conFIEL ID

conFIEL ID lets you use your SAT e.firma (FIEL) directly from your cell phone, without your private key ever leaving your device.

What is an e.firma?
The e.firma (formerly known as FIEL) is your digital identity with the SAT (Mexican Tax Administration Service). With it, you can sign tax returns, invoices, procedures, and contracts with full legal validity. conFIEL ID turns your cell phone into your signature key.

How it works:
1. Import your certificate (.cer) and your private key (.key) into the app.
2. Protect your vault with a PIN and biometrics.
3. Sign SAT procedures from your browser with the conFIEL Chrome extension, or directly from the app.

Relay Mode (with the Chrome extension): When there is a signature request on the SAT portal from your computer, your cell phone receives it instantly. Approve or reject it with a tap. The signature is automatically returned, encrypted end-to-end.

Direct Mode: No computer, no extension. Generate the signed token directly from the app and paste it wherever you need it.

Your key never leaves your phone.
conFIEL ID was designed with a non-custodial model:
- Your private key is stored encrypted with your PIN using PBKDF2
- The cryptographic signature occurs in RAM, never on a server
- None of your credentials are uploaded to the cloud

Ideal for:
- Individual taxpayers with tax obligations
- Accountants and firms that sign documents for their clients
- Companies that need to expedite digital signatures with the SAT (Mexican Tax Administration Service)

Requirements:
- Your .cer and .key files issued by the SAT
- Android 10 or higher