Digital signature: how to create one legally

The digital signature has replaced the printer as the last step in many business processes. Instead of printing a contract, signing it, scanning it and emailing it back, you conclude it right on the screen, in minutes instead of days. This guide sums up what exactly the term means, how a digital signature works and what matters for legal certainty.

What is a digital signature?

In everyday use, a digital signature means any way of signing a document bindingly on a computer, tablet or smartphone, without paper. In precise legal terms, the umbrella term is the electronic signature, which is governed by the European eIDAS Regulation. In everyday language, the two terms are used interchangeably and mean the same thing: a signature that is created digitally and holds up legally.

What matters is what sets a reputable digital signature apart from a mere image of a signature. It documents traceably who signed and when, and it protects the document against unnoticed changes. That is exactly what makes it useful as evidence.

Digital signature, electronic signature and the scanned signature

Three terms regularly cause confusion:

• Digital signature: the everyday term for signing a document electronically.
• Electronic signature: the legal term from the eIDAS Regulation, with three defined levels.
• Scanned signature: merely a photo of a handwritten signature, inserted into a file.

The scan is the weakest option. It can be copied at will, does not link the signature to a verified person and does not protect the document against later changes. A genuine electronic signature does everything the scan cannot: attribution, integrity and provability.

How does a digital signature work?

With a signature platform like SmartDocs, the process takes just a few steps. You upload a document, place the signature fields and send a personal signing link by email. The other party opens the link in the browser, reads the document and signs, with no account and no app, on a computer or a smartphone.

The real work happens in the background. The platform logs every step: when the document was sent, opened and signed, from which IP address and on which device. These events are cryptographically chained, so any later tampering would become visible. At the end, a completion certificate summarizes all the evidence in one PDF file.

Is a digital signature legally valid?

Yes. In Germany and throughout the EU, electronic signatures have had a clear legal framework since the eIDAS Regulation (EU 910/2014). Under Art. 25, an electronic signature may not be denied legal effect and admissibility as evidence solely on the grounds that it is in electronic form.

In addition, most contracts in Germany have no form requirement and are therefore valid even when made orally or with a handshake. For these, the simple electronic signature is already sufficient. Only where the law expressly requires the statutory written form do you need the highest level. Which laws apply here and what counts in a dispute is covered in depth on our page on the legal validity of electronic signatures.

The three levels: SES, AES and QES

The eIDAS Regulation defines three levels that differ in how strongly the signer’s identity is established:

• SES, the simple electronic signature, for everyday contracts with no form requirement.
• AES, the advanced electronic signature, with unambiguous attribution through a second factor such as an SMS code.
• QES, the qualified electronic signature, which is legally equivalent to a handwritten signature and meets the statutory written form under Section 126a BGB (German Civil Code).

Which level is right when is explained in our guide SES, AES, QES: the differences, with every legal provision and a side-by-side table.

A digital signature in four steps

1. Prepare the document. Upload the PDF or open a saved template.
2. Place fields and choose signers. Add signature and text fields by drag and drop and decide who signs in which order.
3. Choose the signature level and send. Choose between SES, AES and QES for each request and send the signing link.
4. Receive the completed document. As soon as everyone has signed, all parties receive the finished document along with the audit trail and completion certificate.

Security and data protection

Contracts are among a company’s most confidential documents. At SmartDocs, they are processed exclusively in a German data center in Nuremberg, encrypted in transit and at rest. There is no transfer to third countries, which removes a major part of any GDPR review from the outset. The cryptographic hash chain of the audit trail ensures that any later change is detected. Learn more on our security page.

What the digital signature is suited for

From quotes and order confirmations to employment contracts, the digital signature covers almost all of day-to-day business. We cover practical examples in separate posts, for example on the employment contract, the lease and signing a PDF. And if the signer is standing right in front of you, you can even skip the email: a dedicated guide shows how to let customers sign on a tablet.

There are limits. Transactions that require notarization, such as real estate purchases or wills, cannot be signed digitally, nor can a few cases excluded by law, such as terminating an employment relationship under Section 623 BGB. For everything else, the digital signature is the faster and better-documented route.

Frequently asked questions

Do I need software to sign digitally? Not as a signer. You open the signing link in your browser and sign there, with no account and no installation.

Is a scanned signature legally equivalent? No. A scan is just an image and weak in a dispute. An electronic signature documents the process and protects the document against changes.

Which level do I need for my contract? For contracts with no form requirement, SES is sufficient. When a lot is at stake, AES is recommended, and where the statutory written form applies, QES is required.

Conclusion

The digital signature is legally sound, done in minutes and better documented than any contract that was printed out and scanned back in. With SmartDocs, you get all three signature levels on one platform, hosted in Germany and starting at €0.