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SealMySignature

Trust This Seal

Every finished document from SealMySignature carries a digital seal. The seal proves the file has not changed since it was sealed, and a timestamp proves when. Adobe Acrobat checks the seal each time it opens the file and reports the result in a bar across the top of the page.

Why Acrobat Says At Least One Signature Has Problems

Acrobat trusts a signature when it can trace the certificate behind it to a list of authorities it already knows. Our seal is not on that list yet. So Acrobat reports "At least one signature has problems" and, in the signature panel, "Signer's identity is unknown", even though the line above it says the document has not been modified since the signature was applied. The seal is genuine and the file is intact. What is missing is an entry on Adobe's list, which is a purchase we have put off while the product is in early access.

Two Ways to Check a Sealed File

  1. Verify it here. Upload the PDF on the verify page. The answer does not depend on Adobe's list. It compares the file against our record, re-checks every signature in it, and recomputes the audit trail behind it.
  2. Tell Acrobat to trust the seal. Download the two certificates below and add them to Acrobat's trusted certificates once. Every file we have sealed, past and future, then shows "Signed and all signatures are valid" on that computer.

Add the Seal to Acrobat

Download the Seal CertificateDownload the Signer Certificate Authority

The seal certificate covers the platform seal on every finished document. The certificate authority covers the per-signer signatures on advanced-level documents. Add both.

  1. Open Preferences: Menu, then Preferences on Windows; Acrobat, then Preferences on a Mac.
  2. Under Categories, select Signatures, then select More for Identities & Trusted Certificates.
  3. Select Trusted Certificates, then Import.
  4. Select Browse, choose the downloaded file, select the certificate that appears, then Trust.
  5. Tick Use This Certificate as a Trusted Root, choose OK, then Import.
  6. Repeat for the second file, then close and reopen the sealed PDF.

Other readers with a trusted-certificate list, such as Foxit, accept the same two files through their own import control. Trust added this way stays on that computer, changes nothing about the file, and a file that fails the check still fails.