What does a message digest provide in cryptography?

A message digest is a fixed-size numerical representation generated from input data of any size and is commonly used in cryptography to ensure data integrity. When data is processed through a hashing algorithm, a unique hash value is produced, which serves as a fingerprint for that data. This hash value can be compared to a later hash of the same data to verify whether it has been altered or tampered with.

When the original data is modified even slightly, the resulting hash will change significantly, indicating that the original data's integrity has been compromised. Thus, by comparing the original hash with a newly generated hash from the data, one can confirm whether the data remains intact and unaltered. This process is crucial in security applications, such as transmitting sensitive information, signing digital documents, and ensuring consistent data integrity across systems.

In contrast, other choices focus on different functionalities. Data encryption pertains to converting plaintext data into a coded format to prevent unauthorized access. Data compression involves reducing the size of data for efficient storage or transmission. Data storage refers to the methods and technologies used to save data, but it does not involve any processes of verification or validation of the data's integrity. Therefore, the correct answer relates specifically to the function of verifying whether data remains unchanged.