(ISC)2 Certified in Cybersecurity Practice Exam

What do you use to encrypt and decrypt in symmetric encryption?

1. Public Key

2. Private Key

3. Same Key

4. Different Keys

The correct answer is: Same Key

In symmetric encryption, the process of encrypting and decrypting data relies on the use of the same key. This means that the key used to convert the plaintext into ciphertext is identical to the key used to convert the ciphertext back into plaintext. This shared key must be kept secret between the parties involved in communication, as anyone with access to the key can decrypt the messages. By using the same key for both operations, symmetric encryption provides a straightforward and efficient means of securing data. However, it also introduces challenges related to key management and distribution, as the key must be securely shared without being intercepted by unauthorized entities. In contrast, public key cryptography, which involves a pair of keys (public and private), is used in asymmetric encryption. Public keys can be shared openly to encrypt messages, while private keys are kept secure to decrypt them. This fundamental difference highlights why symmetric encryption relies exclusively on one key for both encryption and decryption processes.