Crypto-js for JavaScript (Node.js): Complete Guide with Examples

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In modern web development, data security is a critically important aspect. Whether it's storing user passwords, transmitting confidential information over a network, or protecting files from unauthorized access — cryptography is at the core of these processes. The Crypto-js library provides a powerful and convenient set of cryptographic algorithms for the JavaScript ecosystem, working both in the browser and in the Node.js environment.

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This library implements a wide range of standard cryptographic functions: symmetric encryption (AES, DES, TripleDES), hashing (MD5, SHA-1, SHA-256, SHA-512), HMAC computation, as well as random number generation and encoding support (Base64, Hex, UTF-8). Crypto-js does not depend on native operating system modules, making it an ideal choice for isomorphic applications (code running both on the client and server).

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In this article, we will thoroughly cover the library installation, main methods with code examples, and also look at a real practical example of using Crypto-js for data protection in a web application. The material will be useful for both beginner developers and experienced professionals looking to systematize their knowledge of cryptography in JavaScript.

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Installation

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To install Crypto-js in a Node.js project, run the following command in the terminal:

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npm install crypto-js

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After installation, you can import the library into your code:

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// For Node.js (CommonJS)\nconst CryptoJS = require("crypto-js");\n\n// For ES Modules (if "type": "module" is used in package.json)\nimport CryptoJS from "crypto-js";

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Quick Start: Minimal Working Example

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Let's start with a simple example — encrypting and decrypting a string using the AES algorithm:

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const CryptoJS = require("crypto-js");\n\n// Original message\nconst message = "Hello, Crypto-js!";\n\n// Secret key (should be strong in a real application)\nconst secretKey = "my-secret-key-123";\n\n// Encryption\nconst ciphertext = CryptoJS.AES.encrypt(message, secretKey).toString();\nconsole.log("Encrypted message:", ciphertext);\n\n// Decryption\nconst bytes = CryptoJS.AES.decrypt(ciphertext, secretKey);\nconst decryptedMessage = bytes.toString(CryptoJS.enc.Utf8);\nconsole.log("Decrypted message:", decryptedMessage);

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This example demonstrates the basic cycle of working with symmetric encryption: we transform the original text into an encrypted string (Base64), and then restore the original message using the same key.

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Main Methods/Functions/Classes

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Let's look at the key capabilities of Crypto-js. For each method, the signature, a brief description, and a working example are provided.

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1. CryptoJS.AES.encrypt() / CryptoJS.AES.decrypt()

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Signature: CryptoJS.AES.encrypt(message, key, [options]) and CryptoJS.AES.decrypt(ciphertext, key, [options])

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What it does: Implements symmetric encryption and decryption using the AES (Advanced Encryption Standard) algorithm. Supports ECB, CBC, CFB, OFB, CTR modes and key sizes of 128/192/256 bits.

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const CryptoJS = require("crypto-js");\n\nconst message = "Secret data";\nconst key = "supersecretkey123";\n\n// Encryption with specified mode and IV (initialization vector)\nconst iv = CryptoJS.lib.WordArray.random(16); // 16 bytes for AES-128\nconst encrypted = CryptoJS.AES.encrypt(message, key, {\n    iv: iv,\n    mode: CryptoJS.mode.CBC,\n    padding: CryptoJS.pad.Pkcs7\n}).toString();\n\nconsole.log("Encrypted (CBC):", encrypted);\n\n// Decryption\nconst decrypted = CryptoJS.AES.decrypt(encrypted, key, {\n    iv: iv,\n