What describes the method of using the same key for encryption and decryption?

The method of using the same key for both encryption and decryption is referred to as symmetric cryptography. In symmetric cryptography, a single shared key is utilized to encode and decode information, meaning that both the sender and the receiver must possess the same secret key to communicate securely. This approach enables efficient encryption and decryption processes, as the same algorithm and key are applied during both phases.

For example, if a message is encrypted using a symmetric key algorithm like AES, the same key must be used in the reverse process to decrypt the message back into its original form. This model of cryptography relies heavily on key management, as both parties need to securely exchange and maintain the secrecy of the shared key.

Stream ciphers and the Caesar cipher are specific types of encryption techniques, not methods for defining how keys are utilized. Steganography, on the other hand, pertains to hiding the existence of a message rather than encrypting it with a key, which is distinct from the concept of symmetric cryptography. Thus, symmetric cryptography is the appropriate term for this method of using a single key for both encryption and decryption.