An electronic signature or e-signature is a broader concept than a digital signature.

There are various e ‐ signing service providers on the Internet (DocuSign, Signicat, etc.). However, there is some confusion about the legal meaning of the different signatures. An incorrect e-signature can lead to cumbersome disputes over the validity of the signature (eg who exactly gave the signature) or, in the worst case, even the invalidity of the transaction.

There are three different types of e-signatures:

1. Simple Electronic Signature = imprint of an electronically generated signature without any special technical gadgets; for example, an image of a signature copied to a PDF;

2. Advanced Electronic Signatures (AdES) = “electronic signature” with some technical gadgets. This usually means that it is possible to identify the time of signing and the integrity of the content of the document and associate it with a specific signatory. Technically, AdES is similar to QES, but there is no certified interface (see below), which may result in weaker signer identification.

3. Qualified Electronic Signatures (QES) or “qualified e-signature” = in Estonia the so-called digital signature. The signature has been verified by a qualified trust service provider. Is used all kinds of technical gadgets to ensure clarity of signing time, unchanging content, etc. In this way, the identity of the signatory is also clearly identifiable.

What is the legal meaning of different e-signatures?

The correct choice of signature is especially important if the law or the contract prescribes the form of the transaction. The form of the transaction can be, for example:

1. a written form, which means that the document must be signed by hand;

2. an electronic form, which means that the transaction is in a form that can be reproduced permanently, contains the names of the persons who made the transaction and is electronically signed. The electronic form is equivalent to a written form (unless a handwritten signature is required by law);

3. in a form that can be reproduced in writing, which means that the transaction is in a form that can be reproduced permanently and contains the names of the persons who made the transaction, but does not have to be signed.

In Estonia, digital signatures and qualified e-signatures are essentially synonymous. A qualified e-signature has the same legal effect as a handwritten signature. If the form required by law or agreement is a digital signature, it must be a QES signature. If a written form of a document is required by legislation or a contract, both handwritten signing of the document on paper and digital signing are generally suitable for signing.
The situation with AdES signatures is more complicated. The General Part of the Civil Code Act (TsÜS) stipulates that an electronic signature is also a digital signature. Consequently, “electronic signature” is a broader concept than a digital signature. If a document signed by AdES meets the requirements of the electronic form provided for in the CMS, it should also be considered equivalent to a written form. However, there is currently no clear practice.
Certainly, an AdES signature cannot be considered a digital signature, ie if it is in a law or contract required digital signature, only QES signature is suitable. While required
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written form or electronic form of a document could, according to the wording of the CPS, also (68) a compliant AdES signature may in fact be sufficient. It must be borne in mind that the AdES signature is likely to make it more difficult to verify the identity of the signatory. It should also be borne in mind that the legal meaning of the AdES signature is debatable. If the transaction must be concluded in writing, a qualified e-signature (eg digital signature) should be preferred if possible.

Finally, it remains to explore Simple Electronic Signature. A document with such an e-signature can only be considered as a written document in very exceptional cases. Mechanical imitation of a signature shall be considered equivalent to a handwritten signature only if its use is normal between the parties and the other party does not immediately require a handwritten signature. Mechanical imitation of a signature means, for example, a stamp imprint, a copy, a printed signature or the like. This is an exception and in practice the potential for dispute is high. With such a signature, it is very difficult, if not impossible, to prove who actually signed the document.

How to tell if it is a QES signature?

Often one service provider offers different e-signature options and no conclusions about the type of e-signature can be drawn from the service provider alone. The signature certificate must be found in the signed document and its contents examined. Documents can also be checked automatically at: https://webgate.ec.europa.eu/tl-browser/#/search/file/1.
In general, it is reasonable to follow the principle that if it is not clear that it is a QES signature, it is rather assumed that it is not a QES signature. Often sent documents in PDF format and clicking on the signature opens additional information about it (signature certificate). The certificate indicates the issuer (issued by). The name of the issuer can be used to check whether he is a qualified trust service provider in the European Union (see https://webgate.ec.europa.eu/tl-browser/#/) and whether the issuer holds a QES certificate.

What happens if the contract has different types of e-signatures?

If the law or the agreement does not prescribe a mandatory form for the transaction, the parties may also sign the document with any e-signatures, with one party giving the AdES signature and the other the QES signature. It should always be borne in mind that in the event of a dispute, there may be problems in proving the identity of the signatory. There may also be a dispute as to which version of the agreement the parties agreed to, and so on.

If a mandatory form is provided for the transaction, all signatures must at least comply with this mandatory form. It is important to remember that the mandatory form may also result from an agreement between the parties. For example, if the parties have agreed that the document must have at least an AdES e-signature, there should be no direct problem with using a “stronger” QES signature.

Law applicable to the contract

In the case of international agreements, it is worth paying attention to which country’s law applies to the agreement. The legal meaning explained above is relevant primarily in the Estonian legal space. Within the European Union, it can be assured that a qualified e-signature must have the same legal effect as a handwritten signature. In general, however, it is worth paying attention to the regulation of e-signatures in force in each country, as it can be very different.

It is recommended to thoroughly examine each e-signature and make sure what kind of e-signature it is in a particular case. In the case of certificates, their validity and scope must be verified. In case of doubt, it is worth asking the other party for further explanations about the type of signature and the process of issuing it.