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Speaking in Code: 5 Essential Ways to Interface With HSMs

Let’s talk HSM integration

Hardware Security Modules (HSMs) are physically and logically secure cryptographic devices. They provide a secure environment in which to perform encryption tasks, store encryption keys, and manage keys.

HSMs can be interacted with in different ways. Off-the-shelf HSM solutions may feature proprietary software and management interfaces through which users can issue commands. HSMs often integrate with applications via application programming interfaces (APIs). Through the API, an application can call an HSM to perform cryptographic functions, such as encrypting user data or rotating keys.

All of these considerations fall into the category of integration. Integration is imperative for systems architects and IT managers everywhere. When integration goes smoothly, projects get completed on time, and everyone wins. But when integration stalls, it creates headaches with no easy cure.

This blog post breaks down the go-to methods for interfacing with HSMs to demystify the complex paths through the integration journey. As you’ll see, there’s no universal method. Each method caters to different use cases, standards, and preferences.

Let’s dive in:

Standards-based interfaces

A standards-based interface is a set of rules that defines how different systems communicate with each other. In cryptography, standards-based interfaces provide a common language for cryptographic algorithms, protocols, and solutions.

Many HSMs support standards-based interfaces and protocols, allowing different systems and applications to talk to each other.

“Standard” examples

  • PKCS#11 (Public-Key Cryptography Standards #11): A widely used API standard for interfacing with cryptographic tokens, including HSMs.
  • KMIP (Key Management Interoperability Protocol): This protocol allows communication between key management systems and HSMs (as well as some other cryptographic devices)
  • Open Cryptographic Framework (OCF): An open standard for a cryptographic framework that supports HSMs.
  • Microsoft CryptoAPI (CAPI): In Windows environments, HSMs often integrate with Microsoft’s CryptoAPI, allowing applications to use HSM functionality through the standard Windows cryptographic architecture.
  • Java Cryptography Architecture (JCA): Java applications can interact with HSMs using the Java Cryptography Extension (JCE) and the Java Cryptography Architecture. HSM vendors may provide specific Java libraries or interfaces for seamless integration.

Network-based interfaces

Some HSMs support network-based interfaces, allowing remote access to the HSM over a network. This can be useful for scenarios where the HSM needs to be centralized and accessed by multiple systems.

A great example of a network-based interface are RESTful web APIs. RESTful APIs allow applications to communicate with the HSM over standard HTTP methods. This dramatically simplifies integration, especially in web-based or cloud environments.

Proprietary APIs

Some HSM vendors offer proprietary APIs for interfacing with their devices. These APIs may provide additional features tailored to the particular capabilities of the HSM. Developers using proprietary APIs may use vendor-specific SDKs (Software Development Kits) to integrate HSM functionality into their applications.

An example is Futurex’s Excrypt API. This proprietary API is customized to integrate Futurex solutions with numerous business applications. The Excrypt API also communicates with common standards-based interfaces such as PKCS #11 and KMIP. Clients that previously coded to those standards don’t have to do extra integration work on the back end.

Cryptographic Libraries

A cryptographic library is a collection of software functions or routines that implement various cryptographic algorithms and protocols. These libraries provide a set of programming interfaces that developers can use to incorporate cryptographic functionality into their applications.

Cryptographic libraries reduce the complexity of keeping track of cryptographic algorithms and operations. They provide developers with a convenient way to combine secure communication and data integrity in their applications.


OpenSSL and Bouncy Castle are examples of cryptographic libraries. They offer various cryptographic functions, including encryption, decryption, hashing, digital signatures, and more.

Context is key

When choosing an interface method, organizations should take into consideration factors like interoperability, standardization, ease of integration, and specific security requirements should be considered. The choice often depends on the particular use case and the existing infrastructure in which the HSM is deployed.

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Author Futurex

For over 40 years, Futurex has been a trusted provider of hardened, enterprise-class data security solutions. More than 15,000 organizations worldwide have used Futurex’s innovative hardware security modules, key management servers, and cloud HSM solutions to address mission-critical data encryption and key management needs.

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