AdvisorSigning documents

What is an electronic signature, what are the differences and how do I sign electronically on a document?

Today, our daily life takes place in the digital world – we buy clothes online as well as groceries, do banking transactions with our smartphones and also conclude contracts online. However, we often sign contracts still on paper to complete a transaction. The implementation of electronic signatures in the process can prevent this media discontinuity. This guide explains the different types of electronic signatures and how to digitally sign a PDF document.

Advantages of electronically signed PDFs


You can sign and exchange documents much faster.


With an electronically signed document you can ensure who signed it and that nothing has been changed within the document after signing it.


Nowadays, your customers expect a full-digital process. With using electronic signatures, you can ensure this until the conclusion of a contract.

Electronic signature options for PDFs

The PDF document format already offers the option of electronic signatures. Due to the high acceptance of this format, it is suitable for digitally signing documents and contracts.

To sign PDFs electronically, it is possible either to integrate the signature as part of a process in which a PDF is created and signed, or to use signature platforms. They allow any type of PDF upload and electronic signing after identification of the signatory.


This guide focuses on signature portals to provide an easy introduction to the topic. A selection of our partners who offer portals, you can find in our Partner overview:

  1. You choose a signature portal and create a user account.
  2. To be able to sign, you have to identify yourself first to make sure that you are the person you claim to be. Your signature portal provide will guide you through the identification process.
  3. Now, you can upload your desired document to the portal.
  4. Then, you have to select who needs to sign the document. If you select several signatories, they will get a signing invitation through the portal.
  5. Now it’s time to sign. Normally, you can add an optical representation to the document.
  6. You have to confirm the signature with a 2-factor authentication, e.g. installed on your phone . This ensures who is actually signing.
  7. The document has been signed and you download and process it further.


To create an electronic signature, a hash value (compressed value) is generated from the document to be signed according to a specific algorithm. In the next step, a key pair with two keys (one of which is public, the other private) is generated by another algorithm and the signature is then created. Both the hash signed with the private key and the public key are “stapled” to the document and both can be sent with it. The trust service provider ensures that a certain public key belongs to a person (so-called “certificate”, which is located in the document). The recipient has the possibility to check the authenticity of the signature by means of the public key in the attached certificate. If, for example, the source document were to be changed, the hash value would also change – the public key would no longer be able to decrypt the document.

Swisscom Trust Services offers a triangle of electronic signature, ID and key. The ID is the digital identity that is to be uniquely identified. The key is the security tool with which the expression of will is carried out (such as the smartphone) and the signature is finally the triggering of this expression of will.

Suitable devices

Electronic signing works on the desktop as well as on mobile devices. Since web services are used in the background, the signature can basically be used on all end devices that are web-enabled, from PCs to smartphones. To ensure that the signer is really the person they claim to be, a mobile phone is usually used as a second factor (2FA). For example, the signature application runs on the desktop or in the browser and must be confirmed via mobile or app.

Types of documents

The electronic signature at the qualified level is by law equivalent to the handwritten signature. Therefore, almost everything that is signed with a pen can also be transferred to the digital world and signed with an electronic signature. Here is a selection of documents that are signed today:


  • Order forms/Offers
  • Contract renewals
  • Cooperation agreements
  • NDAs
  • Business partner agreements
  • Support agreements
  • Framework agreements
  • Offer confirmations
  • Termination letters

Natural persons

  • Employment contracts
  • Insurance policies or contracts
  • General agreements
  • Bank account openings
  • Onboarding
  • Adjustments of conditions
  • Rental contracts

Digital ID

If a user is in a process for an electronic contract conclusion, he*she hast to get identified. To do so, the signature portal provider checks whether the user has already been identified for the required signature level (qualified or advanced). An interface to a trust service provides the information of the identification and registration status. If the user is already a identified, the electronic signature is triggered, otherwise the signature portal provider guides the user to a selection of various identification methods that are inetrgated in the signature solution. For instance, the user can use video identification for the identification to be able to sign electronically.

Integrating digital ID

As soon as the user’s identity has been confirmed, he or she can sign documents electronically. Swisscom Trust Services transmits a hash (compressed value) of the document. Important: the content of the document cannot be seen by the trust service provider. This hash is signed electronically, ensures that the signature is valid for this document and is then transmitted back to the signature portal provider. This process only takes seconds. The signature portal provider attaches the electornic signature to the document and presents the signed PDF in their front-end to the user. The signatory checks the documents and confirms it finally, using either a smartphone app or entering a password with receiving a SMS pin code. This authentication represents the offical expression of will in a digital way.

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