Digital signature – u:sign

With u:sign, employees of the University of Vienna can legally sign PDF documents (such as agreements, contracts, records) online using the Handy-Signatur (mobile phone signature).

u:sign is based on the product e-Tresor of A-Trust GmbH.

 Direct Link


Activating the mobile phone signature

In order to use u:sign, you need an active Handy-Signatur (mobile phone signature). It consists of your phone number and a signature password, which you define yourself when activating the signature. The mobile phone signature is legally equivalent to the handwritten signature.

For activating the mobile phone signature you need:

  • current place of residence in Austria
  • a mobile phone or a smartphone with an Austrian or German SIM card

The mobile phone signature is activated and operated by A-Trust GmbH. Please make use of the information provided on the website of A-Trust to receive your own mobile phone signature. The activation can take up to two weeks depending on the selected method.

Defining signature confirmation

Every digital signature in u:sign has to be confirmed using your mobile phone. You have two options for doing this:

  • Receive TAN via text message
  • Install a mobile phone signature app and select the type of confirmation yourself

Please use one of the following mobile phone signature apps:

  • Handy-Signatur App by A-Trust GmbH, available free of charge in Google Play or in the App Store
  • App Digitales Amt (digital office) by the Federal Ministry for Digital and Economic Affairs, available free of charge in Google Play or in the App Store

You have to activate the app after the download. You can find user guides on the A-Trust website (in German only).

Specify how you want to issue the confirmation in the app settings. Depending on the app and phone model, you can choose between QR Code, TAN, fingerprint or Face ID.

Activating the u:sign account

Employees of the University of Vienna can activate a u:sign account. It provides access to all functions of u:sign, as well as 5 GB of storage space.

  1. Log in to u:sign using your mobile phone signature.
  2. Click the button u:sign aktivieren (activate u:sign) in the top right corner.
  3. Accept the u:sign terms of use and confirm that you are aware of your rights as a data subject according to the General Data Protection Regulation (GDPR).
  4. You will be forwarded to the weblogin of the University of Vienna. Enter your u:account login details to log in as an employee of the University of Vienna.
  5. A pop-up window will immediately indicate whether the activation was successful or not. 

If the u:sign account was not activated successfully, you can submit a support request.

After termination of your employment, your u:sign account will be deactivated and then deleted after a period of several months. You can find further information in the u:sign terms of use (in German).


Use u:sign exclusively for signing documents and not as data storage or as a filing system. Documents saved in u:sign are not stored on servers of the ZID (Vienna University Computer Center). In case of data loss, they cannot be recovered by the ZID. Download successfully signed documents and store them using a ZID service designed for data storage (e.g. online storage space, share drive) or locally on your own computer.

Signing documents

  1. Log in to u:sign using your mobile phone signature.
  2. Click Einfache Unterschrift (single signature).  
  3. Upload the PDF file that you want to sign: maximum file size 30 MB, portrait format only, no landscape format possible.
  4. Place the signature block in the desired spot. Confirm by clicking the check mark.
  5. Enter your mobile phone signature and click Identifizieren (identify).
  6. Switch to the mobile phone signature app on your smartphone and confirm the signature. If you are not using an app, check your text messages and enter the TAN you received.
  7. Switch back to u:sign. The signed document will be displayed in the inbox.

You can perform further actions using the menu bar.

If necessary, consult the user guide Einfache Unterschrift (single signature, in German).


A PDF file that was signed using the mobile phone signature can no longer be:

  • modified;
  • signed using Adobe Acrobat.

Use signature folder

With the u:sign signature folder in u:sign you can:

  • Sign multiple documents at the same time (User guides)
  • Plan a signature circulation with multiple people (User guides)
  • Bundle signatures to send them with attachments that don't need a signature (User guides)

Generally follow these steps:

  1. Log in with your phone signature ("Handy-Signatur) in u:sign.
  2. Click the folder you want the document(s) saved in.
  3. Click the button Upload documents to import the document(s) in u:sign (portrait format only, no landscape format possible).
  4. Activate the checkbox(es) and click the signature folder icon to put the document(s) in the signature folder.
  5. For every document you can specify who can sign or check it in the signature settings.
  6. Select all required documents in the signature folder.
  7. Click Bring selected documents into circulation. If you don't sign by yourself, the process is now finished.
  8. If you are also signing one or multiple document(s), click Start signature process in the next window.
  9. Type in your phone signature ("Handy-Signatur") and click Identify.
  10. Confirm the signature with your phone. Depending on the selected settings you have to follow different steps. Confirm the signature with your phone.
  11. Go back to u:sign. The bar in the signature folder shows the status of the document(s).

Every signer or checker will be notified via e-mail and asked for signature or approval.

Verifying signatures

You can verify who has signed a digitally signed document, whether the content has been modified or whether the signature and the attached certificate are valid:

  1. Go to the website
  2. Click Datei auswählen (select file) and select a locally saved file.
  3. Then, click Prüfen (verify).

Screenshot Signatur prüfen

After a short moment, the verification report will be displayed. A signature is valid if all verifications in the columns S (signature value) and Z (certificate) were completed with an OK highlighted in green.

If one or more verifications are completed with an error message, the ZID recommends repeating the entire signature run. If an error message is then displayed again, send the document by email to The document is then checked manually.

Screenshot Prüfbericht


If you only have the document in printed form, you cannot verify the validity of the signature.

Terms of use

If you use the u:sign service, you have to comply with the u:sign terms of use (Benutzungsordnung, PDF, in German).