Upload a document, invite your signers, done — quantum-safe by default, whether it's just you or a deal team of ten.
Every signature uses ML-DSA-65, the NIST-standardised post-quantum algorithm (FIPS 204) — built so what you sign today is still valid evidence decades from now. No cryptography knowledge required on either end.
Sign on UbQbit Qausal. Store anywhere. Verify everywhere.
Qausal — a portmanteau of "quantum" and "causal." Causality is the chain of events that proves something happened — which is exactly what a signature does.
Free Trial
Get the full quantum-safe signing experience — solo and multi-party. No credit card, no commitment. Upgrade at any time, or continue on the Starter pay-as-you-go rate when the trial ends.
Limited time
New accounts get 3 MONTHS FREE PILOT access — full multi-party signing, no credit card required.
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Two Doors
You do not have to move your signing process to get quantum-safe. One evidence backbone, two ways in — and most people start with the first.
Door 1 · Made-safe
Already signed elsewhere? Quantum-proof it without changing a byte. Keep your existing platform, keep your process, keep the file exactly as it is — a detached attestation binds its hash, custodian and time.
No switching cost. Nobody retrains. Nothing migrates. Your backfile becomes quantum-safe without touching the originals.
Seal a document
Door 2 · Born-safe
Agreements quantum-safe from the onset — invite anyone, no account needed. Single signer or a deal team of ten, each signing with their own ML-DSA-65 key.
For what comes next. The workflow you already know, running on cryptography that does not expire.
Start a signing
How It Works
You don't need a cryptographer, a procurement team, or an IT department. If you can attach a PDF to an email, you can sign quantum-safe — solo, or with a room full of signatories.
Drop in any PDF — a contract, a deed, an agreement. Qausal generates your quantum-safe keypair automatically; the cryptography stays invisible.
Single-signer, or multi-party with roles. The right people — and only the right people — can act on the document.
Each signer adds their own ML-DSA-65 signature over the exact document state they saw. A visual journey shows who's signed, who's pending, and who declined — and why.
Download the signed PDF and its proof bundle. Every signature in the chain is independently verifiable — on Qausal, with open-source tools, or decades from now.
No platform lock-in at any step. Start per signature with no subscription at all — the same NIST-standardised cryptography that federal mandates require.
Portable Proof
Most e-signature platforms create a dependency: the signature is only valid because the vendor says it is. UbQbit takes the opposite approach — every signed document is a self-contained cryptographic proof.
When a document is signed on Qausal, the PDF itself is modified to embed everything needed for independent verification — forever. A sealed document is the opposite: nothing is added, and the proof travels beside it.
The signed PDF does not reference UbQbit's servers. It does not phone home. It does not expire.
A signed PDF plus proof bundle can be verified using only open-source tools. No vendor account, no API key, no subscription, no internet connection required.
This timestamp is cryptographically bound into your signature — strong evidence for most agreements. For documents that need to survive a future compromise of the signing algorithm decades from now, an independently witnessed timestamp on top is on the roadmap. Also worth knowing: mainstream PDF readers like Adobe Acrobat don't yet natively validate post-quantum signatures — verify with Qausal's tools or the snippet above in the meantime.
Traditional e-Sign
(DocuSign, Adobe Sign)
UbQbit Qausal
Bring any copy from anywhere — we prove what was signed.
Custody
We're the evidence custodian, not the document custodian — and the evidence verifies without us.
The signature record, the public-key and digest snapshots, the immutable audit trail, and the proof bundle. Small, structured, and ours to hold for as long as it takes — this is the part that has to outlive everything.
Your document. Held for collection, not for custody — we hold it to sign it, and briefly so you can collect it. Never to keep it.
Built For
The quantum-safe question isn't "am I a government contractor" — it's "does this document need to be trusted for longer than I can predict." That's a much wider group than the compliance conversation usually suggests.
No deadline needed — just no reason to wait
Conveyancers, family lawyers, accountants, freelancers — anyone signing documents their clients will rely on for years. Pay-as-you-go, no subscription, no procurement process.
Built for deal teams, not just single signers
Upload once, invite every signer by email, and watch the deal move — role-based owner/signer/verifier access, a visual journey showing who's signed and who's pending, decline-with-reason built in.
Deadline: your retention schedule
Property deeds, wills, medical records, long-term financial instruments — a document that must remain verifiable in 2040 cannot rely on a signature scheme expected to fail before then.
Deadline: 2030 (ASD) / Apr 2026 (Canada)
Australia's ASD has set 2030 for retiring quantum-vulnerable cryptography; Canada already writes post-quantum clauses into federal contracts.
Deadline: 2030 (FIPS) / 2031 (signatures)
EO 14412 makes quantum-safe signing a procurement requirement. Contractors touching high-impact systems will be asked for their PQC story in security reviews well before 2031.
Why Now, Not "Someday"
Adversaries don't need a working quantum computer to start — they can collect signed documents right now and forge or repudiate them the moment classical cryptography falls. That's the "harvest now, forge later" threat, and it's already underway.
A signature can't be upgraded after it's created. It's as strong as the day it was made, forever. Every document you sign today with RSA or ECDSA is exposed the day quantum cryptanalysis catches up — whenever that turns out to be.
If you need one more reason, the deadlines are real too — signed, dated government mandates, verifiable by your own compliance team:
Right now
Signed documents are being collected today for future forgery — no deadline required for this to already be true.
Apr 2026
Post-quantum procurement clauses required on federal contracts signed after this date.
22 Jun 2026
Signed executive order mandating quantum-safe signatures on federal high-impact systems.
2030
ASD's deadline for retiring quantum-vulnerable cryptography; same year US federal contractors must comply with post-quantum FIPS.
31 Dec 2031
EO 14412's hard deadline for quantum-safe signing on federal high-impact systems and high-value assets.
Why It Matters
Every contract, deed, and record you sign carries a commitment that must remain verifiable for years or decades. Qausal ensures that commitment holds — no matter what.
Classical digital signatures (RSA, ECDSA) will be breakable by quantum computers. Qausal signs with ML-DSA-65, the NIST-standardised algorithm designed to resist quantum attacks, so your signatures remain legally sound for their entire retention lifecycle.
Hybrid mode applies both a classical ECDSA signature and a quantum-safe ML-DSA signature to every document — so current verification tools still work, while quantum-safe protection is already in place.
Every signing event is logged in a tamper-evident, immutable audit trail — enforced at the database level, not just app convention, so even a compromised admin account can't alter history.
The Real Test of "Quantum-Safe"
Every PQC vendor can tell you they support ML-DSA today. Almost none of them can tell you what happens the day it's deprecated, weakened, or superseded. UbQbit can.
Our algorithm registry lets an administrator mark an algorithm deprecated from a dashboard — no deploy, no downtime — which immediately blocks new signing with it while every signature ever produced with it stays fully verifiable, forever.
A staged migration engine then moves every affected keypair onto the new algorithm in the background, on a schedule you control, with live progress and a full audit trail.
migrating… 1,847 / 2,103
Deprecation blocks new signing instantly. Existing signatures remain verifiable forever. Migration runs in the background with live progress and a full audit trail.
Architecture
What's built today, and where we're going — clearly labeled, item by item, so you can plan your evaluation against what's real.
Layer 01
Live
The cryptographic core — crypto-agile by design, built to survive algorithm changes without a platform rewrite.
Zero-downtime algorithm retirement — flip a flag, not a platform.
Layer 02
A complete workflow with multi-party signing, tamper-evident audit trails, and offline-verifiable proof bundles.
Every signer's proof re-checked independently — not just the first signature in the chain.
Layer 03
Coming Next
The Regulated / Archival tier — adds independent, third-party time-witnessing on top of the signature-bound proof you already get today.
Independently witnessed timestamps — not just tamper-evident ones.
If long-term archival is a requirement for your evaluation timeline, talk to us.
Get Started
Start free
Talk to us
Keep your existing platform. Keep your process. Keep the file exactly as it is. Qausal issues a separate certificate that binds your document’s fingerprint, who vouched for it, and when — and hands your document back untouched.
No migration. No retraining. No change to how your team works. Sealing sits alongside what you already do.
Anything already executed can be sealed — the backfile you already hold, not only the agreements still to come.
Nothing is added to your document, so nothing about it can break — the signatures already on it keep working exactly as they did.
It proves
this exact document existed, vouched for by you, at this time — so nobody can later produce a different version and call it the original.
It doesn’t
sign the document, and it doesn’t upgrade the signatures already on it. Those stay exactly as strong as they were.
Agreements quantum-safe from the onset, whether it is just you or a deal team of ten. The workflow you already know, running on cryptography that does not expire.
One document, every signer, in the order you choose — with roles, a visible journey, and decline-with-reason built in.
The people you are signing with do not need an account. They get a link, verify by email, and sign. Your plan pays — being asked to sign never costs the signer.
Every signature is verifiable by anyone you send the document to, forever — with no account and no call back to us.