The electronic signature is based on a technical triptych that most guides skim over: authentication of the signer, cryptographic sealing of the document, and qualified timestamping. Understanding this mechanism allows for choosing the right level of security without over-engineering the system or underestimating the regulatory requirements related to the eIDAS regulation.
Cryptographic infrastructure behind a reliable electronic signature
Every secure electronic signature relies on a pair of asymmetric keys: a private key, held exclusively by the signer, and a public key embedded in a certificate. When a document is signed, a hash of the file is encrypted with the private key. The recipient verifies the integrity of the document by decrypting this hash with the public key.
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This process guarantees two things simultaneously: the identity of the signer and the integrity of the signed document. If even a single character of the file is modified after signing, the hash no longer matches. The proof of tampering is then immediate.
The signature certificate, issued by a certification authority (CA), is the central link. For advanced and qualified signatures as defined by the eIDAS regulation, this certificate must be issued by a qualified trust service provider (QTSP) listed on the European trust list. We recommend systematically checking this listing before subscribing to a solution, as several commercial offers claim eIDAS compliance without holding this status.
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For those wishing to create an electronic signature with Ideelogique, the process starts with choosing the appropriate signature level for the legal context of the document in question.
eIDAS levels: choosing between simple, advanced, and qualified signatures
The eIDAS regulation defines three levels of electronic signature. Each level adds technical and legal requirements compared to the previous one.
- The simple electronic signature covers the majority of common uses (quotes, purchase orders, standard commercial contracts). No formal identity verification is required. An OTP code sent via SMS is often sufficient as an authentication factor.
- The advanced signature requires a unique link to the signer, its creation under their exclusive control, and the detection of any subsequent modification of the document. It is suitable for employment contracts, leases, or significant financial commitments.
- The qualified signature is the only one that benefits from a presumption of reliability under European law. It requires a qualified certificate issued after face-to-face identity verification (physical or qualified video) and a qualified signature creation device (QSCD). It is mandatory for authentic acts, dematerialized public contracts, and certain regulated documents.
We observe that the majority of French small and medium-sized enterprises adopting electronic signatures remain at the simple level, which effectively covers most of their daily needs. The trap lies in using a simple signature where sectoral regulations require an advanced or qualified level, exposing the company to a challenge of the validity of the act in case of a dispute.
Strong authentication and MFA in secure signature solutions
One point that consumer guides overlook: the signature level alone is not enough to guarantee the security of the process. The robustness of the multi-factor authentication (MFA) applied at the time of signing determines the actual resistance of the system against identity theft.
Recent solutions combine at least two factors from three categories: knowledge (password, PIN code), possession (smartphone, cryptographic USB key), and inherence (facial biometrics, fingerprint). For an advanced signature, the use of a single factor (typically an SMS code) is still tolerated but weakens the evidential value of the system.
We recommend requiring two-factor authentication systematically, even for simple signatures, whenever the document financially commits the company. The additional cost is negligible compared to the risk of repudiation.
Qualified timestamping: a detail that changes everything in case of a dispute
Qualified timestamping associates a date and time certified by a trusted third party with each signature. Without it, a signer can contest the timing of their commitment. With a qualified timestamp, the date of signing becomes legally enforceable.
Not all platforms include this service by default. Ensure that your solution uses a timestamping server compliant with the ETSI EN 319 421 standard, issued by a provider listed on a European trust list.
Impact of eIDAS 2 and the European Digital Identity Wallet on signatures
The revision of the regulation, known as eIDAS 2, introduces the European Digital Identity Wallet. This change will transform the creation of qualified signatures remotely.
The principle: every European citizen will be able to store their verified identity attributes in a digital wallet once and then reuse them to sign documents in just a few clicks, without undergoing identity verification for each act. The current friction of qualified signing (video verification, sending identity documents) will be significantly reduced.
For businesses, this evolution means it will become easier to require a qualified level where they previously settled for a simple signature for convenience. We anticipate a gradual enhancement of practices, particularly in the banking, real estate, and public procurement sectors.
Technical criteria for evaluating an electronic signature solution
The choice of a tool is not limited to comparing prices per envelope of signatures. Several technical criteria deserve special attention:
- The compliance of the trust service provider (verifiable on the European Trusted List), which conditions the legal admissibility of the signatures produced.
- The supported signature format: PAdES for PDFs, XAdES for XML documents, CAdES for binary files. A tool that only offers PAdES may block certain business workflows.
- The ability to integrate a configurable MFA process, tailored to the risk level of each type of document.
- The archiving with probative value and the qualified timestamping included natively, without a paid add-on module.
One last point often overlooked: cryptographic longevity. The hashing and encryption algorithms used today (SHA-256, RSA 2048) will need to evolve in the face of future computing capabilities. A serious solution already plans a roadmap towards post-quantum algorithms.
The electronic signature is not just a comfort tool. It is a building block of documentary infrastructure whose technical solidity conditions the legal value of all the commitments it carries. It is better to invest a few hours in evaluating the system than to discover its flaws in court.