What Is a Qualified Electronic Signature (QES)

The Highest Standard of E-Signature, Full Stop 

A Qualified Electronic Signature (QES) is the gold standard of electronic signing, under eIDAS in the EU and UK eIDAS in the UK, it carries the exact same legal weight as a wet signature. 

So, what sets a QES apart from a standard or advanced e-signature (AES)? 

A QES must: 

• Meet the requirements for an advanced electronic signature. Advanced and qualified electronic signatures must be uniquely linked to an identifiable signatory who retains sole control of the data used to create the signature and must ensure that any later change to the signed documents can be detected. 

• Be backed by a qualified certificate, issued by a qualified trust service provider (QTSP) that has verified the signer’s identity to a rigorous standard. A QTSP is an organisation certified under the EU’s eIDAS regulation and its UK equivalent to provide secure, legally binding trust services – electronic signatures, seals, and timestamps. 

• Be created using a qualified signature creation device (QSCD) — purpose-built, tightly controlled hardware or software that meets strict EU and UK technical standards and remains under the QTSP’s control while still keeping the signing key under the signatory’s sole control. 

The rigorous process of becoming a QTSP is what brings a QES to another level and sits above advanced and standard e-Signatures.

This is what makes QES robust, and non-repudiable: the signer can’t later claim it wasn’t them who signed the documents, because their verified identity and the signing device are locked together and independently certified.