Diluting On-Prem PKI Security Using Cloud Hardware Security Modules (HSM)

Could we be Diluting On-Prem PKI Security Using Cloud Hardware Security Modules (HSM) as a Service?

Compiled and researched by Steve Monti SafeCipher Ltd

Introduction
Using cloud vendors to protect on-premises Public Key Infrastructure (PKI) keys raises significant concerns, especially as the industry increasingly adopts cloud solutions. This report explores the trade-offs and challenges associated with cloud-based HSM services, particularly when they are used to manage sensitive on-premises PKI systems.

On-Premises HSM: Complete Control Over Security
With on-premises HSMs, organizations maintain full physical and administrative control over the devices. This level of control is crucial when managing PKI keys, where trust and security are paramount. Having physical custody of HSMs ensures that cryptographic keys remain within the organization’s perimeter, reducing the risks associated with third-party control.

The Trust Factor: Cloud HSM as a Service
Moving to HSM as a Service introduces a significant trust dependency on the cloud vendor. It’s no longer solely about hardware security but also about trusting the vendor’s security practices, personnel, and legal jurisdictions. Cloud HSMs, typically operating in a multi-tenant environment, are designed to isolate customers logically, but the concept of sharing infrastructure raises concerns in high-security scenarios.

Geographic and Jurisdictional Compliance Issues
Cloud-based HSM solutions may not meet regulatory requirements for certain industries or geographies. Regulations often dictate that cryptographic operations must be conducted within specific jurisdictions, which may conflict with cloud services that utilize global data centers. For example, the UK Government and Ministry of Defence (MOD) have stringent requirements that may preclude the use of cloud-based HSMs for protecting sensitive data.

Impact on Compliance and Industry Standards
Cloud HSM services can complicate compliance with industry-specific standards and government regulations. For MOD customers and certain UK government departments, moving cryptographic key management off-premises is not an option due to legal and security restrictions. The ability to meet these requirements is critical when considering cloud HSM as a service.

Latency and Integration Challenges
Cloud HSMs can introduce latency, which can be problematic for high-throughput environments where cryptographic operations are frequent and time-sensitive. Additionally, integrating cloud HSMs with on-premises PKI systems often requires robust network configurations and a reliable internet connection, which adds complexity to the deployment. This latency and complexity can undermine the operational efficiency of the on-premises PKI infrastructure.

Disaster Recovery and Redundancy
While cloud-based HSMs excel in disaster recovery capabilities, the lack of physical control over recovery and redundancy mechanisms might be a drawback for some organizations. On-premises solutions often allow for more direct control over how backups and recovery processes are handled in the event of an outage.

Security Considerations: Protecting Data in Transit
While cloud HSMs ensure that cryptographic keys themselves are not transmitted over the network, the data and commands related to these keys are transmitted. This creates a need for strong encryption during transit and for robust management of the cloud HSM. The ability to secure the communication channels is essential in maintaining the overall security posture of the system.

Concerns Regarding Harvest Now, Decrypt Later (HNDL)
One critical concern that is often overlooked is the potential vulnerability to Harvest Now, Decrypt Later (HNDL) attacks. This issue, particularly concerning cloud-managed on-premises TLS tunnels, is not widely understood or mitigated. As cloud solutions may lack the proper safeguards against such threats, it is vital that organizations consider the long-term implications of these risks, especially with the eventual advent of quantum computing.

Conclusion
In conclusion, while cloud HSM as a service offers many benefits, such as scalability and disaster recovery, the trade-offs in terms of control, compliance, and latency make it a challenging solution for sensitive on-premises PKI systems. Organizations must weigh these factors carefully before deciding to adopt cloud-based HSM solutions. Additionally, the growing concern over quantum computing and potential HNDL vulnerabilities highlights the need for robust, future-proof cryptographic strategies.

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