Gets or sets the secret key for the symmetric algorithm.
Assembly: mscorlib (in mscorlib.dll)
The secret key is used both for encryption and for decryption. For a symmetric algorithm to be successful, the secret key must be known only to the sender and the receiver. The valid key sizes are specified by the particular symmetric algorithm implementation and are listed in the LegalKeySizes property.
If this property is null when it is used, the GenerateKey method is called to create a new random value.