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How to Add Digital Signature in PDF

To ensure the security and legal importance of documents, several organizations and corporate industries are using digital signatures. It makes the PDF document identifiable and traceable precisely, which reduces the chances of fraudulence. Through this article, you can learn how to add digital signature in PDF in the easiest way. Moreover, you can discover a detailed explanation of digital signatures by giving a quick read. Also, we recommend cost-effective PDF editor - UPDF to add siganture in PDF.

Part 1: What is Digital Signature, and How Does it Work on PDF?

Digital signatures are the type of electronic signatures that are used to testify the legality or verification of a particular individual or organization. It uses a mathematical algorithm to ensure the transparency of digital content and transactions. The main purpose of digital signatures is to create a sense of trust between the consumers, business organizations, and stakeholders.

How Does it Work on PDF?

Digital signatures have widely opted in Western countries such as America, Europe, and the Gulf States as a legally binding system. It is also used in emails, online transactions, and digital communication to validate security and privacy. By reading the following points, you can fetch a clear idea about how digital signatures work on PDF.

  • Cryptographic Hash: When a user digitally signs a PDF, it forms a cryptographic hash. This cryptographic hash is encrypted through a mathematical algorithm. The receiver of the digitally signed PDF decrypts the hash through a Public key to check its authenticity.
  • Use of Public and Private Keys: Every digital sign includes two keys that are public and private keys. The public key is used by the receiver of a digitally signed document to check its validity, whereas the private key is kept confidential by the sender to sign the document.
  • PKI: PKI stands for Public Key Infrastructure, which are the sets of programs, software, individuals, and policies that work in the distribution of the public keys. They provide digital certificates to individuals or organizations to validate their identification.
  • Role of Digital Certificates: Digital Certificates are distributed by CA (Certified Authority) to the people or organizations as a driver’s license to own the certificate. This certificate includes the information of the public key of the organization along with its related information.

Part 2: What are Types of Digital Signatures?

Before jumping into how to add a digital signature in PDF, it's important to know the types of digital signatures. There are three types of digital signatures, as explained below:

Simple Digital Signature

The first category is a simple digital signature as it does not include the encryption process. The most common example of a simple digital signature is the email signature that the user adds at the end of the email. As this kind of digital signature is not encrypted, it cannot be used to identify or validate the authenticity of the owner.

Basic Digital Signature

The basic digital signature is very similar to the simple digital signature, but the difference lies in the basic signature is that it can show the differences in the document after the signing process. A basic digital signature does not include two-factor authentication and cannot ensure the complete authenticity of the identity of the sender.

Advanced and Qualified Digital Signature

As the name indicates, this kind of signature is advanced, which ensures complete security and verification of one's identity. It uses an asymmetric cryptography method and PKI to enhance its level of encryption. It also includes two-factor authentication to provide the individual or organization enhanced security to scan the document for verification purposes.

Part 3. How to Add Signature in PDF with UPDF

UPDF is an easy-to-use PDF tool that also allows you to create signatures in PDF files. If you just want to insert your signature in a PDF file, you can use UPDF to do this. Here are the steps below.

Step 1. Open your PDF file with UPDF by clicking the "Open File" button or dragging and dropping the file into the UPDF window.

open file in updf

Step 2. Select the "Signature" option under the "Annotate" tab, and then click the "Create Signature" button.

Step 3. After that, you can draw your signature easily. Here are three options you can choose to create signature, including keyboard, mouse, and trackpad. You can select one of them to add a signature in your PDF file.

add signature in PDF

Video Tutorial on How to Sign PDF on Mac

Part 4: How to Add Digital Signature in PDF with Adobe

Adobe Acrobat is a popular tool to digitally sign PDF documents with a great level of comfort. This tool gives you the option to either type, draw, or upload a signature on your opened document. You can change the color and font styles according to your desire. Furthermore, you can add the initials of your name as a signature through Adobe to be unique. To add a digital signature to a PDF, read the following instructions carefully:

Step 1: After opening Adobe Acrobat on your system, select "My Computer" from the left panel. Through this, you can upload the PDF file on this tool that you want to digitally sign.

upload file adobe

Step 2: Once the PDF file gets uploaded, access the "Certificates" tool from the "Tool" tab. Now click on "Digital Sign" and then draw anywhere on your PDF to add the digital sign. You will then be asked to configure your digital ID. Proceed further by tapping on the "Configure Digital ID" button.

add digital singature in pdf with digital id

Step 3: Adobe will provide you with multiple options to configure your digital ID such as using a signature creation device, importing a digital ID from a file, or creating a new one. If you want to create a new digital ID, then select this option and tap on the "Continue" button.

Step 4: Now, select where you want to save your digital ID. You can save it as a file on your system or on "Microsoft Certificate Store." After that, tap on the "Continue" button and add all the required details for your digital ID. Move on by tapping on the "Continue" button and add a password to your digital ID to save it.

add digital signature to pdf

Step 5: Your digital ID will now appear on the screen, select it and tap on the "Continue" button. You will be asked to enter the password of your digital ID to sign the PDF. You can also customize the appearance of your sign. Now, tap on the "Sign" button, and your PDF file will be digitally signed.

add digital signature to pdf adobe

Part 5: How to Add Digital Signature in PDF with Foxit PDF

Have you ever used Foxit PDF to digitally sign PDF? This tool offers an advanced environment for the users to add a digital signature to PDF instantly. It gives you tons of options to add desired signatures to your PDF files. For instance, you can add files or import signatures to add them to your document.

You can also hand draw or paste from the clipboard to sign comfortably and can apply different colors. Moreover, users can opt for the simpler way to add a signature by typing it on this tool. To add a digital signature using Foxit on your PDF files, here are the steps.

Step 1: Open the tool Foxit PDF on your computer and click on the "Open" tab from the left-side panel and select the "Computer" option to import your PDF file.

open file with foxit

Step 2: After uploading the PDF file, choose "Protect" from the above toolbar. You have to proceed with the "Sign & Clarity" feature to create your digital ID or import it. Tap on this option and select the "Digital IDs" option.

 digital ID foxit

Step 3: Tap on the "Add ID" present on the top left side of the "Digital IDs" window. Now select one option from the available options on "Add Digital ID" window. If you go with "My existing digital ID from a file", you have to select the file location and enter its password to import it. If you go with "A new digital ID I want to create now", then you will have to select where you want to store the digital ID and add all the required information.

insert the digital id details foxit

Step 4: Now, you have to go back to the "Sign & Clarity" feature and select the "Place Signature" option. Draw anywhere on the PDF where you want to add your digital signature. After that, select your digital ID and add the password for that digital ID as well. You can also customize the reason, location, appearance type, or even lock the document after the sign. Now, tap on the "Sign" button to sign and save the signed document.

sign an clarity

Part 6: How to Add Digital Signature in PDF Online

Are you looking for an online tool to add a digital signature in PDF? DigiSigner is an online tool that promises to offer a secure and reliable platform to users. It is embedded with encrypted technology that keeps all your PDF files well-protected.

Moreover, it deletes the data from its server instantly once you download the file on your computer. You can use its 14-day free trial to use this tool without any cost to sign your documents professionally. Through the following steps, you can learn how to create a digital signature in PDF online:

Step 1: Access the free electronic signature tool of DigiSigner through your web browser. Tap on "Choose File" to upload the PDF file from your device.

Use digisigner to add digital signature

Step 2: Once done with uploading, click on anywhere on the PDF where you want to sign and then choose the type of signature you want to add. You can draw, type or upload the signature. Once done, click on "Sign" and apply the signature on any part.

how to sign in pdf

Step 3: Tap on "Done" and then click "Download Document" to save the file on your device.

how to digitally sign a pdf document


Digital signatures have a lot of advantages as it provides an ease in validating the identity of any individual or organization in digital communication. This article has shed light on how to insert a digital signature in PDF using online and offline tools. With our offered instructions, you can quickly digitally sign PDFs with reliability and ease. Besides of signing signature, UPDF has some advanced features like OCR feature in UPDF, add stamps and stickers for users to explore. Download UPDF today and enjoy your time with PDF files.