# Open .tsd and .m7m timestamp files

> Open an Italian time-stamped .tsd or .m7m file in your browser, extract the document and check the time, authority and imprint of each timestamp.

Free in-browser tool (no upload): https://www.mauriziofonte.it/tools/open-tsd-m7m-timestamp-file

A **.tsd** or **.m7m** file is not a 3D scene: in Italy it is a document, often already signed as a .p7m, packed with its **timestamp** (marca temporale), a trusted date issued by a time-stamping authority. Open it here in your browser, get the document out and see, for each timestamp, the time, the authority and whether the imprint still matches the data. The file is not uploaded.

## How to open a time-stamped file

1. **Load the file** - Drop the .tsd or .m7m on the box, or tap it to pick the file from your phone or computer. The file is not sent to a server.
2. **Read the timestamps** - Each timestamp shows its trusted time, the authority that issued it, whether its imprint matches the data and whether the authority was qualified at that time.
3. **Get the document** - Download the stamped document, or open it in a new tab if it is a PDF or an image. If it is a signed .p7m, the viewer opens it and shows who signed it.
4. **Keep the report** - Copy report gives you a plain text with time, authority and the result of each check, ready to attach to a file or forward.

## What the timestamp check looks at

A timestamp is a small document signed by a time-stamping authority that says: this data existed at this moment. It does not hold the data, it holds its **imprint**, a value computed from the data with a hash function (usually SHA-256). Change one byte of the document and the imprint no longer matches.

The viewer runs three checks on each timestamp. It recomputes the imprint over the data the timestamp travels with and compares it with the one the authority recorded. It verifies the timestamp's signature with the authority certificate carried in the file. It looks the authority up in the EU trusted lists to see whether, on that date, it was a qualified time-stamping service.

In a .tsd the first timestamp covers the content (and the metadata, when the file says they are protected). Later timestamps are **renewals**: each one covers the previous timestamp, so the trusted date outlives the expiry of the authority certificate. The viewer checks the whole chain and tells you which link fails, if one does.

An .m7m holds a single timestamp, computed over the .p7m file packed with it. If the timestamp of another document was paired with it by mistake, the imprint does not match and the viewer says so.

The document inside is extracted as it is. If it is a .p7m, a digitally signed document, the viewer opens it and shows who signed it.

## Glossary

- **Timestamp (marca temporale)**: A statement signed by a time-stamping authority that binds a date and time to the imprint of some data.
- **Imprint**: The output of a hash function computed over the data: it changes completely if a single byte changes.
- **Time-stamping authority (TSA)**: The body that issues timestamps; a qualified one appears in the EU trusted lists.
- **Renewal**: A new timestamp placed over the previous one, so the trusted date outlives the expiry of the authority certificate.

## Questions about TSD and M7M files

### What is a .tsd file from Italy?

It is a document packed with its timestamp in the standard RFC 5544 format, often used by Italian public offices, notaries and accountants. The document inside is frequently a signed .p7m, so the name ends in .pdf.p7m.tsd. Open it here to get the document and see the timestamp details.

### How do I open an .m7m file?

Drop it on this page: the viewer separates the signed .p7m from the timestamp, checks the timestamp and lets you download the document. You do not need the Italian signing software that created it.

### My .tsd file will not open in my 3D program. Is it broken?

Probably not: it is a different kind of file with the same extension. A 3D scene .tsd and an Italian time-stamped .tsd share nothing but the three letters. If the viewer here opens it, it is a timestamp file.

### What does a timestamp prove?

That the data existed in that exact form at that time, as attested by the authority. It does not say who wrote or signed the document: that is the job of the digital signature inside the .p7m.

### What if the imprint does not match?

The data in the file is not what the authority stamped: either the document was changed after stamping or the timestamp belongs to another document. In both cases the trusted date does not apply to this content.

### How do I know the authority was qualified?

The viewer looks the authority up in the EU trusted lists published by the member states and checks the service status on the date of the timestamp. An authority that is not listed issues ordinary timestamps, without the legal presumption of a qualified one.

### Is my file uploaded anywhere?

No. The file is read in your browser and the cryptographic checks use the browser's own functions. The only network request downloads the part of the EU trusted lists that concerns the timestamp authority, chosen by the first byte of its key identifier: nothing about the document is sent.

### Can I rely on this check in court?

It is a technical check that helps you read the file and see whether it holds together, but it does not check certificate revocation and does not issue a report with legal standing. For formal use, rely on the verifier of the timestamp provider.

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Tool by Maurizio Fonte, senior backend engineer. All tools: https://www.mauriziofonte.it/tools/