Electronic Signature: A Beginner's Guide

In today’s digital age, it’s getting easier and easier to get things done online. Signing documents is no exception. More and more business and administrative processes are moving into online environments, and the electronic signature is becoming an essential tool for ensuring the trustworthiness of documents. Are you one of those who are just getting started with e-signatures? We have prepared for you an overview of the basic information you should know about electronic signing, along with detailed instructions on how to sign a document with a qualified electronic signature.

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Electronic signature: What is it?

An electronic signature (also abbreviated as e-signature) is the digital equivalent of a traditional physical signature. Depending on its level, it makes it possible to verify the identity of the person signing the document and to ensure the integrity of the document being signed – i.e., to guarantee that the document has not been altered in transit from the sender to the recipient.

Physically signed documents can be amended or modified relatively easily. This is not possible with electronically signed documents. In fact, any change can be detected quite easily. It is this advantage of electronic signatures that is considered essential.

However, it should also be noted that an electronic signature on a document may not (but can) be visually visible. If it is not visible, a separate tool must be used to validate it.

Informačná ikonka

The NFQES platform provides the possibility of creating a visually attractive graphic signature. More detailed information is available at https://nfqes.com/platform/graphic-signature.

How can you use an electronic signature?

According to the provisions of the Civil Code, “the written form is preserved if the document was signed with a guaranteed electronic signature or a guaranteed electronic seal” (note: the term “guaranteed electronic signature” is no longer used under the eIDAS regulation). What does this mean in practice? If someone requests a signed document from you, an electronic document signed with an electronic signature is legally equivalent.

You can therefore use an e-signature not only when communicating with state institutions (e.g., financial administration, tax authorities, customs, registry court, etc.), but also in everyday communication between citizens or entrepreneurs. If you are engaged in business, it is a way to electronically sign documents of various kinds – for example, orders, contracts with suppliers or customers, invoices, affidavits, and other documents.

If the law does not specifically require the use of a handwritten physical signature or a qualified electronic signature, you can use any level of electronic signature. In business practice, the most widely used level is the advanced electronic signature, which allows you to digitize common paper processes. We will look at the characteristics of each level of signature in the next section.

Electronic signature levels

The EU eIDAS regulation, which regulates the conditions for electronic identification, distinguishes 3 levels of electronic signature in terms of the level of security. In addition to the electronic signature itself, it also defines an improved and qualified electronic signature.

Informačná ikonka

The operator of the NFQES platformBrain:IT, is the certification authority for all levels of electronic signatures. This means that any electronic signature you create through our services will be recognized not only in Slovakia, but also within the European Union.

Simple electronic signature (SES)

The eIDAS regulation defines an electronic signature as data in electronic form that is attached or logically associated with other data in electronic form and that the signatory uses for signing. A simple electronic signature (SES) has a low level of security and has no specified format criteria. In practice, it usually occurs in the form of a scanned handwritten signature (for example, a scan of a signature on an invoice) or the inclusion of the name and surname as a signature in an e-mail.

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The NFQES platform delivers a simple electronic signature in a more secure form – a digital signature. Unlike previous levels where a person obtains a certificate at a certain level to sign, with digital signatures a person does not have their own certificate but uses a certificate from a certificate authority.

Advanced electronic signature (AdES)

An advanced electronic signature (AdES) is a signature that guarantees higher security because it meets the following requirements:

  • it is uniquely associated with the signer and enables his identity to be determined (e.g., via IP address, GPS, e-mail address or phone number, etc.),
  • it is created using data to generate an electronic signature, which the signer can use under their exclusive control with a high level of reliability,
  • it is linked to the data it signs in such a way that any subsequent change to the data can be detected.

An advanced electronic signature is essentially the equivalent of a regular handwritten signature on paper without a notary. In practice, it is used, for example, when signing documents in internet banking, where the user signs by entering a password from the bank’s application (so-called two-factor authentication), or when signing lease agreements.

Qualified electronic signature (QES)

A qualified electronic signature (QES) is an advanced electronic signature, which is additionally:

  • created by a qualified signature creation device (QSCD),
  • is based on a qualified certificate for electronic signatures,
  • is equivalent to a handwritten signature.

This type of signature is recognized in communication with public authorities.

A QES signature can only be created using a qualified certificate issued by the National Security Office or another certification authority, which is stored on a certified medium – usually on an ID card with an electronic chip or on another QSCD device. When using a QSCD card, the signer only needs a mobile phone or a hardware token that does not connect to a computer or mobile in any way.

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You can create a qualified electronic signature (QES) through the NFQES platform, in the client zone available at https://zone.nfqes.com/.

QES represents the highest level of electronic signatures and its legal effect is equivalent to a handwritten signature. If it also contains a time stamp, it has the same legal weight as an officially certified signature, and such a signature cannot be rejected as evidence in court. A qualified electronic signature based on a qualified certificate issued in EU one member state is recognized as a qualified electronic signature in all other member states.

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The term guaranteed electronic signature is no longer used according to the new European legislation. Despite this, there are still uncertainties in its usege. The guaranteed electronic signature (GES) was used as a format suitable for communication with the state until the adoption of the new eIDAS legislation. The eIDAS regulation introduced the term qualified electronic signature (QES), which today is exclusively used for communication with the state. However, GES and QES are not equivalent. Since the adoption of eIDAS, GES is considered as an advanced electronic signature.

Given the security levels of various forms of electronic signatures, their suitability for use varies concerning the transaction value:

  • digital signature – suitable for transactions worth tens of euros; it is used, for example, when receiving a courier delivery or signing insurance contracts,
  • electronic signature – secures transactions worth hundreds to thousands of euros; it is commonly used in situations where the user uploads his ID card – for example, when trading cryptocurrencies or concluding insurance contracts (travel, health insurance),
  • advanced electronic signature – suitable for transactions ranging from tens of thousands to hundreds of thousands of euros, used when signing leasing contracts, business and other contracts,
  • qualified electronic signature – secures transactions worth millions of euros, for example in the transfer of real estate, companies, and similar high-value transactions.

Transaction values and examples of the use for each level of signature

Signature level Value of transactions Examples of usage
Digital signature (Simple electronic signature) tens of euros receiving a courier delivery, signing insurance contracts
Electronic signature stovky až tisíce eur obchodovanie s kryptomenami, zmluvy s poisťovňami (cestovné poistenie, zdravotné poistenie)
Advanced electronic signature tens of thousands to hundreds of thousands of euros signing leasing contracts, business contracts, etc.
Qualified electronic signature millions of euros property or company transfers etc.

How to electronically sign a document?

Various software and platforms are available today for both electronic signature and document validation. Apart from software like D.Signer used on the Slovensko.sk portal, there are other platforms that are usually much more user-friendly.

Let’s look at the options of how to sign an electronic document through the NFQES.com website. When you want to electronically sign a document, you have several options:

  • digital signature – the lowest level of electronic signature, which guarantees the authenticity and integrity of the PDF document at the time of signing,
  • electronic signature with an online certificate, or hardware token – this certifies that you are the one who signed the document; includes all levels of signatures (QES, advanced electronic signature and any other electronic signature),
  • electronic signature with an ID card – the highest level of electronic signature, also usable in an electronic mailbox, which allows signing documents for state institutions.

Electronic signature of documents: Guide to signing with an ID card

Signing with an ID card in the NFQES platform is free. You can sign the document even without logging in and registering. This method allows you to electronically sign 3 documents at once. After registration, you can upload larger files and multiple files at once.

How to sign a document with a qualified electronic signature? To create a qualified electronic signature, you will need:

  • a computer with a Windows, Mac, or Linux operating system,
  • chip card reader with installed drivers,
  • an electronic ID card – also referred to as an eID card or an ID card witch chip,
  • certificates installed on the ID card, which you get when you visit the documents department in person or you download them online,
  • BOK and PIN QES codes,
  • an eID application,
  • the NFQES Web Signer

#1 Upload the file to the NFQES platform

You can upload all types of documents through the NFQES platform. The change is only in the case of signing with a digital signature, when only PDF documents can be uploaded. The maximum file size that you can sign in the free version is 5 MB.

Select the document you want to sign and upload it to NFQES by clicking or dragging.

If you do not have the necessary applications downloaded, the system will notify you with error messages.

#2 Insert ID card with chip

Insert the electronic card reader into the USB port and place the ID card with a chip into it. Launch the eID application and NFQES Web Signer applications.

#3 Agree to the general terms and conditions and press the sign button

In the next step, mark that you agree to the general terms and conditions and choose whether the file should be automatically downloaded to your device after signing or not and press the sign button.



#4 Follow the steps of the selected ID card signing software available in your country

Each country has its own software for signing documents with an ID card. Download the app available in your country and sign the document.

#5 Download the signed document

You can download the signed document and archive it on your computer. If you have chosen to download the file automatically, you will find the file among the downloaded documents.

Výkričník ikonka

When signing documents where a certified signature is required, you must also attach the so-called timestamp. Based on it, it is possible to determine the exact date and time when you signed the document with a qualified electronic signature.

Validation of an electronic signature

You can check whether a document is electronically signed directly in the Adobe Reader application. Open the file and click on Signature Panel. You will see the signatures that apply to the document. In a similar way, you can also validate a graphic signature directly in Adobe Reader – after clicking on the signature, information about its validity will be displayed.

However, you can only use this validation method for signed PDF documents and consider it only informative. A more sophisticated way is to use the NFQES platform for document validation.

#1 Upload the file for validation

Select the Validate document function and upload the files for validation. You can upload 3 documents for signature validation without registration. As a registered user, you can upload multiple documents.


#2 Choose a validation policy

Choose which validation policy you want to use for validation. You can choose between basic and stricter validation:

  • basic validation QES AdESQC TL based – verifies whether the document has not been altered and provides the necessary information about the legal type and validity of electronic signatures and seals according to EU regulation no. 910/2014 (eIDAS),
  • stricter validation QES validation policy – requires valid qualified signatures and seals (qualified electronic signatures have the same legal effect as handwritten signatures according to the eIDAS regulation).


Click to agree to the general terms and conditions and validate the document.

#3 View the validation result

The system will evaluate the uploaded document for you in the “View detail” section. If the electronic signature of the document is executed correctly, NFQES evaluates the verification result as valid.

If the file does not contain an electronic signature, the system evaluates the document as unvalidatable:

Try out electronic document signing through the NFQES platform

Try the benefits of the NFQES platform, which is operated by one of the leading certification authorities in Slovakia, Brain:IT. Signing with an electronic signature through the NFQES website ensures you:

  • authenticity of the sender’s identification and content of the document,
  • integrity of the content,
  • undeniability and trust in electronic transactions and communications.
Informačná ikonka

The NFQES platform offers you much more – a visually attractive graphic signature, mass signing of many documents, timestamps, mailbox, and many other functions.

If you often sign documents with your ID card, the NFQES subscription will help you sign more efficiently and keep track of each signature.

Digitize your signature agenda today and handle all administration conveniently, quickly and simply. In the Brain:IT team, we will be happy to advise you on how to do it.

Contact Brain:IT

The author of the article is

Miroslav Rechtorík