received by the International Bureau on 14 July 2016 (14.07.16)

WHAT IS CLAIMED IS:

1. A multi-level security system, the system comprising:

a storage medium, the storage medium partitionable into a plurality of partitions;

a file system coupleable to the plurality of partitions;

a plurality of enclaves each assigned a security classification level, wherein each one of the plurality of enclaves resides in a different storage partition of the storage medium;

wherein data stored on the storage medium is cryptographically separated at rest on a per-enclave basis, and wherein cryptographic separation occurs at the disk block level thereby allowing individual blocks to be read and decrypted; and

a reference monitor that enforces a system security policy that governs access to information between the plurality of enclaves, wherein the reference monitor allows an enclave of the plurality of enclaves having a first classification level to securely read-down to another enclave of the plurality of enclaves having a second classification level lower than the first classification level and to write to another enclave of the plurality of enclaves having the first classification level.

2. (Amended) A non-transitory computer-readable medium embodying program instructions for execution by a data processing apparatus, the program instructions adapting the data processing apparatus for transmitting information classified at different security classification levels while maintaining data separation of the information, the program instructions comprising:

forming a plurality of enclaves defining disparate security domains by dividing information stored on a storage medium into a plurality of non- overlapping partitions;

assigning a security classification level to each one of the plurality of enclaves;

encrypting each of the plurality of non-overlapping partitions using a unique key for each security classification level; and

enforcing a system security policy that governs the flow of information between the plurality of enclaves, the security policy allowing a first enclave having a first classification level to securely read-down to a second enclave having a second classification level lower than the first classification level and to write to a third enclave having the first classification level.