipher method does 3DES use as part of the algorithm?**

- brute-force
- cryptanalysis
- nonrepudiation
- substitution
- transposition
- Vigenère

**4. What is the term for when a device cannot refute the validity of a message that it has received?**

- brute-force
- cryptanalysis
- nonrepudiation
- substitution
- transposition
- Vigenère

**5. What is the practice and study of determining the meaning of encrypted information, without access to the shared secret key?**

- brute-force
- cryptanalysis
- nonrepudiation
- substitution
- transposition
- Vigenère