Common Encryption and Decryption Algorithms in JavaScript

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🔑 1. Hash Algorithms (Irreversible)

Commonly used for signatures, verification, and password storage (not for decryption).

• MD5

  import CryptoJS from "crypto-js";
  
  const hash = CryptoJS.MD5("hello").toString();
  console.log(hash); // 5d41402abc4b2a76b9719d911017c592
  

• Features: Generates a 32-character hexadecimal string, irreversible.
• Applications: Password hashing, file integrity verification.

• SHA Series (SHA-1, SHA-256, SHA-512)

  const sha256 = CryptoJS.SHA256("hello").toString();
  console.log(sha256);
  

• More secure than MD5.

🔐 2. Symmetric Encryption (Encrypt + Decrypt)

Uses the same key for both encryption and decryption, commonly used for local storage and API encryption.

• AES (Advanced Encryption Standard)

  const secret = "1234567890abcdef"; // 16/24/32 byte key
  
  const ciphertext = CryptoJS.AES.encrypt("hello", secret).toString();
  console.log(ciphertext);
  
  const bytes = CryptoJS.AES.decrypt(ciphertext, secret);
  const original = bytes.toString(CryptoJS.enc.Utf8);
  console.log(original); // hello
  

• One of the most commonly used symmetric encryption algorithms.

• DES / 3DES

  const key = "12345678";
  const encrypted = CryptoJS.DES.encrypt("hello", key).toString();
  const decrypted = CryptoJS.DES.decrypt(encrypted, key).toString(CryptoJS.enc.Utf8);
  

• Previously common, now less secure.

• RC4

• Stream cipher, lightweight but not very secure.

🔏 3. Asymmetric Encryption

Uses public and private keys for encryption and decryption, commonly used for data transmission security and digital signatures.

• RSA

  import JSEncrypt from "jsencrypt";
  
  const encryptor = new JSEncrypt();
  encryptor.setPublicKey(`-----BEGIN PUBLIC KEY-----...-----END PUBLIC KEY-----`);
  const encrypted = encryptor.encrypt("hello");
  
  const decryptor = new JSEncrypt();
  decryptor.setPrivateKey(`-----BEGIN PRIVATE KEY-----...-----END PRIVATE KEY-----`);
  const decrypted = decryptor.decrypt(encrypted);
  

• Public key encryption, private key decryption.

• ECC (Elliptic Curve Cryptography)

• More efficient and secure, but complex to implement, commonly found in SSL/TLS.

🧾 4. Encoding (Strictly Not Encryption)

Commonly used for data transmission and obfuscation, not a secure encryption method.

• Base64

  const str = "hello";
  const encoded = btoa(str);     // aGVsbG8=
  const decoded = atob(encoded); // hello
  

• Hex Encoding

  const hex = Buffer.from("hello").toString("hex"); // 68656c6c6f
  const back = Buffer.from(hex, "hex").toString();  // hello
  

• URL Encoding

  const encoded = encodeURIComponent("你好");
  const decoded = decodeURIComponent(encoded);
  

📌 Summary

• Hashing (MD5, SHA) → Only encrypts, irreversible.
• Symmetric Encryption (AES, DES) → Same key for encryption and decryption.
• Asymmetric Encryption (RSA, ECC) → Public key encryption, private key decryption.
• Encoding (Base64, URL) → Used only for transmission and storage, not considered secure encryption.

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