Learn Security: Encryption vs Hashing — Explained with Examples

Encryption vs Hashing — Explained with Examples

DodaTech Updated Jun 15, 2026 2 min read

Encryption transforms data into ciphertext using a key and is reversible, while hashing produces a fixed-length fingerprint that cannot be reversed.

Encryption and Hashing serve fundamentally different purposes. Encryption protects data confidentiality by making it unreadable without a key. Hashing verifies data integrity by producing a unique, irreversible digest.

Key Differences

Feature	Encryption	Hashing
Reversible	Yes (with key)	No
Output length	Same as input	Fixed length
Key	Required	Not used
Purpose	Confidentiality	Integrity
Example	AES, RSA	SHA-256, MD5

Encryption: Two-Way

const crypto = require('crypto');

const algorithm = 'aes-256-cbc';
const key = crypto.randomBytes(32);
const iv = crypto.randomBytes(16);

// Encrypt
function encrypt(text) {
  const cipher = crypto.createCipheriv(algorithm, key, iv);
  let encrypted = cipher.update(text, 'utf8', 'hex');
  encrypted += cipher.final('hex');
  return encrypted;
}

// Decrypt (reversible with the key)
function decrypt(encrypted) {
  const decipher = crypto.createDecipheriv(algorithm, key, iv);
  let decrypted = decipher.update(encrypted, 'hex', 'utf8');
  decrypted += decipher.final('utf8');
  return decrypted;
}

const message = 'Credit card: 4111-1111-1111-1111';
const encrypted = encrypt(message);
console.log('Encrypted:', encrypted);
console.log('Decrypted:', decrypt(encrypted)); // Original message restored

Hashing: One-Way

const crypto = require('crypto');

function hash(password) {
  return crypto.createHash('sha256').update(password).digest('hex');
}

const password = 'MyP@ssw0rd';
const hashed = hash(password);
console.log('Hash:', hashed);
// e.g., "a591a6d40bf420404a011733cfaff873c5adf1a4ab71c9e7a5e2d1f3e7e5d1f3"

// Verification: hash the input and compare
function verify(input, storedHash) {
  return hash(input) === storedHash;
}

console.log(verify('MyP@ssw0rd', hashed));  // true
console.log(verify('wrong', hashed));         // false

Real-World Analogy

Encryption is like a lockbox. You put a letter inside, lock it with a key, and send it. The recipient uses their key to unlock it and read the letter. Hashing is like a fingerprint. Your fingerprint uniquely identifies you, but you can’t reconstruct your face from it. If someone claims they’re Alice, you check their fingerprint against Alice’s stored fingerprint — but you can’t derive Alice’s appearance from the print.

When to Use Each

Encryption: credit card numbers, messages, files in transit (TLS) or at rest
Hashing: passwords (use bcrypt/argon2, not raw SHA), file integrity checks, digital signatures

Related Terms

TLS/SSL, HTTPS, PKI, Authentication vs Authorization