The electronic signature has become an indispensable tool to streamline processes and facilitate online transactions, and thanks to tools linked to it we can sign PDFs with a digital certificate on Mac, for example.
Digital certificate technology not only guarantees the authenticity and integrity of signed documents, but also provides an additional level of security and trust in the digital world, and that is why we have dedicated a post to it to show you the importance it has and how you must use it and protect it.
What is a digital certificate?
A digital certificate is an electronic document used to confirm the identity of an online entity, such as a person, organization, or website.
Let's say that it works as a kind of "digital identity card" and is issued after a Certification Authority (CA) or a trusted entity validates the identity of the applicant, such as the FNMT, and that will help you sign digital documents as if you were doing it with your own hand.
How to sign a PDF with a digital certificate on Mac?
Signing a PDF with a digital certificate on a Mac is a relatively simple process and you can do it using the “Preview” application installed in the operating system itself.
Get your digital certificate
Make sure you have your digital certificate correctly installed on your Mac, as in an analogous way to what we have indicated in another post similar to this one. This usually involves downloading the certificate and related files, as well as following the steps to install it.
Open the PDF with Preview
Double-click the PDF file you want to sign to open it in the “Preview” application. But if you have selected another PDF viewer like Adobe Acrobat, this app probably won't open for you. To fix this in case “Preview” is not the default app for opening PDF files on your Mac, you can right-click the PDF file, select “Open with,” and then choose “Preview.”
Access the signature function
Once the PDF is open in “Preview,” click the “Tools” menu in the menu bar at the top of the screen and select “Annotate” or “Show annotation toolbar”, depending on the version of macOS you are using.
This will open the annotation toolbar at the top of the PDF.
Add signature and insert it
In the annotation toolbar, you will find an icon with a signature. Click on that icon and select “Create signature from certificate” and you will then be asked to choose a valid digital certificate from your keychain.
After selecting your digital certificate, your signature will be automatically generated and added to the PDF page, leaving us to click and drag the signature to place it in the desired location within the PDF.
Once you have placed your signature on the PDF, make sure you save the changes, clicking “File” in the menu bar and selecting “Save” to save the PDF with your signature added.
Are there any Mac security tips I should keep in mind when using a Digital Certificate?
A digital certificate is something serious, why are we going to lie. Let's be honest, you wouldn't give anyone a checkbook or blank papers signed with your ID, right? Well, more or less that would mean that someone gets hold of your digital certificate, which is a serious problem.
But if you don't want to take risks, we invite you to follow our management advice on the digital certificate:
Keep your operating system up to date
Check keep your macOS operating system and all applications up to date with the latest versions and security patches, as regular updates fix vulnerabilities and improve system security.
This is the first great prevention measure that will help you with all types of potential security incidents with your Mac, and the digital certificate will be no exception.
Use strong passwords
Protect your Mac with a strong, unique password, avoiding using obvious or easy-to-guess passwords, and consider using a password manager to store and manage passwords securely. And related to this, it is important that you protect your digital certificate, saving a copy in a safe place protected with a strong password.
Of course, I don't think it goes without saying that you should avoid sharing your certificate or information related to it with unauthorized people.
Enable Security options on Mac
The built-in firewall in macOS can help protect your Mac against unauthorized network attacks, so It is important to have the firewall enabled and configured correctly in system preferences.
Furthermore, Seriously consider installing antivirus and antimalware software on your Mac to protect it against online threats such as viruses, malware, and phishing.
Encrypt your hard drive
Use FileVault, the disk encryption feature built into macOS, to encrypt the contents of your hard driveeither. This will protect your data in case your Mac is lost or stolen and among them, it will encrypt the digital certificate so that an unauthorized person cannot use it to do whatever they want with your signature.
Use a secure connection
When accessing sensitive websites or conducting online transactions, make sure you use a secure connection via HTTPS and avoid connecting to unsecured public Wi-Fi networks and consider using a VPN to protect your connection if you're traveling abroad, since you don't know who might be using that WiFi and for what purposes.
Manage app permissions
Check and manage the permissions of the applications installed on your Mac to control what data and resources they can access, limiting permissions to only the apps and services you really need.
What to do if my Digital Certificate has been stolen?
If you believe that your digital certificate has been stolen, you will have to act quickly to prevent it from being used maliciously.
Fortunately, the solution is relatively easy: contact the Certification Authority that issued your digital certificate and notify them that you believe it has been compromised, asking for its immediate revocation to prevent it from being used fraudulently.
In this way, the certificate you have will be deactivated and you will be able to issue a new one for future use.