---
title: "Diploma revalidation"
description: "Why digital diploma signatures need revalidation, and how Digiploma restamps the archive timestamp automatically to keep them verifiable."
canonical: "https://docs.lacunasoftware.com/en-us/articles/digiploma/revalidation"
locale: "en"
product: "Digiploma"
last_updated: "2026-10-11"
---

# Diploma revalidation

A digital diploma must remain verifiable for as long as its holder needs it, but every certificate behind its signatures expires: the
certificates of the people and institutions who signed it, and the certificates of the timestamp authorities (*ACTs*) that timestamped
those signatures. **Revalidation** (*revalidação*) is the periodic renewal of the diploma's archive timestamp, which keeps its signatures
verifiable after all of them expire. Digiploma does it automatically and calls it **restamping** (**Renotarização**).

> **Note**
>
> This page is about the signatures of digital diplomas. It is not about the revalidation of diplomas issued abroad, which is an academic
> process outside Digiploma.

## Why signatures need revalidation

The signatures of `DadosDiploma` and `DadosRegistro` carry a signature timestamp, issued by an ICP-Brasil timestamp authority. The
timestamp proves when the signature was made, so the signature stays valid after the signer's certificate expires. But the timestamp is
itself signed, and it can be verified only while the certificate of the timestamp authority is valid. After that, nothing proves any
longer that the signatures existed before their certificates expired.

That is why the diploma XML ends with an **archiving signature** of the whole document, with the ICP-Brasil **AD-RA** policy. It covers
the whole file, including the signatures of `DadosDiploma` and `DadosRegistro`, stores the certificates and revocation lists (LCRs) that
validate it, and carries an **archive timestamp**. Before that archive timestamp expires, a new one, from a newer certificate, is added
over everything; and so on, for as long as the diploma must remain verifiable. The academic documentation XML follows the same rule (see
[Who signs what](https://docs.lacunasoftware.com/en-us/articles/digiploma/signatures#who-signs-what)).

The PKI SDK article [AD-RT signature lifecycle](https://docs.lacunasoftware.com/en-us/articles/pki-sdk/signatures/policies/adrt-lifecycle) shows this timeline, policy by policy.

## How Digiploma revalidates

![The restamp cycle of a signed document in Digiploma](https://docs.lacunasoftware.com/images/digiploma/restamp-cycle.svg)

1. When Signer concludes a document, Digiploma creates a **restamp record** for each signed file, with the date its archive timestamp
   expires: the end of validity of the timestamp authority's certificate in the last archive timestamp.
2. Every night, a job picks the records that expire in less than 180 days (by default).
3. For each one, Digiploma requests a new timestamp from its timestamp server and adds it as a new archive timestamp to the archiving
   signature. The renewed file replaces the one Digiploma keeps.
4. Digiploma creates the next record, for the new expiration date. A restamp that fails is marked `WithError` and retried on the
   following nights.

Digiploma revalidates diplomas (both XML files), final academic transcripts and second copies, curriculums and, when the instance enables
it, registration requests. See [Restamps](https://docs.lacunasoftware.com/en-us/articles/digiploma/api/restamps) for the details.

> **Caution: A new archive timestamp needs a new certificate**
>
> A renewal extends the expiration only if the new timestamp is signed by a different certificate of the timestamp authority than the
> previous archive timestamps. Otherwise the restamp fails and is retried on the following nights.

## Follow the revalidation

* In the web application, the **Renotarizações** (Restamps) menu lists the records of the organization, and each diploma, transcript,
  curriculum and registration has a **Renotarizações** tab with its own records.
* In the API, [`GET /api/restamps`](https://docs.lacunasoftware.com/en-us/articles/digiploma/api/restamps#list-restamps) lists the records, by status: `NonRestamped` (pending), `Restamped`
  or `WithError`.
* The `RestampCreated`, `RestampUpdated`, `RestampApplied` and `RestampApplyingError` [webhooks](https://docs.lacunasoftware.com/en-us/articles/digiploma/api/restamps#webhooks) report each
  step, when the instance enables them.

Download the files from Digiploma after they are revalidated: the copy in Signer does not have the new archive timestamps (see
[Where the signed files are](https://docs.lacunasoftware.com/en-us/articles/digiploma/signatures#signing-a-diploma-end-to-end)).

## On premises

Revalidation needs a timestamp server, under the **Timestamper** section of the settings, and is controlled by the **Restamp** section:
the advance (`RestampDocumentsBeforeExpiringInDays`, 180 days), the number of documents per run, and `DisableRestamp`, which turns it off
for the whole instance. See [Restamp and timestamp settings](https://docs.lacunasoftware.com/en-us/articles/digiploma/on-premises/settings#restamp-and-timestamp-settings). The instance
administrator can also turn it off for a single organization.

## See also

* [AD-RT signature lifecycle](https://docs.lacunasoftware.com/en-us/articles/pki-sdk/signatures/policies/adrt-lifecycle) (PKI SDK)
* [Signatures and Lacuna Signer](https://docs.lacunasoftware.com/en-us/articles/digiploma/signatures)
* [Restamps](https://docs.lacunasoftware.com/en-us/articles/digiploma/api/restamps)