Frequently asked questions
Sealing: technical, legal and operational questions.
For any query not covered in this section, please write to our contact address.
What is a SHA-256 fingerprint?
A 64-character string calculated from the complete content of the file. The same file always produces the same string, and any modification, however small, produces an entirely different one. It is the standard used in the financial sector and in software signing.
Is the document transmitted to any server?
No. Sealing is executed entirely in the user's browser. Only the fingerprint, the file name, the page count and the date are sent to the register. The content of the document never leaves the device.
Can the document be reconstructed from the fingerprint?
No. A hash function operates in one direction only: the fingerprint is derived from the file, but the fingerprint does not allow the file to be recovered. Publishing it on a verification link therefore discloses no information about the content.
What happens if a sealed document is modified?
Its fingerprint ceases to match the one on record and verification returns a negative result. A file cannot be modified while retaining its fingerprint: this is precisely what the SHA-256 function prevents.
Does the seal affect the design of the document?
No. The visible mark occupies approximately 6 millimetres and is applied at 15% opacity in a corner of each page. No fonts or text blocks are embedded, so the layout does not shift. The fingerprint is stored in the PDF metadata.
What value does it hold in proceedings?
It constitutes technical evidence of integrity and of date, and may be submitted as such. It is not a qualified electronic signature within the meaning of the eIDAS Regulation and does not replace one where a procedure requires it. In such cases a qualified provider should be engaged, without prejudice to also sealing the document.
Which formats are supported?
PDF, Word (DOCX), PowerPoint (PPTX), images and plain text, up to 50 MB per document. Formats other than PDF are converted in the browser before sealing, as the seal is always applied to a PDF.
Is an account required in order to verify a document?
No. Verification is free of charge, unlimited and requires neither a user account nor any installation: it is sufficient to open the public link or upload the PDF on the verification page.
Does it work without an internet connection?
Sealing does, as it is executed in the browser. A connection is required for registration of the fingerprint — necessary for the public link to operate — and for checking a verification. Where sealing is performed offline, registration completes once the connection is restored.
Can it be integrated into our own systems?
Yes, by means of the Business plan, which includes a REST API access key. Documentation generated by your software is issued already sealed and with its verification link.
Further enquiries.
For matters not covered in this section, please write to our contact address.