When military organisations collaborate across national boundaries, sharing information securely becomes considerably more complex. Allied Communications Publication 240 (ACP 240) provides an important framework for data-centric security, helping defence organisations protect sensitive information as it moves between systems, networks and coalition partners.
Modern military operations increasingly depend on multinational cooperation. NATO allies and Five Eyes (FVEY) partners must exchange operational intelligence, planning information and mission-critical communications, often across different security domains and technology platforms.
However, sharing information between trusted organisations does not automatically mean that every individual within those organisations should have access to it.
Different nations operate their own security classifications, access policies and information-handling requirements. Even when organisations share a common mission, they may not share identical rules governing who can access particular information.
This creates a fundamental challenge: How can defence organisations share information efficiently while ensuring that security controls remain effective beyond their own networks?
ACP 240 addresses this challenge by establishing an approach to data-centric security interoperability, where protection is associated with the information itself rather than relying exclusively on the security of the network or application carrying it.
ACP 240 (Allied Communications Publication 240) is a defence interoperability publication that establishes concepts, architectural principles and requirements for data-centric security across allied information-sharing environments.
It is developed under the Combined Communications-Electronics Board (CCEB), whose participating nations are Australia, Canada, New Zealand, the United Kingdom and the United States.
Although closely associated with NATO interoperability, ACP 240 is not itself a NATO Standardization Agreement (STANAG). Its origins lie within the Five Eyes community, and its application within NATO requires the appropriate NATO direction.
ACP 240 supports an approach in which information can carry machine-readable security metadata, enabling participating systems to interpret its classification, handling requirements and applicable access policies.
It also addresses mechanisms for protecting information cryptographically, including the Zero Trust Data Format (ZTDF).
The objective is to support secure information sharing between organisations without requiring every participant to operate within an identical network or security architecture.
This is particularly relevant to multinational military operations, where information may pass between national defence systems, coalition networks and mission-specific applications.
Traditional information security has frequently relied on protecting networks and systems.
Sensitive information might be stored within a classified network, accessible only to authorised personnel using approved devices and applications.
While this approach remains important, it becomes more complicated when information needs to move between different organisations.
Consider a multinational military operation involving British, American and other allied forces.
Each participating nation may maintain separate:
An intelligence report produced by one nation may need to be shared with selected personnel from several others.
However, the originating nation must retain appropriate control over how that information is handled.
Simply transferring the report into another organisation’s network does not guarantee that its original security requirements will continue to be enforced.
ACP 240 supports a different approach: protecting information according to its security attributes and applicable policies, rather than relying solely on where that information is stored.
This supports the broader transition towards data-centric security across defence and intelligence environments.
Data-centric security (DCS) is an approach in which security controls are associated with individual information objects.
Rather than assuming that information is protected because it resides within a trusted network, data-centric security considers the sensitivity of the information, the identity and attributes of the person requesting access, and the policies governing its use.
ACP 240 contributes to this approach through several related capabilities.
Information must be identifiable according to its classification and handling requirements.
For example, a document might be classified as NATO SECRET and carry additional restrictions governing which nations or communities may receive it.
Machine-readable metadata allows participating systems to interpret these requirements consistently.
This is closely related to NATO STANAG 4774, which specifies a standardised approach to confidentiality metadata labels.
Rather than relying exclusively on visible document markings, security information can be represented in a structured format that software systems can process.
Security labels are only useful when systems can establish that they genuinely belong to the information they describe.
If a document is classified as SECRET, its security metadata must not become separated from the document or be altered without detection.
NATO STANAG 4778 addresses this requirement through mechanisms for binding confidentiality metadata to information objects.
Cryptographic techniques can help establish the integrity of the relationship between the information and its associated security metadata.
This is particularly important when information moves between applications, organisations or security domains.
Once information has been classified and labelled, systems need to determine who is authorised to access it.
This is where Attribute-Based Access Control (ABAC) becomes particularly relevant.
ABAC evaluates access requests using attributes associated with users, information and operational context.
These attributes might include:
For example, a user might possess the necessary security clearance but still be denied access because the information is not releasable to their nation.
This illustrates an important principle of defence information security:
Security clearance alone does not automatically establish a need to know or permission to access particular information.
ACP 240 supports an architectural approach in which such policies can contribute to protecting information across organisational boundaries.
ACP 240 also addresses the protection of information through encryption and associated access-control mechanisms.
One important component is the Zero Trust Data Format (ZTDF), specified within ACP 240.
ZTDF provides a means of packaging encrypted information together with security metadata and information needed to support policy-controlled access.
This allows protection to remain associated with the information object as it moves between systems.
However, encryption is only one component of data-centric security. Effective interoperability also depends on consistent security labels, trusted identities, compatible policies and appropriate enforcement mechanisms.
Zero Trust Data Format (ZTDF) is a protected data format specified within ACP 240 that combines encrypted information with security metadata and policy-related information to support controlled access.
ZTDF is related to the wider Trusted Data Format family of technologies.
Its purpose is to support the movement of protected information between systems while retaining the information necessary to evaluate access requirements.
A ZTDF-protected object can incorporate several elements:
Encrypted content: The information payload is encrypted to prevent unauthorised disclosure.
Security metadata: Classification and handling information describes the sensitivity of the protected content.
Access policy: Policy information helps determine which users or systems may be authorised to access the information.
Key access information: Information associated with cryptographic key management supports controlled decryption.
When an authorised user requests access, the relevant security services can evaluate applicable policies before making the necessary decryption capability available.
This approach helps separate the protection of information from the particular network or storage system in which it resides.
Nevertheless, ZTDF should not be treated as a universal solution for every defence information-sharing requirement.
For example, protecting an entire document presents different technical challenges from applying granular security controls to individual messages, database fields or elements of operational command-and-control data.
Organisations must therefore consider the information types, operational requirements and interoperability standards relevant to their systems.
ACP 240, STANAG 4774 and STANAG 4778 address related but distinct aspects of data-centric security.
Understanding their different roles is important when designing secure information-sharing environments.
|
Standard |
Primary purpose |
|---|---|
|
ACP 240 |
Establishes data-centric security interoperability concepts and requirements, including protected data formats and cryptographic mechanisms. |
|
STANAG 4774 |
Defines standardised confidentiality metadata labels for information objects. |
|
STANAG 4778 |
Defines mechanisms for binding security metadata to information objects. |
These standards can complement one another.
STANAG 4774 provides a standardised way to describe the security classification of information.
STANAG 4778 provides mechanisms for establishing the integrity of the relationship between information and its security metadata.
ACP 240 addresses the wider architecture for protecting and exchanging information, including mechanisms for cryptographically protected data objects.
Together, these concepts support information-sharing environments in which security controls can remain meaningful beyond the original application or network.
Importantly, compliance with one standard does not automatically establish compliance with the others.
Defence organisations should assess the particular standards, implementation profiles and interoperability requirements applicable to their programmes.
One of the most important applications of data-centric security is multinational military collaboration.
A Mission Partner Environment (MPE) enables participating organisations to collaborate and exchange information in support of a shared operation.
These environments may involve multiple national defence organisations, coalition partners and supporting agencies.
Each participant may retain responsibility for its own infrastructure, security policies and operational systems.
The challenge is enabling information to move between these environments without undermining the controls established by the originating organisation.
ACP 240 supports the architectural principles needed for this type of interoperability.
For example, imagine a coalition operation involving several allied nations.
A British intelligence analyst produces an operational assessment that needs to be shared with selected coalition partners.
The information carries classification and releasability metadata.
When the assessment is made available through an approved information-sharing service, participating systems must determine whether the intended recipients satisfy the relevant security requirements.
A user from one coalition nation may be authorised to access the assessment, while another user with an equivalent clearance may not be authorised because of different releasability restrictions.
The decision depends on more than the security of the communications channel.
It depends on the information’s security attributes, the user’s attributes and the policies governing access.
This is the central advantage of data-centric security: the ability to make access decisions based on the information itself and the applicable security policy.
ACP 240 provides a framework relevant to implementing this approach across allied environments.
However, the publication alone does not create interoperability. Participating organisations must also establish compatible policies, trusted identity mechanisms, information-handling processes and approved technical implementations.
Zero Trust security is based on the principle that access should not be granted simply because a user or system is operating within a trusted network.
Instead, access decisions should be based on appropriate verification and policy evaluation.
In defence environments, this is particularly important because information may move between different national systems and operational security domains.
ACP 240 supports this approach by helping move security controls closer to the information being protected.
Rather than assuming that all authorised users within a particular network should have access to the same information, systems can evaluate the requirements associated with individual information objects.
For example, an authorised military user might have access to a coalition collaboration platform but not to every document, operational assessment or intelligence product available through it.
Access may depend on additional attributes, including mission membership, releasability and need-to-know restrictions.
Data-centric security and Zero Trust are therefore closely related.
However, they are not interchangeable.
Zero Trust describes a broader security approach involving identity, devices, applications, networks and continuous policy evaluation.
Data-centric security concentrates on protecting information according to its attributes and handling requirements.
ACP 240 contributes to the information-protection aspects of this wider security architecture.
Although ACP 240 provides an important framework, implementing data-centric security across defence organisations introduces practical challenges.
Coalition partners may use different classification structures, releasability rules and information-handling policies.
These differences must be understood and appropriately mapped before automated access decisions can be trusted.
Many defence organisations continue to operate established communications platforms that were not originally designed around data-centric security.
These systems may lack native support for machine-readable security labels, cryptographic metadata binding or granular policy enforcement.
Integrating data-centric security capabilities into existing environments may therefore require additional services, gateways or application-level development.
ABAC depends on reliable information about users and their authorisations.
In multinational environments, attributes may originate from different national identity systems.
Participating organisations need mechanisms for establishing which identity providers and attribute authorities can be trusted.
Military communications must often operate in challenging environments.
Connectivity may be limited, disrupted or unavailable, particularly in deployed and tactical situations.
Security architectures must account for how authentication, policy evaluation and cryptographic services behave under these conditions.
Adopting a common standard does not automatically guarantee that independently developed systems will interoperate.
Differences in supported profiles, policy interpretation and implementation choices can create practical incompatibilities.
Testing and agreed implementation requirements remain essential.
Data-centric security is not solely a document-management challenge.
Modern defence operations depend on continuous communication between individuals, teams and organisations.
Operational messages, collaborative discussions and shared intelligence may all contain information subject to classification and releasability requirements.
A secure collaboration platform therefore needs to do more than encrypt communications.
It must also support the wider security policies governing who can participate in conversations, access particular information and exchange data with other organisations.
For defence organisations, important considerations include:
These requirements are particularly relevant when communications must extend beyond a single organisation.
A collaboration platform may provide strong encryption and still be unsuitable for certain classified information-sharing scenarios if it cannot enforce the necessary access and releasability restrictions.
MindLink develops secure collaboration technology for organisations operating in security-sensitive and mission-critical environments.
Its approach recognises that secure communication requires more than protecting information in transit.
Organisations must also be able to control access to conversations, users and information according to their operational and security requirements.
MindLink’s work around secure mission collaboration, data-centric security and attribute-based access control is relevant to the challenges addressed by ACP 240 and associated NATO interoperability standards.
For organisations considering a transition towards data-centric security, secure collaboration platforms form an important part of the wider architecture.
They provide the operational environment in which authorised personnel communicate and collaborate, while integrating with the security services and policies needed to govern information access.
The objective is to enable effective communication without compromising the controls required in defence and intelligence environments.
ACP 240 provides important architectural direction for allied information-sharing environments. Secure collaboration technologies must work within those wider architectures to support controlled, resilient and interoperable communications.
MindLink’s support for particular ACP 240 requirements or ZTDF implementation profiles should be assessed against the relevant technical specifications rather than assumed from its broader data-centric security capabilities.
ACP 240 stands for Allied Communications Publication 240. It is a publication developed under the Combined Communications-Electronics Board (CCEB) that addresses data-centric security interoperability for allied information-sharing environments.
ACP 240 originates from the Five Eyes community through the CCEB rather than being a NATO Standardization Agreement. It is closely related to NATO data-centric security initiatives, but its application within NATO is subject to the appropriate NATO arrangements.
ACP 240 provides architectural concepts and requirements supporting secure information sharing between allied organisations. It addresses data-centric security, interoperability and mechanisms for protecting information as it moves between systems and security environments.
STANAG 4774 specifies standardised confidentiality metadata labels for information objects. ACP 240 addresses broader data-centric security interoperability requirements and includes approaches that can use these labels to support protected information sharing.
STANAG 4778 defines mechanisms for binding security metadata to information objects. ACP 240 addresses a wider set of data-centric security concepts, architectures and protection mechanisms, including the Zero Trust Data Format.
Zero Trust Data Format (ZTDF) is a protected data format specified within ACP 240. It combines encrypted content with security metadata and policy-related information to support controlled access to protected information objects.
ACP 240 supports the development of interoperable information-protection mechanisms that can help allied organisations exchange sensitive information while respecting classification, releasability and access-control requirements.
No. ACP 240 supports a data-centric approach that complements existing network and system security controls. Its objective is to help protect information according to its security attributes, including when it moves beyond the original network or application.
Attribute-Based Access Control (ABAC) evaluates access requests using attributes associated with users, information and operational context. ABAC can support the policy-driven information protection approaches addressed by ACP 240.
Military communications increasingly involve multiple organisations and security domains. ACP 240 provides relevant architectural concepts for protecting information across these boundaries, helping organisations develop secure and interoperable information-sharing environments.
The ability to share information securely between allied organisations is essential to modern military operations.
However, multinational collaboration introduces security challenges that cannot be addressed through network protection alone.
Information must remain appropriately protected as it moves between national systems, coalition environments and operational applications.
ACP 240 represents an important development in the transition towards data-centric security, supporting an approach in which information protection is associated with the data itself.
Alongside NATO STANAG 4774, STANAG 4778 and attribute-based access control, it contributes to the technical and architectural foundations needed for secure information sharing.
For defence organisations, the challenge is translating these principles into practical, interoperable systems that support operational requirements without compromising information security.
Secure collaboration technologies have an important role in that transition, enabling authorised personnel to communicate and work together within the security frameworks established by their organisations.
Discover how MindLink supports secure mission-critical collaboration and data-centric security in demanding defence environments.