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CFDi v4.0 Examples

Here are some example XML documents for Anexo 20 Versión 4.0​ (CFDi v4.0) as specified by the Servicio de Administración Tributaria (SAT) in Mexico as published December 2021. The analysis and signing were carried out using v10.40.1 of FirmaSAT. For our summary of the latest information and links for the complementos, see Complementos and Complementos Concepto.

We hope you will find these useful in your own tests, but be aware that the values used for the attributes are nonsense ones picked at random just for testing purposes. Most examples just assign a random, but valid, value to every possible node in the XSD structure. The resulting documents are still valid XML (against the XSD) but will probably not comply with the guidelines in, say, GuíaAnexo20.pdf. This does not matter for our purposes of creating the cadena original and the Sello.

All the XML documents below have been validated against the XSD files published by SAT using independent XSD validation software, and each pipe-string (cadena original) provided here has been confirmed using the latest XSLT files published by SAT, again using independent XML stylesheet software.

See how to form the cadena original and compute its SHA-256 digest.

If you think there is an error here, or if something is out of date, please send us a message.

Notes

1. The file cfdv40-ejemplo-signed-tfd.xml is the file cfdv40-ejemplo.xml signed by the holder of the certificate with serial number 30001000000300023708. The corresponding private key has password 12345678a (files available in zip file below).
2. The TimbreFiscalDigital element in the file cfdv40-ejemplo-signed-tfd.xml has been signed by the holder of the certificate with serial number 30001000000300023699. The cadena original de un timbre (TFD pipe-string) has digest value a276a2bf9d32066f2d553d67a99c6b016524ef90d699654be6eaa3f21f44a5e9. You can extract the pipe-string for the TFD using the "-f" option on the command line:

   FirmaSAT PIPESTRING -f cfdv40-ejemplo-signed-tfd.xml
   

   and compute its digest value with

   FirmaSAT FORMDIGEST -f cfdv40-ejemplo-signed-tfd.xml
   

Forming the cadena original and computing its digest

Forming the cadena original (pipe-string) is the crucial part of computing the signature (sello) of the CFDi document. The signature is the SHA-256 digest value of the cadena original string signed (encrypted) by the signer's private key.

The signature is verified by re-constructing the cadena original from the XML document, computing its digest value, and checking that the value decrypted using the signer's public key is equal to this recomputed digest value.

It should be obvious that, if you cannot accurately and consistently form the cadena original, attempts to create and verify the signature will fail.

Using the command line

FirmaSAT PIPESTRING cfdv40-ejemplo.xml

||4.0|A|123ABC|...|Tasa|1.600000|360000|360000||

FirmaSAT FORMDIGEST cfdv40-ejemplo.xml

c1492662dbd98ddbb7892d027c10808236e296eded13deec87179c2a8fdc742e

for %f in (cfdv40*.xml) do @firmasat PIPESTRING -o cadenas\%~nf-cadena.txt %f

for %f in (cfdv40*.xml) do @echo/|set /p="%f " & @firmasat FORMDIGEST %f

cfdv40-ejemplo-signed-tfd.xml c1492662dbd98ddbb7892d027c10808236e296eded13deec87179c2a8fdc742e
cfdv40-ejemplo-signed.xml c1492662dbd98ddbb7892d027c10808236e296eded13deec87179c2a8fdc742e
cfdv40-ejemplo.xml c1492662dbd98ddbb7892d027c10808236e296eded13deec87179c2a8fdc742e
cfdv40-min-signed.xml 51566373abf060f9fe79e2967ddc84bc4944c47f7e1346b3873aa62b1b2b15b0
....

Example signing certificates and keys

Old CFD v3.3 Examples

Historical CFD v3.3 Examples from 2017.

Reference documents

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This page first published 22 December 2021. Last updated 26 December 2021.

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