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Cybersecurity · head to head

Cosign vs HCP Terraform

Cosign logo

Cosign

Cybersecurity

Signs and verifies container images and artifacts, with or without managing keys

From
Free
Free plan
Yes
HCP Terraform logo

HCP Terraform

Developer Tools

Infrastructure as code provisioning and management, formerly Terraform Cloud

From
Free
Free plan
Yes

The short version

  • Each has a real cost: Cosign keyless signing inherits every weakness of the identity provider behind it. Sigstore’s own threat model states that if an identity provider is compromised, Sigstore will issue certificates to those identities, so a compromised account produces perfectly valid signatures.; HCP Terraform legacy free version deprecated; no current freemium tier
  • Prices and features above were last checked on 31 August 2026.

Where they differ

Only the attributes on which Cosign and HCP Terraform actually diverge.

Attributes where Cosign and HCP Terraform differ
AttributeCosignHCP Terraform
Pricing modelOpen source, no licence feeusage-based
PlatformsmacOS, Linux, Windows, DockerWeb
CategoryCybersecurityDeveloper Tools

Identical on both: starting price (Free), free tier (Yes), user rating (Not yet rated).

What each one covers

Drawn from each product's published feature list. An absence here means we hold no record of it - not that the product lacks it.

Only in Cosign

  • Keyless signing
  • Key and KMS signing
  • Registry-native storage
  • In-toto attestations
  • Offline verification
  • Trusted root and signing config

Only in HCP Terraform

Nothing recorded that Cosign does not also cover.

What people use each for

The jobs each tool is most often brought in to do.

Cosign

  • Signing container images in a build pipeline without managing long-lived private keysnot HCP Terraform
  • Attaching a signed bill of materials to a release so consumers can verify its provenancenot HCP Terraform
  • Meeting a customer or regulatory requirement for signed artifactsnot HCP Terraform
  • Verifying third-party images before they enter an internal registrynot HCP Terraform

HCP Terraform

  • Infrastructure as Code managementnot Cosign
  • Cloud resource provisioningnot Cosign

Where each one falls short

Documented limitations, not opinions. Every one is a constraint you would hit in normal use.

Cosign

  • Keyless signing inherits every weakness of the identity provider behind it. Sigstore’s own threat model states that if an identity provider is compromised, Sigstore will issue certificates to those identities, so a compromised account produces perfectly valid signatures.
  • A signature proves who signed, never whether they should have. The documentation is explicit that Sigstore cannot determine authorisation, so every consumer must write and maintain their own identity and issuer policy or verification means nothing.
  • Nothing is enforced without an admission controller. Signing changes what you can prove, not what runs, and the official policy controller has a small maintainer base for a component sitting in a cluster admission path.
  • Upgrades break pipelines. Version 3 changed defaults, version 4 is announced as removing legacy functionality and roughly half the command line flags, and two official client libraries still lacked support for the new log format as of mid 2026.
  • Signatures do not expire. An artifact signed before a maintainer account was compromised and one signed after are indistinguishable unless somebody is actively monitoring the transparency log, and almost nobody is.

HCP Terraform

  • Legacy free version deprecated; no current freemium tier
  • New users receive $500 credit but still require usage to continue service
  • Terraform Enterprise requires custom pricing

Pricing, plan by plan

Cosign

Free
  • CosignFree
    • Apache-2.0
    • Public Sigstore infrastructure free to use
    • No usage limits published

HCP Terraform

Free
  • Essentials$0.1/month
    • Per resource pricing
    • Remote state storage
    • VCS connection
  • Standard$0.47/month
    • Per resource pricing
    • Essentials features plus unlimited modules
    • Module deprecation
  • Premium$0.99/month
    • Per resource pricing
    • Standard features plus module revocation
    • Waypoint actions

Which should you pick?

Choose Cosign if

  • You need keyless signing.
  • You want to start without paying.
  • You work on macOS, Linux, Windows, Docker.
  • You also want key and kms signing.

Choose HCP Terraform if

  • You want to start without paying.

Questions people ask

Is Cosign or HCP Terraform better?
Neither clearly leads. Cosign starts at Free and HCP Terraform at Free, and user ratings are close enough to be indistinguishable. Choose on capability and platform support.
Which is cheaper, Cosign or HCP Terraform?
Cosign starts at Free and HCP Terraform at Free.
Does Cosign or HCP Terraform run on more platforms?
Cosign runs on macOS, Linux, Windows, Docker. HCP Terraform runs on Web.
Can I use Cosign for free?
Both have a free tier, so you can try either at no cost before committing.
What is Cosign best used for?
Cosign is most often used for signing container images in a build pipeline without managing long-lived private keys, attaching a signed bill of materials to a release so consumers can verify its provenance, meeting a customer or regulatory requirement for signed artifacts, verifying third-party images before they enter an internal registry. Of those, signing container images in a build pipeline without managing long-lived private keys and attaching a signed bill of materials to a release so consumers can verify its provenance are not what HCP Terraform is typically brought in for.
What can Cosign do that HCP Terraform cannot?
Cosign covers Keyless signing, Key and KMS signing, Registry-native storage, In-toto attestations.

Answered from the vendors’ own pages

Cosign: Does Cosign tell me if an image is vulnerable?

No. It has no vulnerability knowledge whatsoever. It can carry an SBOM as a signed attestation but never reads it. Pair it with a scanner.

HCP Terraform: How much does HCP Terraform cost?

HCP Terraform uses per-resource pricing starting at $0.10/month/resource for Essentials, $0.47/month/resource for Standard, and $0.99/month/resource for Premium.

Source
Cosign: Is signing alone enough?

No. Verification is a command somebody runs. Without an admission controller enforcing it, an unsigned image still runs.

HCP Terraform: Does HCP Terraform offer a free tier?

No, the legacy free version has been deprecated. However, new users receive $500 credit to try the service.

Source
Cosign: What does a bare cosign verify actually prove?

Very little. Without a pinned certificate identity and OIDC issuer, it accepts a valid signature from any identity at all.

HCP Terraform: What does the Standard plan include?

Standard plan at $0.47/month/resource includes unlimited modules, module deprecation, team notifications, no-code provisioning, and Waypoint templates.

Source
Cosign: What is the risk of keyless signing?

Your OIDC provider becomes the root of trust. Compromise of that account yields genuine, verifiable signatures, so account security is the control that matters.

Cosign: Should we expect breaking changes?

Yes. Version 4 is announced to remove roughly half the flags, and a post-quantum migration is named as a further breaking change after that.

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