What is Advanced Electronic Signature (AdES)?

A middle-tier eIDAS signature that uniquely identifies the signer and detects any later changes to the document.

An Advanced Electronic Signature (AdES) under eIDAS Article 26 must (a) be uniquely linked to the signer, (b) be capable of identifying the signer, (c) be created using signature-creation data that the signer can use with a high level of confidence under their sole control, and (d) be linked to the data signed in such a way that any subsequent change in the data is detectable. AdES is the sweet spot for most B2B EU contracts: stronger evidentiary value than SES, none of the QES overhead.

AdES building blocks

In practice, AdES combines a captured signature with a PKI digital signature certificate. The signer's identity is verified (typically email + ID document upload + selfie liveness), the signing key is held by them (or by the TSP on their behalf with strict access controls), and the document is hashed and signed cryptographically so any byte change is detectable.

AdES vs QES

AdES doesn't require the certificate to come from a Qualified TSP — any TSP that meets the technical bar will do. AdES also doesn't require a hardware QSCD. This keeps the cost roughly 10x cheaper than QES while still providing strong tamper-evidence and signer identification.

When AdES is enough

Most commercial contracts, NDAs, employment agreements, vendor agreements, sales contracts, lease agreements — all are valid with AdES under eIDAS. PDF Verified offers AdES via TSP integration on Business Plus.