A qualified electronic seal is a regulated trust service used by an organization to attach proof of origin and integrity to an electronic document or data set. Unlike an electronic signature, which identifies a natural person, a seal represents the legal person behind the document. It is created with a qualified certificate and a protected seal-creation device, so recipients can verify that the document came from the stated organization and was not altered after sealing.
In cyber security, seals matter because they help defend against document forgery, tampering, and spoofed business communications. They are commonly used for invoices, statements, onboarding records, and other documents that must remain trustworthy after delivery. Defenders rely on seal validation, key protection, access control, and audit logs to reduce abuse. Attackers may try to steal sealing keys, impersonate an issuing system, or tamper with the workflow before sealing happens. A valid seal does not prove the internal accuracy of the content, but it does provide strong evidence that the organization issued that exact file.