The first key architectural challenge common to all of these development efforts is the need to preserve critical military requirements, including:

• Survivability
• Proof of sender’s identity
• Proof of delivery
• Content integrity
• Non-disclosure

A second key challenge involves the migration of existing military e-mail systems toward commercial packages to take advantage of marketplace pricing, feature-sets and lifecycle support. Because of long development cycles, government-specific systems are often outdated by the time they’re deployed. The hope is that by adopting commercially oriented systems, military messaging can become more cost-effective and extensible. In addition, this trend toward integrating commercial capabilities will help address the growing requirement for interoperability between tactical and non-tactical military systems, such as strategic and support organizations.

Because of the mission-critical nature of these systems, a delicate balancing act is required to gain the benefits of widely available, cost-effective commercial e-mail solutions without compromising the stringent requirements of tactical military messaging. This dichotomy is spawning a new class of software often referred to as GOTS (Government Off The Shelf), which consists of government-targeted commercial software with some additional capability added, either built-in or through add-on modules.

Another factor complicating the forward-migration of military messaging systems is the nature of the platforms on which they are typically deployed. The current dependence on dissimilar operating systems and user interfaces across the tactical and strategic environments (e.g., UNIX vs. Windows) makes it more difficult to deploy messaging systems with a universal look-and-feel. Tactical messaging systems must be able to withstand the harsh conditions encountered in battlefield situations.

In addition to providing interoperability within a specific country’s tactical, logistical and strategic functions, the next generation of military messaging systems must also provide communications between the separate military organizations of all Allied nations. Toward this end, the Allied nations, including Australia, Canada, New Zealand, the United Kingdom and the United States, have established a set of Allied Communications Protocols (ACPs) to define the mutually interoperable functionality required by each country’s new-generation military messaging system. The requirement for such ACP-based inter-country messaging capabilities has already been seen in real-world "hot" field deployments, such as the multinational Allied operation in Bosnia.

Solving this multi-faceted challenge will require a comprehensive effort on the part of each Allied nation that includes:

• Migrating today’s widely different tactical systems to new software/hardware platforms, which will allow use of standards-based messaging products, interoperability and future extensibility without compromising tactical imperatives such as security and survivability.
• Increasing users’ familiarity and efficiency through implementation of a common user-interface for messaging applications across tactical, strategic and support environments.
• Leveraging commercial e-mail products and workgroup computing/communications environments to maximize user effectiveness and system extensibility.
• Laying the groundwork for the evolution to seamless interoperability between tactical, logistical, and strategic messaging systems.
• Building in mechanisms for implementing automated country-specific security procedures along with ACP-compliant functionality for inter-country tactical and strategic communications.

In parallel with other Allied nations, the Canadian Department of National Defence (DND) is currently implementing new-generation messaging systems across both tactical and non-tactical environments. The balance of this paper details many of the specific implementation issues and decisions that have been made to date and describes the potential for future extensions and enhancements to DND’s overall messaging environment.

Within the Canadian Land Forces, the TCCCS/Iris (Tactical Command Control and Communications Systems) program provides the overall structure under which tactical messaging is being implemented, through the Tactical Message Handling System (TMHS) program. As the prime contractor, Computing Devices Canada (CDC) is responsible for the TCCCS/Iris program, with Electronic Data Systems (EDS) acting as a major subcontractor for the TMHS messaging portion.

After reviewing all of the development and deployment alternatives, the major objectives for TMHS were established to:

• Implement standards-based systems (e.g., the X.400 Message Transfer System)
• Provide maximum survivability
• Support deployment into ruggedized battalion-level tactical environments
• Provide effective messaging capability to all levels of fielded deployment
• Ensure messaging capabilities exist within a highly mobile frequency hopping combat net radio environment
• Allow for long term useful life (extending over a 20 year life cycle)

Early on, the decision was made to maximize survivability through the use of a fully-matrixed architecture, in which every tactical messaging system is a completely self-contained, field-replaceable unit. Each field deployable TMHS Personal Data Terminal (PDT) contains its own Message Transfer Agent (MTA), Message Store, and User Agent all within a single TCCCS/Iris compatible Pentium-based platform, running the UNIX operating system. Because every messaging system is fully-matrixed within the network, they all communicate directly with each other, rather than routing messages through a "backbone" message transport. As a result, the loss of any particular messaging system has no impact on the other systems or the network as a whole.

The TMHS architecture has now been approved as the standard for tactical messaging throughout the Canadian military. This means that any system which touches upon tactical messaging must incorporate, or be able to interoperate with, the TMHS technology. As a consequence other programs, such as Low Level Air Defence System (LLADS), are already including TMHS in their design and procurement specifications to leverage compatibility with the common DND messaging environment.

As TCCCS/Iris expanded to include non-tactical messaging, it became clear that overall user efficiency could be greatly enhanced through the deployment of workgroup computing environments, which integrate messaging with productivity enhancing features such as scheduling, calendar management, etc. Compatibility with the Windows-based standards for workgroup computing was considered a critical requirement for successful implementation of non-tactical messaging. Client/server e-mail clients were selected for adaptation to military requirements.

The logistical and strategic messaging portions of TCCCS/Iris are being addressed by the Athene program, which is designed to effectively combine groupware functionality and a client/server compliant e-mail environment with a mechanism for secure ACP 123 messaging standards. By leveraging similar underlying technologies and ACP 123-compliant messaging products, the TMHS and Athene programs will ultimately provide the foundation for seamless interoperability between all of Land Forces’ tactical and non-tactical messaging environments.

A critical element enabling us to meet this objective is the deployment of a militarized messaging client that adds ACP 123 standards and military grade messaging functionality to workgroup computing environment. Additionally, because X.400 and user agents are being deployed on the tactical side as part of TMHS, the use of this militarized client provides a direct connection for seamless interoperability between strategic, logistical, and tactical field messaging systems.

It is likely that the successful implementation of the program for non-tactical land-based messaging and workgroup functions will provide a useful model for other DND messaging systems. For instance, the secure Military Message Handling System (MMHS) Proof of Concept have already shown that the required system functionality can be achieved through the use of a militarized messaging client. Essentially, its extensions enable the client/server e-mail to be interfaced to either the server for unclassified messaging or directly to the X.400 MTA infrastructure for higher security traffic, such as that required under ACP 123.

Within Canada’s Department of National Defence, the Defence Message Handling System (DMHS) will be composed of two main components, a secure MMHS and the unclassified Defence Electronic Messaging System (DEMS). DND’s current movement toward DEMS-II will incorporate commercial workgroup features.

MMHS will replace Canada’s existing ADDN to provide high security military messaging, much as the United States’ Defense Messaging System (DMS) is slated to replace AUTODIN. MMHS is compliant with ACP 123 to provide compatibility with other Allied nations’ X.400-based messaging systems. In addition, MMHS will incorporate X.500 directory functions to use the Department of National Defence X.500 directory system. This directory service will contain all e-mail addresses, white pages information and a DND-wide X.509-based Public Key Infrastructure (PKI) for security.

To maintain security across such a system, the militarized messaging client is designed for compatibility with existing security and key-encryption methods. For instance, the Canadian implementation uses public-key technologies. The Canadian government selected a cryptography provider for all DND messaging systems, including TMHS, Athene, DEMS, and MMHS systems. Ultimately, these built-in security mechanisms will enable users in non-tactical environments to communicate from within their familiar workgroup environment to users in tactical situations, under the umbrella of user-transparent security protocols.

As this next generation of military messaging systems further evolves, it is likely that some portion of the commercial innovations, functionality and cost-effectiveness now being incorporated into non-tactical environments will migrate into tactical environments as well. For instance, we are already seeing a number of applications migrating onto ruggedized PC platforms that are deployed into the same tactical environments as the TMHS UNIX-based messaging systems. Because physical space and weight limitations are a key concern in tactical situations, serious consideration is being given to merging the messaging system and other applications onto a common platform.

In the Canadian Land Forces, the selection of compatible user agents for tactical UNIX-based deployments and non-tactical environments has laid a ready-made foundation for a rational evolution to user agents throughout the system. The same militarized messaging client, which interface with server-based mail servers in the non-tactical environments, can also connect to X.400 Message Stores, which are currently being deployed as part of TMHS.

Through the combination of the TCCCS/Iris TMHS and Athene programs for the Land-Based Forces, and the MMHS and DEMS-II initiatives for military-wide messaging, the Canadian Department of National Defence has positioned itself to take maximum advantage of both today’s and tomorrow’s messaging technologies.

By choosing ACP 123 compliant X.400 messaging agents, a compliant militarized messaging client and X.500 directory services, the Canadian military is already deploying next generation messaging throughout their Land Forces. At the same time, they have laid the groundwork for smoothly migrating to a fully interoperable, cost-effective DND-wide messaging system.

As such, the DND has set the stage for both immediate and future implementations of number of interoperable configurations to address tactical, strategic and support functions.

These include:

• The current TMHS UNIX-based configuration, which incorporates an X.400 MTA, message store and user agent into a fully-matrixed, modular, field-replaceable tactical system.
• Messaging connected to X.500 directory services along with the addition of ACP 123 compliant security.
• The potential future migration of a TMHS-like highly-matrixed tactical environment to a client/server-based platform, in conjunction with X.400 MTA and message store.
• Future DND-wide integration and interoperability programs, such as DEMS-II using SMIME support.