Microsoft Opens Up Azure Integrated HSM as Project Tessera

What Project Tessera includes

According to Microsoft, Project Tessera carries forward the workload-attached HSM architecture introduced by Azure Integrated HSM. The architecture, specifications, protocols, drivers, software, firmware and reproducible build environments are being made open source for the broader community.

Microsoft says the initiative will, over time, move toward a fully open-source silicon implementation while making hardware broadly available. The aim is for organizations across the ecosystem to adopt, integrate and contribute to the platform. The specifications, protocols, software libraries, drivers, firmware and hardware are available through the Tessera Integrated HSM GitHub repository, which Microsoft says will add more open-source silicon, new hardware designs and community enhancements.

The company links the effort to Caliptra, a fully open-source silicon root-of-trust that it says has been broadly adopted across the hardware ecosystem. Tessera applies the same model of transparency and collaboration to key protection.

Why Microsoft points to AI and quantum threats

Microsoft argues that two shifts are reshaping cybersecurity. First, AI-orchestrated attacks are increasing the scale, speed and sophistication of attacks and compressing the time between vulnerability discovery and exploitation. The company says this amplifies risks such as credential theft, key exfiltration and signing abuse.

Second, quantum computing presents a risk to many current cryptographic algorithms. Microsoft says a sufficiently powerful quantum computer could break widely used public-key cryptography, undermining digital signatures, authentication and identity verification. It expects HSM-backed signing infrastructure to be among the first critical systems to migrate, which requires HSMs that support post-quantum cryptography and interoperate with classical HSMs.

Azure Integrated HSM performs cryptographic operations closer to the workload while keys stay within the HSM security boundary. Microsoft says this strengthens key protection, improves cryptographic performance, offers crypto-agility and provides a simpler operational model. Tessera incorporates lessons from deploying Azure Integrated HSM at scale.

Targeting key management anti-patterns

Microsoft says central HSM deployments, where the HSM is separate from compute, force cryptographic operations across the network. The resulting latency and operational dependencies can push enterprises toward workarounds that weaken key protection.

The anti-patterns it lists include:

• HSM keys acting as certificate authorities and endorsing externally generated keys that lack the same hardware protection
• HSM-generated keys created as extractable and exported in wrapped form
• Caching keys outside HSMs for resilience
• Using software-held keys to cut network latency to remote HSMs
• Sharing keys and security domains to simplify governance
• Relying on proprietary protocols for interoperability

The project will deliver Tessera Integrated HSM, designed to consistently enforce FIPS 140-3 Level 3 key protection throughout the key's lifecycle. Microsoft says native support for quantum-resilient cryptography will help ease the industry's move to post-quantum cryptography.

Interoperability demo and confidential computing

At the summit, Microsoft and Marvell demonstrated Tessera Integrated HSM transfer protocols establishing HSM partition cloning and resiliency rings across a Tessera Integrated HSM and a Marvell LiquidSecurity 2 HSM. According to Microsoft, this showed two heterogeneous HSMs operating in a resilient, unified security domain. Non-extractable keys stay protected within the HSMs and remain under the sole control of the partition owner. The Tessera protocols use post-quantum cryptography to protect communication between HSMs.

Early collaborators are also exploring how the architecture can extend to systems without dedicated HSM hardware. The project is making a minimal, unikernel-based Tessera firmware stack open source, designed to run inside hardware-isolated confidential computing environments. It uses the same firmware stack as the hardware HSM. Keys are protected within a confidential computing container that provides cryptographic services to bound workloads, including worker containers and virtual machines. The initial implementation uses AMD SEV-SNP and integrates with open-source virtualization technologies such as OpenVMM, and the Open Compute community is working to support other confidential computing architectures.

What it means

For organizations that depend on HSMs, Tessera offers an open, inspectable implementation with open protocols and a path to mixing hardware from different vendors, as the Marvell demonstration suggests. Microsoft frames the project as a way to support the move to post-quantum cryptography without giving up consistent key protection. The source does not give availability dates or pricing for Tessera hardware.