NfcReaderLib 1.0.0

NfcReaderLib

NFC/Smart card utilities library providing PC/SC communication, SL Token generation (SHA-256 based tokens from ICC certificates), and utility functions for card data processing.

?? Installation

NuGet Package Manager

Install-Package NfcReaderLib -Version 1.0.0

.NET CLI

dotnet add package NfcReaderLib --version 1.0.0

Package Reference

<PackageReference Include="NfcReaderLib" Version="1.0.0" />

?? Target Framework

• .NET Framework 4.7.2

? Features

• ?? PC/SC Communication - Low-level smart card reader communication
• ?? SL Token Generation - SHA-256 based secure tokens from ICC certificates
• ??? Card Utilities - Helper functions for card data processing
• ?? Data Formatting - Byte array and hex string conversions
• ?? TLV Parsing Support - Tag-Length-Value structure handling

?? Quick Start

Basic PC/SC Communication

using NfcReaderLib;

// Initialize card reader
var reader = new CardReader();
reader.Initialize();

// Connect to card
reader.Connect("ACS ACR122U PICC Interface 0");

// Send APDU command
byte[] apdu = { 0x00, 0xA4, 0x04, 0x00, 0x00 };
byte[] response = reader.SendApdu(apdu);

SL Token Generation

using NfcReaderLib;

// Generate SL Token from ICC certificate
byte[] iccCert = GetIccCertificate(); // Tag 9F46
string slToken = SLCard.GenerateToken(iccCert);

// Output: "E3 B0 C4 42 98 FC 1C 14..." (SHA-256 hash)

Utility Functions

using NfcReaderLib;

// Convert hex string to byte array
byte[] data = Util.HexStringToByteArray("00A4040000");

// Convert byte array to hex string
string hex = Util.ByteArrayToHexString(data);

// Format card number
string pan = Util.FormatCardNumber("1234567890123456");
// Output: "1234 5678 9012 3456"

?? Main Components

SLCard Class

Purpose: Card data model with ICC certificate parsing and token generation

Key Methods:

• GenerateToken(byte[] iccCertificate) - Generate SL Token from ICC cert
• ParseIccCertificate(byte[] data) - Parse ICC public key certificate

Properties:

• CardNumber - Primary Account Number (PAN)
• ExpiryDate - Card expiration date
• CardholderName - Name on card
• IccCertificate - ICC Public Key Certificate (Tag 9F46)
• SlToken - Generated secure link token

Util Class

Purpose: Utility functions for data conversion and formatting

Key Methods:

• HexStringToByteArray(string hex) - Convert hex to bytes
• ByteArrayToHexString(byte[] bytes) - Convert bytes to hex
• FormatCardNumber(string pan) - Format PAN with spaces
• FormatExpiryDate(string date) - Format expiry as MM/YY

?? SL Token Details

What is SL Token?

The SL (Secure Link) Token is a unique cryptographic identifier derived from the card's ICC Public Key Certificate using SHA-256 hashing.

Token Generation Process

ICC Certificate (Tag 9F46) ? SHA-256 Hash ? Hex String ? SL Token

Example:

byte[] iccCert = new byte[] { /* ICC cert data */ };
string token = SLCard.GenerateToken(iccCert);
// Output: "E3 B0 C4 42 98 FC 1C 14 9A FB F4 C8 99 6F B9 24..."

Properties

? Unique - Each card generates unique token
? Consistent - Same card always generates same token
? Secure - One-way hash, cannot be reversed
? Privacy-Friendly - No PAN or sensitive data exposed
? Format - Space-separated hex string (95 characters)

Use Cases

• ?? Loyalty program card identification
• ?? Card binding to user accounts
• ?? Transaction correlation
• ?? Duplicate card detection
• ?? Analytics without storing sensitive data

?? Requirements

Runtime Requirements

• .NET Framework 4.7.2 or later
• Windows 7 or later
• PC/SC smart card service (SCardSvr)

Dependencies

• System.Security.Cryptography.Algorithms (4.3.0) - For SHA-256 hashing

?? PC/SC Integration

Supported Readers

This library works with any PC/SC compliant smart card reader:

• ? ACR122U (contactless)
• ? SCM SCR331 (contact)
• ? Omnikey 5321 (dual interface)
• ? Generic PC/SC readers

PC/SC Service

Ensure the PC/SC service is running:

# Check service status
Get-Service SCardSvr

# Start service if stopped
Start-Service SCardSvr

?? Documentation

For complete documentation, see the main project:

• EMVReaderSL Repository

?? Contributing

Contributions welcome! Please submit issues and pull requests on GitHub.

?? License

Copyright � Johan Henningsson 2024

This project is licensed under the MIT License.

?? Related Packages

• EMVCard.Core - High-level EMV card reading functionality
• AztecQRGenerator.Core - QR code generation for card data

?? Author

Johan Henningsson

• GitHub: @johanhenningsson4-hash
• Repository: EMVReaderSL

?? Support

If you find this library useful, please ? star the repository on GitHub!

Version 1.0.0 | .NET Framework 4.7.2 | MIT License