What is synonymous with symmetric cryptography?

In the context of cryptography, symmetric cryptography is synonymous with secret key cryptography because both terms refer to the same underlying concept: a single key that is used for both encryption and decryption of information. In symmetric key systems, the same key must be kept secret and shared between the communicating parties. This key is crucial for both encrypting the plaintext into ciphertext and decrypting it back into plaintext, which means its security is paramount. If an unauthorized party gains access to this key, the confidentiality of the encrypted information is compromised.

The other terms mentioned relate to different cryptographic mechanisms. Public key cryptography refers to asymmetric cryptography, where two different keys are used (a public key for encryption and a private key for decryption). Asymmetric encryption specifically delineates this two-key method, while hash functions are used for creating a fixed-size hash value from data, primarily for integrity verification, rather than for encryption and decryption. Thus, the term that most accurately describes symmetric cryptography is indeed secret key cryptography, thereby reinforcing the understanding of how symmetric encryption uniquely operates.