Soft POS Application - Android Kotlin/Jetpack Compose

A complete Point of Sale (POS) application for Android devices with NFC support, built using Kotlin and Jetpack Compose. This application enables contactless EMV chip card transactions with ISO8583 message processing.

Features

🚀 Core Functionality

• NFC EMV Card Reading - Contactless chip card processing using Android NFC APIs
• ISO8583 Message Processing - Complete message formatting and parsing
• Transaction Management - Authorization, reversal, and settlement requests
• Host Communication - TCP/IP and SSL/TLS support for payment processors
• Real-time UI Updates - Reactive interface with Jetpack Compose

🛡️ Security Features

• Android Keystore Integration - Secure key management
• Data Encryption - Sensitive data protection
• Network Security - SSL/TLS communication with certificate pinning
• Card Data Masking - PCI DSS compliance considerations

📱 Modern Android Architecture

• MVVM Pattern - Clean architecture with ViewModel and StateFlow
• Jetpack Compose - Modern declarative UI
• Kotlin Coroutines - Async operations and structured concurrency
• Material Design 3 - Contemporary UI components

Prerequisites

Hardware Requirements

• Android device with NFC (API level 23+)
• EMV chip cards for testing
• Network connectivity for payment host communication

Software Requirements

• Android Studio Electric Eel (2022.1.1) or newer
• Android SDK API 23-34
• Kotlin 1.9.22+
• Gradle 8.0+

Installation

1. Clone the Repository

git clone https://github.com/yourusername/soft-pos-android.git
cd soft-pos-android

2. Open in Android Studio

• Open Android Studio
• Select "Open an existing project"
• Navigate to the cloned directory
• Wait for Gradle sync to complete

3. Configure the Application

Update configuration in Constants.kt:

const val DEFAULT_HOST_IP = "your-payment-host.com"
const val DEFAULT_HOST_PORT = 443
const val DEFAULT_TERMINAL_ID = "your-terminal-id"
const val DEFAULT_MERCHANT_ID = "your-merchant-id"

4. Build and Install

./gradlew assembleDebug
./gradlew installDebug

Usage

Basic Transaction Flow

1. Launch Application

   • Ensure NFC is enabled on device
   • Application displays transaction screen

2. Enter Transaction Amount

   • Input amount in decimal format (e.g., 10.00)
   • Tap "Start Transaction" button

3. Tap Card

   • Hold EMV chip card near device NFC antenna
   • Application reads card data automatically

4. Process Transaction

   • App sends authorization request to payment host
   • Displays approval/decline result

Configuration

Access settings through PreferencesManager:

val prefsManager = PreferencesManager(context)
prefsManager.setHostIP("192.168.1.100")
prefsManager.setHostPort(8080)
prefsManager.setTerminalId("12345678")

Testing

Unit Tests

./gradlew test

Instrumented Tests

./gradlew connectedAndroidTest

Manual Testing

1. Use demo mode with mock card data
2. Test with EMV test cards
3. Verify network communication with test host

Security Considerations

Development Environment

• Uses HTTP for localhost testing
• Mock responses for offline development
• Debug logging enabled

Production Environment

• Enable HTTPS only in network security config
• Implement certificate pinning for payment hosts
• Add proper key management for sensitive data
• Follow PCI DSS requirements for card data handling
• Enable ProGuard for code obfuscation

PCI DSS Compliance

// Example: Secure card data handling
val encryptedPAN = SecurityUtils.encryptData(cardData.pan)
val maskedPAN = cardData.getMaskedPAN() // For display only

API Documentation

EMV Card Reading

val cardReader = NFCCardReader()
val cardData: EMVCardData = cardReader.readCard(nfcTag)

ISO8583 Message Creation

val message = ISO8583Message("0100") // Authorization request
message.setField(2, pan)
message.setField(4, amount)
val packedMessage = message.pack()

Host Communication

val hostComm = HostCommunication(hostIP, hostPort)
hostComm.connect()
val response = hostComm.sendMessage(requestData)

Troubleshooting

Common Issues

NFC Not Working

• Verify NFC is enabled in device settings
• Check if device supports ISO-DEP
• Ensure proper card positioning

Network Connection Failed

• Verify host IP and port configuration
• Check network connectivity
• Confirm firewall settings

Card Reading Errors

• Try different EMV cards
• Clean card contacts
• Adjust card positioning

Debug Logging

Enable verbose logging in debug builds:

if (BuildConfig.DEBUG) {
    Log.d(TAG, "Debug information")
}

Contributing

1. Fork the repository
2. Create feature branch (git checkout -b feature/new-feature)
3. Commit changes (git commit -am 'Add new feature')
4. Push to branch (git push origin feature/new-feature)
5. Create Pull Request

Code Standards

• Follow Kotlin coding conventions
• Use meaningful variable names
• Add documentation for public APIs
• Include unit tests for new features

License

This project is licensed under the MIT License - see the LICENSE file for details.

Support

For support and questions:

• Create an issue on GitHub
• Email: support@mpayer.ng
• Documentation: https://softpos-docs.mpayer.ng

Acknowledgments

• Android NFC documentation and samples
• EMVCo specifications
• ISO8583 standard documentation
• Jetpack Compose development guides

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⚠️ Important: This is a development/demo implementation. For production use, ensure proper security audits, PCI DSS compliance, and certification from payment networks. #mpayer-softpos