Confidentiality via Camouflage (CVC) is a practical method for giving unlimited, correct, numerical responses to queries of on-line databases without compromising confidential numerical data. We identify two distinct types of insider information, knowledge of data or of the algorithm used to answer queries. Alternative forms of CVC are shown to protect against one or the other type of threat. A combination can be used when we are unable to specify the type of threat that is present.