diff --git a/CHANGELOG.md b/CHANGELOG.md
index bbaf66e6..17b484cb 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -22,6 +22,7 @@ before starting to add changes. Use example [placed in the end of the page](#exa
   - Fix digital post commands
   - Updated versions in GitHub Actions `uses` steps
 - Updating the display of os2forms package on the status page
+- Adding os2forms_digital_signature module
 
 ## [4.0.0] 2025-03-06
 
diff --git a/modules/os2forms_attachment/os2forms_attachment.services.yml b/modules/os2forms_attachment/os2forms_attachment.services.yml
index 34d2d676..e477d46f 100644
--- a/modules/os2forms_attachment/os2forms_attachment.services.yml
+++ b/modules/os2forms_attachment/os2forms_attachment.services.yml
@@ -1,4 +1,4 @@
 services:
   os2forms_attachment.print_builder:
     class: Drupal\os2forms_attachment\Os2formsAttachmentPrintBuilder
-    arguments: ['@entity_print.renderer_factory', '@event_dispatcher', '@string_translation']
+    arguments: ['@entity_print.renderer_factory', '@event_dispatcher', '@string_translation', '@file_system']
diff --git a/modules/os2forms_attachment/src/Element/AttachmentElement.php b/modules/os2forms_attachment/src/Element/AttachmentElement.php
index 05d37e4c..cdf3ae44 100644
--- a/modules/os2forms_attachment/src/Element/AttachmentElement.php
+++ b/modules/os2forms_attachment/src/Element/AttachmentElement.php
@@ -20,6 +20,7 @@ public function getInfo() {
     return parent::getInfo() + [
       '#view_mode' => 'html',
       '#export_type' => 'pdf',
+      '#digital_signature' => FALSE,
       '#template' => '',
     ];
   }
@@ -28,6 +29,8 @@ public function getInfo() {
    * {@inheritdoc}
    */
   public static function getFileContent(array $element, WebformSubmissionInterface $webform_submission) {
+    $submissionUuid = $webform_submission->uuid();
+
     // Override webform settings.
     static::overrideWebformSettings($element, $webform_submission);
 
@@ -51,18 +54,43 @@ public static function getFileContent(array $element, WebformSubmissionInterface
     \Drupal::request()->request->set('_webform_submissions_view_mode', $view_mode);
 
     if ($element['#export_type'] === 'pdf') {
-      // Get scheme.
-      $scheme = 'temporary';
-
-      // Get filename.
-      $file_name = 'webform-entity-print-attachment--' . $webform_submission->getWebform()->id() . '-' . $webform_submission->id() . '.pdf';
-
-      // Save printable document.
-      $print_engine = $print_engine_manager->createSelectedInstance($element['#export_type']);
-      $temporary_file_path = $print_builder->savePrintable([$webform_submission], $print_engine, $scheme, $file_name);
-      if ($temporary_file_path) {
-        $contents = file_get_contents($temporary_file_path);
-        \Drupal::service('file_system')->delete($temporary_file_path);
+      $file_path = NULL;
+
+      // If attachment with digital signatur, check if we already have one.
+      if (isset($element['#digital_signature']) && $element['#digital_signature']) {
+        // Get scheme.
+        $scheme = 'private';
+
+        // Get filename.
+        $file_name = 'webform/' . $webform_submission->getWebform()->id() . '/digital_signature/' . $submissionUuid . '.pdf';
+        $file_path = "$scheme://$file_name";
+      }
+
+      if (!$file_path || !file_exists($file_path)) {
+        // Get scheme.
+        $scheme = 'temporary';
+        // Get filename.
+        $file_name = 'webform-entity-print-attachment--' . $webform_submission->getWebform()->id() . '-' . $webform_submission->id() . '.pdf';
+
+        // Save printable document.
+        $print_engine = $print_engine_manager->createSelectedInstance($element['#export_type']);
+
+        // Adding digital signature.
+        if (isset($element['#digital_signature']) && $element['#digital_signature']) {
+          $file_path = $print_builder->savePrintableDigitalSignature([$webform_submission], $print_engine, $scheme, $file_name);
+        }
+        else {
+          $file_path = $print_builder->savePrintable([$webform_submission], $print_engine, $scheme, $file_name);
+        }
+      }
+
+      if ($file_path) {
+        $contents = file_get_contents($file_path);
+
+        // Deleting temporary file.
+        if ($scheme == 'temporary') {
+          \Drupal::service('file_system')->delete($file_path);
+        }
       }
       else {
         // Log error.
diff --git a/modules/os2forms_attachment/src/Os2formsAttachmentPrintBuilder.php b/modules/os2forms_attachment/src/Os2formsAttachmentPrintBuilder.php
index 67a0c99a..1f8a9f38 100644
--- a/modules/os2forms_attachment/src/Os2formsAttachmentPrintBuilder.php
+++ b/modules/os2forms_attachment/src/Os2formsAttachmentPrintBuilder.php
@@ -3,14 +3,28 @@
 namespace Drupal\os2forms_attachment;
 
 use Drupal\Core\Entity\EntityInterface;
+use Drupal\Core\File\FileExists;
+use Drupal\Core\File\FileSystemInterface;
+use Drupal\Core\StringTranslation\TranslationInterface;
+use Drupal\entity_print\Event\PreSendPrintEvent;
+use Drupal\entity_print\Event\PrintEvents;
 use Drupal\entity_print\Plugin\PrintEngineInterface;
 use Drupal\entity_print\PrintBuilder;
+use Drupal\entity_print\Renderer\RendererFactoryInterface;
+use Symfony\Component\EventDispatcher\EventDispatcherInterface;
 
 /**
  * The OS2Forms attachment print builder service.
  */
 class Os2formsAttachmentPrintBuilder extends PrintBuilder {
 
+  /**
+   * {@inheritdoc}
+   */
+  public function __construct(RendererFactoryInterface $renderer_factory, EventDispatcherInterface $event_dispatcher, TranslationInterface $string_translation, protected readonly FileSystemInterface $file_system) {
+    parent::__construct($renderer_factory, $event_dispatcher, $string_translation);
+  }
+
   /**
    * {@inheritdoc}
    */
@@ -27,10 +41,56 @@ public function printHtml(EntityInterface $entity, $use_default_css = TRUE, $opt
     return $renderer->generateHtml([$entity], $render, $use_default_css, $optimize_css);
   }
 
+  /**
+   * Modified version of the original savePrintable() function.
+   *
+   * The only difference is modified call to prepareRenderer with digitalPost
+   * flag TRUE.
+   *
+   * @see PrintBuilder::savePrintable()
+   *
+   * @return string
+   *   FALSE or the URI to the file. E.g. public://my-file.pdf.
+   */
+  public function savePrintableDigitalSignature(array $entities, PrintEngineInterface $print_engine, $scheme = 'public', $filename = FALSE, $use_default_css = TRUE) {
+    $renderer = $this->prepareRenderer($entities, $print_engine, $use_default_css, TRUE);
+
+    // Allow other modules to alter the generated Print object.
+    $this->dispatcher->dispatch(new PreSendPrintEvent($print_engine, $entities), PrintEvents::PRE_SEND);
+
+    // If we didn't have a URI passed in the generate one.
+    if (!$filename) {
+      $filename = $renderer->getFilename($entities) . '.' . $print_engine->getExportType()->getFileExtension();
+    }
+
+    $uri = "$scheme://$filename";
+
+    // Save the file.
+    return $this->file_system->saveData($print_engine->getBlob(), $uri, FileExists::Replace);
+  }
+
   /**
    * {@inheritdoc}
    */
-  protected function prepareRenderer(array $entities, PrintEngineInterface $print_engine, $use_default_css) {
+
+  /**
+   * Override prepareRenderer() the print engine with the passed entities.
+   *
+   * @param array $entities
+   *   An array of entities.
+   * @param \Drupal\entity_print\Plugin\PrintEngineInterface $print_engine
+   *   The print engine.
+   * @param bool $use_default_css
+   *   TRUE if we want the default CSS included.
+   * @param bool $digitalSignature
+   *   If the digital signature message needs to be added.
+   *
+   * @return \Drupal\entity_print\Renderer\RendererInterface
+   *   A print renderer.
+   *
+   * @see PrintBuilder::prepareRenderer
+   */
+  protected function prepareRenderer(array $entities, PrintEngineInterface $print_engine, $use_default_css, $digitalSignature = FALSE) {
     if (empty($entities)) {
       throw new \InvalidArgumentException('You must pass at least 1 entity');
     }
@@ -50,6 +110,9 @@ protected function prepareRenderer(array $entities, PrintEngineInterface $print_
     // structure. That margin is automatically added in PDF and PDF only.
     $generatedHtml = (string) $renderer->generateHtml($entities, $render, $use_default_css, TRUE);
     $generatedHtml .= "<style>fieldset legend {margin-left: -12px;}</style>";
+    if ($digitalSignature) {
+      $generatedHtml .= $this->t('You can validate the signature on this PDF file via validering.nemlog-in.dk.');
+    }
 
     $print_engine->addPage($generatedHtml);
 
diff --git a/modules/os2forms_attachment/src/Plugin/WebformElement/AttachmentElement.php b/modules/os2forms_attachment/src/Plugin/WebformElement/AttachmentElement.php
index 4f2215d6..7ec580bd 100644
--- a/modules/os2forms_attachment/src/Plugin/WebformElement/AttachmentElement.php
+++ b/modules/os2forms_attachment/src/Plugin/WebformElement/AttachmentElement.php
@@ -27,6 +27,7 @@ protected function defineDefaultProperties() {
       'view_mode' => 'html',
       'template' => '',
       'export_type' => '',
+      'digital_signature' => '',
       'exclude_empty' => '',
       'exclude_empty_checkbox' => '',
       'excluded_elements' => '',
@@ -88,6 +89,11 @@ public function form(array $form, FormStateInterface $form_state) {
         'html' => $this->t('HTML'),
       ],
     ];
+    $form['attachment']['digital_signature'] = [
+      '#type' => 'checkbox',
+      '#title' => $this->t('Digital signature'),
+    ];
+
     // Set #access so that help is always visible.
     WebformElementHelper::setPropertyRecursive($form['attachment']['help'], '#access', TRUE);
 
diff --git a/modules/os2forms_digital_signature/README.md b/modules/os2forms_digital_signature/README.md
new file mode 100644
index 00000000..242fa541
--- /dev/null
+++ b/modules/os2forms_digital_signature/README.md
@@ -0,0 +1,40 @@
+# OS2Forms Digital Signature module
+
+## Module purpose
+
+This module provides functionality for adding digital signature to the webform PDF submissions.
+
+## How does it work
+
+### Activating Digital Signature
+
+1. Add the OS2forms attachment element to the form.
+2. Indicate that the OS2Forms attachment requires a digital signature.
+3. Add the Digital Signature Handler to the webform.
+4. If the form requires an email handler, ensure the trigger is set to **...when submission is locked** in the handler’s
+*Additional settings*.
+
+### Flow Explained
+
+1. Upon form submission, a PDF is generated, saved in the private directory, and sent to the signature service via URL.
+2. The user is redirected to the signature service to provide their signature.
+3. After signing, the user is redirected back to the webform solution.
+4. The signed PDF is downloaded and stored in Drupal’s private directory.
+5. When a submission PDF is requested (e.g., via download link or email), the signed PDF is served instead of generating
+a new one on the fly.
+
+## Settings page
+
+URL: `admin/os2forms_digital_signature/settings`
+
+- **Signature server URL**
+
+  The URL of the service providing digital signature. This is the example of a known service [https://signering.bellcom.dk/sign.php?](https://signering.bellcom.dk/sign.php?)
+
+- **Hash Salt used for signature**
+
+  Must match hash salt on the signature server
+
+- **List IPs which can download unsigned PDF submissions**
+
+  Only requests from this IP will be able to download PDF which are to be signed.
diff --git a/modules/os2forms_digital_signature/os2forms_digital_signature.info.yml b/modules/os2forms_digital_signature/os2forms_digital_signature.info.yml
new file mode 100644
index 00000000..29547e43
--- /dev/null
+++ b/modules/os2forms_digital_signature/os2forms_digital_signature.info.yml
@@ -0,0 +1,9 @@
+name: 'OS2Forms Digital Signature'
+type: module
+description: 'Provides digital signature functionality'
+package: 'OS2Forms'
+core_version_requirement: ^9 || ^10
+dependencies:
+  - 'webform:webform'
+
+configure: os2forms_digital_signature.settings
diff --git a/modules/os2forms_digital_signature/os2forms_digital_signature.links.menu.yml b/modules/os2forms_digital_signature/os2forms_digital_signature.links.menu.yml
new file mode 100644
index 00000000..2fc07d22
--- /dev/null
+++ b/modules/os2forms_digital_signature/os2forms_digital_signature.links.menu.yml
@@ -0,0 +1,5 @@
+os2forms_digital_signature.admin.settings:
+  title: OS2Forms digital signature
+  description: Configure the OS2Forms digital signature module
+  parent: system.admin_config_system
+  route_name: os2forms_digital_signature.settings
diff --git a/modules/os2forms_digital_signature/os2forms_digital_signature.module b/modules/os2forms_digital_signature/os2forms_digital_signature.module
new file mode 100644
index 00000000..6e12a210
--- /dev/null
+++ b/modules/os2forms_digital_signature/os2forms_digital_signature.module
@@ -0,0 +1,77 @@
+<?php
+
+/**
+ * @file
+ * This module enables Digital Signature functionality for Webforms.
+ */
+
+use Drupal\Core\Form\FormStateInterface;
+use Drupal\Core\StreamWrapper\StreamWrapperManager;
+use Drupal\os2forms_digital_signature\Form\SettingsForm;
+
+/**
+ * Implements hook_cron().
+ *
+ * Deletes stalled webform submissions that were left unsigned.
+ */
+function os2forms_digital_signature_cron() {
+  /** @var \Drupal\os2forms_digital_signature\Service\SigningService $service */
+  $service = \Drupal::service('os2forms_digital_signature.signing_service');
+  $service->deleteStalledSubmissions();
+}
+
+/**
+ * Implements hook_webform_submission_form_alter().
+ *
+ * Replaces submit button title, if digital signature present.
+ */
+function os2forms_digital_signature_webform_submission_form_alter(array &$form, FormStateInterface $form_state, $form_id) {
+  /** @var \Drupal\webform\WebformSubmissionInterface Interface $webformSubmission */
+  $webformSubmission = $form_state->getFormObject()->getEntity();
+  /** @var \Drupal\webform\WebformInterface $webform */
+  $webform = $webformSubmission->getWebform();
+
+  // Checking for os2forms_digital_signature handler presence.
+  foreach ($webform->getHandlers()->getConfiguration() as $handlerConf) {
+    if ($handlerConf['id'] == 'os2forms_digital_signature') {
+      $config = \Drupal::config('webform.settings');
+      $settings = $config->get('settings');
+
+      // Checking if the title has not been overridden.
+      if ($settings['default_submit_button_label'] == $form['actions']['submit']['#value']) {
+        $form['actions']['submit']['#value'] = t('Sign and submit');
+      }
+    }
+  }
+}
+
+/**
+ * Implements hook_file_download().
+ *
+ * Custom access control for private files.
+ */
+function os2forms_digital_signature_file_download($uri) {
+  // Only operate on files in the private directory.
+  if (StreamWrapperManager::getScheme($uri) === 'private' && str_starts_with(StreamWrapperManager::getTarget($uri), 'signing/')) {
+    // Get allowed IPs settings.
+    $config = \Drupal::config(SettingsForm::$configName);
+    $allowedIps = $config->get('os2forms_digital_signature_submission_allowed_ips');
+
+    $allowedIpsArr = explode(',', $allowedIps);
+    $remoteIp = Drupal::request()->getClientIp();
+
+    // IP list is empty, or request IP is allowed.
+    if (empty($allowedIpsArr) || in_array($remoteIp, $allowedIpsArr)) {
+      $basename = basename($uri);
+      return [
+        'Content-disposition' => 'attachment; filename="' . $basename . '"',
+      ];
+    }
+
+    // Otherwise - Deny access.
+    return -1;
+  }
+
+  // Not submission file, allow normal access.
+  return NULL;
+}
diff --git a/modules/os2forms_digital_signature/os2forms_digital_signature.routing.yml b/modules/os2forms_digital_signature/os2forms_digital_signature.routing.yml
new file mode 100644
index 00000000..41dbc321
--- /dev/null
+++ b/modules/os2forms_digital_signature/os2forms_digital_signature.routing.yml
@@ -0,0 +1,15 @@
+# Webform os2forms_attachment_component routes.
+os2forms_digital_signature.sign_callback:
+  path: '/os2forms_digital_signature/{uuid}/{hash}/sign_callback/{fid}'
+  defaults:
+    _controller: '\Drupal\os2forms_digital_signature\Controller\DigitalSignatureController::signCallback'
+    fid: ''
+  requirements:
+    _permission: 'access content'
+os2forms_digital_signature.settings:
+  path: '/admin/os2forms_digital_signature/settings'
+  defaults:
+    _form: '\Drupal\os2forms_digital_signature\Form\SettingsForm'
+    _title: 'Digital signature settings'
+  requirements:
+    _permission: 'administer site configuration'
diff --git a/modules/os2forms_digital_signature/os2forms_digital_signature.services.yml b/modules/os2forms_digital_signature/os2forms_digital_signature.services.yml
new file mode 100644
index 00000000..33848830
--- /dev/null
+++ b/modules/os2forms_digital_signature/os2forms_digital_signature.services.yml
@@ -0,0 +1,13 @@
+services:
+  logger.channel.os2forms_digital_signature:
+    parent: logger.channel_base
+    arguments: [ 'os2forms_digital_signature' ]
+
+  os2forms_digital_signature.signing_service:
+    class: Drupal\os2forms_digital_signature\Service\SigningService
+    arguments:
+      - '@http_client'
+      - '@datetime.time'
+      - '@config.factory'
+      - '@entity_type.manager'
+      - '@logger.channel.os2forms_digital_signature'
diff --git a/modules/os2forms_digital_signature/src/Controller/DigitalSignatureController.php b/modules/os2forms_digital_signature/src/Controller/DigitalSignatureController.php
new file mode 100644
index 00000000..656bf7d4
--- /dev/null
+++ b/modules/os2forms_digital_signature/src/Controller/DigitalSignatureController.php
@@ -0,0 +1,166 @@
+<?php
+
+namespace Drupal\os2forms_digital_signature\Controller;
+
+use Drupal\Component\Utility\Crypt;
+use Drupal\Core\Controller\ControllerBase;
+use Drupal\Core\Entity\EntityStorageInterface;
+use Drupal\Core\File\FileExists;
+use Drupal\Core\File\FileSystemInterface;
+use Drupal\Core\Site\Settings;
+use Drupal\Core\Url;
+use Drupal\os2forms_digital_signature\Service\SigningService;
+use Psr\Log\LoggerInterface;
+use Symfony\Component\DependencyInjection\ContainerInterface;
+use Symfony\Component\HttpFoundation\RedirectResponse;
+use Symfony\Component\HttpFoundation\RequestStack;
+use Symfony\Component\HttpKernel\Exception\NotFoundHttpException;
+
+/**
+ * Digital Signature Controller.
+ */
+class DigitalSignatureController extends ControllerBase {
+
+  /**
+   * File Storage.
+   *
+   * @var \Drupal\Core\Entity\EntityStorageInterface
+   */
+  protected EntityStorageInterface $fileStorage;
+
+  /**
+   * Constructor.
+   */
+  public function __construct(
+    private readonly LoggerInterface $logger,
+    private readonly Settings $settings,
+    private readonly SigningService $signingService,
+    private readonly FileSystemInterface $fileSystem,
+    private readonly RequestStack $requestStack,
+  ) {
+    $this->fileStorage = $this->entityTypeManager()->getStorage('file');
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public static function create(ContainerInterface $container) {
+    return new static(
+      $container->get('logger.channel.os2forms_digital_signature'),
+      $container->get('settings'),
+      $container->get('os2forms_digital_signature.signing_service'),
+      $container->get('file_system'),
+      $container->get('request_stack'),
+    );
+  }
+
+  /**
+   * Callback for the file being signed.
+   *
+   * Expecting the file name to be coming as GET parameter.
+   *
+   * @param string $uuid
+   *   Webform submission UUID.
+   * @param string $hash
+   *   Hash to check if the request is authentic.
+   * @param int|null $fid
+   *   File to replace (optional).
+   *
+   * @return \Symfony\Component\HttpFoundation\RedirectResponse
+   *   Redirect response to form submission confirmation.
+   *
+   * @throws \Drupal\Component\Plugin\Exception\InvalidPluginDefinitionException
+   * @throws \Drupal\Component\Plugin\Exception\PluginNotFoundException
+   */
+  public function signCallback($uuid, $hash, $fid = NULL) {
+    // Load the webform submission entity by UUID.
+    $submissions = $this->entityTypeManager()
+      ->getStorage('webform_submission')
+      ->loadByProperties(['uuid' => $uuid]);
+
+    // Since loadByProperties returns an array, we need to fetch the first item.
+    /** @var \Drupal\webform\WebformSubmissionInterface $webformSubmission */
+    $webformSubmission = $submissions ? reset($submissions) : NULL;
+    if (!$webformSubmission) {
+      // Submission does not exist.
+      throw new NotFoundHttpException();
+    }
+
+    $webformId = $webformSubmission->getWebform()->id();
+
+    // Checking the action.
+    $request = $this->requestStack->getCurrentRequest();
+
+    $action = $request->query->get('action');
+    if ($action == 'cancel') {
+      $cancelUrl = $webformSubmission->getWebform()->toUrl()->toString();
+
+      // Redirect to the webform confirmation page.
+      $response = new RedirectResponse($cancelUrl);
+      return $response;
+    }
+
+    // Checking hash.
+    $salt = $this->settings->get('hash_salt');
+    $tmpHash = Crypt::hashBase64($uuid . $webformId . $salt);
+    if ($hash !== $tmpHash) {
+      // Submission exist, but the provided hash is incorrect.
+      throw new NotFoundHttpException();
+    }
+
+    $signedFilename = $request->get('file');
+    $signedFileContent = $this->signingService->download($signedFilename);
+    if (!$signedFileContent) {
+      $this->logger->warning('Missing file on remote server %file.', ['%file' => $signedFilename]);
+      throw new NotFoundHttpException();
+    }
+
+    // If $fid is present - we are replacing uploaded/managed file, otherwise
+    // creating a new one.
+    if ($fid) {
+      $file = $this->fileStorage->load($fid);
+      $expectedFileUri = $file->getFileUri();
+    }
+    else {
+      // Prepare the directory to ensure it exists and is writable.
+      $expectedFileUri = "private://webform/$webformId/digital_signature/$uuid.pdf";
+      $directory = dirname($expectedFileUri);
+
+      if (!$this->fileSystem->prepareDirectory($directory, FileSystemInterface::CREATE_DIRECTORY)) {
+        $this->logger->error('Failed to prepare directory %directory.', ['%directory' => $directory]);
+      }
+    }
+
+    // Write the data to the file using Drupal's file system service.
+    try {
+      $this->fileSystem->saveData($signedFileContent, $expectedFileUri, FileExists::Replace);
+
+      // Updating webform submission.
+      $webformSubmission->setLocked(TRUE);
+      $webformSubmission->save();
+
+      // If file existing, resave the file to update the size and etc.
+      if ($fid) {
+        $this->fileStorage->load($fid)?->save();
+      }
+    }
+    catch (\Exception $e) {
+      $this->logger->error('Failed to write to file %uri: @message',
+        [
+          '%uri' => $expectedFileUri,
+          '@message' => $e->getMessage(),
+        ]);
+    }
+
+    // Build the URL for the webform submission confirmation page.
+    $confirmation_url = Url::fromRoute('entity.webform.confirmation', [
+      'webform' => $webformId,
+      'webform_submission' => $webformSubmission->id(),
+    ])->toString();
+
+    // Redirect to the webform confirmation page.
+    $response = new RedirectResponse($confirmation_url);
+    return $response;
+  }
+
+}
diff --git a/modules/os2forms_digital_signature/src/Element/DigitalSignatureDocument.php b/modules/os2forms_digital_signature/src/Element/DigitalSignatureDocument.php
new file mode 100644
index 00000000..7ac75c97
--- /dev/null
+++ b/modules/os2forms_digital_signature/src/Element/DigitalSignatureDocument.php
@@ -0,0 +1,19 @@
+<?php
+
+namespace Drupal\os2forms_digital_signature\Element;
+
+use Drupal\webform\Element\WebformManagedFileBase;
+
+/**
+ * Provides a element for an 'os2forms_digital_signature_document' element.
+ *
+ * @FormElement("os2forms_digital_signature_document")
+ */
+class DigitalSignatureDocument extends WebformManagedFileBase {
+
+  /**
+   * {@inheritdoc}
+   */
+  protected static $accept = 'application/pdf';
+
+}
diff --git a/modules/os2forms_digital_signature/src/Form/SettingsForm.php b/modules/os2forms_digital_signature/src/Form/SettingsForm.php
new file mode 100644
index 00000000..a05ec886
--- /dev/null
+++ b/modules/os2forms_digital_signature/src/Form/SettingsForm.php
@@ -0,0 +1,83 @@
+<?php
+
+namespace Drupal\os2forms_digital_signature\Form;
+
+use Drupal\Core\Form\ConfigFormBase;
+use Drupal\Core\Form\FormStateInterface;
+use Drupal\Core\StringTranslation\StringTranslationTrait;
+
+/**
+ * Digital post settings form.
+ */
+class SettingsForm extends ConfigFormBase {
+  use StringTranslationTrait;
+
+  /**
+   * Name of the config.
+   *
+   * @var string
+   */
+  public static $configName = 'os2forms_digital_signature.settings';
+
+  /**
+   * {@inheritdoc}
+   */
+  public function getFormId() {
+    return 'os2forms_digital_signature_settings';
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  protected function getEditableConfigNames() {
+    return [self::$configName];
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function buildForm(array $form, FormStateInterface $form_state) {
+    $form['os2forms_digital_signature_remote_service_url'] = [
+      '#type' => 'textfield',
+      '#title' => $this->t('Signature server URL'),
+      '#default_value' => $this->config(self::$configName)->get('os2forms_digital_signature_remote_service_url'),
+      '#description' => $this->t('E.g. https://signering.bellcom.dk/sign.php?'),
+    ];
+    $form['os2forms_digital_signature_sign_hash_salt'] = [
+      '#type' => 'textfield',
+      '#title' => $this->t('Hash Salt used for signature'),
+      '#default_value' => $this->config(self::$configName)->get('os2forms_digital_signature_sign_hash_salt'),
+      '#description' => $this->t('Must match hash salt on the signature server'),
+    ];
+    $form['os2forms_digital_signature_submission_allowed_ips'] = [
+      '#type' => 'textfield',
+      '#title' => $this->t('List IPs which can download unsigned PDF submissions'),
+      '#default_value' => $this->config(self::$configName)->get('os2forms_digital_signature_submission_allowed_ips'),
+      '#description' => $this->t('Comma separated. e.g. 192.168.1.1,192.168.2.1'),
+    ];
+    $form['os2forms_digital_signature_submission_retention_period'] = [
+      '#type' => 'textfield',
+      '#title' => $this->t('Unsigned submission timespan (s)'),
+      '#default_value' => ($this->config(self::$configName)->get('os2forms_digital_signature_submission_retention_period')) ?? 300,
+      '#description' => $this->t('How many seconds can unsigned submission exist before being automatically deleted'),
+    ];
+
+    return parent::buildForm($form, $form_state);
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function submitForm(array &$form, FormStateInterface $form_state) {
+    $values = $form_state->getValues();
+
+    $config = $this->config(self::$configName);
+    foreach ($values as $key => $value) {
+      $config->set($key, $value);
+    }
+    $config->save();
+
+    parent::submitForm($form, $form_state);
+  }
+
+}
diff --git a/modules/os2forms_digital_signature/src/Plugin/WebformElement/DigitalSignatureDocument.php b/modules/os2forms_digital_signature/src/Plugin/WebformElement/DigitalSignatureDocument.php
new file mode 100644
index 00000000..dcf727d8
--- /dev/null
+++ b/modules/os2forms_digital_signature/src/Plugin/WebformElement/DigitalSignatureDocument.php
@@ -0,0 +1,82 @@
+<?php
+
+namespace Drupal\os2forms_digital_signature\Plugin\WebformElement;
+
+use Drupal\webform\Plugin\WebformElement\WebformManagedFileBase;
+use Drupal\webform\WebformSubmissionInterface;
+
+/**
+ * Provides a 'os2forms_digital_signature_document' element.
+ *
+ * @WebformElement(
+ *   id = "os2forms_digital_signature_document",
+ *   label = @Translation("OS2forms digital signature document"),
+ *   description = @Translation("Upload PDF file for digital signature."),
+ *   category = @Translation("OS2Forms"),
+ *   states_wrapper = TRUE,
+ *   dependencies = {
+ *     "file",
+ *   }
+ * )
+ */
+class DigitalSignatureDocument extends WebformManagedFileBase {
+
+  /**
+   * {@inheritdoc}
+   */
+  public function getItemFormats() {
+    $formats = parent::getItemFormats();
+    $formats['file'] = $this->t('PDF file for signature');
+    return $formats;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  protected function getFileExtensions(?array $element = NULL) {
+    return 'pdf';
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  protected function formatHtmlItem(array $element, WebformSubmissionInterface $webform_submission, array $options = []) {
+    $value = $this->getValue($element, $webform_submission, $options);
+    $file = $this->getFile($element, $value, $options);
+
+    if (empty($file)) {
+      return '';
+    }
+
+    $format = $this->getItemFormat($element);
+    switch ($format) {
+      case 'basename':
+      case 'extension':
+      case 'data':
+      case 'id':
+      case 'mime':
+      case 'name':
+      case 'raw':
+      case 'size':
+      case 'url':
+      case 'value':
+        return $this->formatTextItem($element, $webform_submission, $options);
+
+      case 'link':
+        return [
+          '#theme' => 'file_link',
+          '#file' => $file,
+        ];
+
+      default:
+        return [
+          '#theme' => 'webform_element_document_file',
+          '#element' => $element,
+          '#value' => $value,
+          '#options' => $options,
+          '#file' => $file,
+        ];
+    }
+  }
+
+}
diff --git a/modules/os2forms_digital_signature/src/Plugin/WebformHandler/DigitalSignatureWebformHandler.php b/modules/os2forms_digital_signature/src/Plugin/WebformHandler/DigitalSignatureWebformHandler.php
new file mode 100644
index 00000000..9a616bfc
--- /dev/null
+++ b/modules/os2forms_digital_signature/src/Plugin/WebformHandler/DigitalSignatureWebformHandler.php
@@ -0,0 +1,247 @@
+<?php
+
+namespace Drupal\os2forms_digital_signature\Plugin\WebformHandler;
+
+use Drupal\Component\Utility\Crypt;
+use Drupal\Core\Extension\ModuleHandlerInterface;
+use Drupal\Core\File\FileExists;
+use Drupal\Core\File\FileSystemInterface;
+use Drupal\Core\File\FileUrlGeneratorInterface;
+use Drupal\Core\Site\Settings;
+use Drupal\Core\Url;
+use Drupal\file\FileRepositoryInterface;
+use Drupal\os2forms_digital_signature\Service\SigningService;
+use Drupal\webform\Plugin\WebformElementManagerInterface;
+use Drupal\webform\Plugin\WebformHandlerBase;
+use Drupal\webform\WebformSubmissionInterface;
+use Psr\Log\LoggerInterface;
+use Symfony\Component\DependencyInjection\ContainerInterface;
+
+/**
+ * Digital signature webform handler.
+ *
+ * @WebformHandler(
+ *   id = "os2forms_digital_signature",
+ *   label = @Translation("Digital Signature"),
+ *   category = @Translation("OS2Forms"),
+ *   description = @Translation("Sends file to digital signature."),
+ *   cardinality = \Drupal\webform\Plugin\WebformHandlerInterface::CARDINALITY_SINGLE,
+ *   results = \Drupal\webform\Plugin\WebformHandlerInterface::RESULTS_PROCESSED,
+ *   submission = \Drupal\webform\Plugin\WebformHandlerInterface::SUBMISSION_OPTIONAL,
+ * )
+ */
+class DigitalSignatureWebformHandler extends WebformHandlerBase {
+
+  /**
+   * The module handler.
+   *
+   * @var \Drupal\Core\Extension\ModuleHandlerInterface
+   */
+  private readonly ModuleHandlerInterface $moduleHandler;
+
+  /**
+   * The webform element plugin manager.
+   *
+   * @var \Drupal\webform\Plugin\WebformElementManagerInterface
+   */
+  private readonly WebformElementManagerInterface $elementManager;
+
+  /**
+   * Logger for channel - os2forms_digital_signature.
+   *
+   * @var \Psr\Log\LoggerInterface
+   */
+  private readonly LoggerInterface $logger;
+
+  /**
+   * File system interface.
+   *
+   * @var \Drupal\Core\File\FileSystemInterface
+   */
+  private readonly FileSystemInterface $fileSystem;
+
+  /**
+   * File repository.
+   *
+   * @var \Drupal\file\FileRepositoryInterface
+   */
+  private readonly FileRepositoryInterface $fileRepository;
+
+  /**
+   * File URL generator.
+   *
+   * @var \Drupal\Core\File\FileUrlGeneratorInterface
+   */
+  private readonly FileUrlGeneratorInterface $fileUrlGenerator;
+
+  /**
+   * OS2Forms signing service.
+   *
+   * @var \Drupal\os2forms_digital_signature\Service\SigningService
+   */
+  private readonly SigningService $signingService;
+
+  /**
+   * Settings service.
+   *
+   * @var \Drupal\Core\Site\Settings
+   */
+  private readonly Settings $settings;
+
+  /**
+   * {@inheritdoc}
+   */
+  public static function create(ContainerInterface $container, array $configuration, $plugin_id, $plugin_definition) {
+    $instance = parent::create($container, $configuration, $plugin_id, $plugin_definition);
+    $instance->moduleHandler = $container->get('module_handler');
+    $instance->elementManager = $container->get('plugin.manager.webform.element');
+    $instance->logger = $container->get('logger.channel.os2forms_digital_signature');
+    $instance->fileSystem = $container->get('file_system');
+    $instance->fileRepository = $container->get('file.repository');
+    $instance->fileUrlGenerator = $container->get('file_url_generator');
+    $instance->signingService = $container->get('os2forms_digital_signature.signing_service');
+    $instance->settings = $container->get('settings');
+
+    return $instance;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function preSave(WebformSubmissionInterface $webform_submission) {
+    $webform = $webform_submission->getWebform();
+
+    if ($webform_submission->isLocked()) {
+      return;
+    }
+
+    $attachment = $this->getSubmissionAttachment($webform_submission);
+    if (!$attachment) {
+      $this->logger->error('Attachment cannot be created webform: %webform, webform_submission: %webform_submission',
+        [
+          '%webform' => $webform->id(),
+          '%webform_submission' => $webform_submission->uuid(),
+        ]
+      );
+      return;
+    }
+
+    $destinationDir = 'private://signing';
+    if (!$this->fileSystem->prepareDirectory($destinationDir, FileSystemInterface::CREATE_DIRECTORY)) {
+      $this->logger->error('File directory cannot be created: %filedirectory', ['%filedirectory' => $destinationDir]);
+      return;
+    }
+
+    $fileUri = $destinationDir . '/' . $webform_submission->uuid() . '.pdf';
+
+    // Save the file data.
+    try {
+      $fileToSign = $this->fileRepository->writeData($attachment['filecontent'], $fileUri, FileExists::Replace);
+    }
+    catch (\Exception $e) {
+      $this->logger->error('File cannot be saved: %fileUri, error: %error',
+        [
+          '%fileUri' => $fileUri,
+          '%error' => $e->getMessage(),
+        ]);
+      return;
+    }
+
+    $fileToSign->save();
+    $fileToSignPublicUrl = $this->fileUrlGenerator->generateAbsoluteString($fileToSign->getFileUri());
+
+    $cid = $this->signingService->getCid();
+    if (empty($cid)) {
+      $this->logger->error('Failed to obtain cid. Is server running?');
+      return;
+    }
+
+    // Creating hash.
+    $salt = $this->settings->get('hash_salt');
+    $hash = Crypt::hashBase64($webform_submission->uuid() . $webform->id() . $salt);
+
+    $attachmentFid = $attachment['fid'] ?? NULL;
+    $signatureCallbackUrl = Url::fromRoute('os2forms_digital_signature.sign_callback',
+      [
+        'uuid' => $webform_submission->uuid(),
+        'hash' => $hash,
+        'fid' => $attachmentFid,
+      ]
+    );
+
+    // Starting signing, if everything is correct - this funcition will start
+    // redirect.
+    $this->signingService->sign($fileToSignPublicUrl, $cid, $signatureCallbackUrl->setAbsolute()->toString());
+  }
+
+  /**
+   * Get OS2forms file attachment.
+   *
+   * @param \Drupal\webform\WebformSubmissionInterface $webform_submission
+   *   A webform submission.
+   *
+   * @return array|null
+   *   Array of attachment data.
+   *
+   * @throws \Exception
+   */
+  protected function getSubmissionAttachment(WebformSubmissionInterface $webform_submission) {
+    $attachments = NULL;
+    $attachment = NULL;
+
+    // Getting all element types that are added to the webform.
+    //
+    // Priority is the following: check for os2forms_digital_signature_document,
+    // is not found try serving os2forms_attachment.
+    $elementTypes = array_column($this->getWebform()->getElementsDecodedAndFlattened(), '#type');
+    $attachmentType = '';
+    if (in_array('os2forms_digital_signature_document', $elementTypes)) {
+      $attachmentType = 'os2forms_digital_signature_document';
+    }
+    elseif (in_array('os2forms_attachment', $elementTypes)) {
+      $attachmentType = 'os2forms_attachment';
+    }
+
+    $elements = $this->getWebform()->getElementsInitializedAndFlattened();
+    $element_attachments = $this->getWebform()->getElementsAttachments();
+    foreach ($element_attachments as $element_attachment) {
+      // Check if the element attachment key is excluded and should not attach
+      // any files.
+      if (isset($this->configuration['excluded_elements'][$element_attachment])) {
+        continue;
+      }
+
+      $element = $elements[$element_attachment];
+
+      if ($element['#type'] == $attachmentType) {
+        /** @var \Drupal\webform\Plugin\WebformElementAttachmentInterface $element_plugin */
+        $element_plugin = $this->elementManager->getElementInstance($element);
+        $attachments = $element_plugin->getEmailAttachments($element, $webform_submission);
+
+        // If we are dealing with an uploaded file, attach the FID.
+        if ($fid = $webform_submission->getElementData($element_attachment)) {
+          $attachments[0]['fid'] = $fid;
+        }
+        break;
+      }
+    }
+
+    if (!empty($attachments)) {
+      $attachment = reset($attachments);
+    }
+
+    // For SwiftMailer && Mime Mail use filecontent and not the filepath.
+    // @see \Drupal\swiftmailer\Plugin\Mail\SwiftMailer::attachAsMimeMail
+    // @see \Drupal\mimemail\Utility\MimeMailFormatHelper::mimeMailFile
+    // @see https://www.drupal.org/project/webform/issues/3232756
+    if ($this->moduleHandler->moduleExists('swiftmailer')
+      || $this->moduleHandler->moduleExists('mimemail')) {
+      if (isset($attachment['filecontent']) && isset($attachment['filepath'])) {
+        unset($attachment['filepath']);
+      }
+    }
+
+    return $attachment;
+  }
+
+}
diff --git a/modules/os2forms_digital_signature/src/Service/SigningService.php b/modules/os2forms_digital_signature/src/Service/SigningService.php
new file mode 100644
index 00000000..47505243
--- /dev/null
+++ b/modules/os2forms_digital_signature/src/Service/SigningService.php
@@ -0,0 +1,259 @@
+<?php
+
+namespace Drupal\os2forms_digital_signature\Service;
+
+use Drupal\Component\Datetime\TimeInterface;
+use Drupal\Core\Config\ConfigFactoryInterface;
+use Drupal\Core\Config\ImmutableConfig;
+use Drupal\Core\Entity\EntityStorageInterface;
+use Drupal\Core\Entity\EntityTypeManager;
+use Drupal\Core\Logger\LoggerChannelInterface;
+use Drupal\os2forms_digital_signature\Form\SettingsForm;
+use GuzzleHttp\ClientInterface;
+use Symfony\Component\HttpFoundation\RedirectResponse;
+
+/**
+ * Digital signing service.
+ */
+class SigningService {
+
+  /**
+   * The config.
+   *
+   * @var \Drupal\Core\Config\ImmutableConfig
+   */
+  private readonly ImmutableConfig $config;
+
+  /**
+   * Webform storage.
+   *
+   * @var \Drupal\Core\Entity\EntityStorageInterface
+   */
+  private readonly EntityStorageInterface $webformStorage;
+
+  /**
+   * WebformSubmission storage.
+   *
+   * @var \Drupal\Core\Entity\EntityStorageInterface
+   */
+  private readonly EntityStorageInterface $webformSubmissionStorage;
+
+  public function __construct(
+    private readonly ClientInterface $httpClient,
+    private readonly TimeInterface $time,
+    ConfigFactoryInterface $configFactory,
+    EntityTypeManager $entityTypeManager,
+    private readonly LoggerChannelInterface $logger,
+  ) {
+    $this->config = $configFactory->get(SettingsForm::$configName);
+    $this->webformStorage = $entityTypeManager->getStorage('webform');
+    $this->webformSubmissionStorage = $entityTypeManager->getStorage('webform_submission');
+  }
+
+  /**
+   * Fetch a new cid.
+   *
+   * @return string|null
+   *   The correlation id.
+   */
+  public function getCid() : ?string {
+    $url = $this->getServiceUrl() . http_build_query(['action' => 'getcid']);
+    $response = $this->httpClient->request('GET', $url);
+    $result = $response->getBody()->getContents();
+
+    $reply = json_decode($result, JSON_OBJECT_AS_ARRAY);
+
+    return $reply['cid'] ?? NULL;
+  }
+
+  /**
+   * Sign the document.
+   *
+   * Signing is done by redirecting the user's browser to a url on the signing
+   * server that takes the user through the signing flow.
+   *
+   * This function will never return.
+   *
+   * @param string $document_uri
+   *   A uri to a file on the local server that we want to sign or the file name
+   *   on the signing server in the SIGN_PDF_UPLOAD_DIR.
+   *   In case of a local file, it must be prefixed by 'http://' or 'https://'
+   *   and be readable from the signing server.
+   * @param string $cid
+   *   The cid made available by the getCid() function.
+   * @param string $forward_url
+   *   The url on the local server to forward user to afterwards.
+   */
+  public function sign(string $document_uri, string $cid, string $forward_url):void {
+    if (empty($document_uri) || empty($cid) || empty($forward_url)) {
+      $this->logger->error('Cannot initiate signing process, check params: document_uri: %document_uri, cid: %cid, forward_url: %forward_url',
+        [
+          '%document_uri' => $document_uri,
+          '%cid' => $cid,
+          '%forward_url' => $forward_url,
+        ]
+      );
+      return;
+    }
+
+    $hash = $this->getHash($forward_url);
+    $params = [
+      'action' => 'sign',
+      'cid' => $cid,
+      'hash' => $hash,
+      'uri' => base64_encode($document_uri),
+      'forward_url' => base64_encode($forward_url),
+    ];
+    $url = $this->getServiceUrl() . http_build_query($params);
+
+    $response = new RedirectResponse($url);
+    $response->send();
+  }
+
+  /**
+   * Download the pdf file and return it as a binary string.
+   *
+   * @param string $filename
+   *   The filename as given by the signing server.
+   * @param bool $leave
+   *   If TRUE, leave the file on the remote server, default is to remove the
+   *   file after download.
+   * @param bool $annotate
+   *   If TRUE, download a pdf with an annotation page.
+   * @param array $attributes
+   *   An array of pairs of prompts and values that will be added to the
+   *   annotation box, e.g.
+   *   [
+   *     'IP' => $_SERVER['REMOTE_ADDR'],
+   *     'Region' => 'Capital Region Copenhagen'
+   *   ].
+   *
+   * @return mixed|bool
+   *   The binary data of the pdf or FALSE if an error occurred.
+   */
+  public function download(string $filename, $leave = FALSE, $annotate = FALSE, $attributes = []) {
+    if (empty($filename)) {
+      return FALSE;
+    }
+    if (!preg_match('/^[a-f0-9]{32}\.pdf$/', $filename)) {
+      return FALSE;
+    }
+    $params = [
+      'action' => 'download',
+      'file' => $filename,
+      'leave' => $leave,
+      'annotate' => $annotate,
+      'attributes' => $attributes,
+    ];
+    $url = $this->getServiceUrl() . http_build_query($params);
+
+    $response = $this->httpClient->request('GET', $url);
+    $return = $response->getBody()->getContents();
+
+    if (empty($return)) {
+      return FALSE;
+    }
+    elseif (substr($return, 0, 5) !== '%PDF-') {
+      return FALSE;
+    }
+
+    return $return;
+  }
+
+  /**
+   * Calculate the hash value.
+   *
+   * @param string $value
+   *   The value to hash including salt.
+   *
+   * @return string
+   *   The hash value (sha1).
+   */
+  private function getHash(string $value) : string {
+    $hashSalt = $this->config->get('os2forms_digital_signature_sign_hash_salt');
+    return sha1($hashSalt . $value);
+  }
+
+  /**
+   * Deletes stalled webform submissions that were left unsigned.
+   *
+   * Only checked the webforms that have digital_signature handler enabled and
+   * the submission is older that a specified period.
+   *
+   * @throws \Drupal\Core\Entity\EntityStorageException
+   */
+  public function deleteStalledSubmissions() : void {
+    $digitalSignatureWebforms = [];
+
+    // Finding webforms that have any handler.
+    $query = $this->webformStorage->getQuery()
+      ->exists('handlers');
+    $handler_webform_ids = $query->execute();
+
+    // No webforms with handlers, aborting.
+    if (empty($handler_webform_ids)) {
+      return;
+    }
+
+    // Find all with os2forms_digital_signature handlers enabled.
+    foreach ($handler_webform_ids as $webform_id) {
+      $webform = $this->webformStorage->load($webform_id);
+      if (!$webform) {
+        continue;
+      }
+
+      $handlers = $webform->getHandlers();
+      foreach ($handlers as $handler) {
+        // Check if the handler is of type 'os2forms_digital_signature'.
+        if ($handler->getPluginId() === 'os2forms_digital_signature' && $handler->isEnabled()) {
+          $digitalSignatureWebforms[] = $webform->id();
+          break;
+        }
+      }
+    }
+
+    // No webforms, aborting.
+    if (empty($digitalSignatureWebforms)) {
+      return;
+    }
+
+    // Find all stalled webform submissions of digital signature forms.
+    $retention_period = ($this->config->get('os2forms_digital_signature_submission_retention_period')) ?? 300;
+    $timestamp_threshold = $this->time->getRequestTime() - $retention_period;
+    $query = $this->webformSubmissionStorage->getQuery()
+      ->accessCheck(FALSE)
+      ->condition('webform_id', $digitalSignatureWebforms, 'IN')
+      ->condition('locked', 0)
+      ->condition('created', $timestamp_threshold, '<');
+    $submission_ids = $query->execute();
+
+    // No submissions, aborting.
+    if (empty($submission_ids)) {
+      return;
+    }
+
+    // Deleting all stalled webform submissions.
+    foreach ($submission_ids as $submission_id) {
+      $submission = $this->webformSubmissionStorage->load($submission_id);
+      $submission->delete();
+    }
+  }
+
+  /**
+   * Returns Remote signature service URL.
+   *
+   * @return string
+   *   Remote Service URL, if missing '?' or '&', '?' will be added
+   *   automatically.
+   */
+  public function getServiceUrl() : string {
+    $url = $this->config->get('os2forms_digital_signature_remote_service_url');
+    // Handling URL, if it does not end with '?' or '&'.
+    if (!str_ends_with($url, '?') && !str_ends_with($url, '&')) {
+      return $url . '?';
+    }
+
+    return $url;
+  }
+
+}