Represents the abstract base class from which all implementations of symmetric algorithms must inherit.
Assembly: mscorlib (in mscorlib.dll)
The classes that derive from the class use a chaining mode called cipher block chaining (CBC), which requires a key (Key) and an initialization vector (IV) to perform cryptographic transformations on data. To decrypt data that was encrypted using one of the classes, you must set the Key property and the IV property to the same values that were used for encryption. For a symmetric algorithm to be useful, the secret key must be known only to the sender and the receiver.
Note that when using derived classes, it is not enough, from a security perspective, to simply force a garbage collection after you have finished using the object. You must explicitly call the Clear method on the object to zero out any sensitive data within the object before it is released. Note that garbage collection does not zero out the contents of collected objects but simply marks the memory as available for reallocation. Thus the data contained within a garbage collected object may still be present in the memory heap in unallocated memory. In the case of cryptographic objects, this data could contain sensitive information such as key data or a block of plain text.
All cryptographic classes in the .NET Framework that hold sensitive data implement a Clear method. When called, the Clear method overwrites all sensitive data within the object with zeros and then releases the object so that it can be safely garbage collected. When the object has been zeroed and released, you should then call the Dispose method with the disposing parameter set to True to dispose of all managed and unmanaged resources associated with the object.Notes to Inheritors:
The following code example uses the RijndaelManaged class with the specified Key property and initialization vector (IV) to encrypt a file specified by inName, and outputs the encrypted result to the file specified by outName. The desKey and desIV parameters to the method are 8-byte arrays. You must have the high encryption pack installed to run this example.
Windows 7, Windows Vista, Windows XP SP2, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP Starter Edition, Windows Server 2008 R2, Windows Server 2008, Windows Server 2003, Windows Server 2000 SP4, Windows Millennium Edition, Windows 98, Windows CE, Windows Mobile for Smartphone, Windows Mobile for Pocket PC
The .NET Framework and .NET Compact Framework do not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.