The secret key for HMACSHA512 encryption. The key can be any length. However, the recommended size is 128 bytes. If the key is more than 128 bytes long, it is hashed (using SHA-512) to derive a 128-byte key. If it is less than 128 bytes long, it is padded to 128 bytes.
Windows 8.1, Windows Server 2012 R2, Windows 8, Windows Server 2012, Windows 7, Windows Vista SP2, Windows Server 2008 (Server Core Role not supported), Windows Server 2008 R2 (Server Core Role supported with SP1 or later; Itanium not supported)