How do I create a legally valid sealed PDF document?

To create a legally valid sealed PDF with a qualified electronic timestamp: (1) Upload your PDF to Swiss Trust Layer; (2) The platform computes a SHA-256 cryptographic hash of your document; (3) The hash is submitted to a QTSP (Qualified Trust Service Provider) on the EU Trusted List, which issues a qualified electronic timestamp per eIDAS Art. 42; (4) The timestamp is embedded in the PDF in accordance with PAdES (PDF Advanced Electronic Signatures) format, defined in ETSI EN 319 132; (5) You receive a sealed PDF that any recipient can verify. The result is a court-admissible sealed PDF with a legal presumption under eIDAS Art. 41(2) that it existed in its exact form at the recorded date. This presumption is valid across all 27 EU member states and Switzerland.

What is the difference between a sealed PDF and a signed PDF?

A sealed PDF has been processed with an electronic seal or qualified timestamp that proves the document was not altered from a specific point in time. It authenticates the document's integrity and date, but does not identify a specific individual as having consented. A signed PDF has an electronic signature applied by a named individual, proving that person authenticated and consented to the content. For IP protection (proving a document existed in a specific form at a specific date), a qualified electronic timestamp is the appropriate tool, with no counterparty needed. For contracts and agreements (proving specific individuals agreed to terms), an electronic signature is required. Swiss Trust Layer provides qualified electronic timestamps; for electronic signatures you would use a QTSP electronic signature service.

Can a sealed PDF be altered after sealing?

No. A sealed PDF contains a cryptographic hash of the document's exact content at the time of sealing. Any alteration to the document, even a single character change, produces a completely different hash, making the seal invalid. When you or any third party verifies the sealed PDF, the verification tool recomputes the hash of the current document and compares it to the hash embedded in the qualified timestamp. If they match, the document is unaltered. If they differ, verification fails and the document is flagged as modified. This tamper-evidence property is cryptographic. It does not rely on trust in any party. Swiss Trust Layer's verification page allows anyone to verify a sealed document without login.

Is a sealed PDF valid as evidence in EU courts?

Yes, when the seal is a qualified electronic timestamp from a QTSP on the EU Trusted List under eIDAS Art. 22. A qualified electronic timestamp carries a legal presumption under Art. 41(2) that the data it covers was created at the time indicated. This presumption is directly applicable in all 27 EU member states and constitutes legally admissible evidence without additional authentication requirements. For Swiss courts, the equivalent is a qualified electronic timestamp from a recognised certification service provider under ZertES SR 943.03. Swiss Trust Layer's timestamping service meets both eIDAS and ZertES standards, making sealed PDFs from the platform valid evidence in both Swiss and EU proceedings.

How long is a sealed PDF legally valid?

A sealed PDF's legal validity is technically permanent. The cryptographic hash proves the document's state at the time of sealing indefinitely. However, the cryptographic algorithms used (e.g., SHA-256, RSA-2048) may eventually become obsolete as computing power increases. To protect long-term validity, PAdES long-term validation (LTV) profiles (ETSI EN 319 132) embed all verification material (certificate chain, revocation status) at the time of signing, ensuring the sealed PDF can be verified even after certificates have expired. Swiss Trust Layer applies PAdES-LTV profiles automatically, protecting sealed PDFs for decades. For documents that require very long-term legal validity (30+ years), re-timestamping every 10 to 15 years as an additional security measure is recommended.

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Come Sigillare un Documento PDF Online con Marca Temporale Legale

Philipp Stuppnik · Co-Founder & IP Strategy

3 giugno 2026 8 min letturaUltimo aggiornamento 8 settembre 2026

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In short

Guida passo dopo passo all'applicazione di un sigillo crittografico certificato ZertES a qualsiasi PDF. Ammissibile in giudizio in Svizzera e nei 27 Stati membri dell'UE. Nessun token hardware richiesto.

Nel marzo 2025, un'agenzia UX con sede a Basilea ha consegnato un'identità di marca completa a una startup in fase Series A prima che il contratto fosse controfirmato. Due settimane dopo, il nuovo designer interno della startup ha rivendicato il lavoro come proprio. L'agenzia non disponeva di un timestamp qualificato sui file di consegna. Gli avvocati della startup avevano una sola domanda: dimostrare di aver creato il lavoro per prima. L'agenzia non è riuscita a rispondere in tribunale. La controversia è durata cinque mesi ed è costata CHF 180.000 in spese legali. L'agenzia ha perso sia la causa che il rapporto con il cliente.

Apporre un sigillo su un documento PDF online con un timestamp legale è uno dei passi più diretti che un individuo o un'azienda possa compiere per proteggere l'integrità e la provenienza dei propri documenti. Un sigillo crittografico certificato ZertES crea una prova ammissibile in giudizio che un PDF specifico esisteva nella sua forma esatta in un momento certificato. Tale prova è valida in Svizzera, in tutti i 27 Stati membri dell'UE e in 181 paesi della Convenzione di Berna nel mondo.

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