Signed code provenance
also: cryptographic code provenance · tamper-evident provenance
Signed code provenance is an authorship record protected by a cryptographic signature, so it can be verified and is tamper-evident. For AI code, it means each attribution — which agent wrote which lines — is signed with a key the organization controls, producing audit-grade evidence rather than an editable log.
Why provenance has to be signed
An unsigned provenance log is just text — anyone with write access could alter it, and an auditor has no way to trust it. Signing closes that gap. A cryptographic signature lets anyone verify that a provenance record was produced by a specific key and has not been changed since, turning a log into evidence.
How ed25519-signed traces work
AgentDiff gives each developer an ed25519 keypair. When a commit is made, the pre-commit step builds the attribution record (the AgentTrace) and signs it; the post-commit step appends the signed record to a dedicated git ref. Verification checks each signature against your organization's published public keys — so provenance can be trusted without trusting a hosted dashboard.
- Tamper-evident — any change to a signed trace invalidates its signature.
- Independently verifiable — anyone with the public keys can check authenticity, no vendor required.
- Organization-controlled — the signing keys belong to you, not to a SaaS provider.
Audit-grade by design
Because the evidence is signed and stored in git, it satisfies the properties auditors care about: integrity, attribution, and portability. As traceability requirements tighten under frameworks like ISO 42001 and the EU AI Act, signed provenance is positioned as a supporting control teams can point to.
“If a vendor experiences a security issue, compliance teams may eventually want evidence showing not only who approved the change, but whether an AI agent generated it and under what controls.”
Frequently asked questions
What makes code provenance tamper-evident?+
A cryptographic signature. If the provenance record is altered after signing, the signature no longer verifies against the signer's public key, so any tampering is detectable.
Why ed25519?+
ed25519 is a modern, fast, and widely trusted signature scheme with small keys and signatures. AgentDiff uses it to sign each attribution record so authorship can be verified efficiently and offline.
Who controls the signing keys?+
Your organization. Each developer holds an ed25519 keypair, and verification uses your published public keys — provenance never depends on trusting a third-party service.
See line-level provenance on a real repo.
AgentDiff records which agent wrote which line, signs it, and keeps it in your git history. Open the live dashboard or book a walkthrough.