Can I use Able2Extract to sign PDF documents?

Yes, starting from Able2Extract Professional 14.0, you can use the Digital Signatures functionality to create and interact with digital signatures. 

To access this functionality, ensure that you are in Conversion Mode and have the PDF Review Panels open.

This tool offers 2 functionalities: Signing and Digital Signature Validation.

Signing a PDF Document

Able2Extract allows you to sign a PDF using either a signature image and/or a digital certificate. It is important to note that Able2Extract only allows you to select valid certificates that are designed for document signing purposes. It is only possible to obtain such a certificate from a reputable authority on a USB-token (an external physical device that stores the certificate). Thus, to digitally sign a PDF with a cryptographic signature, you will need to insert that device into your computer before opening the Digital Signatures Panel in order to access and apply a specific certificate.

Note that this functionality will modify the original source document. Digitally signing a document with a certificate will first save all changes that were made to the document and will then attach the cryptographic signature to it and save the document again.

Depending on the document signing option you choose in the Signatures dialog, Able2Extract creates different type of signatures:

1. Image Signature: A graphical or electronic signature is attached to the document. This type of signature cannot be verified.
2. Digital Signature without an image: A cryptographic signature that is created with a digital certificate and then attached to the document. This type of signature will have no visual representation, but can be verified.
3. Digital Signature with an image: A cryptographic signature is attached to the document and a signature image is positioned on the page as specified. This signature can be verified.

1. How to add an image signature?

1. Open your PDF file in Able2Extract Professional 14.0.
2. When the document is opened, PDF Review Panels will appear on the right side of the screen. On this panel, please click on the Digital Signatures button.
3. Now click on the Choose Signature… button.
4. In the Signatures panel please make sure that the Add Signature Image check-box is checked. Then click on the Create button.
5. This will open a new dialog, so here please specify how you would like to create a signature image by selecting one of these three options: Type, Draw or Import.
   - Type command allows you to type in your signature in the Text field. If needed, you can also specify its properties (font and colour).
   - Choosing the Draw command allows you to create a signature by drawing it with your mouse (while keeping the left mouse button pressed).
   - Import command allows you to click on the Browse… button so as to find, select and load an already existing image file of your signature.
   To undo your signature or start over, simply click on the Clear button. Once you are satisfied with your image signature, click on Add.
6. Now select the desired signature image and uncheck Digitally Sign the Document check-box.
   Note: You can add multiple image signatures to your list. On the other hand, if you wish to remove from the signature image list the one you have previously created, select it and then click Remove.
7. Now click on the Sign button.
8. Use your mouse to place the signature image on a desired location (in your PDF file). To do so, simply hover over the page to where you want the signature placed, then left-click on the spot to define the signature image size and apply it to the page.
9. To save the changes you have made to your PDF, click on the Save button on the toolbar.
   (To save the edited PDF file under the different name, select Save As… option from the File menu.)

2. How to add a digital signature without an image?

1. Open your PDF file in Able2Extract Professional 14.0.
2. When the document is opened, PDF Review Panels will appear on the right side of the screen. On this panel, please click on the Digital Signatures button.
3. Now click on the Choose Signature… button.
4. Uncheck the Add Signature Image check-box and make sure that Digitally Sign the Document is checked.
5. Able2Extract will only show fully valid certificates that are suitable for document signing purposes. Once you see your digital certificate, select it and click Sign.
6. The following message will pop-up: “The document will be saved after the digital signature has been added. Would you like to continue?”, so please, click Yes.

When the certificate appears in the Signatures panel, this will mean that your document has been digitally signed with a certificate.

3. How to add a digital signature with an image?

1. Open your PDF file in Able2Extract Professional 14.0.
2. When the document is opened, PDF Review Panels will appear on the right side of the screen. On this panel, please click on the Digital Signatures button.
3. Now click on the Choose Signature… button.
4. In the Signatures panel please make sure that both the Add Signature Image check-box and the Digitally Sign the Document check-box are checked.
5. Select the desired signature image.
   (If you don’t have one yet, you can easily create it by clicking on the Create button and choosing one of the three creation methods: Type, Draw or Import. When you have created the signature, click Add.)
6. Select also your digital certificate.
7. Then click Sign.
8. Use your mouse to place the signature image on the page. To do so, simply hover over the page to where you want the signature placed, then left-click on the spot to define the signature image size and apply it to the page.
9. Once you have done this, a dialog will appear with the following question: “The document will be saved after the digital signature has been added. Would you like to continue?”. On the dialog please click Yes, and the certificate will appear in the Signatures panel.

Validate Existing Digital Signatures Attached to the Document
Note: Only applicable to cryptographic signatures

If the opened PDF has a digital cryptographic signature, Able2Extract will automatically validate the signature and display the validation status in the document’s tab beside the title of the document.

You may see a green, orange or red padlock icon right in front of the document title in the tab. The color of the sign gives basic information about the validity of the signature:

• Green: The signature is valid.
• Orange: The signature is valid, but there are some minor problems.
• Red: The signature is invalid.

If there is no padlock icon, then there is no cryptographic signature found in the document.

A digital cryptographic signature becomes invalid once the content of a signed document has been changed or modified. The digital certificate that was used to sign the document, itself, however, still remains valid. A digital certificate is an encryption key that is used to create the cryptographic signature which is used to authenticate a document; it is not affected by changes made to the document’s content.

In the Digital Signatures Panel, you will see all the digital signatures that are presently attached to the document under the Existing Digital Signatures section. The name of the PDF signer and the date the PDF was signed will be visible. To view more information, simply click on it to expand the certificate’s details.

This article refers to Able2Extract Professional.