How employers prove an employee signed

Why employee signatures get challenged

Employers collect signatures on offer letters, employment agreements, confidentiality agreements, policy and handbook acknowledgments, commission plans, equipment agreements and, in some places, arbitration agreements. Most are never questioned. When one is, it is often long after signing, in a dispute, and the arguments are familiar:

• "I never saw that policy."
• "Someone in HR clicked it for me."
• "That isn't the version I signed."
• "I signed it after the date shown."

Each is a claim about facts, not about whether electronic signatures count. In the United States, the ESIGN Act says a signature "may not be denied legal effect, validity, or enforceability solely because it is in electronic form" (15 U.S.C. 7001(a)). What a challenge tests is proof, and the employer, as the party relying on the document, is generally the one who has to produce it:

• In US federal courts, the party offering a document "must produce evidence sufficient to support a finding that the item is what the proponent claims it is" (Federal Rule of Evidence 901(a)). One accepted way is "evidence describing a process or system and showing that it produces an accurate result" (Rule 901(b)(9)).
• Under the Uniform Electronic Transactions Act (UETA), the model law most US states have enacted, an electronic signature is attributable to a person "if it was the act of the person", which "may be shown in any manner, including a showing of the efficacy of any security procedure" (section 9(a)).
• In Canada, the person offering an electronic document "has the burden of proving its authenticity" under the federal Canada Evidence Act (section 31.1), and provincial acts say the same, such as Ontario's Evidence Act (section 34.1(4)).

Courts weigh the evidence in each case. This page is general information, not legal advice.

Evidence the employer controls, and evidence it doesn't

An HR system's log is the employer's own record. It can be accurate and still be easy to attack: the employee's lawyer can ask who could edit it, whether a manager could have clicked through on the employee's behalf, and whether the PDF in the file is the one the employee saw. The stronger evidence is the kind the employer could not have made by itself.

What a challenge asks	Evidence the employer controls alone	Evidence the employee's own key made
Was it the employee?	A log entry saying the employee's account clicked "I agree"	A cryptographic signature made by a passkey registered to the employee's email address, which had to confirm the signer was present and verified
Did they see this document?	A system note that the document was delivered	A signed statement that begins "I have reviewed and I sign", naming the document's fingerprint
Is it the same version?	The PDF in the personnel file	The document's fingerprint inside the employee's signed statement, and the same sealed copy in the employee's hands
When?	A date typed on the form	A signing time sealed into the signature and anchored on a public blockchain
Can the other side check it?	Only through the employer's system	Anyone, free, with an open-source verifier

A fingerprint (a SHA-256 hash) is a short code calculated from a file's contents: change one character and it changes completely. A passkey is a cryptographic key only the signer controls, unlocked with Face ID, Touch ID, Windows Hello or the device PIN.

How Attest records an employee's signature

1. The employee gets their own link by email, which acts on that one document only.
2. They set up a passkey from that link, with no account to create and no password. Every document on Attest is end-to-end encrypted, so salary figures and terms stay between the employee and the people you send it to: Attest can't read them, so it can't open the document for a new employee either. When an employee new to Attest has set up their key, HR is emailed and releases the document to that employee's key from the agreement, approving with HR's passkey. The employee then reviews it, decrypted in their browser.
3. They sign with the passkey. The passkey must confirm the employee is present and verified, and it signs a statement naming the document's fingerprint and the fingerprint of everything they entered. Attest checks the signature against the passkey's public key before recording it, and the signature is anchored on Horizen, a public blockchain, from the employee's own wallet (a blockchain account Attest creates and runs for each user).
4. The finished record is sealed. When the last signer signs, the signed state (the document's fingerprint and, for each signer, who signed, when and the fingerprint of their entries) is anchored on Horizen. The audit trail itself isn't put on the blockchain: Attest's anchored record of the agreement includes the trail's fingerprint, so a trail changed afterward no longer matches it.
5. Everyone holds the same copy. The employee, HR and every other party download the same sealed PDF, which carries the evidence, the original document and an open-source verifier inside it.

Attest never sees a passkey's secret, so it can't make an employee's signature, and every signature comes from a passkey registered to the employee's email address, which is why that address matters. And because the employee holds the same sealed copy, "that isn't the version I signed" can be settled by comparing two files.

Whose mailbox it is: what that means for the evidence

Attest confirms control of the email address and the passkey, not a government ID. Whoever controls the employee's mailbox can use that address in two ways: before the employee has an Attest key, they can set one up from a signing link the employee hasn't used, and at any time they can sign in with that address and reset the employee's key, which needs no passkey or recovery phrase and gives them a new key and passkey in the employee's name. Attest emails the reset to that same mailbox.

A company controls its employees' work mailboxes. A signature collected at a work address shows that a passkey registered to that address signed the exact document, but on its own it can't rule out someone at the company who could reach that mailbox, and an employee's lawyer can ask exactly that. Three things make the evidence stronger:

• A personal email address, where appropriate. Send the documents that matter, such as the offer letter, the employment agreement or a confidentiality agreement, to an address only the employee controls, such as the personal address they gave you. The mailbox behind the passkey is then one the company can't reach.
• The audit trail, with each step's time. The audit trail in the signed copy lists each step up to completion with its time in UTC, such as when the employee opened their signing link, set up their key and signed. Keep it with your onboarding records, so those times can be checked against them.
• A second release is a reason to ask. A reset sends documents waiting for the employee's signature back to you to release again. If a document you had already released to an employee needs releasing again, their key was reset: confirm with the employee, in person or by phone, that they did it.

Steps for HR: collect signatures that hold up

1. Send to an address only the employee controls, such as the personal address they gave you, where appropriate. Attest ties each signature to that address and to a passkey registered to it, which must confirm the employee was present and verified, and a work mailbox is one the company itself can reach.
2. Send each employee their own document. The evidence then names one person and one document, which is what a challenge asks about.
3. Put the full text in the PDF. If an employee acknowledges a policy, include the policy itself rather than a link to a page that can change later. The signature covers the file's fingerprint, and only what is in the file.
4. To countersign, check Add me as a signer (sign in-app, no email), and choose In order under Signing order with Last next to I sign if HR should sign last. HR gets no signing email: when it's HR's turn, the document shows under Action needed in the dashboard, where HR signs.
5. Choose Private for sensitive letters. Under Verification, Private makes the certificate visible only to the parties; anyone else who looks it up is told it exists and is private.
6. Give the employee a signature field and a Date signed field when you place the fields.
7. Never forward a signing link. Each link belongs to one person.
8. File the sealed copy. When the document completes, download the signed copy into the personnel record, and verify it once with the verifier inside it, or on attest.datahubz.com/verify, which fingerprints it in your browser and confirms it is the exact file that was recorded and anchored.

Some employment documents have form rules of their own. In Germany, for example, an employment termination by notice or by agreement can't be made in electronic form (BGB section 623). Check the rule for yours.

When an employee disputes a signature

1. Keep the signed copy exactly as downloaded, and verify it. The verifier checks each signer's passkey signature, the original document, the pages you see and Attest's anchored record on Horizen, in the browser, without any Attest service.
2. Show the statement the employee's passkey signed. It names the document and its fingerprint, and the audit trail up to completion lists, in UTC, when the employee opened their signing link, set up their key and signed.
3. Point the other side to the same check. The employee already holds the same copy: their signing link opens it for 30 days after completion, and signing in with their email opens it after that. Verification is free and needs no account.
4. Add the context. Because attribution "may be shown in any manner", onboarding emails, payroll records and the employee's later conduct under the agreement can support the signature.
5. Get legal advice before acting on anything significant.

Electronic signatures are recognized for most agreements in the United States (the ESIGN Act and UETA) and the European Union (eIDAS). Some documents, such as wills or certain notarized deeds, have special rules in many places: check yours.