In which encryption method do both the sender and receiver share the same key?

Symmetric encryption is characterized by the use of a single key for both the encryption and decryption processes. In this method, both the sender and the receiver must securely share this key before communicating. Because the same key is used to encode and decode the information, symmetric encryption enables fast and efficient encryption and decryption speeds, making it ideal for encrypting large amounts of data.

In contrast, asymmetric encryption employs a pair of keys—one public and one private—for secure communication. This method relies on different keys for encryption and decryption, meaning that the sender does not need to share a key with the receiver.

Cryptographic hashing doesn't involve keys at all; it creates a fixed-size string (hash) from input data, which is not meant to be reversed back into the original data.

Public key infrastructure is a framework that utilizes asymmetric encryption and includes components such as digital certificates and certificate authorities to manage keys and ensure secure communications.

Therefore, symmetric encryption is the method that fits the criteria of both the sender and receiver sharing the same key to encrypt and decrypt messages.