Electronic Signature Glossary: All Terms Explained

The qualified electronic signature is the most robust signature level defined by the eIDAS regulation. It is legally equivalent to a handwritten signature in all EU member states — the only level for which this equivalence is established by law.

To be qualified, a signature must rely on a qualified certificate issued by a qualified trust service provider (QTSP), and be created using a qualified signature creation device (QSCD). It guarantees the signer’s identity, the integrity of the document and non-repudiation: the signer cannot deny having signed.

QES is required by certain administrations — notably the French INPI for trademark filings — and recommended for all documents with significant legal stakes (employment contracts, notarial deeds, public procurement).

Companies using Odoo as their ERP can now send quotations, contracts and HR documents for qualified signature directly from their Odoo records, thanks to the native e-Signature.eu module for Odoo.
→ Discover the Odoo integration

The advanced electronic signature is the intermediate level of the eIDAS regulation. It must meet four conditions: be uniquely linked to the signer, allow their identification, be created using data under their sole control, and allow detection of any later change to the document.

AES offers strong evidential value but is not legally equivalent to a handwritten signature — unlike QES. It is suitable for most business-to-business contracts, non-disclosure agreements, quotations and orders, when no law explicitly requires QES.

On e-Signature.eu, the Veriff method delivers AES signatures covering 198 countries.

The simple electronic signature is the basic level defined by eIDAS. It covers any data in electronic form which is attached to or logically associated with other electronic data, used as a signature. An OTP code sent by email, a checked box or a scanned handwritten signature are examples of SES.

Its legal value is limited: it can serve as initial evidence, but does not formally guarantee the signer’s identity. It is suitable for low-stakes documents — internal purchase orders, light approvals, informal agreements.

Note: an SES is never equivalent to a handwritten signature under European law.

The eIDAS regulation (Electronic IDentification, Authentication and trust Services) is European regulation n° 910/2014, which establishes the common legal framework for electronic signatures, electronic seals, timestamps and trust services within the European Union.

It defines the three signature levels (SES, AES, QES), imposes mutual recognition of qualified signatures between member states, and establishes the list of qualified trust service providers (QTSP) via the European trusted list (EU Trusted List).

A QES issued in one EU member state is automatically recognized in all other member states: this is the eIDAS interoperability principle, one of the pillars of the European digital single market.

eIDAS 2.0 is the revision of the eIDAS regulation, which entered into force in 2024 and continues to be rolled out through 2026-2027. Its main novelty is the introduction of the European Digital Identity Wallet (EUDIW), which will allow every European citizen to have a certified digital identity interoperable across the EU.

For electronic signature, eIDAS 2.0 strengthens requirements on qualified providers, extends the list of recognized trust services and prepares the integration of the identity wallet as an authentication method for QES. It is a structuring evolution for the entire signature ecosystem in Europe.

A QTSP (Qualified Trust Service Provider) is an organization accredited by a national supervisory authority to deliver qualified trust services — notably qualified certificates allowing the issuance of QES signatures. In France, ANSSI (the National Agency for the Security of Information Systems) is the supervisory authority.

The full list of European QTSPs is published on the EU Trusted List, accessible via the European Commission. Only signatures backed by a qualified certificate issued by a QTSP on this list can claim QES status.

e-Signature.eu relies on accredited QTSPs for all its qualified signature methods (itsme® and Evrotrust).

A qualified certificate is a digital certificate issued by a QTSP, formally attesting to the identity of a natural or legal person. It is the technical basis of a qualified signature (QES): without a qualified certificate, there is no QES.

It contains the holder’s identity information (name, and where applicable an identification number), information about the issuing QTSP, the validity period and a cryptographic key. It is associated with a private key controlled solely by the holder, which guarantees that the signature can only be applied with their active consent.

The French National Institute of Industrial Property (INPI) is the public body responsible for registering trademarks, patents, designs and models, as well as company formalities. It is one of the few bodies that explicitly requires a qualified signature (QES) for online filings and formalities.

To sign a document intended for the INPI via e-Signature.eu, the itsme® or Evrotrust methods (both QES) are required. Simple signature (OTP) or advanced signature (Veriff) are not accepted for these formalities.

The EU Trusted List is an official register, maintained by each member state under the supervision of the European Commission, listing all qualified trust service providers (QTSP) accredited in the EU. It is the reference for checking whether a signature service is genuinely qualified under eIDAS.

Any signature solution claiming QES level must rely on a QTSP listed here. This is a fundamental guarantee for users.

itsme® is a digital identity application developed by Belgian Mobile ID, which allows users to identify themselves and sign documents electronically from their smartphone. It is recognized as an authentication method for qualified signature (QES) in 32 European countries.

To use itsme® as a signing method on e-Signature.eu, the signer must have the app installed on their smartphone and have previously verified their identity (via an ID card and a selfie). The signature takes just seconds: the signer receives a notification, approves it on their phone, and the qualified signature is applied.

itsme® is the most widely used qualified signature method in the Benelux region and is e-Signature.eu’s flagship method.

Since 2026, itsme® is also available as a signing method directly within e-Signature.eu’s Odoo integration module: Odoo users can send a quotation or contract for qualified signature via itsme® without leaving their ERP.
→ Discover the Odoo integration

Evrotrust is a Bulgarian qualified trust service provider (QTSP), listed on the EU Trusted List, offering a qualified signature (QES) solution via mobile app. Its geographic coverage is one of the widest on the market: 62 countries, covering Europe, North America, Oceania and part of the Middle East.

Available on e-Signature.eu since 2026, Evrotrust allows the issuance of eIDAS-compliant QES signatures for signers located outside the itsme® footprint. The process is similar: app download, identity verification, then signature in a few taps from the smartphone.

Evrotrust is complementary to itsme®: where itsme® stops, Evrotrust takes over — allowing e-Signature.eu to cover almost all qualified signature needs across Europe and beyond.

Veriff is an Estonian company specializing in AI-powered identity verification. On e-Signature.eu, Veriff is used as the authentication method for advanced electronic signature (AES) in 198 countries.

Veriff’s verification process happens entirely online: the signer photographs their ID document and takes a video selfie, automatically analyzed to confirm their identity. The signature is then applied with strong biometric traceability.

Veriff is the ideal method for international contractual exchanges with partners located outside QES coverage (itsme® or Evrotrust). It offers higher evidential value than simple signature (OTP), with worldwide geographic coverage.

An OTP (One-Time Password) is a numerical code automatically generated, sent by email to the signer, and valid for a single operation. On e-Signature.eu, email OTP constitutes the simple signature (SES) method.

The OTP proves that the signer had access to the email address at the time of signing. It does not formally authenticate their identity — which limits its legal value. It is nevertheless sufficient for low-stakes agreements, internal approvals or cases where light evidence suffices.

Advantage: OTP requires no application nor prior identity verification. It is the fastest method to implement, available anywhere in the world.

A QSCD (Qualified Signature Creation Device) is the secure device — hardware or software — used to create a qualified signature. It ensures that the signer’s private key is generated, stored and used in a secure environment, inaccessible to third parties.

Mobile applications like itsme® and Evrotrust integrate a certified software QSCD: the signer’s smartphone plays this role, after secure identity enrolment. It is this QSCD certification that allows these methods to deliver signatures at QES level.

The audit trail is a chronological, automatic record of all events occurring during a signature request: invitation sent, document viewed, signature applied, download, contact detail changes, any abandonment.

On e-Signature.eu, the audit trail is automatically activated for every request, regardless of the signature level chosen. It can be viewed in real time from the dashboard while the request is in progress, then downloaded as a timestamped PDF once the request is finalized.

In the event of a dispute, the audit trail constitutes admissible evidence: it proves that the signer received the invitation, viewed the document and applied their signature, with precise dates and times.

A timestamp is a cryptographic mechanism that certifies a digital document existed in a given state at a precise moment and has not been modified since. It is issued by a Time Stamping Authority (TSA) and constitutes proof of precedence and integrity.

On e-Signature.eu, the audit trail PDF is protected by a timestamp at the moment it is generated. This guarantees that the traceability report has not been altered after creation — strengthening its evidential value in case of dispute.

Non-repudiation is the property that prevents a signer from denying they signed a document. It is one of the fundamental guarantees of the qualified electronic signature (QES): thanks to the qualified certificate and the QSCD device, it is cryptographically impossible for the signer to claim they did not apply the signature.

Simple signatures (SES) offer only partial non-repudiation, as they do not formally authenticate the signer’s identity. QES offers the strongest non-repudiation — which is why it is required for documents with high legal stakes.

The integrity of an electronically signed document refers to the guarantee that its content has not been modified after signing. It is ensured by a cryptographic mechanism: at the time of signing, a digital fingerprint (hash) of the document is calculated and embedded in the signature. Any later modification of the document invalidates this fingerprint — and therefore the signature itself.

Compatible PDF readers (notably Adobe Acrobat Reader) automatically flag if a signed document’s integrity has been compromised. This is one of the reasons the PAdES format is preferred for signing PDF documents.

Evidence is considered admissible when it can be produced and accepted before a court to establish a fact. In the context of electronic signature, the admissibility of evidence depends directly on the signature level used:

— QES benefits from a legal presumption of reliability and strong non-repudiation. It is the strongest evidence.
— AES offers strong evidential value, but without automatic legal presumption.
— SES constitutes initial evidence, whose value depends on context and supporting elements (audit trail, explicit consent, etc.).

PAdES (PDF Advanced Electronic Signatures) is the standard format for electronic signatures applied to PDF documents. It is defined by the ETSI EN 319 132 standard and recognized by the eIDAS regulation.

The PAdES signature is embedded directly in the PDF file: it is visible in the signature panel of Adobe Acrobat Reader and can be verified by any compatible software. It can embed a qualified timestamp and certificate revocation information, guaranteeing long-term verifiability.

It is the format used by e-Signature.eu for all documents signed in PDF format.

XAdES (XML Advanced Electronic Signatures) is the electronic signature format adapted to XML documents. It is defined by the ETSI EN 319 132 standard and recognized by eIDAS. It is used mainly in structured data exchanges between systems (e-invoicing, administrative data, API integrations).

Less visible than PAdES to the end user, XAdES is common in automated processes and B2B or B2G (Business to Government) exchanges.

CAdES (CMS Advanced Electronic Signatures) is the electronic signature format applicable to any file type (not only PDF or XML). It wraps the signed document in a cryptographic container. Less common than PAdES in everyday use, it is used in certain archiving contexts or system-to-system exchanges.

A hash (or digital fingerprint) is a fixed-length string calculated from a file’s content by a one-way mathematical function. Two identical files always produce the same hash; the slightest modification to the file — even a single character — produces a completely different hash.

In electronic signature, the document’s hash is calculated at the time of signing, then encrypted with the signer’s private key. This guarantees the document’s integrity: if the document is modified after signing, the hash no longer matches the signature — invalidating it.

A PKI (Public Key Infrastructure) is the set of technical and organizational components that manage cryptographic key pairs (private key / public key) and their associated digital certificates.

In electronic signature, PKI guarantees that:
— The private key belongs exclusively to the signer and is used to sign.
— The public key, included in the certificate, allows anyone to verify the signature.
— The certificate, issued by a recognized certification authority (CA), attests to the identity of the key’s holder.

The initiator is the person or company that creates the signature request on e-Signature.eu. They choose the document to sign, designate the signers, select the signature method and trigger the sending of invitations.

The initiator uses the credits purchased on the platform (1 credit per signer for a QES). They have access to the dashboard and audit trail throughout the process.

The signer is the person invited to apply their electronic signature to one or more documents. They receive an invitation email containing a secure link to the document to sign.

Depending on the method chosen, the signer may need the itsme® or Evrotrust app (previously installed and registered) for a QES, or simply access to their email for an SES (OTP). For Veriff (AES), they will need to complete an identity verification during signing.

A credit is consumed per signer, regardless of the number of documents included in the request.

The signer groups feature, introduced on e-Signature.eu in 2026, allows a sequential signing order to be defined between several groups. For example, group 1 (internal stakeholders) must sign before invitations are sent to group 2 (external partners).

This feature is particularly useful for hierarchical approval processes — contracts requiring a manager’s approval before the client’s signature — or documents involving several parties in a predefined order.

The automatic reminder is a feature available on e-Signature.eu that automatically resends an invitation email to a signer who has not yet signed after a defined delay. This saves the initiator from having to manually chase each signer and speeds up the finalization of multi-signer requests.

A webhook is a mechanism by which an application automatically sends an HTTP notification to a defined URL whenever a specific event occurs. In the context of the e-Signature.eu API, webhooks allow your system to receive real-time updates on signature requests: signature completed, request finalized, document available for download (in Base64 format), etc.

Webhooks are essential for integrations that require automatic processing without periodic polling of the API.

Pay-as-you-go is a consumption-based pricing model: you only pay for what you actually use, with no monthly subscription or volume commitment.

On e-Signature.eu, this means: you buy a pack of prepaid credits, and each signature consumes a number of credits depending on the method used (1 credit for a QES, 0.7 for an AES, 0.4 for an SES). Unused credits remain available with no expiration date.

This model is particularly suited to SMEs, freelancers and independent professionals whose signature needs are irregular — unlike competing solutions (DocuSign, Adobe Sign, Yousign) which charge a fixed monthly subscription.

On e-Signature.eu, the credit is the unit of consumption. 1 credit = 1 signer, regardless of the number of documents included in the signature request. The credit cost varies by signature level:

— 1 credit for a qualified QES signature (itsme® or Evrotrust)
— 0.7 credit for an advanced AES signature (Veriff)
— 0.4 credit for a simple SES signature (email OTP)

Credits are purchased in prepaid packs. Pricing is tiered: the larger the pack, the lower the cost per credit.

Tiered pricing refers to a model in which the unit price decreases as the volume purchased increases. On e-Signature.eu, this means the cost per credit is lower for a 100-credit pack than for a 10-credit pack.

This mechanism allows companies with high volumes to benefit from optimized pricing, while retaining the flexibility of pay-as-you-go — without committing to a monthly subscription.