Abstract: Virtual machines in a network may be isolated by encrypting transmissions between the virtual machines with keys possessed only by an intended recipient. Within a network, the virtual machines may be logically organized into a number of community-of-interest (COI) groups. Each COI may use an encryption key to secure communications within the COI, such that only other virtual machines in the COI may decrypt the message. Virtual machines may further be isolated through a virtual gateway assigned to handle all communications between a virtual machine and a device outside of the virtual machine's COI. The virtual gateway may be a separate virtual machine for handling decrypting and encrypting messages for transmission between virtual machines and other devices.