# Sign

The **Sign** function adds a digital signature to a PDF document.

***

## Properties

### Input <a href="#input" id="input"></a>

The following properties specify the PDF document to be loaded and modified by the operation:

#### File path <a href="#file-path" id="file-path"></a>

Path to the PDF file.

#### Authentication type <a href="#authentication-type" id="authentication-type"></a>

PDF files can be protected using a password or a certificate. This field indicates which type of authentication to attempt when loading the PDF.

1. **None**\
   The document is unprotected and can be opened immediately.
2. **Password**\
   The document is protected by a password.
3. **Certificate**\
   The document is protected by a certificate.

**Password**:

Only displayed when **Authentication type** is 'Password'.

* **Password**: Password required to access the PDF file.

{% hint style="info" %}

> **Note:**\
> All passwords entered into this function's properties will be visible in plain text in the Linx solution file and in the compiled .NET assembly.
> {% endhint %}

**Certificate**

Only displayed when **Authentication type** is 'Certificate'.

**Certificate source**:\
Source to load the certificate from:

1. **File** - Load a certificate from a .pfx file.
2. **Store** - Load a certificate from the Windows certificate store.

**File**

Displayed when **Certificate source** is 'File'.

* **Certificate file path**: Path to a .pfx file containing a certificate.
* **Certificate file password**: Password needed to open the certificate file.

**Store**

Displayed when **Certificate source** is 'Store'.

* **Certificate**: Certificate in the Windows keystore.

{% hint style="info" %}

> **Note:**\
> Certificate protected files are not supported by the "Fill form," "Sign," "Add watermark," and "Concatenate" operations. If you need to use the operations on a certificate-protected document, first remove the certificate protection using the "Change protection" operation. The certificate must include the private key to be able to load the document.
> {% endhint %}

***

### Misc <a href="#misc" id="misc"></a>

* **Signed at**: Location where the signing took place.
* **Reason**: Reason for signing the document.
* **Lock document after signing**: Lock the document to prevent further changes.

***

### Output <a href="#output" id="output"></a>

#### File path <a href="#output-file-path" id="output-file-path"></a>

Path of the PDF file to write to.

***

### Signature <a href="#signature" id="signature"></a>

#### Signature placement <a href="#signature-placement" id="signature-placement"></a>

Where to place the signature in the document:

1. **No visible signature** - Don't display a visible signature.
2. **Form signature field** - Insert the signature into an existing signature form field.
3. **On page** - Place a visible signature on a specific page in the document.

**Form signature field**

Displayed when **Signature placement** is 'Form signature field'.

* **Field name**: Form field name to place the signature in.
* **Background image**: Path to an image to use as the background for the signature field. This can be left blank if no background image is needed.

**On page**

Displayed when **Signature placement** is 'On page'.

* **Position X (mm)**: Distance of the left side of the signature from the


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Perform an HTTP GET request on the current page URL with the `ask` query parameter:

```
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```

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Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.