# sumatrapdf-tool sign

or [SumatraPDF.exe sign](Tools.md)

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

**Usage:** `sumatrapdf-tool sign [options] input.pdf [signature object numbers]`

`sign` lists, signs and verifies the digital signatures in a PDF. It works with the signature fields the PDF already has and a certificate file (`.pfx` / `.p12`); it can't add a new signature field. To sign in SumatraPDF, including adding a new signature box, see [Sign a PDF](Sign-a-PDF.md).

List the signature fields and their object numbers:

```
sumatrapdf-tool sign form.pdf
```

```
   12: Signature is not signed.
```

Sign field `12` with a certificate file:

```
sumatrapdf-tool sign -s me.pfx -P password -o signed.pdf form.pdf 12
```

Without `-o` the signed PDF is written to `out.pdf`. Without object numbers, all signature fields are processed.

Verify the signatures:

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

```
Verifying signature 12:
	Distinguished name: cn=Jamie Rivera, o=Example, ou=, email=, c=
	Certificate error: Self-signed certificate.
	The document is unchanged since signing.
	The fields signed by this signature are unchanged.
```

`-c` clears signatures. A signature marked read-only can't be cleared: `sign` prints `read only signature cannot be cleared` and writes no file.

## All options

```
Usage: SumatraPDF sign [options] input.pdf [signature object numbers]
	-p -	password
	-v 	verify signature
	-c 	clear signatures
	-s -	sign signatures using certificate file
	-P -	certificate password
	-o -	output file name
```

`-p` is the password of an encrypted PDF; `-P` is the password of the certificate file.