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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如何在线为 PDF 文件加封并附带法律时间戳

Philipp Stuppnik · Co-Founder & IP Strategy

2026年6月3日 8 分钟阅读最后更新 2026年9月8日

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In short

为任意 PDF 添加符合 ZertES 认证的加密封印的分步指南。在瑞士和 27 个欧盟成员国均可作为法庭证据，无需硬件令牌。

2025年3月，一家总部位于巴塞尔的UX设计公司在合同签署之前就向一家A轮初创公司交付了完整的品牌形象方案。两周后，该初创公司新聘的内部设计师声称这些作品是自己的成果。该机构没有对交付文件加盖合格时间戳。初创公司的律师只问了一个问题：证明你们先完成了这些工作。该机构无法在法庭上给出答复。纠纷持续了五个月，产生了18万瑞士法郎的法律费用。该机构既输了官司，也失去了客户关系。

在线为PDF文档加盖带有法律效力的时间戳，是个人或企业保护文档完整性和来源的最直接措施之一。经ZertES认证的密码学印章能创建具有司法可采性的证据，证明特定PDF在经过认证的时间点以其确切的当前形式存在。这一证据在瑞士、所有27个欧盟成员国以及181个伯尔尼公约成员国均有效。

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使用由 Swisscom Trust Services 支持的司法认可 e-Seal 封存您的知识产权。

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