What is an advanced electronic signature?
An advanced electronic signature (AES)is a digital signature that meets four requirements in the EU’s eIDAS regulation: it is uniquely linked to the signer, can identify them, is generated with data under the signer’s sole control, and any subsequent change to the signed data is detectable. In Denmark it is typically created by signing with MitID.
The four eIDAS requirements
For a signature to be an AES, it must meet four requirements:
- it is uniquely linked to the signer,
- it can identify the signer,
- it is created using electronic signature creation data that the signer can, with a high level of confidence, use under their sole control, and
- it is linked to the signed data so that any subsequent change is detectable.
In practice this means the signer logs in with their eID (MitID), and the signature is cryptographically bound to the document’s contents. Alter so much as a single character afterwards and the signature breaks, exposing the change.
AES or SES - which should you choose?
A simple electronic signature (SES) - drawn, typed, or uploaded - is quick and fine for low-risk everyday documents. But it does not by itself prove who signed. Choose an AES when the agreement has value: contracts, employment, leases, loans, and board documents. On Kaddye both are included on every plan, so you can match the signature to the importance of each document.
See also: Sign documents with MitID.
Valid for years - and independently verifiable
Documents signed with AES on Kaddye are sealed with a certificate from a trust service provider on the EU’s official Trusted Lists using the PAdES standard. PAdES-LTA archive timestamps keep the seal valid even after the certificates expire, and anyone can verify it against those lists at any time via the EU’s signature validator.
Frequently asked questions
What's the difference between a simple and an advanced electronic signature?
A simple electronic signature (SES) is, for example, a drawn or typed signature - quick, but it does not by itself prove who signed. An advanced electronic signature (AES) requires identity verification (e.g. MitID), is uniquely linked to the signer, and any subsequent change to the document is detectable.
Is an AES legally binding?
Yes. Under eIDAS, an electronic signature cannot be denied legal effect solely because it is electronic. An AES additionally gives strong evidence of who signed and that the document is unchanged, and it is recognised across all 27 EU member states.
When should I use an AES instead of an SES?
Use an AES whenever it matters that you can prove identity: employment contracts, supplier and customer agreements, leases, loan documents, and board documents. Use an SES for low-risk everyday documents where speed matters most.
How do I create an AES with MitID?
On Kaddye, the signer verifies their identity with MitID or MitID Erhverv. The document is then sealed with a qualified certificate from a trust service provider on the EU Trusted Lists using the PAdES standard, with PAdES-LTA archive timestamps, so the seal can be verified for many years.
What is a qualified electronic signature (QES)?
A QES is the third tier in eIDAS: an AES created with a qualified signature-creation device and a qualified certificate. It is legally equivalent to a handwritten signature, but is only required in special cases - for the vast majority of business agreements an AES is sufficient.
Get started with AES
Every signing method is included on every plan - pay per document from 30 kr., or 130 kr./month for unlimited sending. See pricing or get started.