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About keys in Managed HSM

Azure Key Vault Managed HSM is a fully managed, highly available, single-tenant cloud service that uses FIPS 140-3 Level 3 validated hardware security modules to protect your cryptographic keys. All keys in a Managed HSM instance are HSM-protected; Managed HSM doesn't store software-protected keys.

Each Managed HSM instance is an isolated single-tenant pool with its own security domain, which provides complete cryptographic isolation from all other Managed HSM instances that share the same underlying hardware. The data-plane endpoint base URL for a Managed HSM instance is https://<hsm-name>.managedhsm.azure.net.

Cryptographic keys in Managed HSM are represented as JSON Web Key (JWK) objects, as defined by the following specifications:

The base JWK/JWA specifications are extended to enable key types unique to the Managed HSM implementation.

Supported key types and sizes

Key type Sizes / curves
RSA-HSM — RSA key 2,048-bit, 3,072-bit, 4,096-bit
EC-HSM — Elliptic Curve key P-256, P-256K (secp256k1), P-384, P-521
oct-HSM — Symmetric (AES) key 128-bit, 192-bit, 256-bit

You can generate keys directly in a Managed HSM instance, import RSA or EC keys from a PEM file, or securely transport keys (RSA, EC, or oct-HSM) from a supported on-premises HSM by using the BYOK (bring your own key) specification. For more information, see Manage keys in Managed HSM and Import HSM-protected keys to Managed HSM (BYOK).

For details on supported algorithms, operations, attributes, and tags, see Key types, algorithms, and operations.

Compliance

All keys in Managed HSM are HSM-protected by FIPS 140-3 Level 3 validated hardware. There is a single protection tier; Managed HSM doesn't expose multiple HSM platforms or a software-protected option. For details on the hardware environment, validated standards (FedRAMP-High, PCI, SOC 1/2/3, ISO 270x), and the broader Azure compliance program, see Managed HSM technical details.

Quantum-resistant cryptography

"Quantum-resistant", "quantum-safe", and "post-quantum" cryptography are terms used to describe cryptographic algorithms believed to be resistant to cryptanalytic attacks from both classical and quantum computers. oct-HSM 256-bit keys used with the AES algorithms offered by Managed HSM are quantum-resistant. For more information, see The Commercial National Security Algorithm Suite 2.0 and Quantum Computing FAQ.

Key attestation

Managed HSM can attest that a key was generated and resides inside an HSM that Microsoft operates. Asymmetric keys receive both public and private key attestation; symmetric (oct-HSM) keys receive private key attestation only. For more information, see Validate Azure Managed HSM keys with key attestation.

Usage scenarios

When to use Examples
Azure server-side data encryption with customer-managed keys Server-side encryption using customer-managed keys in Azure Key Vault
Client-side data encryption Client-Side Encryption with Azure Key Vault
Keyless TLS Azure Managed HSM TLS Offload Library