Adopting hybrid cloud systems—blending private on-premises infrastructure with public cloud services—has surged as organizations seek scalability, cost-efficiency, and flexibility. However, securing Controlled Unclassified Information (CUI) in these environments remains a critical challenge. These systems will use encryption to protect this data… but hybrid clouds introduce unique complexities due to data mobility, shared responsibility models, and varying compliance requirements.

This article explores robust encryption strategies for safeguarding CUI in hybrid cloud architectures.

Understanding CUI and Hybrid Cloud Challenges

CUI refers to unclassified data that demands safeguarding due to its sensitivity, the governance of which is enshrined in CMMC requirements. Examples include export-controlled technical data, law enforcement records, and proprietary business information. Hybrid cloud systems, while advantageous, create security gaps because data traverses multiple environments—each with distinct security postures. Key challenges include:

Data Mobility: CUI moves between on-premises servers and public clouds, increasing exposure risks.
Compliance Complexity: Regulations may differ across jurisdictions where cloud providers operate.
Shared Responsibility: Cloud providers secure infrastructure, but customers must protect data and access controls.
Interoperability: Ensuring encryption mechanisms work seamlessly across platforms.

Organizations risk data breaches, compliance penalties, and reputational damage without a cohesive strategy.

Encryption Strategies for CUI in Hybrid Cloud Systems

As CUI traverses these interconnected systems, it becomes vulnerable to exposure during storage, transmission, and processing at multiple points. A robust encryption framework must comply with stringent regulations like NIST SP 800-171 and CMMC, accounting for the complexities of shared responsibility models, cross-platform interoperability, and evolving cyber threats.

Data Classification and Discovery

Before encrypting data, organizations must classify CUI. Automated tools like Data Loss Prevention (DLP) software and AI-driven discovery platforms scan hybrid environments to tag sensitive data. For instance, a defense contractor might use Microsoft Azure Purview to classify export-controlled technical drawings stored across on-premises servers and AWS S3 buckets. Classification ensures encryption resources target high-risk assets.

Encryption at Rest

Encrypting CUI at rest is non-negotiable. AES-256, the industry standard for symmetric encryption, protects data stored in databases, file systems, and cloud storage.

On-Premises: Deploy hardware security modules (HSMs) or software-based solutions like VeraCrypt for full-disk encryption.
Public Cloud: Leverage native services but retain key control (see Key Management).
Multi-Cloud: Ensure consistency using vendor-agnostic tools like HashiCorp Vault, which centralizes platform encryption.

Encryption in Transit

CUI is vulnerable when moving between on-premises and cloud environments. Implement:

TLS 1.3: Encrypt data in transit using the latest TLS protocols.
VPNs/IPSec: Secure connections between private data centers and cloud providers.
API Security: Encrypt RESTful APIs with OAuth 2.0 and HTTPS to protect data exchanged between microservices.

Encryption in Use

Encrypting data during processing (in use) is challenging but critical. Although encrypting during use is rare in public life, protecting data in an app or device is just as crucial in these military applications.

Confidential Computing: Use secure enclaves to process CUI in isolated, encrypted memory regions.
Homomorphic Encryption: Allows computations on encrypted data without decryption, though still nascent for widespread use.

Robust Key Management

Poor key management undermines encryption because no matter how strong your encryption is, it will not work if the keys are lost, stolen, or compromised.

Bring Your Own Key (BYOK): Retain ownership of keys using cloud-agnostic HSMs or services like Google Cloud External Key Manager.
Centralized Management: Use tools like Thales CipherTrust to unify key lifecycle processes (generation, rotation, revocation) across hybrid environments.
Automated Rotation: Enforce policies to rotate keys every 90 days or after security incidents.

Access Controls and Zero Trust

Encryption alone isn’t always enough. You’ll need to have other controls in mind, precisely zero trust, to keep attackers from accessing the systems that hold that data.

Role-Based Access Control (RBAC): Restrict decryption rights to authorized personnel.
Just-in-Time Access: Use solutions like Azure AD Privileged Identity Management to grant temporary decryption privileges.
Multi-Factor Authentication (MFA): MFA is required to access encryption keys or sensitive datasets.

Monitoring and Auditing

Monitor encrypted CUI without compromising security (that is, exposing data in its unencrypted form during usually routine scans and audits):

SIEM Integration: Feed logs from encryption tools into Splunk or IBM QRadar to detect anomalies.
Metadata Analysis: Track access patterns (unusual decryption requests) to identify breaches.
Audit Trails: Maintain immutable logs for compliance reporting, ensuring auditors can verify encryption practices.

Best Practices for Implementation

As we’ve covered, encryption strategies can get complex, spreading over every aspect of an IT system, from storage to transit and compliance. Accordingly, you must have some best practices in place:

Layered Defense: Combine encryption with tokenization, network segmentation, and intrusion detection.
Performance Optimization: Use hardware acceleration to reduce encryption latency.
Incident Response: Regularly test decryption recovery processes to ensure business continuity.
Training: Educate employees on handling encrypted CUI and recognizing phishing attacks targeting keys.

Embed Compliant Encryption Throughout Your Infrastructure with Continuum GRC

Protecting CUI in hybrid cloud systems demands a proactive, multifaceted encryption strategy. Organizations can mitigate risks by classifying data, enforcing encryption at all lifecycle stages, rigorously managing keys, and integrating zero-trust principles while leveraging hybrid cloud benefits.

Continuum GRC is a cloud platform that stays ahead of the curve, including support for all certifications (along with our sister company and assessors, Lazarus Alliance).

We are the only FedRAMP and StateRAMP-authorized compliance and risk management solution worldwide.

Continuum GRC is a proactive cyber security® and the only FedRAMP and StateRAMP-authorized cybersecurity audit platform worldwide. Call 1-888-896-6207 to discuss your organization’s cybersecurity needs and learn how we can help protect its systems and ensure compliance.

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Encryption Strategies for Controlled Unclassified Information (CUI) in Hybrid Cloud Systems