How many keys does symmetric encryption typically use to encrypt and decrypt data at rest?

• A. 2
• B. 1
• C. 3
• D. 4

Answer: (B)

Symmetric encryption relies on a single key to perform both the encryption and decryption processes. This means that the same key is used to secure the data when it is written to storage (data at rest) and to access the data when it is retrieved. The primary advantage of this approach is efficiency; symmetric encryption is generally faster than its asymmetric counterpart because it requires fewer computational resources.

Using only one key simplifies key management but also raises security concerns: if the key is compromised, both encryption and decryption are at risk. This is why securely storing and managing the symmetric key is critical in maintaining the confidentiality and integrity of the encrypted data.

In contrast, asymmetric encryption uses a pair of keys (a public key and a private key), which distinguishes it significantly from symmetric methods. Other options like two, three, or four keys would not apply to the standard operation of symmetric encryption.