Containers have revolutionized software delivery. These lightweight software packages include everything needed to run in any environment, making them the preferred choice for modern application deployment. They’re portable, fast, and scalable, perfect for today’s dynamic infrastructure.
But these advantages can also create security blind spots. When teams pull container images from public registries without proper validation or governance, they risk introducing unverified code, hidden dependencies, and unmanaged assets into their environments.
The core issue isn’t just scale – it’s trust. How can you be sure the container image you’re deploying hasn’t been tampered with or forged along the way?
Code signing solves this problem.
Code signing builds trust between developers and their audiences to ensure code hasn’t been corrupted. By building this trust, you can maintain long-lasting relationships with audiences and prevent breaches.
Code Signing for Containers
Code signing for containers uses a private key to sign the certificate and a public key to verify. In container workflows, signing ties identity and integrity directly to each image, chart, or manifest.
Here are some of the key benefits:
- Authenticity: assurance that an image really comes from the claimed developer/organization
- Integrity: cryptographic proof that the certificate hasn’t been altered in transit or in a registry
- Accountability: the ability to tie an image to a signing identity with audit logs
Code Signing: Solving 4 Major Container Security Challenges
Code signing solves four major container security challenges.
Here are some real-life scenarios:
- The poisoned registry
- The compromised pipeline
- Stolen keys
- Patchwork policies and teams
The Poisoned Registry
Developer Tim pulls a lightweight base image from a public registry. It looks clean, and it builds fine. A few weeks later, Tim and his team learn that the image contained crypto-mining malware.
Without detection, the bad image spreads across production. Once it is identified, it can take several days to respond, which increases the chances for data theft or intentional damage.
A combination of policy enforcement and visibility could have prevented these threats. Had the code certificates been signed, the registry would have rejected the tampered image immediately.
The Compromised Pipeline
After developer Phoebe and her team sign out for the day, they don’t realize an attacker slipped into a CI/CD server to alter build artifacts before they’re pushed. Phoebe’s team discovers the attack four days later. By then, dozens of services carry compromised workloads.
Phoebe and her team could have prevented this attack by signing at build time. Signing at build time forces every artifact to carry a verifiable signature, and wouldn’t validate the image downstream. The earlier an artifact is signed, the more secure and managed it is.
Stolen Keys
Dave, a developer, keeps a signing key on a local laptop for convenience. Dave knows it’s not a great idea from a security standpoint, but it saves so much time.
One day, a hacker steals the signing key. They create rogue images that look authentic, then use the stolen key to sign them, hiding behind a legitimate identity.
If Dave had been securing his keys, this wouldn’t have happened. Keys need proper protection, such as hardware security modules (HSMs) or vaults. When they’re stored properly, keys will never leave a secure environment, and hackers will have nothing to steal.
Patchwork Policies and Teams
Sean and Marina both lead DevOps teams. However, they run their teams differently. Marina’s team is diligent about signing containers. Sean’s team tends to skip that step because it slows them down. Marina doesn’t say anything directly to her colleague, but she does tell her team members not to trust the work Sean’s team is doing because they’re not taking proper precautions.
However, due to Sean’s team being lax about security, unsigned images creep into production. Because there isn’t a standard policy on signing containers, the department’s leadership doesn’t know which teams are following security practices and which aren’t.
Enforcing policies across the DevOps organization is a best practice that would have prevented this situation. By centralizing policies for enforcement, such as the signing of code certificates and running frequent audits, signing becomes mandatory. Moreover, policy enforcement builds trust. When Marina knows Sean’s team is following policies because they have to, she and her team can trust their colleagues’ work. It also boosts efficiency. Teams spend less time remediating hacks.
Benefits of Signing Code Certificates for Containers
Enforcing signing code certificates for containers supports critical elements of good governance:
- Operational resilience
- Software integrity and provenance for trust at scale
Operational Resilience
Unsigned containers are big threats. Think of them like Pandora’s box. You don’t know who packed it or what’s inside. And you have no idea what you’ll unleash when you open it. Some surprises aren’t worth it.
Signatures reduce the risk of breaches as well as costly remediation efforts. Instead of your team wasting valuable time resolving security incidents, they could be working on more important, more valuable activities.
Additionally, signatures increase resiliency. Resiliency is about reducing downtime but also shortening recovery time so the scope of the breach is smaller.
Software Integrity and Provenance for Trust at Scale
Over the years, standards have been introduced to ensure secure software. The National Institute of Standards and Technology’s Secure Software Development Framework (NIST SSDF) and the EU Cyber Resilience Act both require software integrity and provenance. You must be able to prove that the code hasn’t been altered or tampered with, and where it came from.
When customers are bombarded with news stories about cyber attacks every week, their trust in organizations deteriorates. Moreover, regulators want assurance of safe containerized workloads. Signing code certificates creates auditable proof. It significantly reduces the chances that there’s a compromised workload in the pipeline.
Security Best Practices: Signing Code Certificates
Signing code certificates makes it easier to apply enterprise threat detection mechanisms to identify and resolve security threats. Moreover, signed code certificates reflect zero-trust principles.
Signed code certificates will become more important as a defense to emerging quantum computing capabilities that will make it easier for bad actors to break encryption and breach information networks.protect against quantum computers’ ability to overcome current security measures.
Looking Ahead: Automating Certificate Signing
Certificate lifecycle automation allows you to sign certificates at scale to maintain security without delaying production. Scalable, automated code signing protects your code, containers, and DevOps pipelines from tampering.
Signum centralizes key protection, enforces policies, and integrates seamlessly with modern build workflows — so you can ship software fast while maintaining customer and regulator trust.
