This field is used to prevent users from changing the key of a keyed hash algorithm during a hash operation. When a key change is legitimate, the value of this field is zero both before and after a hash operation. When a key change is not legitimate, the value of this field is nonzero.

Namespace: System.Security.Cryptography
Assembly: mscorlib (in mscorlib.dll)
Assembly Versions: 1.0.5000.0, 2.0.0.0, 4.0.0.0