Network Defense Essentials (NDE) Practice Exam

What characteristic does a symmetric algorithm primarily base its operations on?

1. Same key for encryption and decryption

2. Two different keys

3. Public key infrastructure

4. No key requirement

The correct answer is: Same key for encryption and decryption

A symmetric algorithm primarily bases its operations on the use of the same key for both encryption and decryption. In symmetric encryption, the key must remain secret and shared between the parties involved in the communication. This key is used to encrypt the plaintext into ciphertext and then to successfully decrypt that ciphertext back into the original plaintext. The security of symmetric encryption relies heavily on the secrecy of this key; if an unauthorized party gains access to it, they can decrypt any messages encrypted with it. This characteristic contrasts with other types of encryption methods, such as asymmetric algorithms, which use a pair of keys (private and public) for their operations, or methods that have no key requirement, which typically do not offer the same level of security and are infrequently used in practice. By focusing on the need for a single shared key, symmetric encryption provides a balance of performance and security, making it ideal for many applications where speed and efficiency are crucial.