---
title: "Subject identifier formats configuration (SubjectIdentifier) - Rest PKI Core"
description: "How to restrict on the dashboard the SubjectIdentifier formats (CPF, CNPJ and e-mail) accepted in Rest PKI Core biometric sessions."
canonical: "https://docs.lacunasoftware.com/en-us/articles/rest-pki/core/integration/bio-sessions/configs/subject-identifier-formats"
locale: "en"
product: "Rest PKI Core"
last_updated: "2026-10-12"
---

# Subject identifier formats configuration (SubjectIdentifier) - Rest PKI Core

`SubjectIdentifier` is a field that ties the biometric session to a specific person using your system.

By default, the system accepts any identifier format. If you want to restrict which formats are allowed in your application's sessions,
follow the steps below:

1. Sign in to the dashboard of your instance.
2. On the left menu, click **Settings**.
3. Find the **Biometric settings** section.
![Biometric settings section](https://docs.lacunasoftware.com/images/rest-pki/core/subject-identifier-section.png)
4. Click **Edit** and, under **Allowed subject identifier formats**, select the formats you want to allow: CPF, CNPJ and/or Email.
![Allowed subject identifier formats](https://docs.lacunasoftware.com/images/rest-pki/core/subject-identifier-config.png)
5. Click **Save** to apply the settings.