---
title: "Signature types"
description: "Signer's Simple, Advanced and Qualified signature types: what each produces, when the ITI validator accepts it, the API default and what happens to a PDF that arrives already signed."
canonical: "https://docs.lacunasoftware.com/en-us/articles/signer/concepts/signature-types"
locale: "en"
product: "Signer"
last_updated: "2026-10-22"
---

# Signature types

When the instance has signature types turned on, whoever creates a document picks one of these types:
**Simple**, **Advanced** or **Qualified**. The type sets how participants can sign and how Signer validates the
signatures.

The instance's `SignatureTypes` setting turns the types on and sets the screen default. See
[*Signature Types* settings](https://docs.lacunasoftware.com/en-us/articles/signer/on-premises/settings#app-signature-types).

## What each type produces

| Type | How the participant signs | What the file gets | What validation accepts |
|---|---|---|---|
| Simple | Electronic signature only. | One platform signature, added when the document is concluded. | Simple electronic signatures. It also accepts advanced ones if `Simple.AllowAdvancedElectronicSignatures` is on. |
| Advanced | With the means the **security context** allows. The context is required and sets the accepted authentications and the trusted certificates. | One signature per signer. | What the security context accepts. It accepts simple electronic signatures only if `Advanced.AllowSimpleElectronicSignatures` is on. |
| Qualified | Digital certificate only. Electronic signature is off. | One signature per signer. | Digital certificates only. By default, only ICP-Brasil certificates. |

For an electronic signature, Signer signs the file with a certificate of the platform itself. By default, that
certificate is **self-signed**, that is, no Certificate Authority issued it.

## ITI validator

The ITI (gov.br) signature validator accepts a qualified signature made with the signer's own ICP-Brasil
certificate. You do not need to set anything up.

The validator rejects electronic signatures of the Simple and Advanced types, because the platform certificate is
self-signed. For the validator to accept them, the instance must sign with an ICP-Brasil certificate, such as the
company's e-CNPJ A1. From version 1.52.0, the instance uses the PFX file in the `certificates` folder of its
Blob Storage. The [`SignatureCertificate`](https://docs.lacunasoftware.com/en-us/articles/signer/on-premises/settings#signature-certificate) section
names the file and its password, and the `ElectronicSignature:UseSignatureCertificateAsSelfSignedCertificate`
setting makes Signer use that certificate instead of the self-signed one.

The validator shows the name in the certificate. With an e-CNPJ, it shows the company name.

> **Note: SaaS**
>
> If you use Signer in the cloud (SaaS), send the PFX and its password to Lacuna support through a secure channel.
> Support sets it up.

## Document created through the API without a type

If the creation request does not send the `signatureType` field, the document has **no type** (`None`). Signer
does not use the screen default (`SignatureTypes:DefaultType`), because that setting applies to the screen only.

A document without a type follows the rules of none of the three types. Each participant signs with the means the
request gave, and Signer does not restrict the authentication or the certificate.

To get a type, send `signatureType` on creation. For the `Advanced` type, also send `securityContextId`. A document
created from a template gets the template's type. See
[Creating documents](https://docs.lacunasoftware.com/en-us/articles/signer/integration/documents).

## A PDF that arrives already signed

Signer adds new signatures without rewriting the file. So signatures made outside Signer stay valid, in any type.

There are some exceptions and limits:

* An **envelope** joins several PDFs into one. When joining them, Signer removes the signatures the PDFs already
  had, because they would no longer be valid.
* Conversion to PDF/A also removes existing signatures.
* On a signed PDF, Signer does not apply the validation stamp. Initials and other placed marks may also be
  missing.
* With the Qualified type, an external signature made with a certificate from outside ICP-Brasil shows as invalid
  in Signer's validation. The file does not change.

If the external signatures must stay in the file, do not send the PDF inside an envelope.