Which type of encryption is characterized by the use of a single key for both encryption and decryption?

The type of encryption characterized by the use of a single key for both encryption and decryption is symmetric encryption. In symmetric encryption, the same secret key is utilized to both encrypt plaintext into ciphertext and to subsequently decrypt that ciphertext back into plaintext. This means that both the sender and the receiver must have access to the same key and keep it confidential to ensure secure communication.

Since symmetric encryption relies on a shared key, it is typically faster and more efficient for processing large amounts of data compared to asymmetric encryption, which uses a pair of keys (public and private). Symmetric algorithms, such as AES (Advanced Encryption Standard) and DES (Data Encryption Standard), are widely used in various applications because of their speed and efficiency in data encryption.

The other options describe different concepts in cryptography: asymmetric encryption employs a pair of keys for encryption and decryption, hashing is a one-way function that converts data into a fixed-size hash value (not reversible), and salting is a technique used to enhance the security of password hashing by adding random data to passwords before hashing them. None of these options utilize a single key for both encryption and decryption, which is why symmetric encryption is the correct choice.