How to download an e.firma public certificate

On this page we explain how to verify if an e.firma is valid and how to download the corresponding public certificates (.cer files).

Before starting, it is necessary that you have the RFC you want to consult at hand.

The e.firma issued by the SAT has three components:

• Private key (.key file).
• Password.
• Public certificate (.cer file).

The first two are private and should never be shared with anyone. On the other hand, the public certificate, as its name says, is available for anyone to check if it is valid or not and also to download it.

1. Go to the page enabled by the SAT for certificate retrieval.
2. In the initial window, enter the code shown in the image. If it is not very clear, click on 'Intentar otro código' to try a new one. When you have typed it, press the 'Aceptar' button.
   
3. If the code is correct, the following window will appear, where the system will allow you to perform the search in two ways:
   1. Recuperación por RFC (retrieval by RFC, recommended).
   2. Recuperación por número de serie (retrieval by serial number).
   
   In any case you choose, type the information in the corresponding field (RFC or serial number) and type the captcha.
   
   If you choose to search by RFC we recommend you do the default search for 'Todos los certificados expedidos' (all issued certificates).
   
   When you have filled in the information and captcha, click on 'Buscar'.
4. A new window will open with the information of the issued certificates corresponding to the RFC you entered.
5. Download the certificate
   1. Search for the current e.firma. Since the system arranges the certificates in reverse chronological order, you will find it at the top of the list.
   2. To download the certificate, click on the serial number, which is shown in the first column. Make sure that in the 'Estado' column it appears as Activo and in the 'Tipo' column it says FIEL, so that you get a current certificate.

What does this information mean?

Número de Serie (Serial Number)

This is the specific number assigned by the SAT to each of the certificates issued in order to identify them.

Estado (Status)

• Activo (Active): The certificate is valid and can be used.
• Caduco (Expired): The certificate is no longer valid because it has reached its expiration date.
• Revocado (Revoked): The certificate was cancelled by the owner, so it is no longer active.

Tipo (Type)

SAT issues two types of certificates:

• Sello: Also known as Certificado de Sello Digital (CSD), it is a file used specifically for generating valid digital invoices.
• FIEL: These are the e.firma certificates and therefore, the ones you need in Mifiel to sign documents.