Software supply chains have become prime targets for cyber attackers. These complex networks, spanning developers, open-source contributors, and vendors across the globe, offer threat actors the opportunity to compromise thousands (or even millions) of users with a single point of infection.
By injecting malicious code early in the development or distribution process, attackers can embed threats that go undetected for months. Because the affected software often appears to come from trusted sources, such attacks can cause significant damage before anyone realizes something is (very) wrong.
This is why code signing has become a crucial practice in securing the software supply chain. When a company signs its software, it is publicly vouching for the integrity and authenticity of the code. But if the signing process is weak, mismanaged, or compromised, trust is lost — and the company is held responsible.
In this article, you’ll learn:
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Why code signing is essential to building secure and trustworthy software, especially in distributed and international development environments.
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Common pitfalls in code signing operations, from poor key management to inconsistent policy enforcement.
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The role of code signing certificates in reassuring customers and partners that your applications haven’t been tampered with.
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How SignServer helps Public Key Infrastructure (PKI) teams secure signing workflows, enforce policies, and integrate with modern CI/CD pipelines.
Whether you’re a software developer, security architect, or IT manager, understanding these principles is key to protecting your organization and your users — no matter where they are in the world. Let’s dive in!
Why Software Supply Chains Need Code Signing
The software supply chain offers malicious actors many chances to slip a threat into the chain. Developers use code signing to digitally “sign” software components, binaries, scripts, and containers to prove their origin and integrity.
Any good software development process includes code signing for several reasons, including:
- Computers use these signatures to validate software authenticity. If packages are unsigned (or have an outdated code signing certificate), the computer may trigger a user warning to confirm whether they trust the software’s developer and want to install the program.
- Code signing restricts software from being tampered with once it leaves the build environment. Changes could invalidate the signature (which will trigger a warning to the user before installation).
- Code signing makes it faster to identify and remediate malicious code. Your company could be held liable if your software caused damages from injected malware, so code signing protects both the software’s users and the company itself.
- Verified code signatures keep threat actors from exploiting CI/CD pipelines to inject malware into packages.
- In zero-trust architecture (ZTA) and DevSecOps pipelines, signed code acts as a machine identity for your software. It’s up to your organization to ensure there aren’t any hidden threats before you sign your code. The earlier code signing begins in the supply chain, the easier it is to identify and stop threats.
Code Signing Certificates: The Root of Software Integrity
At the core of each signed artifact in your software package is a code signing certificate. This is an X.509 cert bound to a verified identity and private key. These certificates are issued by a trusted certificate authority (CA), internal or external, and must be carefully managed to avoid compromise or expiry.
The biggest risk for your code signing certificates is improper handling. Storing private keys in shared file systems or unsecured build servers is like leaving a vault door open. If malicious actors access your keys, they can impersonate your organization, misleading and endangering your users.
Focus your software release processes on implementing secure issuance, renewal, storage (using HSMs or cloud-based key vaults), and revocation policies for keys. Essentially, protect your PKI at every possible stage of the certificate lifecycle, preferably through a secure, automated tool.
However, there are a few common pitfalls in code signing operations:
- Decentralized certificate management: Dev teams often self-issue or reuse stale certs without central oversight. This can lead to rogue certificates that could be used by attackers.
- Over-permissioned access: Build servers or CI/CD runners might have broad access to signing keys, increasing the blast radius of a compromise. Make sure zero-trust access controls are in place for your code signing certificates.
- Lack of auditing: Detailed logging and auditing provides insights into authorized and unauthorized user behavior. Without auditing, it becomes more difficult to identify and fix compromises.
These issues mirror the certificate management challenges faced across PKI infrastructure. Centralized visibility and automation is the best way to limit exposure to costly mistakes.
5 Tips for Building a Secure Code Signing Program
Here are five easy tips to keep your certificates clear, well-designed, and secure:
Centralize certificate issuance and inventory.
- Use a centralized platform (like Keyfactor Command) to issue and track code signing certificates from approved internal or public certificate authorities (CAs).
- Maintain a complete inventory of active, expired, and revoked code signing certificates across development teams. This is easiest with an automated tool.
Enforce policy-based access controls.
- Implement role-based permissions and approval workflows so only designated systems or teams can request and use signing keys.
- Leverage Keyfactor’s integration with DevOps toolchains to enforce access controls without disrupting development speed.
Protect private keys with hardware-backed security.
- Store private keys used for signing in FIPS-compliant HSMs or secure cloud vaults with API-based access. This allows keys to be stored and generated inside the HSM, safe from unauthorized access, while still being available to sign code.
- Rotate and audit these keys regularly to reduce exposure and meet compliance requirements. Keys should be replaced well before they expire, and this process is best automated.
Automate signing workflows.
- Integrate signing operations into CI/CD pipelines with tools like SignServer Enterprise and Keyfactor Signum.
- Apply time-stamping and signature validation as part of every build release to enhance traceability and integrity.
Monitor and audit every signing event.
- Use centralized logging and monitoring tools to track every signing request and verify against policy.
- Implement real-time alerting for anomalies such as signing from unusual sources or outside approved time windows.
How to Scale Secure Code Signing
As containerized workloads, microservices, and cloud-native development increase, your signing processes need to scale as well. Ensure they can evolve to support whatever speed and scale you require. Code signing must be as agile as the development process it supports.
For example, Keyfactor’s approach is API-first for seamless integration into DevOps pipelines, offering both speed and scalability. This includes short-lived certificates for ephemeral workloads, self-service issuance for developers, and automated renewals that align with fast-moving CI/CD cycles. Keep your code secure, no matter how many moving parts there are.
Your Turn: Protect Your Software
Think of code signing certificates as the digital proof that your software is safe. Unfortunately, manual or scattered certificate management can make it hard to track and secure signing keys. Here’s how to stay ahead:
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Automate certificate management to reduce human error and eliminate gaps in coverage
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Secure your private keys with centralized, policy-enforced access
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Streamline code signing workflows that integrate directly into modern DevOps and CI/CD pipelines
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Meet compliance standards and prove software integrity at every release
Don’t leave software trust to chance. Start protecting your code signing infrastructure. Show your users and partners that security is built into every release.
👉 Learn how SignServer secures code signing at scale.
Explore SignServer and how it helps PKI teams enforce signing policies, secure keys, and integrate with modern build systems.