Definition
Encrypting a message body using a cryptographic key.
How it works
Asymmetric Cryptography
Asymmetric encryption is typically accomplished using public and private key certificates based on the X.509 standard. The sender encrypts messages using the recipient's public key and the receipt decrypts the message using their private key. Standards that can be used to implement user message encryption include S/MIME (Secure/Multipurpose Internet Mail Extensions) and PGP.
Symmetric Cryptography
Symmetric encryption uses the same cryptographic key by both the sender and receiver to encrypt and decrypt a message. Asymmetric key exchange protocols such as Diffie-Hellman can be used to share the cryptographic key with the recipient. For synchronous or low-latency environments (like a message bus), a pre-shared or dynamically derived symmetric key is typically used to minimize computational overhead.
Considerations
- Separate configuration settings to enable message encryption are often needed for each messenger client (e.g. webmail, desktop client, mobile).
- Continuous monitoring to ensure private keys are not compromised and the certificate authority (CA) is trusted.
- Secure transfer of private keys between multiple devices.
- Encryption adds latency and increases CPU utilization; while negligible for user-to-user messages, it can be a critical factor for real-time bus systems.
Implementation perspective
Message Encryption should be treated as a technical defensive capability rather than a product checkbox. In practice, teams should define the protected scope, the conditions under which the technique acts, and the observable evidence that demonstrates the intended behavior. For this technique, likely engineering context includes Digital Message.
Use the technique to increase the effort, prerequisites, or constraints an adversary must overcome before exploitation or misuse succeeds.
Questions to ask
- Which component, configuration, credential, interface, or behavior is being hardened?
- What secure baseline or policy defines the intended state?
- How are exceptions approved, time-limited, and reviewed?
- How is the hardened state verified after deployment and significant change?
Evidence and validation
- Approved hardening standards and configuration baselines
- Automated configuration or integrity assessment results
- Exception records with owners, rationale, and expiration dates
- Test results demonstrating that the intended restriction is enforced
Common failure patterns
- A secure setting is documented but not enforced consistently across the environment.
- Hardening breaks required functions and is permanently weakened through undocumented exceptions.
- Teams measure deployment of a product rather than verification of the hardened condition.
This implementation perspective is original Bare Metal Cyber educational content. It does not replace the official D3FEND definition or establish that a specific product implements the technique.
Technique hierarchy
Top-level family
Parent techniques
Direct child techniques
None listed at this level.
Artifacts and ontology entities
These relationships describe how D3FEND connects a defensive technique to artifacts or other ontology entities. They describe graph semantics, not a product certification.
Explicit technique relationships
Show inferred artifact relationship paths (1)
ATT&CK Enterprise mitigation relationships
These links come from the D3FEND ontology’s ATT&CK mitigation mapping. They help users navigate between the knowledge bases and do not guarantee mitigation effectiveness.
Offensive-technique relationships
These relationships are generated from D3FEND graph paths and are explicitly experimental. They should be treated as hypotheses for defensive analysis—not as proof that the technique prevents, detects, or removes an offensive behavior.
ATT&CK for ICS (32)
Authoritative sources
- Open this technique on the official D3FEND website ↗
- Open the official ontology resources ↗
- Secure/Multipurpose Internet Mail Extensions (S/MIME) Version 3.1 Message Specification ↗Internet Engineering Task Force (IETF) · SpecificationReference
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