Cybersecurity · head to head
Cosign vs Semperis
Cosign
Cybersecurity
Signs and verifies container images and artifacts, with or without managing keys
- From
- Free
- Rated
- -
Semperis
Cybersecurity
Identity threat detection and Active Directory forest recovery for AD, Entra ID and Okta, from a privately held US vendor.
- From
- On request
- Rated
- -
The short version
- Only Cosign has a free tier, so it costs nothing to try first.
- 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.; Semperis scope is limited to Active Directory, Entra ID and Okta, so an organisation whose critical identity lives elsewhere gets little from it, and the recovery value declines in direct proportion to how much has already moved off on-premises AD.
- They diverge on capability: Cosign covers Keyless signing, Semperis covers Active Directory Forest Recovery.
- Prices and features above were last checked on 31 August 2026.
Where they differ
Only the attributes on which Cosign and Semperis actually diverge.
Identical on both: user rating (Not yet rated), category (Cybersecurity).
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 Semperis
- Active Directory Forest Recovery
- Malware-free restore
- Replication-stream monitoring
- Automated rollback
- Attack indicator scoring
- Entra ID and Okta coverage
- Purple Knight
- Forest Druid
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 Semperis
- Attaching a signed bill of materials to a release so consumers can verify its provenancenot Semperis
- Meeting a customer or regulatory requirement for signed artifactsnot Semperis
- Verifying third-party images before they enter an internal registrynot Semperis
Semperis
- An organisation that cannot answer an auditor or insurer asking how long it would take to rebuild Active Directory after a destructive attacknot Cosign
- Post-incident recovery where domain controllers are compromised and restoring from system-state backup would reintroduce the attacker's footholdnot Cosign
- Continuous detection of privileged group changes and directory-level tampering that domain controller security logs missnot Cosign
- Hybrid estates where AD, Entra ID and Okta all matter and no single tool currently shows changes across the threenot 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.
Semperis
- Scope is limited to Active Directory, Entra ID and Okta, so an organisation whose critical identity lives elsewhere gets little from it, and the recovery value declines in direct proportion to how much has already moved off on-premises AD.
- The licence buys tooling, not a proven runbook: forest recovery is only worth what your last rehearsal demonstrated, and a plan that has never been executed end to end in a lab is an untested assumption regardless of what was purchased.
- It overlaps with backup and directory management products from Quest, Veeam, Commvault and others, so the buyer must argue internally why a dedicated product is needed alongside a backup contract that already claims to protect Active Directory.
- Running Directory Services Protector well requires someone who understands AD internals, replication metadata and Tier 0 attack paths, and without that person the alerts on privileged changes are either ignored or auto-reverted in ways that break legitimate administration.
- Licensing is driven by identity object counts, so directories carrying years of stale user accounts and service principals pay for objects that should have been deleted, and the cleanup project that would reduce the bill is the one nobody has time for.
Pricing, plan by plan
Cosign
Free- CosignFree
- Apache-2.0
- Public Sigstore infrastructure free to use
- No usage limits published
Semperis
On requestNo published plan breakdown. See the Semperis review.
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 Semperis if
- You need active directory forest recovery.
- You also want malware-free restore.
Questions people ask
- Is Cosign or Semperis better?
- Neither clearly leads. Cosign starts at Free and Semperis at On request, and user ratings are close enough to be indistinguishable. Choose on capability and platform support.
- Which is cheaper, Cosign or Semperis?
- Cosign has a free tier; the other does not. Paid plans start at Free for Cosign and On request for Semperis.
- Does Cosign or Semperis run on more platforms?
- Cosign runs on macOS, Linux, Windows, Docker. Semperis runs on Web.
- Can I use Cosign for free?
- Yes. Cosign has a free tier, so you can try it without paying. Semperis starts at On request.
- 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 Semperis is typically brought in for.
- What can Cosign do that Semperis cannot?
- Cosign covers Keyless signing, Key and KMS signing, Registry-native storage, In-toto attestations. Semperis covers Active Directory Forest Recovery, Malware-free restore, Replication-stream monitoring, Automated rollback.
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.
Semperis: Does this replace my backups?
No. It replaces the Active Directory recovery procedure specifically. You still need backups for everything else, and the point of Semperis is that a generic system-state backup of a domain controller is a poor way to recover a forest because it restores the operating system along with whatever compromised it.
Cosign: Is signing alone enough?
No. Verification is a command somebody runs. Without an admission controller enforcing it, an unsigned image still runs.
Semperis: Is it useful if we are cloud-only on Entra ID?
Partly. Directory Services Protector covers Entra ID and Okta for change tracking and posture, but the forest recovery product, which is the strongest reason to buy, applies to on-premises Active Directory. A genuinely cloud-only organisation should weigh it against Microsoft's own tooling.
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.
Semperis: Are Purple Knight and Forest Druid really free?
Yes, both are free downloads with no licence requirement, and they are widely used by organisations that are not Semperis customers. They are also, transparently, the top of the sales funnel.
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.
Semperis: How long does forest recovery actually take?
The honest answer is whatever your rehearsal took. The vendor's case is hours instead of days, and automation genuinely removes most manual steps, but the number that matters for your board is the one from a test in your own environment.
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.
Semperis: Does it require agents on domain controllers?
It collects directory changes from the AD replication stream, which is what lets it see changes that bypass the security log. Deployment details vary by product and version, so confirm the exact architecture against your domain controller change-control rules.
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