.NET Framework Security

Using Keyed Hash Functions

Keyed hash functions are a subset of cryptographic hash functions that provide data authentication services in addition to integrity protection. As their name implies, keyed hash functions work by mixing a shared secret key with the to-be-hashed message to generate a hash value. That is, the hash value h = f(M, k), where f() is the keyed hash function, M is the to-be-hashed message (of arbitrary length), and k is the secret key. Changing either the message or the secret key will change the computed hash value.

Keyed hash functions are represented in the .NET Framework as subclasses of the KeyedHashAlgorithm abstract class, which itself is a subclass of HashAlgorithm. Because every KeyedHashAlgorithm is a HashAlgorithm ...