In modern operating systems, cryptographic file systems can protect confidential data from unauthorized access. However, once an authorized process has accessed data from a cryptographic file system, the data can appear as plaintext in the unprotected virtual memory backing store, even after system shutdown. The solution described in this paper uses swap encryption for processes in possession of confidential data. Volatile encryption keys are chosen randomly, and remain valid only for short periods. Invalid encryption keys are deleted, effectively erasing all data that was encrypted with them. ; http://deepblue.lib.umich.edu/bitstream/2027.42/107904/1/citi-tr-00-3.pdf