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Process automation is the engine of competitiveness, but issuing thousands of digital documents a day requires an irrefutable mechanism that guarantees their origin and prevents tampering. The electronic seal is the definitive cryptographic tool that solves this challenge. Acting as the digital and secure equivalent of the traditional corporate rubber stamp, it allows legal entities to authenticate documents on a massive scale without human intervention.
If you’re wondering what an electronic seal is, what the differences are between an electronic signature and an electronic seal, or how the eIDAS Regulation governs their validity across Europe, this technical guide covers everything you need to know to implement it in your company.
What is an electronic seal?
An electronic seal is a set of data in digital format, attached or logically associated with an electronic document, which serves to guarantee the origin and unalterable integrity of said document. Unlike other digital identity solutions, the electronic seal is linked solely and exclusively to a legal entity (a company, institution, or government entity), and not to a natural person.
Its purpose is not to express human consent regarding a contract, but to automatically certify that a document has been officially issued by an organization and has not been altered since the time of its sealing.
Types of Electronic Seals
Regulation (EU) No. 910/2014 (known as eIDAS) classifies seals into three levels, depending on their technological robustness and their evidentiary weight in court. Choosing the appropriate type is essential to ensure the validity of transactions and avoid legal risks in the corporate environment:
- Simple electronic seal: Consists of electronic data attached to other data. It is fast but offers a low level of security, as it does not allow the issuing company to be identified with full guarantees against repudiation.
- Advanced electronic seal: Meets strict security requirements. It is uniquely linked to the creator, allows for the identification of the legal entity, is created using data under its exclusive control, and detects any subsequent modification to the file.
- Qualified electronic seal: This is the highest security standard. It is an advanced seal created using a Qualified Seal Creation Device (QSCD) and backed by a qualified certificate issued by a Qualified Trust Service Provider (QTSP). It enjoys a legal presumption of integrity throughout the European Union.
How an electronic seal works
The operation of the electronic seal is based on Public Key Infrastructure (PKI) and asymmetric cryptography. This system uses a pair of linked mathematical keys: a private key (securely stored in an HSM or cryptographic server by the company) and a public key that is available for any recipient to quickly verify the document.
To ensure maximum technical robustness, the process operates under three unbreakable principles, starting with the principle of authenticity. This mechanism irrefutably ensures that the document originates exactly from the legal entity claiming to have issued it, eliminating any risk of identity theft in digital workflows.
Furthermore, the principle of integrity guarantees that the content has not been altered in any way, since if a single bit is changed, the seal is immediately broken, alerting to the tampering. Added to this is the principle of Non-Repudiation, which prevents the issuing company from denying authorship of the issuance, as the private key is under its exclusive control.
The step-by-step sealing process
When an organization automates its sealing process through internal systems such as an ERP or CRM, the technology executes a series of sequential steps in a matter of milliseconds to ensure the cryptographic security of each issuance without slowing down operational efficiency:
- Hash generation: The software takes the original file (PDF or XML) and generates a unique alphanumeric digital fingerprint called a "hash."
- Asymmetric encryption: The system uses the company’s private key to encrypt that hash, linking it to the organization’s identity.
- Timestamping: A qualified timestamp from a trusted third party is added, certifying the exact time (second, minute, and hour) of the transaction.
- Issuance and public verification: The document is sent to the recipient. The recipient uses the company’s public key to decrypt the hash; if the result matches the received document, the origin is confirmed as legitimate and the content is intact.
One of the most common questions in the corporate environment is understanding the differences between electronic signatures and electronic seals. Although both tools use identical cryptographic foundations, their legal purpose and use cases are substantially different.
An electronic signature is linked to a natural person and requires their conscious, manual action at the time of signing to demonstrate consent, approval, or legal intent regarding an employment contract or commercial agreement. In contrast, an electronic seal is linked to a legal entity and can be generated automatically and in bulk without human intervention, with the sole purpose of guaranteeing the origin and integrity of data in bulk invoices, pay stubs, or delivery receipts.
Can a company use both? Absolutely. In fact, it is the best operational practice within a comprehensive digitization strategy. A company will use the business electronic seal in its automated processes, such as sending a thousand structured invoices per month unattended, while it will require the electronic signature of its legal representatives when it needs to carry out actions involving human intent, such as closing a commercial agreement with a new supplier, signing an NDA, or formalizing a termination.
What is the electronic seal used for? Practical use cases
To better understand its application, an example of an electronic seal can be visualized in daily corporate automation processes. Since it does not require human intervention, it is ideal for preventing fraud across multiple sectors:
- Electronic invoicing: This is the most critical use case. When issuing invoices in structured formats (such as Facturae or UBL), the seal guarantees to the Tax Agency and the customer that the amounts and line items have not been tampered with.
- Banking and financial sector: To seal account statements, transfer receipts, and bulk policies, providing immediate legal validity to the customer without requiring signatures from authorized representatives.
- Human resources: Automation of the issuance of thousands of monthly pay stubs, withholding certificates, and official shift schedules.
- Healthcare and laboratories: Automated sealing of clinical test results, medical records, and electronic prescriptions to ensure traceability and compliance with the GDPR.
- Public sector and institutions: Universities use it to issue digital academic degrees and grade transcripts that are impossible to forge.
Key benefits of the electronic seal
The adoption of the electronic seal for businesses is not just a matter of regulatory compliance, but a direct strategy for optimizing resources and mitigating operational risks. Corporate benefits include:
- Automation without bottlenecks: Since manual intervention by an authorized representative or administrator to “sign” each document is not required, workflows become immediate and scalable.
- Cost and paper reduction: It eliminates the need to print, stamp, scan, and physically file corporate documents, drastically reducing administrative expenses.
- Protection against fraud and phishing: By sending sealed documents, clients and recipients have the technical assurance that they are not falling victim to identity theft.
- Brand trust: It projects an image of modernity, security, and transparency in the market, especially in B2B transactions.
Corporate benefits include these operational improvements that provide legal protection for any large-scale process. As a result, the company can focus on scaling its business model without fear of potential security breaches.
Legal Framework for Electronic Seals in Europe and Spain
The validity of electronic seals in Europe is guaranteed by the eIDAS Regulation (EU Regulation No. 910/2014), which establishes a unified framework of trust and legal guarantees.
It provides a cross-border legal framework where a qualified electronic seal issued in Spain has exactly the same legal recognition throughout the European Union.
It also grants enhanced evidentiary validity, whereby the sealed document is presumed authentic in court, reversing the burden of proof in the event of a dispute; thus, whoever alleges that it is false must prove it.
Legal Requirements for the Validity of an Advanced Seal
According to Article 36 of the eIDAS Regulation, for an electronic seal to enjoy full guarantees and not be easily repudiated in court, it must comply with these mandatory technical requirements that ensure its absolute reliability. First, it is essential that the seal be uniquely linked to the seal creator—that is, the legal entity—thus allowing for the unambiguous identification of that entity.
Furthermore, this seal must have been generated using creation data that the holder can manage under their exclusive control, either through the use of secure hardware or through its cloud-based custody by a Qualified Trust Service Provider (QTSP). Finally, it must be associated with the document in such a way that any subsequent attempt at manipulation or alteration is immediately and cryptographically detected by the validation software.
Is the electronic seal mandatory in any cases?
Yes, legislation is moving toward its mandatory use in numerous scenarios, establishing the qualified or advanced electronic seal as the standard technology to guarantee the authenticity and integrity of operations in the following key areas:
- B2G Invoicing: It is strictly mandatory when sending structured invoices (Facturae) to the General Entry Points of Public Administrations (such as FACe in Spain).
- B2B Invoicing: With the entry into force of the Crea y Crece Law in Spain, electronic invoicing will become mandatory for all companies and self-employed individuals on a phased basis. The technical regulation implementing this law requires methods that guarantee the authenticity and integrity of the invoice, establishing the advanced qualified electronic seal as the standard technology for compliance.
- Highly Regulated Sectors: Areas such as banking, insurance, and healthcare (where data traceability is mandatory) require the use of seals to comply with sector-specific regulations on anti-money laundering and data protection.
How to Implement Electronic Seals in Your Company
To obtain a signed and automated electronic seal quickly, companies must move away from manual processes and integrate solutions via APIs, ensuring secure implementation by connecting their management software.
Below, we detail the key steps for a successful implementation that allows for the issuance of secure documents without operational friction:
- Identifying needs: Define which internal or external document processes require urgent automation (for example: bulk issuance of invoices, standardized contracts, delivery notes, or pay stubs).
- Selecting a QTSP and obtaining the certificate: You must obtain the legal entity representative certificate for the electronic seal through a Qualified Trust Service Provider (QTSP) accredited by the relevant ministries or the EU.
- Verification process: As a legal entity, to obtain the certificate you must provide reliable proof of the company’s legal existence and the legal representatives’ authorization to request the seal.
- Secure custody and technological integration: The certificate must never be installed on vulnerable local computers. It can be hosted on a secure local server (HSM) or, as is more common today, stored in the cloud. This is done by connecting the company’s management software (ERP, CRM, or billing system) to the QTSP platform via real-time APIs.
- Automated issuance: When the ERP generates a final document, it automatically calls the trusted platform’s API. The platform applies the seal and the qualified time stamp in milliseconds, and returns the document secured, tamper-proof, and ready for automatic delivery to the customer.
Platforms and solutions for using electronic seals without complexity
The use of specialized platforms transforms document management, eliminating friction and automating comprehensive regulatory compliance (eIDAS and GDPR). Notable solutions include Tecalis Sign, which allows for the bulk signing and automated sealing of PDF or XML documents. Integrating the electronic seal via APIs from leading providers reduces internal development costs and ensures that the cryptography used is always up to date with European regulations.
