Use this property to set the InitVector after construction. (Usually you will want to set this when the class is constructed in the constructor)
The InitVector may be initialized with anything, but the recipient needs to know what it was initialized with, or it won't be able to decrypt. Some programs and protocols simplify this, like SSH, where iv is simply initialized to zero. If this parameter is skipped then the iv will be "00000000". The InitVector should always be a 8 character value.