Abstract. The use of Commercial Off-The-Shelf (COTS) software products as components of large-scale systems has become more and more pervasive. One of the interesting questions that has arisen is "Can you build secure applications using insecure components?" We have been investigating ways to protect data that is shared between two or more independent, insecure applications. Our initial attempts to accomplish secure data storage and transfer have been directed toward building data encryption tools that interact with various COTS products. The goal was to test our theory that security wrappers for COTS products are feasible. This paper describes a security wrapper technology that we have implemented for selected (COTS) software products. The technology focuses on interchangeability for COTS software components, portability for the wrapper, and security for communications between applications via the wrapper. By applying this security wrapper technology, one COTS software component to be wrapped can be replaced by another without significantly modifying the wrapper; the wrapper can work with a variety of operating systems; and data can be encrypted and stored temporarily or permanently.