From 70992c9a462fcfd53eb9aba4b52c21d3ba7facf2 Mon Sep 17 00:00:00 2001
From: "ashutosh.nehete" <ashutosh.nehete@marcoaiot.com>
Date: Mon, 1 Dec 2025 15:05:20 +0530
Subject: [PATCH] Update the decryptresponse service

---
 src/services/decryptResponse.js | 99 +++++++++++++++++++--------------
 1 file changed, 58 insertions(+), 41 deletions(-)

diff --git a/src/services/decryptResponse.js b/src/services/decryptResponse.js
index 52b8a93a..9f66214e 100644
--- a/src/services/decryptResponse.js
+++ b/src/services/decryptResponse.js
@@ -1,47 +1,64 @@
-// Helper to convert Base64 to ArrayBuffer
-const base64ToArrayBuffer = (base64) => {
-  const binaryString = window.atob(base64);
-  const len = binaryString.length;
-  const bytes = new Uint8Array(len);
-  for (let i = 0; i < len; i++) {
-    bytes[i] = binaryString.charCodeAt(i);
-  }
-  return bytes.buffer;
-};
+import CryptoJS from 'crypto-js';
 
-// Main Decryption Function
-export const decryptResponse = async (encryptedBase64) => {
-  const keyBase64 = "h9J4kL2mN5pQ8rS1tV3wX6yZ0aB7cD9eF1gH3jK5mN6="; // Same key
-  
-  // 1. Parse Key
-  const keyBytes = base64ToArrayBuffer(keyBase64);
-  const key = await window.crypto.subtle.importKey(
-    "raw", 
-    keyBytes, 
-    { name: "AES-GCM" }, 
-    false, 
-    ["decrypt"]
-  );
+// The key from your C# Middleware
+// In a real app, prefer storing this in process.env.REACT_APP_ENCRYPTION_KEY
+const KEY_BASE64 = "h9J4kL2mN5pQ8rS1tV3wX6yZ0aB7cD9eF1gH3jK5mN6=";
 
-  // 2. Parse Encrypted Data
-  const encryptedBytes = new Uint8Array(base64ToArrayBuffer(encryptedBase64));
+/**
+ * Decrypts the specific format sent by the C# EncryptionMiddleware.
+ * Format: Base64([IV (16 bytes)] + [Encrypted Data])
+ * * @param {string} encryptedBase64Str - The raw response text from the API
+ * @returns {any} - The parsed JSON object or string
+ */
+export const decryptResponse = (encryptedBase64Str) => {
+    try {
+        // 1. Parse the Key
+        const key = CryptoJS.enc.Base64.parse(KEY_BASE64);
 
-  // 3. Extract Parts (Nonce is first 12 bytes)
-  const nonce = encryptedBytes.slice(0, 12);
-  const ciphertextWithTag = encryptedBytes.slice(12); // Web Crypto expects Tag appended to Ciphertext
+        // 2. Parse the incoming Base64 string to a WordArray
+        const fullWordArray = CryptoJS.enc.Base64.parse(encryptedBase64Str);
 
-  // 4. Decrypt
-  try {
-    const decryptedBuffer = await window.crypto.subtle.decrypt(
-      { name: "AES-GCM", iv: nonce },
-      key,
-      ciphertextWithTag
-    );
+        // 3. Convert to Hex to easily slice the IV (16 bytes = 32 hex chars)
+        // This is safer than manipulating WordArray indices directly
+        const fullHex = CryptoJS.enc.Hex.stringify(fullWordArray);
 
-    const decoded = new TextDecoder().decode(decryptedBuffer);
-    return JSON.parse(decoded);
-  } catch (e) {
-    console.error("Decryption failed:", e);
-    return null;
-  }
+        // 4. Extract IV (First 16 bytes / 32 hex characters)
+        const ivHex = fullHex.substring(0, 32);
+        const iv = CryptoJS.enc.Hex.parse(ivHex);
+
+        // 5. Extract Ciphertext (The rest of the string)
+        const cipherTextHex = fullHex.substring(32);
+        const cipherParams = CryptoJS.lib.CipherParams.create({
+            ciphertext: CryptoJS.enc.Hex.parse(cipherTextHex)
+        });
+
+        // 6. Decrypt
+        const decrypted = CryptoJS.AES.decrypt(
+            cipherParams,
+            key,
+            {
+                iv: iv,
+                mode: CryptoJS.mode.CBC,
+                padding: CryptoJS.pad.Pkcs7
+            }
+        );
+
+        // 7. Convert to UTF-8 String
+        const decryptedString = decrypted.toString(CryptoJS.enc.Utf8);
+
+        if (!decryptedString) {
+            throw new Error("Decryption produced empty result (Wrong Key/IV?)");
+        }
+
+        // 8. Try to parse JSON, otherwise return plain string
+        try {
+            return JSON.parse(decryptedString);
+        } catch {
+            return decryptedString;
+        }
+
+    } catch (error) {
+        console.error("Decryption Failed:", error);
+        return null;
+    }
 };
\ No newline at end of file