Open a .p7m signed file

You can open a .p7m file in your browser with Klarbon: drop it on the page and you get the original document back, with its real name, plus who signed it and whether the file has changed since it was signed. It is free, needs no account and the file never leaves your device. Opening .p7m files is in beta.

What is a .p7m file?

A .p7m file is a document wrapped in a digital signature. Inside is the original file, a PDF, an XML invoice, a Word document or an image, together with the signer's certificate and the signature itself, in the Cryptographic Message Syntax (RFC 5652) with the CAdES profile (ETSI EN 319 122-1). In Italy the qualified electronic signature, the firma digitale, is very often a .p7m (AgID, in Italian), which is why contracts, certificates and e-invoices arrive as name.pdf.p7m or name.xml.p7m. More in what is a .p7m file.

Double-clicking one usually fails because the computer does not know the .p7m extension. The document is still there, inside the signature.

How do I open it?

1. Choose the .p7m file or drop it on the page. A file signed more than once (.p7m.p7m) and a .p7m saved as base64 text both work.
2. Klarbon reads the signature on your device and gives back the original file, named without the .p7m.
3. A PDF or an image appears in the page; a text file is shown as text. An e-invoice inside opens in the invoice viewer.
4. Choose Save to keep the original, for example contratto.pdf, and open it in the app you normally use.

What does the signature check show?

For each signer Klarbon shows the name, the organisation, the tax code where the certificate has one, who issued the certificate, its serial number and validity dates, the signing time written in the file and whether the certificate says it is qualified.

It also checks two things on your device: that the content still matches the digest that was signed, and that the signature verifies with the signer's certificate key (RSA, RSA-PSS or ECDSA). When both hold, it says the file is unchanged since it was signed with this certificate.

For a legally relevant verification, use the verification service of a qualified trust service provider.

Is my file uploaded?

No. The signature is read and removed entirely in your browser, so the document stays on your device. See what happens to your files.

What if the file is an e-invoice?

An Italian IT01234567890_00001.xml.p7m holds a FatturaPA invoice. Klarbon opens it straight in the FatturaPA viewer, so you read the supplier, the lines, the VAT and the amount due, and can save a PDF copy. For the rules in Italy, see e-invoicing in Italy.

What next?

• Open any other e-invoice
• Prices and limits and the help centre
• All tools: Klarbon tools