  Protecting data from malicious computer users continues to grow in
importance. Whether preventing unauthorized access to personal photographs,
ensuring compliance with federal regulations, or ensuring the integrity of
corporate secrets, all applications require increased security to protect data
from talented intruders. Specifically, as more and more files are preserved on
disk the requirement to provide secure storage has increased in importance.
This paper presents a survey of techniques for securely storing data, including
theoretical approaches, prototype systems, and existing systems currently
available. Due to the wide variety of potential solutions available and the
variety of techniques to arrive at a particular solution, it is important to
review the entire field prior to selecting an implementation that satisfies
particular requirements. This paper provides an overview of the prominent
characteristics of several systems to provide a foundation for making an
informed decision. Initially, the paper establishes a set of criteria for
evaluating a storage solution based on confidentiality, integrity,
availability, and performance. Then, using these criteria, the paper explains
the relevant characteristics of select storage systems and provides a
comparison of the major differences.
