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The digital signature explained

Gloria Dzida
Updated on 17.03.2023

What is a digital signature?

A digital signature is a method of signing digital documents and verifying the signature of a document. This allows the authenticity of the electronic document to be established. A digital signature works like a human fingerprint in that each document has its own unique electronic fingerprint. No other document can have the same digital signature. If a digital document is "sealed" with a signature, then it can be proven that

  • the file has not been changed after it has been signed (integrity).
  • a specific person has signed the document (authentication).
  • the person signing the document really did sign it. The person cannot deny having signed the document after a digital signature has been created.
  • the document that is present is not a forgery.

Digital signatures are now widely used in business and the financial industry, for example, to authorize bank payments (money transfer), exchange signed electronic documents, sign digital contracts, and in many other scenarios.

Advantages of digitally signed documents

Have you ever lost important documents or can't find where you filed your contracts? Put an end to the tedious administrative work! Rely on a modern and reliable electronic signature solution with an integrated archiving system. Digital signatures and storage eliminate the risk of physical documents being lost or damaged. Invest in the future and optimize your document management!

In summary, digital signatures:

  • Save valuable time
  • Save costs
  • Improve the user experience for your customers
  • Improve the security of document signatures
  • Secure the future viability of your business

What is the difference between an electronic signature and a digital signature?

It is very easy to confuse the terms "electronic signature" and "digital signature". Often, the terms are used interchangeably, but when looked at closely, they are not the same thing.

The electronic signature

The electronic signature (or e-signature) is a modern alternative to the handwritten signature in the analog world. It enables efficient, verifiable and legally binding approval of electronic documents. Similar to a handwritten signature, an electronic signature confirms a person's intention to approve a document or accept the terms of a document. Thus, electronic signature is a legal term and encompasses several categories.

An electronic signature is a method of entering into a legal agreement in a digital environment. It is, so to speak, the digital equivalent of signing a paper document, such as a sales contract. A person signing an agreement creates an electronic signature when they sign an electronic document by clicking a button or drawing their signature with a mouse, touchpad, or other input device.

An electronic signature is defined in the eIDAS Regulation as "data in electronic form that is attached to or logically associated with other data in electronic form and used by the signer to sign."

There are several methods to express agreements, consents and acknowledgements in a digital environment, including:

  • Clicking a button to agree to text on the screen, such as terms and conditions.
  • Clicking and/or drawing your signature to sign an electronic document
  • Making an audio or video recording of a verbal confirmation
  • Authenticating your identity using an electronic identification device (eID).

Not all of these methods are considered electronic signatures, and which method to use depends on the situation. Because the legal implications of these methods can vary widely, factors such as implementation cost, ease of use (customer experience), legislation, company policy, and assessed business risk usually determine which method to use in a given situation.

Even in the electronic signature category, there are different levels, and which level is appropriate for a given situation depends on the same factors mentioned above.

The digital signature

A digital signature is an electronic signature based on asymmetric cryptographic algorithms. It can only be created with a private key, but anyone can verify it with the public key.

Due to cryptographic technology, digital signature provides a higher level of security and integrity of the document compared to electronic signature. For example, an e-signature can also be simply an image of the signature or a simple email signature.

Digital signatures are also used to approve and validate documents in electronic form. However, they use complex cryptographic mechanisms to authenticate digital documents, confirm the identity of signers, and protect data from tampering and corruption during transmission.

Digital signatures are equipped with back-end tools that ensure that only an authorized person can sign a document and which prevent changes after signing. A digital signature is generated with a unique digital ID called a "digital certificate" or "public-key certificate".

The differences in a nutshell

While an electronic signature proves the approval of the document's signer, a digital signature is proof of the authenticity of the document itself. The two work together and are required to make a digital agreement verifiable and legally enforceable.

Important: A digital signature is always an electronic signature, while an electronic signature is not always a digital signature!

e-Signature standards: Forms of electronic signature

Basically, a distinction is made between three types of electronic signature, which are defined by the eIDAS Regulation and serve as the legal framework.

  • Simple electronic signature (SES)
  • Advanced electronic signature (AES)
  • Qualified electronic signature (QES)

The qualified electronic signature (QES) meets the highest quality criteria and is legally 100% equivalent to the handwritten signature.

There are numerous application areas for digital signatures that span various industries. The switch to electronic signatures by means of a software solution is a worthwhile investment for almost every company, which achieves a measurable effect on efficiency and cost reduction.

QES, AES, SES: Overview of all eSignature-Standards

There are different types of digital signatures and a specific signature standard must be selected depending on the use case and requirements. The legal basis for this in the EU is the eIDAS Regulation, which defines requirements for the individual forms. The three most important signature standards and their various properties are explained in this article.
Read more

Digital vs. scanned

The word "scanned signature" reveals that it is a digital image of a handwritten signature. This is obtained by converting one's signature, which exists on paper, into a digital format (.jpg, .doc, .pdf, etc.) using a scanner or camera.

In principle, scanned signatures are valid unless a written form is required for the declaration of intent.

However, a scanned signature is not legally valid because the signer cannot be identified and consent cannot be proven.

A scanned signature carries a high risk of forgery. Since any recipient of the signed contract can easily copy your scanned signature (#SnippingTool #Screenshot). It is obvious that this is not legal.

A scanned signature has no probative value in court, as it is just a copy of your original signature. Without proof of how the signature was created, it is considered a mere copy and not an authentic signature. For this reason, it is not valid for contract processes, especially in companies.

With an electronic signature solution, legally binding and provable contracts can be concluded quickly, easily and without complications.


  • No printer or scanner required
  • End-to-end electronic process
  • AES and QES are eIDAS-compliant and provable
  • QES for documents that require the written form
  • Can be integrated into existing systems
  • No media discontinuity - everything completely digital

Evidential value and legal validity

Legal validity

A legally binding contract is concluded when both parties reconcile their declarations of intent. The legislator gives the contracting parties the freedom to decide for themselves whether they wish to conclude an agreement orally, in writing on paper or electronically.

However, there is a written form requirement for some documents. In this case, the declaration of intent must either be signed by hand on paper or provided with a qualified electronic signature (QES). A scanned signature is not valid.

However, for documents without a written form requirement, a scanned signature can be legally valid, but in this case the provability may be questioned.

Evidential value

Facts and evidence can be used to prove something, and a fact can be proven. A scanned signature or simple electronic signature has no probative value because the person signing cannot be clearly identified.

With the advanced electronic signature (AES), the probative value is high because identification of the person signing can be established by cell phone number or e-mail address.

The qualified electronic signature (QES) has the highest possible probative value, since the person must identify himself with a verified eID or perform a video identification once. In addition, the cell phone number is required for 2-factor authentication .

Signing contracts legally online (and having them signed) - what you need to know

Tedious contract processes are a thing of the past - but how does it work to sign contracts easily and securely online? In this article, you will learn how contracts are signed online or how signatures can be obtained on the web.