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 SymmetricAlgorithm.LegalKeySizes property.

This field is accessed through the SymmetricAlgorithm.Key property.

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