Advanced electronic signature (AES)

An advanced electronic signature (AES) is the middle tier of electronic signature defined by the EU's eIDAS regulation, sitting between simple and qualified signatures. To count as an advanced e-signature, it must meet four requirements set out in Article 26: it is uniquely linked to the signatory, it is capable of identifying the signatory, it is created using signature creation data the signatory can use under their sole control with a high level of confidence, and it is linked to the signed data so that any subsequent change is detectable.

In practice, most AES implementations rely on digital signature technology. The signer's identity is verified in some way, a key pair is associated with them, and the document is cryptographically signed so tampering breaks the signature. The level of identity checking varies by provider; it might involve an ID document check, a bank login, or a certificate issued after verification.

Consider a recruitment agency in the Netherlands placing contractors with clients across the EU. For higher-value framework agreements, the agency's clients ask for signatures that tie each contractor to a verified identity. An AES workflow, with ID verification before signing and a certificate-based signature on the PDF, gives both sides more confidence than a typed name.

A common misconception is that an AES has the same legal effect as a handwritten signature everywhere in the EU. That automatic equivalence belongs only to the qualified electronic signature. An AES is still just admissible evidence under Article 25, though generally stronger evidence than a simple signature because of the identity and integrity guarantees. Another myth is that AES is a US concept. US law under the ESIGN Act and UETA does not define tiers at all.

People also sometimes think that recording a document hash is enough to make a signature advanced. Detecting changes is only one of the four criteria. Without reliable identification of the signer and sole control over the signing data, a signature remains simple, however good its audit trail.

Our take: AES is a useful middle ground for cross-border deals and documents with real money or regulatory exposure. It is overkill for most routine paperwork, and vendors that label every signature advanced without explaining how they meet each criterion deserve some scepticism.

eSignSimple does not provide advanced electronic signatures today. We offer simple electronic signatures backed by an audit trail, a certificate of completion and a SHA-256 hash checkable on our /verify page. Identity verification features are on our roadmap.