How to use the AES algorithm to decrypt the data returned by the backend in front-end?

To decrypt the data returned from the backend using the AES algorithm in the frontend, you can use the encryption library provided in JavaScript, such as CryptoJS.

Installation/Import#

First, make sure to import the CryptoJS library in your frontend HTML file.
1.1 You can import CryptoJS in your HTML file by adding the following code inside the tag:

<script src="https://cdnjs.cloudflare.com/ajax/libs/crypto-js/4.0.0/crypto-js.min.js"></script>

1.2 To install CryptoJS using npm, follow these steps:

1.2.1 Open the terminal or command line interface in your project directory.

1.2.2 Run the following command to install CryptoJS:

npm install crypto-js

This will download the CryptoJS library and its dependencies from the npm repository and save them in the node_modules directory of your project.

In your JavaScript file, use the require or import statement to import the required CryptoJS module, for example:

// Using require
const CryptoJS = require('crypto-js');

// Using import
import CryptoJS from 'crypto-js';

Choose the appropriate import method depending on the module system used in your project (CommonJS or ES module).

Now, you can use various encryption algorithms and utility functions of the CryptoJS library, including the AES algorithm, in your frontend code.

Note that when using npm to install CryptoJS, make sure that your frontend project is built and bundled using a build tool (such as Webpack, Parcel, Rollup, etc.). This way, the installed library will be correctly included in your final project file. If you are directly using CryptoJS in a simple HTML file, you can use the CDN import method instead of npm installation.

Next, use the following code example to demonstrate how to decrypt the data returned from the backend using the AES algorithm in the frontend:

// Encrypted data
const encryptedData = "encrypted data from backend";

// Key
const key = CryptoJS.enc.Utf8.parse("your-secret-key");

// Initialization Vector (IV)
const iv = CryptoJS.enc.Utf8.parse("your-iv");

// Decryption
const decryptedData = CryptoJS.AES.decrypt(encryptedData, key, {
  iv: iv,
  mode: CryptoJS.mode.CBC,
  padding: CryptoJS.pad.Pkcs7
});

// Decrypted plaintext
const decryptedText = decryptedData.toString(CryptoJS.enc.Utf8);

console.log(decryptedText);

In the above code, you need to replace encryptedData with the ciphertext data returned from the backend. Then, replace your-secret-key with the key used for encryption and decryption. your-iv is the initialization vector for the AES algorithm. Note that the key and IV need to match the values used in the backend.

The decryption process involves calling the CryptoJS.AES.decrypt() method to perform the decryption operation. Decrypt the ciphertext data into plaintext data using the provided key, IV, mode, and padding. Finally, convert the decrypted data into a readable string form using the toString() method with the specified character encoding (e.g., CryptoJS.enc.Utf8).

Note that the key to successful decryption using an encryption algorithm is to ensure that the same key, IV, mode, and padding are negotiated and used between the frontend and backend. Additionally, to ensure the security of the data, the key and IV should be properly safeguarded and managed to ensure that only authorized personnel can access and use them.