What is an advanced electronic signature (AES)?
An advanced electronic signature (AES) is the middle of the three levels of electronic signature in the EU's eIDAS Regulation. It must be uniquely linked to the signer, capable of identifying them, created with signing data under their sole control, and linked to the signed data so that any later change can be detected.
Also called: AES, Advanced e-signature, eIDAS advanced signature
Updated October 15, 2026 · By the PDFZyro team
The four requirements in practice
Being uniquely linked to the signer and able to identify them means the signature points to one specific person, not just to an inbox anyone could open. Sole control means only the signer could have made it: in practice, a private key protected by something only they have or know, such as a password, a phone or a smart card. Detecting changes means the signature is tied to the exact document, usually with a certificate-based digital signature, so altering a single character breaks it.
eIDAS doesn't prescribe one technology. Many AES services verify the signer's identity, for example with an ID document check, a bank ID or a national eID, then sign with a certificate issued to that person, kept on their device or held by the service on their behalf.
AES vs simple and qualified signatures
A simple electronic signature, such as a typed name or a click, has legal effect but little built-in proof of who signed. An AES gives much stronger evidence of identity and integrity. A qualified electronic signature (QES) is an AES that also uses a qualified certificate and a certified signing device, and only a QES automatically has the same legal effect as a handwritten signature across the EU.
An AES is a common choice for business contracts, HR documents and other agreements where a simple signature would be harder to defend but a QES isn't required.
Whether a signature counts as an AES
Whether a signature meets the four requirements depends on how the signer was identified and how the signature was made, so providers and lawyers can disagree about a particular method. If a document must carry an AES, ask whoever requires it which providers or methods they accept. The AES in this term has nothing to do with AES encryption, the cipher used to protect files. This is general information, not legal advice.
Advanced electronic signatures and PDFZyro
- PDFZyro doesn't present its signatures as advanced electronic signatures under eIDAS, and doesn't verify signers with ID documents or national eIDs.
- What it does give you is strong evidence: signature requests can check each signer with a personal email link, an access code or a text-message code, record every step in a tamper-evident audit trail, and seal the signed PDF so any change can be detected.
- You can also sign with your own Digital ID, including one issued by a certificate authority. Whether a particular signature meets the AES requirements is a question for your legal adviser.
Tools and guides
Related terms
- Qualified electronic signature (QES)The highest level of e-signature under the EU's eIDAS Regulation, equal in law to a handwritten one.
- Electronic signature (e-signature)Any electronic sign that shows a person agrees to a document, from a typed name to a drawn signature.
- Signer authenticationChecking that the person signing a document electronically is the person it was sent to.
- Digital ID (signing certificate)A certificate and a private key that identify you and let you add digital signatures to PDFs.