Is code signing at install time enough, or does it need to happen at boot too?

Verifying signatures only at install time leaves a device vulnerable to post-install tampering of stored firmware or software, so code signing should be paired with secure boot, which re-verifies signatures every time the device starts, to defend against an attacker who modifies code on the device after it has already passed an initial install-time check.

What does FDA expect manufacturers to describe about code signing in a premarket cybersecurity submission?

Describe update authenticity and integrity verification, trusted-key provisioning, private-key protection, rotation, revocation and recovery. Cite the February 2026 FDA guidance and verify any separate standards-clause claim against licensed text.

What is the most damaging mistake manufacturers make in code-signing key management?

Storing signing keys in source control, unencrypted on CI/CD build servers, or sharing a single signing key across multiple product lines for many years are the most damaging mistakes, since a compromised key of that scope lets an attacker sign malicious firmware that the device will trust for every product using it; keys should be stored in a hardware security module or hardware-backed key store, with rotation and per-product or per-release key scoping to limit blast radius.

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CybersecurityConnected & Cyber-Physical Devices Software Lifecycle

Code Signing

Digital signatures used to verify software or firmware integrity and signer authorization.

Reviewed by Christian Espinosa, Founder, Blue Goat CyberLast reviewed June 20, 2026

Definition

Code signing digitally signs code or firmware with a private key. A verifier checks integrity and authorization using a trusted public key, which may be provisioned directly or trusted through a certificate chain. Reject code when signature verification fails, content was modified after signing, or the signer is not authorized. Signing alone does not ensure that code is safe or that verification is enforced at boot.

What the regulation says

FDA February 2026 guidance recommends authenticity and integrity protections and appropriate cryptographic key management. Do not assert that IEC 81001-5-1 clauses 5.7.2 and 9.6 or AAMI SW96 universally require signed updates without verified original clause text.

What this means in practice

Document update verification and signing-key lifecycle controls. Hardware-backed private-key protection may be appropriate to risk; avoid unsupported claims about the prevalence or severity of medical-device incidents caused by specific key-storage failures.

Examples

Illustrative: A patient monitoring device uses code signing to ensure that over-the-air firmware updates are genuinely from the manufacturer and have not been tampered with before installation.
Illustrative: During the boot process, an implantable medical device verifies the digital signature of its operating system to prevent the execution of unauthorized or malicious software.
Illustrative: A diagnostic imaging system relies on code signing to authenticate software patches, preventing the introduction of unverified code that could compromise data integrity or system functionality.

Common pitfalls

•Storing signing keys in CI/CD environment variables or unencrypted on build servers, keys belong in an HSM or hardware-backed key store.
•Using the same signing key across product lines and over many years, key rotation and per-product or per-release keys limit blast radius.
•Verifying signatures only at install time, not at boot, pair code signing with secure boot to defend against post-install tampering.

Frequently asked questions

Code signing cryptographically binds a firmware image, software package, or OTA update to a trusted publisher's private key, so that when the device verifies the signature against the corresponding public key it can reject any code that was modified after signing or that did not originate from an authorized publisher, protecting against tampered updates, counterfeit firmware, and unauthorized code execution.

Grouped by theme

Editor's picks

· Hand-selected related concepts

Cybersecurity

AAMI SW96

AAMI/ANSI standard establishing requirements for medical-device cybersecurity activities throughout the lifecycle.

Cybersecurity

Hardware Root of Trust(HRoT)

Hardware-enforced trust anchor for selected security functions, subject to implementation and threat assumptions.

Cybersecurity

IEC 81001-5-1

International standard defining secure-product-lifecycle activities for health software, including medical devices.

Cybersecurity

Over-the-Air Updates(OTA)

Remote, network-delivered software or firmware updates to a fielded medical device.

More in Cybersecurity

· Same category

Cybersecurity

Patchability

The designed-in ability to deploy security updates to a fielded medical device in a timely, controlled, and verifiable manner.

Cybersecurity

Premarket Cybersecurity Submission

The bundle of cybersecurity artifacts a sponsor includes in a 510(k), De Novo, PMA, or HDE submission for a cyber device.

Cybersecurity

Secure Boot

A chain-of-trust mechanism that ensures only cryptographically signed firmware and software can run on a device.

Cybersecurity

AAMI TIR57

AAMI Technical Information Report providing MedTech-specific guidance on cybersecurity risk management.

Cited by

Where this term appears across MedTech Terms.

Ecosystems (2)

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Sources

5 sources

Sources support the definition or relevant regulatory context, not necessarily every claim on this page. Each is graded against our source-tier hierarchy so you can see what rests on binding law versus commentary.

Official-source claim check: 2026-11-01

Digital signatures support code integrity and source authentication, contingent on verification and trust/key management.

Partial review: verified corrections are applied, but this is not a full accuracy certification. The last full review date is unchanged.

Remaining verification limits

Secondary regulatory, standards-clause, market-prevalence or procurement claims were not fully substantiated by accessible original text.

Tier 2Regulator guidance and consensus· 5

Link health: 3 verified 2 unchecked· last checked 2026-06-20

FDA·2NIST·2MDCG·1

Inline markers like [1] jump to the matching reference above.

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Sources: 5
Updated: 6/20/2026

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Learn in 60 seconds

Digital signatures used to verify software or firmware integrity and signer authorization.

·Document update verification and signing-key lifecycle controls.
·Hardware-backed private-key protection may be appropriate to risk; avoid unsupported claims about the prevalence or severity of medical-device incidents caused by specific key-storage failures.
·A verifier checks integrity and authorization using a trusted public key, which may be provisioned directly or trusted through a certificate chain.

Remember this

Watch out: Storing signing keys in CI/CD environment variables or unencrypted on build servers, keys belong in an HSM or hardware-backed key store.

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