Which method of cryptography is primarily focused on ensuring both confidentiality and integrity through the use of keys?

The method of cryptography that focuses on ensuring both confidentiality and integrity through the use of keys is symmetric cryptography. In symmetric cryptography, the same key is utilized for both encryption and decryption processes. This key needs to be kept secure, as anyone with access to it can decrypt the sensitive information. By using this method, data can remain confidential when encrypted, while the use of the key ensures that any changes made to the encrypted data can be detected, thereby maintaining its integrity.

In symmetric key systems, confidentiality is typically achieved through algorithms that transform plaintext into ciphertext, rendering the information unreadable without the key. Integrating integrity into this model usually involves combining cryptographic hash functions with symmetric encryption, allowing for verification that the data has not been altered. Thus, symmetric cryptography effectively supports both key objectives of confidentiality and integrity.