How to open a .p7m file

What is a .p7m file?

P7M is the file format of a CAdES digital signature, the European standard that Italian companies, public offices, notaries and accountants use to sign documents. The file is not the bare document: it is a cryptographic envelope that holds three things together:

• the original document (a PDF, an XML invoice, a Word file, an image…);
• the signature computed over the content, which reveals any later change;
• the signer’s certificate, with their name, Italian tax code (codice fiscale) and the certificate authority that issued it.

That is why signed files often have a double extension: contract.pdf.p7m is a signed PDF, IT01234567890_00001.xml.p7m is a signed Italian e-invoice, minutes.docx.p7m a signed Word document.

Where these files come from

If you live, work or do business in Italy, you will meet .p7m files sooner or later: e-invoices (fatture elettroniche) from Italian suppliers, which travel through the tax agency’s exchange system (SdI) and often arrive as .xml.p7m; contracts and rental agreements signed by an Italian landlord or agency; documents from an accountant (commercialista), a notary or a public office; and attachments received by PEC, Italian certified email.

Why your computer cannot open it

Windows, macOS, iOS and Android have no built-in P7M viewer: double-click the file and the system asks which app to use. Renaming the file to remove “.p7m” usually does not work, because the document is still inside the cryptographic envelope, preceded by the signature data.

Three ways to open a .p7m

1. Digital-signature software distributed by Italian certificate authorities. It works well, but it is mostly in Italian, has to be installed and often needs administrator rights.
2. An online verification service: convenient, but in most cases the file is uploaded to someone else’s server. For contracts, deeds or invoices that is not always acceptable.
3. ApriP7M, in your browser: the page already contains all the code it needs and opens the envelope on your device. The file is not transmitted, and the page technically prevents the browser from sending it anywhere.

Opening a .p7m with ApriP7M, step by step

1. Drop the file onto the box above, or tap “choose from your device”.
2. The name of the enclosed document appears straight away, with the result of the integrity check (“Signature intact” or “Signature NOT intact”).
3. Press Download to save the original document (PDF, XML, DOCX…). If it is an Italian e-invoice, you already see it as a readable document with English labels, and you can print it or download it as a PDF.

Reading an Italian e-invoice

An Italian e-invoice is an XML file in the FatturaPA format, which is hard to read as raw text. ApriP7M shows it as a normal invoice: supplier (cedente/prestatore) and customer (cessionario/committente), invoice lines, the VAT summary with rates and VAT “nature” codes, totals, payment terms, due dates and IBAN. Codes such as TD01 (invoice), MP05 (bank transfer) or N6.3 (reverse charge in construction subcontracting) are spelled out in English. Descriptions written by the supplier are shown as written, usually in Italian.

The readable view and the PDF are courtesy copies. The legally valid invoice is the original XML file, so keep it (and the .p7m) for your records or your accountant.

What the signature check means

ApriP7M checks that the document has not been changed since it was signed and shows the certificate details. It is not a qualified verification: it does not consult the EU or AgID trusted lists or the certificate revocation lists, and it cannot tell you whether a document is legally valid. If you need an official verification, use a qualified validation service.

Supported files

• .pdf.p7m, .xml.p7m, .docx.p7m and any other CAdES-signed document (including streamed BER encoding);
• files with several nested signatures (.p7m.p7m), with every signer listed;
• .p7m files saved as Base64 or PEM, as some PEC mailboxes do;
• timestamped .m7m and .tsd files;
• unsigned Italian e-invoice XML files.

.p7s files contain only the signature, without the document: for now ApriP7M recognises them and tells you so.