Complete guide to managing your digital certificate on your mobile phone

Using your mobile phone to carry out administrative procedures is no longer science fiction: with a digital certificate correctly installed on the phone You can identify yourself, sign documents, and access public and private services without touching your computer. That said, the theory sounds great… but in practice, a thousand questions arise: types of certificates, steps involved, where they're stored on Android or iOS, what to do if you already have one on your PC, etc.

In this guide you will find a Detailed, step-by-step explanation of how to manage your digital certificate on your mobile phoneFrom the initial download with the FNMT app, the different ways to verify your identity (video, electronic ID card or in person), to installation, copying, importing, using it to sign documents and secure deletion on both Android and... iPhone.

What is a digital certificate on a mobile phone and what is it used for?

A digital certificate is, basically, a electronic document that links your real identity to a cryptographic keyIt would be the digital equivalent of your ID card or driver's license, but in file format (.pfx, .p12, .cer, .crt). When you install it on your mobile phone, the system and the apps Compatible users can use it to verify that you are you.

Several types of certificates coexist on the phone: on the one hand, there are the system certificates (or root and trusted certificates)which come pre-installed to enable secure connections, apps, and services Googleetc.; on the other hand, there are the certificates that you install manually, for example, the Citizen certificate issued by the FNMT to access the Tax Office, Social Security, DGT (Spanish Traffic Authority) or "My Citizen Folder". There may also be specific variations, such as the consumer certificates on Android that manage permissions and trust in some apps and networks.

Thanks to this certificate you will be able to to identify yourself to public bodies and some private entities, submit declarations, download reports, consult files, manage fines or even connect to certain high-security Wi-Fi networks (universities, companies, administrations) that require a certificate to authorize access.

In addition to identification, the certificate allows you Sign electronic documents directly from your mobile phoneThis simplifies processes that previously required a computer, card reader, and specific software. With the official FNMT Digital Certificate app, for example, you can select a PDF and apply the signature with a few touches.

How to obtain the FNMT digital certificate on your mobile phone

The FNMT allows you to request the Certificate software for individuals directly from your mobile device with its official app "FNMT Digital Certificate", available for free on Android and iOS. The process is divided into four main steps that must be followed in order: download the app, request the certificate, verify your identity, and finally, download and install the certificate.

Before starting, it is important to be clear that You can only have one active individual certificate per citizen.If you already have one issued by the FNMT and request another through the app, the previous one will be automatically revoked, although you can always install the new one on your PC or other devices using the backup.

1. Download the FNMT Digital Certificate app

The first step is to install the official application from your device's store: Google Play on Android or App Store on iPhoneSearch for "FNMT Digital Certificate" and download the app from the official developer of the National Mint and Stamp Factory.

Once installed, the app will become the Gateway to request, download, install, share, and sign with your digital certificateFrom there you will manage the entire process without needing to use your mobile browser.

2. Requesting the certificate from your mobile phone

Open the app and choose the option "Request a Digital Certificate"Depending on your situation, you can select three main methods to verify your identity: video payment identification, reading the electronic ID card chip with NFC, or in-person application.

In all cases you will have to provide your basic personal details (ID or NIE, first surname and a valid email address). You will receive an email to confirm that the email address is yours, usually with a link or code that you will need to enter in the app.

3. Verify your identity: video, electronic ID card (DNIe) or in person

In order for the FNMT to issue the certificate, it is mandatory that Verify your identity through a secure channelThe app offers three different ways to do this, covering virtually any case.

Video identification (at a cost)

The video identification option is the most convenient because You don't have to go to any officeAfter filling in your details in the app and confirming your email, select "Video Identification €2,99 plus VAT" and follow the steps.

The app will ask you to enter your mobile number to Receive an SMS with a verification code Then, you'll need to complete a guided process using the camera: show your face, focus on your ID, scan the document, etc. Everything is done from your phone.

Once the video is uploaded, it will take approximately They process the request and review the recording within 48 business hours.If everything is correct, you will receive an email indicating that your identity has been verified and that you can now proceed to download the certificate.

Reading the electronic ID card with NFC

If your mobile phone has NFC and you have saved the PIN for your electronic ID card, the app allows you to read directly from the chip of the electronic ID card to verify your identity, without video call or prior appointment.

The steps are simple: choose "DNIe Reading," accept the terms and conditions, enter your email address, and confirm the email with the code they send you. Then the app will ask you to Please verify the address shown on your ID card. and that you enter the CAN (the number that appears in the lower right corner of the document).

Then you will have to write the The PIN for the electronic ID card (DNIe) is given in a sealed envelope when you renew it. or the new one you got at the police station. To read the chip, place the ID card on a flat surface, with the chip facing up, and place the upper back of your mobile phone directly on top; press "Read DNIe" and wait for the reading to finish.

When the process is completed successfully, the app itself will allow you download, install the certificate on your mobile device and even share it with other devices, for which you will need the password you define when generating it.

In-person application at an office

If you prefer the traditional method, you can use the app only to generate the request and complete the accreditation at a registration office (Tax Agency, Social Security, or other collaborating offices). Many of them require an appointment, so it's best to check beforehand.

In the app, select "In-person application," accept the terms, enter your ID or NIE number, surname, and email address. You will receive an email with the subject "Request for a citizen certificate through the FNMT Mobile App", where you will have to press "Confirm email address".

Once confirmed, the application will show you a QR code that the office will use to locate your application and verify your identityFrom the app itself you can search for the nearest accreditation office, go on the day of the appointment and complete the in-person identification.

4. Download and install the certificate from the app

After verifying your identity using any of the three methods, it's time for the Download the digital certificate to your mobile phoneYou can do this from the link sent to you in the confirmation email or by accessing the "View requested certificates" section within the app.

If you used video identification, before downloading you will need to Enter your billing information and pay for the serviceNext, you will set a password to protect the certificate file; write it down or memorize it well because you will need it to install it on other devices.

The app will save a copy of the certificate, usually in the the phone's "Downloads" folder, protected with the password you setFrom there you can send it by email, upload it to the cloud, or move it to another device if you want to install it on a PC or another mobile device.

Install an existing digital certificate on your mobile device

Many people already have the FNMT certificate installed on their computer and what they want is Carry it on your mobile phone too, without ordering a new one.In this case, the first step is to export a valid copy of the certificate from the browser or the PC's certificate store.

En WindowsFor example, you can go to Control Panel > Internet Options > Content > Certificates > "Personal" tabSelect the certificate and use the "Export" option. In the wizard, choose "Export the private key," and select the format. exchange of personal information (.PFX or .P12)Set an export password and save the file to your computer.

Once you have the backup, you will be able to Transfer the file to your phone via cable, Bluetooth, messaging apps, email, or cloud services such as Google Drive or iCloud, and from there follow the installation process on Android or iOS.

Please note that if you request a new certificate from the FNMT mobile app, The previous certificate will be automatically revokedYou can only have one valid personal account at a time, but you can use that same account on multiple devices as long as you keep the copy and the password.

Manage digital certificates on Android

Android includes a credential store where all installed certificates are storedThis includes both system certificates and user-added certificates. From the settings, you can view, import, use, and delete certificates, although the exact path varies slightly depending on the version and manufacturer's layer.

View the certificates installed on Android

In Android 7 and later, to check user certificates you have to go to the Device settings and enter the security sectionDepending on the model, the route may be called "Security", "Security and Privacy" or "Biometric Data and Security".

Once inside, look for options like "Lock screen and security", "Other security settings" or directly “Encryption and credentials”Inside you will find the section "User certificates" or "User credentials", where you will see the list of installed certificates and, on many devices, data such as the NIF and the name and surname.

If you get lost among the menus, you can use the search settings by typing "certificates" or "credentials"It almost always takes you directly to the correct section. However, the exact text may vary slightly depending on the brand.

In Android 6 or earlier versions things get more complicated: It is not always possible to view the list of user certificates from the settingsIn these cases, the only way to check which certificates are installed is to access a procedure that requires a certificate (for example, on the AEAT website). When you open the procedure, the system will display the store with the available certificates so you can choose one.

Root and Trust Certificates in Android

In addition to user certificates, Android maintains a set of root and trusted certificates that They allow you to verify the security of websites, VPN and appsThese are not the ones you use to identify yourself, but the ones the system uses to verify that it trusts the issuing entities.

According to the Android version, the path to view these root certificates It's slightly different, although it's usually also in the "Security" section:

On Android 9, you will usually have to go into "Settings > Biometrics and security > Other security settings > View security certificates"In Android 8 the option is usually called "Security and privacy > Trusted credentials", while in Android 7 and 6 it appears as "Screen lock and security > Trusted credentials" or "Security > Trusted credentials".

Inside you will see two main tabs: in The certificates that come pre-installed appear under "System". by the manufacturer or Google, and in "User" those that you have added manually (for example, CA certificates for corporate Wi-Fi networks or VPN).

Install a digital certificate on Android from a file

Once you have the certificate file on your mobile device, the installation process is quite straightforward. Ideally, the file should have the .cert extension. .pfx or .p12 and that it comes password protected, whether you exported it from your PC or downloaded it from the FNMT website or app.

The steps may vary depending on the brand, but on most devices you simply need to go to Settings > Security (or Security and Privacy) > Encryption and CredentialsThere you will find options such as "Install a certificate", "Install from storage" or "Install certificates from phone memory".

By choosing that option, the system will allow you explore the storage internal storage, the SD card, or even file providers like Google Drive To locate the certificate, select the file, enter the password for the copy when prompted, and click OK to continue.

Then you will have to give a Identifying name for the certificate (avoid spaces if the system complains) and select its intended use: "VPN and apps," "User," or "Wi-Fi," depending on the type. For the citizen certificate you'll use with the government, it's common to choose the user or VPN and apps category.

Import the certificate from your email or any other location

If you have sent yourself the certificate by email, you can Open the email from your mobile browser (Chrome, Edge, Firefox) and download the .PFX or .P12 attachmentIn many cases, simply touching the file launches the Android installation wizard.

Your browser may ask for permission to Download files and have Android ask you which app you want to open them with.In that case, select "Certificate Installer" or "Credential Installer." Then enter the backup password, choose the certificate type (usually "VPN and Application User Certificate"), and change the name if desired.

If the file is on an SD card, in the folder of downloads Or, on another route, go to Settings > Passwords and Security > Privacy > Encryption and Credentials > Install Certificates from SD (or a similar path) and look for the certificate. Once imported, it often disappears from the SD card or the list to prevent duplicates.

In all cases, Android will require you to have configured a locking method (PIN, pattern, fingerprint)If you don't already have it, you will be required to create it before completing the certificate installation for security reasons.

Install Wi-Fi certificates and use with WPA-Enterprise

Some workplaces, universities, and public bodies use Wi-Fi networks with WPA/WPA2/WPA3-Enterprise securitywhich require a certificate to validate access. Android allows you to install a specific Wi-Fi certificate for these connections.

From Settings, go to "Security and privacy > More security settings > Encryption and credentials" and choose the option to "Install a certificate > Wi-Fi certificate"Locate the file, enter the password if necessary, give it a name, and click OK.

Next, go to "Network & Internet > Internet > Add Network" and configure the Enterprise network with the information provided by your network administrator (EAP type, identity, CA certificate, user certificate, etc.). If any information is missing, You might not be able to connect properlyTherefore, it is important to have all the information.

Note that, for security reasons, Android 11 removed the option to "Do not validate" the server certificate in EAP-PEAP, EAP-TLS, and EAP-TTLS configurations. New networks can no longer be created with that insecure configuration, although existing saved networks can continue to function until you edit or recreate them.

Removing certificates on Android and precautions

At some point, you may no longer need a certificate or you may want to delete it for security reasons. To do this, return to Settings > Security > Encryption & Credentials and go to "Credential Storage".

From there you can enter "User credentials" to remove specific certificates (by selecting one and choosing delete) or use the "Delete credentials" option to clear all user certificates at once. This latter option does not affect permanent system certificates, although it may cause some Wi-Fi or other services that used those certificates to stop working.

It's important not to lightly delete system certificates or tinker with advanced options you're unfamiliar with, because You could cause connection problems or lose trust in legitimate websites and services.Limit yourself to user certificates that you have installed yourself.

Common problems and recommended browsers

When installing or using certificates on Android, errors such as the following may appear: "unrecognized certificate", warning screens or connection failures. If the message appears "The connection is not private."The problem sometimes lies in expired root certificates or the device date, and the solutions may vary depending on the source.

In general, the browser that usually gives the least trouble is Google Chromebecause it integrates very well with the Android certificate storeOther browsers may manage certificates differently, or even maintain their own store, which can sometimes lead to confusion. If you need a more technical guide on how the process works, you can consult how manage digital certificates in different web browsers.

If the errors are related to the connection to the server (for example, on a website of a public body), the most sensible thing to do is contact the technical support of the organization itself to check if there's a problem on your end. If you suspect the issue is with the certificate, removing and reinstalling it, carefully following all the steps, may help.

Install and manage digital certificates on iPhone (iOS)

In iOS, the system handles certificates through the configuration profilesAlthough the process has a few extra steps compared to Android, it is still perfectly manageable if you have the correct file (.pfx, .p12, .cer or .crt) and know the certificate password.

These certificates allow access to official apps such as My DGT or My Citizen Folderas well as government services that require an extra level of security. Without the certificate, in many of these cases a username and password, or even two-factor authentication, will not be enough; in these scenarios you can also consider other access options and consult the ways to get Cl@ve game as an alternative.

Steps to install a digital certificate on iOS

It is usual to download the certificate to your computer first (Mac or PC) and then send it to your iPhone. On a Mac, you'll almost always find it in the "Downloads" folder or the location you chose when you downloaded itIf you can't find it, you can use Finder and the "Go > Downloads" menu.

Then you will have to send the file to the iPhone via iCloud, email, or messaging apps (WhatsApp(Telegram, etc.). The method doesn't really matter as long as the file arrives intact on the device and you can open it with the "Files" app.

On your iPhone, open the app "Files" and locate the digital certificate in the folder or cloud service where you saved it. Tap it to open it; the system will detect that it's a profile or certificate and ask if you want to install it on the device.

Choose your iPhone as the destination and follow the setup wizard. You will need to Enter the iPhone passcode and, if the file is protected, the certificate password.After completing this first step, the profile will be "downloaded" but not fully active.

To activate it, go to Settings > Top of screenThere you'll see a message that says "Profile downloaded." Open it, tap "Install," re-enter your passcode, and confirm. Once completed, the certificate will be installed as a profile in the general settings options, at the bottom of the menu.

Sign documents and use the digital certificate from your mobile phone

With the certificate installed, you will be able to both Android and iPhone to carry out administrative procedures, access electronic offices and sign documents without needing a computer. The FNMT Digital Certificate app greatly simplifies the signing process.

To sign a document from the FNMT app, open the application and choose the option "Sign documents" or similarYou will usually be able to select a file from your mobile storage (for example, a PDF you have in Downloads or in a connected cloud).

Once you have selected the document, the app will ask you to choose the certificate you want to sign withChoose your citizen certificate and confirm the operation; the application will generate the electronic signature and, at the end, you can save the signed document or share it directly by email, administration platforms or messaging.

In addition to the signature, many official websites and applications automatically detect if you have it. a valid certificate in the system storeIf you encounter problems identifying yourself in procedures, it may be helpful to review the Problems accessing the electronic headquarters and its solutions.

Security and best practices with the digital certificate on your mobile phone

Since it is a tool that allows you to act on your behalf before government agenciesIt's advisable to take extra precautions. Having the certificate on your mobile phone is safe as long as you take basic security measures.

The first thing is to make sure that your device It always has an active locking method (PIN, pattern, fingerprint, or facial recognition) and that no one else knows it. It's also highly recommended that you keep your operating system updated and only install apps from official stores.

Try never to share the certificate copy password Do not forward the file through insecure channels. If you send the certificate to another device, always do so encrypted (for example, via email, but password protected) and delete any copies you no longer need.

It is advisable to maintain a back up the certificate in a secure location (For example, on an encrypted external drive or in a well-protected cloud). This way, if you change phones or lose yours, you can reinstall the certificate without having to repeat the entire application and accreditation process.

When you see that the certificate is approaching its expiration date or if you detect suspicious use, it's a good idea Check its status on the FNMT website or contact the issuing entityFrom the "Check status" section of the FNMT you can check the validity or even proceed with the revocation if you consider it necessary.

Managing your digital certificate on your mobile phone is no longer a headache; it's become a very practical tool for your daily life: You'll be able to manage your affairs with the administration, connect to secure networks, and sign documents from anywhere.as long as you keep your file, password, and device security under control.