Qualified electronic signature (QES)

What is a qualified electronic signature?

The qualified electronic signature (QES) meets the highest security standards of all three types of electronic signatures. It is the digital equivalent of a handwritten signature and is the only electronic signature that can be compared with a conventional signature.

In addition to the requirements for an advanced electronic signature, it is generated by a qualified signature creation device (QSCD) and is based on a qualified certificate for electronic signatures. The issuance of qualified certificates for electronic signatures is the responsibility of certain trust service providers.

These enhanced security standards mean that it offers the strongest legal protection. Under EU and British law, the qualified electronic signature has the same legal force as a classic signature.

Technical implementation of the qualified electronic signature

Qualified electronic signatures are generated using the same procedure as advanced qualified signatures. A Public Key Infrastructure (PKI) is used to generate a private and a public key. The signer holds the private key and the public key is used to verify the authenticity and integrity of the signature.

The main difference in the qualified electronic signature is the qualified certificate used. This must be issued by a qualified trust service provider (QTSP). Only certain service providers are registered for this, and the eIDAS Regulation defines precisely the underlying criteria. The signature itself must be generated using a qualified signature creation device (QSCD). This qualified signature creation device is usually a specialized software and hardware device over which the signer has control, such as a USB device or card reader. It can also be used as a software-only solution.

In addition, a qualified electronic signature requires prior verification of the signer. This is usually done by a face-to-face meeting or a video call before he or she can then sign his or her first document. Subsequently, multi-factor authentication is performed for each signature.

What is meant by trust service provider?

The qualified trust service provider (QTSP) is the basis for implementing the qualified signature. The trust service provider must meet strict criteria precisely defined by the relevant authorities. If these criteria are met, the provider is added to a list of trust service providers.

When do I use the qualified electronic signature?

The qualified electronic signature offers the highest level of security and the strongest legal effect. However, it is also the most difficult and expensive technology to use. The effort required to authenticate the signer and multi-factor authentication can also make it cumbersome and unusable for simple applications. Therefore, this type of electronic signature is used especially for documents and contracts of great value, such as large business contracts or real estate transactions.

The legislator requires the so-called written form for some documents. This can only be fulfilled by a handwritten signature on paper or a qualified electronic signature. Although the qualified electronic signature is virtually equivalent to the handwritten signature on paper, there are documents for which the legislator requires a paper copy, such as contracts to be notarized or the termination of an employment relationship.

What type of electronic signature should I use?

The type of electronic signature you should use depends on your workflow and individual requirements, but most users want to strike a balance between ease of use and legal enforceability. With this in mind, we recommend using the simple or advanced electronic signature if you want to sign documents.