What breaks when cryptographic keys and machine identities are not protected in hardware?

Why This Matters for Security Teams

When cryptographic keys and machine identities live only in software, the trust boundary becomes thin. Attackers who reach the host, build pipeline, container image, or endpoint can often copy the key, reuse it elsewhere, or alter the identity material without immediate detection. That is a direct problem for code signing, PKI, certificate authorities, workload attestation, and automated service-to-service trust.

This is not a theoretical hardening issue. The practical risk is that one compromised machine identity can impersonate a trusted workload, sign malicious updates, or pivot through trust relationships that were assumed to be safe. NHI Mgmt Group notes that 80% of identity breaches involved compromised non-human identities such as service accounts and API keys in the Ultimate Guide to NHIs, which is why hardware-backed protection is now a core control, not an optional enhancement. For broader control mapping, teams often anchor this work to NIST Cybersecurity Framework 2.0 and NIST SP 800-53 Rev 5 Security and Privacy Controls.

In practice, many security teams discover the weakness only after a signing key, token, or certificate has already been reused outside its intended trust boundary.

How It Works in Practice

Hardware-backed protection keeps private keys inside a boundary such as a TPM, HSM, secure element, or enclave so the key material is not directly exportable. The software can ask the hardware to sign, decrypt, or attest, but it should not be able to read the raw secret. That distinction matters because attackers who gain code execution often look first for secrets in memory, files, CI jobs, or environment variables.

For machine identities, the operational goal is to bind identity to a specific workload or device state, then limit what that identity can do and for how long. In mature setups, the workload presents a short-lived certificate or token, and the underlying private key remains hardware-protected. This reduces the blast radius of theft and improves confidence in certificate issuance, mutual TLS, code-signing pipelines, and automated agent authentication. The pattern aligns well with incident lessons documented in cases like JetBrains GitHub plugin token exposure and Microsoft Azure Key Breach, where exposed machine credential became the path to broader trust abuse.

• Store signing and authentication keys in hardware when the identity can affect build integrity, release trust, or privileged automation.
• Use attestation where possible so the verifier can check device or workload state before accepting a certificate or token.
• Pair hardware protection with short-lived credentials, because hardware alone does not fix overlong token validity.
• Restrict export, duplication, and offline backup paths for keys that anchor PKI or code-signing trust.

Used this way, hardware protection helps preserve the integrity of machine-to-machine trust even when the host or pipeline is partially compromised. These controls tend to break down in legacy automation estates where keys must be imported into software libraries that cannot use hardware-backed signing.

Common Variations and Edge Cases

Tighter hardware protection often increases operational overhead, so organisations must balance stronger key isolation against deployment complexity, cost, and recovery procedures. That tradeoff is especially visible in CI/CD, ephemeral containers, and hybrid clouds where teams want fast automation but still need tamper resistance.

Best practice is evolving for workloads that cannot use a dedicated HSM or TPM. In those cases, current guidance suggests reducing exposure by shortening credential TTLs, separating signing from general-purpose runtime access, and using stronger monitoring around key use. This is also where software supply chain controls become critical. If a key can sign artifacts, then compromise of the signing path can be as damaging as compromise of the application itself. Events such as Code Formatting Tools Credential Leaks and Hard-Coded Secrets in VSCode Extensions show how quickly software-only secret handling can fail once secrets are embedded in developer tooling.

There is no universal standard for every hardware design yet, and teams should validate whether the control protects only at-rest key material or also enforces policy on use. In distributed systems with frequent rotation, remote attestation gaps, or multi-tenant build platforms, hardware-backed identity can still be undermined by weak lifecycle controls, poor revocation, or insecure secret delivery.

Related resources from NHI Mgmt Group

• How should security teams govern cryptographic keys and certificates across human and machine identities?
• What breaks when Machine Account Quota and ADCS templates are left loose?
• What breaks when SSH keys are copied across multiple administrators instead of being isolated and rotated?
• What breaks when non-human identities are not mapped before a breach response starts?