Verify a signed document
Anyone who has the signed PDF can verify it without an account. The QR code on the seal confirms the signature details, and the organization’s certificate seal confirms that the file has not changed.
Scan the QR code
Section titled “Scan the QR code”Scanning the QR code on the seal opens the Signature Verification page, which shows the result and four details: Signer, Email, Signed and Document (the envelope identifier). If the link is incomplete, the page shows “This link is missing its verification details. Scan the QR code on the signed document again, or open the link exactly as it appears there.”
“Valid Signature” result
Section titled ““Valid Signature” result”Valid Signature means that the details on the seal (signer, email, date and envelope) match what bb-sign recorded at the time of signing. To check this, bb-sign recomputes the seal’s fingerprint, SHA-256(name|email|date|documentId|certFingerprint), from the recorded details and the organization’s active certificate, and compares it with the fingerprint printed on the seal.
“Invalid Signature” result
Section titled ““Invalid Signature” result”Invalid Signature means the fingerprint does not match. Possible causes:
- a QR code or link that does not correspond to a recorded signature, such as a badly copied link;
- a certificate change in the organization after the signature: the fingerprint includes the certificate, so earlier seals stop matching even though the document is intact;
- no active certificate to compare against (“Certificate not available for verification”).
In any of these cases, the organization that sent the document can confirm the signature from the envelope’s history.
Check the PDF’s integrity
Section titled “Check the PDF’s integrity”When the envelope completes, bb-sign seals every PDF with the organization’s certificate. Open the file in Adobe Acrobat Reader and open the signature panel (the pen icon in the side bar). There you can see:
- whether the file changed after it was sealed, which Acrobat shows next to the signature;
- whose name the certificate is in. An organization with its own certificate appears under its name. If the organization uses the default Binary Bridges testing certificate, Acrobat marks it as untrusted. See Your own certificate.
The PDF embeds the end certificate without the full chain, so Acrobat may ask you to trust it manually.
If the service does not respond
Section titled “If the service does not respond”If the page shows “We could not reach the verification service. This does not mean the signature is invalid — please try again in a moment.”, the service is temporarily unavailable. Scan the QR code again later.