Glossary
SES, AES and QES: the three types of electronic signature
The EU’s eIDAS Regulation defines three tiers of electronic signature, and it has become the reference model worldwide. Here’s what Simple, Advanced and Qualified signatures mean, how their legal weight differs, and which one SignLab provides.
SES — Simple Electronic Signature
What SignLab providesThe baseline. Any electronic data attached to a document to sign it — drawing a signature, ticking “I agree”, or typing a name — backed by a record of who did it and when.
Examples: a drawn signature on a contract, click-to-agree on terms.
Legal weight: Legally valid and admissible for the vast majority of everyday commercial agreements. Cannot be denied legal effect just for being “simple” (eIDAS Article 25).
AES — Advanced Electronic Signature
A signature that is uniquely linked to the signer, capable of identifying them, created using means under the signer’s sole control, and linked to the document so any later change is detectable.
Typically built on public-key cryptography (a digital signature).
Legal weight: Higher assurance than SES. Used for higher-value or higher-risk contracts. Identity is more strongly bound to the signature.
QES — Qualified Electronic Signature
An Advanced signature created with a qualified certificate issued by a Qualified Trust Service Provider, using a qualified signature-creation device.
Requires identity verification by a trust service provider.
Legal weight: The highest tier. Under eIDAS it has the same legal effect as a handwritten signature and is recognised across all EU member states.
Which tier do you need?
For the overwhelming majority of business documents — service agreements, NDAs, engagement letters, quotes, approvals, offer letters — a Simple Electronic Signature with a solid audit trail is enforceable and appropriate. That’s what SignLab provides, with SHA-256 tamper-evidence and a full record of every event.
You may need AES or QES only for specific regulated, high-value, or formality-bound transactions (some financial instruments, certain notarised acts, or where a counterparty or regulator explicitly requires it). SignLab does not currently issue AES or QES — if a document demands one, use a qualified trust service provider and take legal advice.
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