What is the primary objective of cryptography that ensures data is genuine and has not been altered?

The primary objective of cryptography that ensures data is genuine and has not been altered is authentication. Authentication verifies the identity of the parties involved in a communication or the integrity of the data itself. By ensuring that the sender is indeed who they claim to be and that the received data corresponds exactly to what was sent, authentication helps to prevent unauthorized access and modifications.

This process often involves using digital signatures or cryptographic hash functions, which can provide a way to check whether the content has changed during transit. When data is authenticated, recipients can trust that the information is reliable and has not been tampered with, which is crucial in various applications, especially in secure communications and data storage.

While encryption protects data confidentiality by making it unreadable to unauthorized users, and non-repudiation ensures that a sender cannot deny sending a message, the specific focus of ensuring data authenticity is best captured by the concept of authentication.