README for Scanteen GDG Task 2

Check out the Implementation video https://drive.google.com/file/d/1gL2VZOY1MDIuv0orFxCcF_BhvbAEQVVd/view?usp=sharing

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Overview

This document explains the functionality implemented in the Scanteen project for QR Code Creation and Deletion Operations. The code handles generating encrypted QR codes for orders, saving them as PNG files and in the database, and managing QR code retrieval and deletion.

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Package: com.example.scanteen

Key Components:

1. Controller: OrdersController

• Purpose: Manages HTTP requests for order-related operations.
• Endpoints:
  • DELETE /orders/{orderId}
    Deletes the order and its associated QR code.
  • POST /orders/qr
    Generates a QR code for the given order and saves it.
  • GET /orders/{orderId}/qr
    Retrieves and decrypts the QR code for a specific order.

2. Service: OrdersService

• Purpose: Implements business logic for handling QR codes.
• Methods:
  • insertQRCode(Map<String, Object> qrRequest)
    • Takes order details and creates a QR code.
    • Encrypts order data using AES encryption.
    • Generates and saves the QR code as:
      • A PNG file in a specified folder.
      • An entry in the database with Base64-encoded data.
  • getQRCodeByOrderId(Long orderId)
    • Retrieves the QR code for a given order.
    • Decrypts the data and prepares it for response.

3. Encryption Service: AESService

• Purpose: Handles AES encryption and decryption.
• Key Features:
  • Reads the AES secret key from the configuration (application.properties).
  • Encrypts order data to protect sensitive information.
  • Decrypts QR code data for retrieval.

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Code Details:

QR Code Generation

• Inputs:
  • orderId from the request body.
  • Corresponding Orders object fetched from the database.
• Process:
  1. Data Preparation: Concatenate orderId, orderDate, and status.
  2. Encryption: Secure data using AES encryption.
  3. QR Code Creation: Use encrypted data to generate a QR code.
  4. Storage: Save the QR code:
     • As a PNG file in the C:\\Users\\udhya\\OneDrive\\Desktop\\OpenMITian\\ directory.
     • As Base64-encoded data in the database.
• Response: Returns QR code details (e.g., ID, status, and Base64 data).

QR Code Retrieval

• Inputs: orderId as a path parameter.
• Process:
  1. Fetch the QR code from the database.
  2. Decode and decrypt the QR code.
  3. Prepare response with order and QR details.

Order Deletion

• Inputs: orderId as a path parameter.
• Process:
  1. Locate the order in the database.
  2. Delete the order and its associated QR code.
  3. Return success or error message.

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AES Encryption/Decryption

Key Functions:

• encrypt(String message):
  • Converts input string to bytes.
  • Encrypts using AES/GCM/NoPadding mode.
  • Returns Base64-encoded encrypted data and IV.
• decrypt(String encryptedMessage):
  • Splits the encrypted message into data and IV.
  • Decrypts using the AES key and IV.
  • Returns the original message.

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Dependencies and Tools

• Spring Boot: For the REST API and dependency injection.
• ZXing Library: For QR code generation and decoding.
• Base64 Encoding: To encode and store QR codes.
• AES Encryption: To secure sensitive order data.
• Java AWT and IO: For handling QR code images.

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Folder Structure

• Generated QR Codes: Saved as PNG files in the OpenMITian folder.
• Database: Stores QR codes in Base64 format.

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Example Request and Response

Insert QR Code

• Request:
  POST /orders/qr

  {
    "orderId": "7"
  }

• Response:

  {
  "qrCode": "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",
  "qrId": 3,
  "message": "QR code added successfully",
  "status": "not-scanned"
  }

Get QR Code

• Request:
  GET /orders/7/qr
• Response:

  {
  "qrCode": "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",
  "orderId": 5,
  "scannedBy": "Not Scanned",
  "qrId": 1,
  "actualData": "OrderID: 5\nOrderDate: 2025-01-01T23:34:57.316916\nStatus: ORDERED\n"
  }

Delete Order

• Request:
  DELETE /orders/5
• Response:

  {
    "message": "Order deleted successfully"
  }

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