What is a message digest or hash value created by?

A message digest, also known as a hash value, is created through the process of hashing. Hashing takes an input (or 'message') and produces a fixed-size string of characters, which appears to be random. This process is designed such that even a small change in the input will result in a significantly different output, highlighting its sensitivity and uniqueness.

Hashing has essential applications, particularly in ensuring data integrity. It allows for quick verification of whether data has remained unchanged during transmission or storage. For example, if a file is sent over a network, the sender and receiver can compare their respective hash values to check if the file is intact, ensuring that no alterations have occurred.

In contrast, the other processes mentioned involve different objectives. Tokenization replaces sensitive data with non-sensitive equivalents (tokens), encryption scrambles data to prevent unauthorized access, and masking obscures data to protect it while retaining its usability. Each of these serves its purpose in information security, but none produce a hash value like the hashing process does.