What is the main feature of symmetric encryption?

The main feature of symmetric encryption is that it utilizes a single secret key for both the encryption and decryption processes. This means that the same key used to encrypt the data must also be used to decrypt it, which emphasizes the importance of keeping the key secure. In symmetric encryption, both parties involved must have access to the same secret key to communicate effectively, thus ensuring confidentiality of the information being shared.

In contrast, other options describe functionalities associated with different forms of encryption. The notion of using two keys pertains to asymmetric encryption, where a public key encrypts data and a private key decrypts it. Public and private key pairs are fundamental to asymmetric encryption and do not apply to symmetric encryption. Furthermore, encrypting data without any key is a misunderstanding, as encryption fundamentally relies on keys to secure data, whether symmetric or asymmetric.