IMPORTANT : To be able to sign from Android with the AOC Signature Holder, it is necessary to have a personal certificate on the device (type T-CAT P) .

Below you will find the steps to be able to sign the requests of the AOC Portasignatures from an Android.

1. Export your certificate to your Android device

First, you need to export the certificate file to your Android device in order to be able to install it or call it later from Portasignatures. To do this you will need the original installation file or, if you do not have it, you can create a new file by exporting it from a browser where you have it installed . The file will have the extension .p12 or .pfx.

Once you have the certificate file, follow these steps:

  • Send the file to a mailbox that you manage from your smartphone or tablet or upload it to Drive or another cloud service.
  • Save the file to a location on your Android device.

2. Install the certificate on your device

Important: This step is not essential, as it is possible to sign without having the certificate installed, just by having it saved in the device files or on the drive. If you prefer not to install the certificate, you can go directly to the next step.

To install the certificate, run the file with the extension .p12 or .pfx, which you have saved in a location on your device, by clicking on it.


The system will ask you for the password with which you protected the file when exporting. If it is a T-CAT P and the file is the original (not an export), the file password is the suspension code received in the download mail.



It will then ask you for a name for the certificate, we recommend that you enter a sufficiently identifying name.



Once the name is added, the system will notify you that it has been successfully installed.

3. Download the Viafirma app from Google Play

To be able to sign with the Portasignatures from an Android device, you need to download the Viafirma Mobile application from Google Play.


4. Sign in with your Android device

Once both the certificate (if you have decided to install it) and the Viafirma Mobile application are installed, if you are a Portasignatures user, you can access the tray from your mobile device by accessing https://portasignatures.aoc .cat/ in a browser or by clicking on the link you will receive in your email inbox when you have a pending request. If you only receive documents to sign as an external user in the tool, you will be able to access only from the link in the mail.


When accessing the AOC's Portasignatures either from the direct link or from the email link, you must click the button to access with certificate.


Once you click on "Enter with local certificate" you will be redirected to the Viafirma Mobile app.

You have two ways to authenticate:

  • Credential keychain: Refers to the certificate installed on the device.
  • P12 or Pfx format: With this option it would not be necessary to install the certificate, just have it among our files inside the Android device and we would have to indicate the installation code every time we use it.


Once the desired option has been selected, you will enter the tray of pending requests to be signed. Here you just have to choose the request you want to sign, review it and press "Signature with local certificate".


Then you will again have the option to choose between the installed certificate or the .p12 or .pfx file. Once the option is chosen and the pin is indicated, if applicable, the system will display a warning that the document has been signed correctly.