DFeSigner.NET

.NET library for digitally signing Brazilian electronic fiscal documents (DF-e) using X.509 certificates. Supports NF-e, NFC-e, CT-e and MDF-e XML signatures following official SEFAZ standards.

GitHub Nuget Package

Overview

DFeSigner.NET is a C# library designed to simplify the process of digitally signing Brazilian electronic fiscal documents (DF-e).

The library integrates with X.509 digital certificates (A1 or A3) and uses the .NET XML cryptography APIs to generate valid XML digital signatures required by SEFAZ systems.

Its modular architecture allows easy extension for additional document types in the future.

Supported Documents

NF-e — Nota Fiscal Eletrônica (model 55)
NFC-e — Nota Fiscal de Consumidor Eletrônica (model 65)
CT-e — Conhecimento de Transporte Eletrônico (model 57)
MDF-e — Manifesto Eletrônico de Documentos Fiscais (model 58)

Features

Digital signing of DF-e XML documents
Signature validation to verify document integrity
Support for X.509 digital certificates (A1 and A3)
Document type validation before signing
Robust error handling with custom exceptions
Unit tests using xUnit
Modular architecture for extensibility

Technologies

.NET / C#
System.Xml
System.Security.Cryptography.Xml
X509Certificates
xUnit

Example Usage


using DFeSigner.Core.Signers;
using System.Security.Cryptography.X509Certificates;

X509Certificate2 certificate = new X509Certificate2("certificado.pfx", "senha");

string xmlContent = File.ReadAllText("nfe.xml");

NFeXmlSigner signer = new NFeXmlSigner();

string signedXml = signer.Sign(xmlContent, certificate);

bool isValid = signer.IsSignatureValid(signedXml);

Error Handling

Invalid certificate or missing private key
Invalid XML format
Unexpected document model
Missing signature elements
Missing reference IDs