What process converts data into a fixed-size value to ensure integrity?

Hashing is a process that takes an input (or 'message') and produces a fixed-size string of bytes that typically appears random. This fixed-size output, known as a hash value or hash code, serves as a unique identifier for the input data. The primary use of hashing is to ensure data integrity by allowing verification that data has not been altered. When data integrity checks are performed, the original data is hashed again, and if the newly generated hash matches the stored one, it confirms that the data remains unchanged.

The effectiveness of hashing in ensuring integrity comes from its properties: even the slightest change to the input data will result in a significantly different hash output. This makes it easy to detect unauthorized changes or corruption of the data.

In contrast, encryption transforms data to protect its confidentiality, but it does not guarantee that the data has remained unchanged. Authentication is about verifying identities rather than ensuring data integrity. Encoding is a way to convert data into a different format for various purposes, such as data representation, but it does not serve to verify integrity in the manner that hashing does.