# Verify a PDF signature

See whether the digital signatures in a PDF are valid, including qualified signatures under EU Regulation 910/2014. SumatraPDF checks them when you open the PDF and shows the result above the document.

**Available in [pre-release 3.7](https://www.sumatrapdfreader.org/prerelease)**

Note: signature validation is on Windows only.

**Open the signed PDF and read the bar above the document.** At a glance:

- **Bar:** says whether all the document's signatures are valid.
- **Signatures view:** the sidebar's list of signatures, with a row per signature (`CmdShowSignatures`).
- **Status icon:** on each signature visible on the page.
- **Signature Properties:** the dialog with one signature's status, why it has that status, and who signed.
- **Properties** (`Ctrl + D`): every signature's details, with revocation checked online.

![A signed PDF: the bar above the document, the Signatures view in the sidebar and the status icon on the signature](https://files.sumatrapdfreader.org/assets/sumatrapdf/docs/img/signature-panel-e06d.png)

## Check whether a document's signatures are valid

Open the PDF. The bar says one of:

- Signed with a qualified signature, and all signatures are valid.
- Signed, and all signatures are valid.
- At least one signature has problems.
- At least one signature is invalid.

A problem or an invalid signature changes the bar's color:

![The yellow bar: at least one signature has problems](https://files.sumatrapdfreader.org/assets/sumatrapdf/docs/img/signature-bar-problem-0084.png)

![The red bar: at least one signature is invalid](https://files.sumatrapdfreader.org/assets/sumatrapdf/docs/img/signature-bar-invalid-4489.png)

Each signature has its own status:

- **Valid qualified electronic signature** or **seal:** a qualified certificate on a qualified device, from a provider the EU Trusted List says was granted that service at the time. This is what a qualified signature means under EU Regulation 910/2014.
- **Valid signature:** the signed part is intact and the signer's certificate is trusted, by Windows or through the EU Trusted List.
- **Validity unknown:** the signer's identity couldn't be verified, or the document changed after signing.
- **Invalid:** the signed part doesn't match the signature, or the certificate was revoked.

## See the signatures in a document

Show the **Signatures** view of the sidebar:

- click **Signature Panel** in the bar
- click its icon at the top of the sidebar
- press `Ctrl + K`, then `Show Signatures` (`CmdShowSignatures`)

Each row shows the signer and the status. Click a row to go to the signature's page.

## See a signature's details

Open **Signature Properties**:

- double-click a row in the **Signatures** view
- click the signature on the page

It shows the status, a **Validity Summary** and **Signer Info**. **Show Signer's Certificate...** opens the certificate.

![The Signature Properties dialog for a valid qualified electronic signature](https://files.sumatrapdfreader.org/assets/sumatrapdf/docs/img/signature-properties-c3e8.png)

**Properties** (`Ctrl + D`) lists the same details for every signature. It also shows the signer and whether the document changed since signing:

- A certifying signature shows what it allows (_Certified: no changes allowed_).
- A last-signer lock shows _Locks the document: no changes allowed after this signature_.
- In a chain of signatures the earlier ones say _N later signature(s) were added; the bytes this signature covers are intact_ rather than that the document was changed, because a signature added on top is not an edit of what came before.

## How signatures are checked

A signature is checked as of the time a trusted timestamp proves it was made, so it stays valid after its certificate expires. Without one it's checked as of now, because the signer's clock proves nothing.

Revocation is checked from the CRLs and OCSP responses in the document, then from Windows' cache. Opening **Properties** also asks the certificate authorities online. A signature with no revocation data still counts as valid, and **Properties** says it wasn't checked.

## Update the EU Trusted List

The EU Trusted List downloads by itself when a signed PDF needs it, and again after a week. **Update EU Trusted List** in **Properties** does it right away.

## Turn off the bar

The bar closes with its ✕, for that tab. To turn it off, set `ShowSignatureStatus = false` in [advanced settings](Advanced-options-settings.md).

## Verify from the command line

```
sumatrapdf-tool sign -v signed.pdf
```

See [Tool sign](Tool-sign.md). It prints the signer and whether the document changed, not the statuses above.

## See also

- [Sign a PDF](Sign-a-PDF.md): add your own signature
- [Show PDF info](Show-PDF-info.md): what **Properties** shows
- [Tool sign](Tool-sign.md): list, sign and verify from the command line