Advanced electronic signature (AES)

What is an advanced electronic signature?

The advanced electronic signature (AES) enables the authenticity and integrity of signed data to be verified. It establishes a unique link to the signer and enables the signer to be identified. In addition, it is linked to the signed data in such a way that any subsequent modification of the data can be detected.

For almost all agreements in the private sector, the advanced electronic signature is the most common choice because it is evidential and can be done easily, quickly and without complications.

According to the eIDAS Regulation, an advanced electronic signature must meet the following requirements:

• The electronic signature is uniquely associated with the signer.
• It enables the signatory to be identified.
• It is created using electronic signature creation data that the signer can use with a high degree of confidence under his sole control.
• It is linked to the data signed in this way in such a way that subsequent modification of the data can be detected.

The following documents are typical use cases for advanced electronic signatures:

• Data protection declarations
• Unlimited employment contracts
• Insurance applications
• Liability disclaimers
• Powers of attorney
• SEPA mandates
• Non-disclosure agreements
• Quotations, etc.

Technical implementation of the advanced electronic signature

The advanced electronic signature requires a technical implementation in order to meet the strict verification requirements. The signature is created using electronic signature creation data.

The advanced electronic signature is usually implemented using digital certificates from a public key infrastructure (PKI). A key pair is used: a public and a private key. The advanced electronic signature is created by using the signer’s private signature key, which is kept only by the signer.

Recipients of the signed document also receive the public key. If the signature has not changed, the recipient can decrypt the signature using the public key. If it has changed, the advanced electronic signature cannot be decrypted correctly and it may be considered invalid.

What type of electronic signature should I use?

The type of electronic signature you should use depends on your workflow and individual requirements, but most users want to strike a balance between ease of use and legal enforceability. With this in mind, we recommend using the simple or advanced electronic signature if you want to sign documents.