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Evolving Encryption Key Management Best Practices: Part 2

By Rich

This is the second in a four-part series on evolving encryption key management best practices. The first post is available here. This research is also posted at GitHub for public review and feedback. My thanks to Hewlett Packard Enterprise for licensing this research, in accordance with our strict Totally Transparent Research policy, which enables us to release our independent and objective research for free.

Best Practices

If there is one thread tying together all the current trends influencing data centers and how we build applications, it’s distribution. We have greater demand for encryption in more locations in our application stacks – which now span physical environments, virtual environments, and increasing barriers even within our traditional environments.

Some of the best practices we will highlight have long been familiar to anyone responsible for enterprise encryption. Separation of duties, key rotation, and meeting compliance requirements have been on the checklist for a long time. Others are familiar, but have new importance thanks changes occurring in data centers. Providing key management as a service, and dispersing and integrating into required architectures aren’t technically new, but they are in much greater demand than before. Then there are the practices which might not make the list, such as supporting APIs and distributed architectures (potentially spanning physical and virtual appliances).

As you will see, the name of the game is consolidation for consistency and control; simultaneous with distribution to support diverse encryption needs, architectures, and project requirements.

But before we jump into recommendations, keep our focus in mind. This research is for enterprise data centers, including virtualization and cloud computing. There are plenty of other encryption use cases out there which don’t necessarily require everything we discuss, although you can likely still pick up a few good ideas.

Build a key management service

Supporting multiple projects with different needs can easily result in a bunch of key management silos using different tools and technologies, which become difficult to support. One for application data, another for databases, another for backup tapes, another for SANs, and possibly even multiple deployments for the same functions, as individual teams pick and choose their own preferred technologies. This is especially true in the project-based agile world of the cloud, microservices, and containers. There’s nothing inherently wrong with these silos, assuming they are all properly managed, but that is unfortunately rare. And overlapping technologies often increase costs.

Overall we tend to recommend building centralized security services to support the organization, and this definitely applies to encryption. Let a smaller team of security and product pros manage what they are best at and support everyone else, rather than merely issuing policy requirements that slow down projects or drive them underground.

For this to work the central service needs to be agile and responsive, ideally with internal Service Level Agreements to keep everyone accountable. Projects request encryption support; the team managing the central service determines the best way to integrate, and to meet security and compliance requirements; then they provide access and technical support to make it happen.

This enables you to consolidate and better manage key management tools, while maintaining security and compliance requirements such as audit and separation of duties. Whatever tool(s) you select clearly need to support your various distributed requirements. The last thing you want to do is centralize but establish processes, tools, and requirements that interfere with projects meeting their own goals.

And don’t focus so exclusively on new projects and technologies that you forget about what’s already in place. Our advice isn’t merely for projects based on microservices containers, and the cloud – it applies equally for backup tapes and SAN encryption.

Centralize but disperse, and support distributed needs

Once you establish a centralized service you need to support distributed access. There are two primary approaches, but we only recommend one for most organizations:

  • Allow access from anywhere. In this model you position the key manager in a location accessible from wherever it might be needed. Typically organizations select this option when they want to only maintain a single key manager (or cluster). It was common in traditional data centers, but isn’t well-suited for the kinds of situations we increasingly see today.
  • Distributed architecture. In this model you maintain a core “root of trust” key manager (which can, again, be a cluster), but then you position distributed key managers which tie back to the central service. These can be a mix of physical and virtual appliances or servers. Typically they only hold the keys for the local application, device, etc. that needs them (especially when using virtual appliances or software on a shared service). Rather than connecting back to complete every key operation, the local key manager handles those while synchronizing keys and configuration back to the central root of trust.

Why distribute key managers which still need a connection back home? Because they enable you to support greater local administrative control and meet local performance requirements. This architecture also keeps applications and services up and running in case of a network outage or other problem accessing the central service. This model provides an excellent balance between security and performance.

For example you could support a virtual appliance in a cloud project, physical appliances in backup data centers, and backup keys used within your cloud provider with their built-in encryption service.

This way you can also support different technologies for distributed projects. The local key manager doesn’t necessarily need to be the exact same product as the central one, so long as they can communicate and both meet your security and compliance requirements. We have seen architectures where the central service is a cluster of Hardware Security Modules (appliances with key management features) supporting a distributed set of HSMs, virtual appliances, and even custom software.

The biggest potential obstacle is providing safe, secure access back to the core. Architecturally you can usually manage this with some bastion systems to support key exchange, without opening the core to the Internet. There may still be use cases where you cannot tie everything together, but that should be your last option.

Be flexible: use the right tool for the right job

Building on our previous recommendation, you don’t need to force every project to use a single tool. One of the great things about key management is that modern systems support a number of standards for intercommunication. And when you get down to it, an encryption key is merely a chunk of text – not even a very large one.

With encryption systems, keys and the encryption engine don’t need to be the same product. Even your remote key manager doesn’t need to be the same as the central service if you need something different for that particular project.

We have seen large encryption projects fail because they tried to shoehorn everything into a single monolithic stack. You can increase your chances for success by allowing some flexibility in remote tools, so long as they meet your security requirements. This is especially true for the encryption engines that perform actual crypto operations.

Provide APIs, SDKs, and toolkits

Even off-the-shelf encryption engines sometimes ship with less than ideal defaults, and can easily be used incorrectly. Building a key management service isn’t merely creating a central key manager – you also need to provide hooks to support projects, along with processes and guidance to ensure they are able to get up and running quickly and securely.

  • Application Programming Interfaces: Most key management tools already support APIs, and this should be a selection requirement. Make sure you support RESTful APIs, which are particularly ubiquitous in the cloud and containers. SOAP APIs are considered burdensome these days.
  • Software Development Kits: SDKs are pre-built code modules that allow rapid integration into custom applications. Provide SDKs for common programming languages compatible with your key management service/products. If possible you can even pre-configure them to meet your encryption requirements and integrate with your service.
  • Toolkits: A toolkit includes all the technical pieces a team needs to get started. It can include SDKs, preconfigured software agents, configuration files, and anything else a project might need to integrate encryption into anyything from a new application to an old tape backup system.

Provide templates and recommendations, not just standards and requirements

All too often security sends out requirements, but fails to provide specific instructions for meeting those requirements. One of the advantages of standardization around a smaller set of tools is that you can provide detailed recommendations, instructions, and templates to satisfy requirements.

The more detail you can provide the better. We recommend literally creating instructional documents for how to use all approved tools, likely with screenshots, to meet encryption needs and integrate with your key management service. Make them easily available, perhaps through code repositories to better support application developers. On the operations side, include them not only for programming and APIs, but for software agents and integration into supported storage repositories and backup systems.

If a project comes up which doesn’t fit any existing toolkit or recommendations, build them with that project team and add the new guidance to your central repository. This dramatically speeds up encryption initiatives for existing and new platforms.

Meet core security requirements

So far we have focused on newer requirements to meet evolving data center architectures, the impact of the cloud, and new application design patterns; but all the old key management practices still apply:

  • Enforce separation of duties: Implement multiple levels of administrators. Ideally require dual authorities for operations directly impacting key security and other major administrative functions.
  • Support key rotation: Ideally key rotation shouldn’t create downtime. This typically requires both support in the key manager and configuration within encryption engines and agents.
  • Enable usage logs for audit, including purpose codes: Logs may be required for compliance, but are also key for security. Purpose codes tell you why a key was requested, not just by who or when.
  • Support standards: Whatever you use for key management must support both major encryption standards and key exchange/management standards. Don’t rely on fully proprietary systems that will overly limit your choices.
  • Understand the role of FIPS and its different flavors, and ensure you meet your requirements: FIPS 140-2 is the most commonly accepted standard for cryptographic modules and systems. Many products advertise FIPS compliance (which is often a requirement for other compliance, such as PCI). But FIPS is a graded standard with different levels ranging from a software module, to plugin cards, to a fully tamper-resistant dedicated appliance. Understand your FIPS requirements, and if you evaluate a “FIPS certified” ‘appliance’, don’t assume the entire appliance is certified – it might be only the software, not the whole system. You may not always need the highest level of assurance, but start by understanding your requirements, and then ensure your tool actually meets them.

There are many more technical best practices beyond the scope of this research, but the core advice that might differ from what you have seen in the past is:

  • Provide key management as a service to meet diverse encryption needs.
  • Be able to support distributed architectures and a range of use cases.
  • Be flexible on tool choice, then provide technical components and clear guidance on how to properly use tools and integrate them into your key management program.
  • Don’t neglect core security requirements.

In our next section we will start looking at specific use cases, some of which we have already hinted at.

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