rebuilderd

Post-quantum rebuild attestations

Every package this instance reproduces is attested with a signature that remains valid after Ed25519 and RSA are broken. The attestations and the public key below are what make that verifiable — later, offline, and without trusting this website.

Why this exists

A sufficiently capable quantum computer breaks Ed25519, RSA and ECDSA. On that day every classically-signed package becomes forgeable: an attacker can mint a fresh, perfectly valid signature over a package you did not want. Signatures made after that point prove nothing.

The defensive form of harvest now, decrypt later is sign now, verify later. A post-quantum signature is only worth anything if it already existed before the transition — which is why these attestations are being produced today, well ahead of any need for them.

A rebuilder is unusually well placed to be useful here. Its claim does not depend on any distributor's keys: “I rebuilt this from these inputs and got this output hash.” Attach a post-quantum signature to that claim and it survives the transition intact.

Latest results

Artifacts shown

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Reproduced

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Not reproduced

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With attestation

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Artifact Version Arch Built Status Attestation
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The public key

This is the key to archive. Verification after the transition is only meaningful against a key you already held — a key fetched afterwards over a classically-protected connection can be substituted along with everything else.

ML-DSA-65 post-quantum

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Ed25519 classical

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Kept for compatibility with existing tooling. It is the signature that stops meaning anything after the transition.

Verifying a package yourself

Now, while it still costs nothing

Archive the key and the attestations you care about.

curl -o rebuilderd.pqc.pub …
rebuildctl pkgs attestation --name anarchism > attestation.json

Later, after the transition

Verify offline. No network, no daemon, and no classical cryptography anywhere in the trust path. 

rebuildctl verify-artifact anarchism_15.3-5_all.deb \
    --attestation attestation.json \
    --pqc-key rebuilderd.pqc.pub \
    --require-pqc

A pass means the file you hold is bit-identical to what an independent rebuilder produced from the recorded inputs, and that binding rests on a signature a quantum adversary cannot forge. The distributor's own signature is never consulted.

What this does not prove
  • That the source is honest. The attestation binds inputs to outputs. Confirming the source genuinely produces that binary means rebuilding it yourself, which needs the .buildinfo — check it against the signed materials hash, then build.
  • That this instance is trustworthy. One rebuilder agreeing with itself proves little. The value comes from several independent rebuilders reaching the same answer.
  • That the key is ours. Nothing here establishes that — the key's authority comes entirely from you having obtained it early, through a channel you trusted at the time.