A qualified electronic signature (QES) is the most reliable type of electronic signature, and by law it is treated as equal to a handwritten one. Let's look at what it is, how it differs from simpler signatures, and how signing works right in the browser.
What a qualified electronic signature is
A qualified electronic signature is electronic data attached to a document that unambiguously confirms two things: who signed the document and that it was not changed after signing. A QES is created on the basis of a qualified certificate issued by an accredited trust service provider and is generated under the state cryptographic standard DSTU 4145.
In plain words: it is your digital equivalent of a signature and stamp that cannot be forged or silently altered. Every QES is firmly tied to a specific person or organization through a certificate, so it is always possible to establish exactly who signed and when.
How QES differs from simple and advanced signatures
The law distinguishes several levels of electronic signature. The difference lies in reliability and legal consequences.
- Simple electronic signature — for example, an SMS code or an "I agree" checkbox. It confirms intent but offers weak protection against forgery.
- Advanced electronic signature — already linked to the signer and able to detect changes to the document, but it does not have qualified status.
- Qualified electronic signature (QES) — the highest level. Only this one is treated by default as equal to a handwritten signature.
Legal force: why QES equals a handwritten signature
Under the Law of Ukraine "On Electronic Identification and Electronic Trust Services," a qualified electronic signature has the same legal force as a handwritten one. This means a contract, act or order signed with QES is a full-fledged original and is accepted by courts, regulators and counterparties.
This matters especially where the Civil Code requires the written form of a transaction: a QES satisfies that requirement without paper. We cover this in more detail in the piece on the legal force of the electronic signature in Ukraine.
How signing in the browser works
The most common worry is "is it safe to sign online?" In a properly built system — yes. Here is how it works in eObig:
- You open the document in the browser and choose the "Sign" action.
- You load your key file and enter its password.
- The cryptographic operations run locally, on your device — the private key and password never leave the browser and are never sent to the server.
- The generated signature is attached to the document, and you receive a signed original.
The cryptographic core that makes this possible holds a positive conclusion from Ukraine's State Service of Special Communications (DSSZZI). That is why signing happens with no plugins and no installed software. For more technical detail, see the article on browser-based signing security, and the general protection principles are described on the security page.
What you need to sign a document
To apply a QES you need very little:
| What you need | Explanation |
|---|---|
| Key file | Usually .dat, .jks or .pfx, issued by a trust service provider |
| Key password | Known only to you; processed locally |
| Browser | A modern browser on a computer or smartphone |
For the basic scenario no tokens, drivers or extra software are required. If your key is stored on a secure medium, the system will support that scenario too.
Where to get a QES key
The key file is issued by an accredited provider of qualified electronic trust services. For sole traders and companies this can be, among others, a state service or the bank where you are a customer. Once you have the key and password, you can sign documents online right away — no additional setup is needed. We describe the signing process itself in detail in the article on how to sign a document online without plugins.
The key points in brief
A qualified electronic signature is a legally full, reliable and convenient way to sign documents. It protects against forgery, confirms document integrity and saves time, because everything happens online. And thanks to local signing, your key stays under your control.
Ready to try? We laid out the step-by-step scenario in the article how to sign a document online without plugins, and you can start free right now at portal.eobig.com or by requesting a demo.