Electronic Signature — complete legal and practical guide

An electronic signature is any electronic means of expressing consent to the content of a document. It can be as simple as typing your name into an email, or as sophisticated as a cryptographically secured signature created using a certificate from an accredited provider. The law distinguishes three levels — and each carries a different degree of legal protection.

The key insight is that an electronic signature is not just an image of your handwriting inserted into a PDF. A genuine electronic signature is a technical mechanism that links your identity to the document's content in a way that makes any post-signing change detectable.

According to a European Commission survey (2023), more than 60% of EU businesses use some form of electronic signature. In Slovakia, adoption grows at approximately 18% year-on-year. Companies that have moved to digital signing have reduced their contract-closing time from an average of 4.2 days to 18 minutes.

The foundation for the entire EU is eIDAS Regulation No. 910/2014/EU — a directly applicable legal instrument valid in all 27 EU countries since 1 July 2016. eIDAS defines three classes of signature, determines their legal effects and requires member states to mutually recognise them.

In Slovakia, eIDAS is supplemented by Act No. 272/2016 Coll. on trust services, which regulates Slovak trust service providers and designates the National Security Authority (NBÚ) as the supervisory body. Key articles:

• Art. 25(1) eIDAS — An electronic signature shall not be denied legal effect and admissibility as evidence in legal proceedings solely on the grounds that it is in electronic form.
• Art. 25(2) eIDAS — A qualified electronic signature shall have the equivalent legal effect of a handwritten signature.
• Art. 26 eIDAS — Requirements for an advanced electronic signature (AdES).

Important update: eIDAS 2.0 (EU Regulation 2024/1183) introduces the European Digital Identity Wallet (EUDIW). Member states must make the wallet available by approximately May 2026.

eIDAS distinguishes three classes of electronic signature. The right class depends on the value and legal requirements of the document being signed:

1. Simple Electronic Signature (SES) — Any electronic expression of consent: a name in an email, clicking "I agree", or a finger-drawn signature on a mobile screen. No technical requirements. Suitable for low-risk transactions (orders, terms acceptance). Lowest evidential value.

2. Advanced Electronic Signature (AdES) — Technically linked to the signatory, detectable if the document is altered, created using data under the signatory's exclusive control (e.g. a private key). Meets the requirements of Art. 26 eIDAS. zipzipdoc uses AdES with OTP verification and a cryptographic hash of the document. Suitable for 95% of commercial contracts.

3. Qualified Electronic Signature (QES) — The highest level. Requires a qualified certificate from an accredited provider (QTSP) listed in the NBÚ Trust List, typically a hardware token or eID card reader. Has the same legal effect as a handwritten signature (Art. 25(2) eIDAS). Required for signing with public authorities.

Not every document can be signed with a simple click. Certain legal acts require a specific signature level:

Electronic signing follows four steps. The whole process takes less than 5 minutes:

1. Prepare the document — Upload a PDF or Word file to zipzipdoc, or let AI generate a new document from your brief. Review the content before sending.
2. Add signers — Enter the name and email of each signing party. Set the signing order (e.g. client first, then you) and optional expiry deadlines.
3. Send for signing — zipzipdoc sends each signer a unique link by email. The signer clicks the link, verifies their identity via OTP code (SMS or email), and signs electronically directly in the browser — no software installation required.
4. Download the signed PDF and audit trail — After all parties have signed, you receive the final PDF with an embedded digital signature, qualified timestamp and audit trail — records of the time, IP address and OTP verification of each signer.

Myths and mistakes about electronic signatures continue to circulate. Here are the most common:

• Myth: "An image of my hand is an electronic signature" — A scanned image of a signature inserted into a PDF is not even a simple electronic signature under eIDAS. It has no technical link to identity or document content.
• Myth: "Electronic signatures are less valid than handwritten ones" — On the contrary, AdES and QES provide better evidence than paper because they contain a cryptographic hash of the document and a timestamp.
• Mistake: Using SES for sensitive contracts — A simple signature without OTP verification is difficult to prove in a dispute. For contracts worth more than €500, we recommend at least AdES with OTP.
• Mistake: Signing without reviewing the content — Always review the entire document before signing. An electronic signature is as binding as a handwritten one — "I did not read it" is not a defence.
• Myth: "A foreign company may not recognise an electronic signature" — Within the EU, AdES and QES must be recognised by all member states. For countries outside the EU, it depends on national legislation.