Criptografia e Hashing de Dados
Aprenda a criptografar dados confidenciais armazenados e em trânsito e a usar técnicas adequadas de hashing para senhas de usuários.
Criptografia e Hashing de Dados é uma aula grátis de Node.js Backend Development Bootcamp no CoddyKit. Esta é a aula 3 de 4. Você pode ler a aula completa abaixo gratuitamente — depois pratica ao vivo no navegador com um editor de código integrado e um tutor de IA 24/7. Faz parte do caminho de aprendizado de Node.js Backend Development Bootcamp, e seu progresso é sincronizado entre a web e o app CoddyKit. O curso de Node.js Backend Development Bootcamp inclui 4 aulas no total.
Partes desta aula ainda não foram traduzidas e aparecem em inglês.
Data Security Essentials
Welcome to Data Encryption & Hashing! In today's digital world, protecting sensitive information is paramount. Whether it's user passwords, personal data, or financial details, securing this data is a core responsibility for any developer.
This lesson will equip you with the knowledge and tools to implement robust data protection strategies in your Node.js applications.
Encryption vs. Hashing
Before diving into techniques, let's understand two fundamental concepts:
- Encryption: A two-way process that transforms data (plaintext) into an unreadable format (ciphertext) using a key. It's reversible, meaning the ciphertext can be converted back to plaintext with the correct key.
- Hashing: A one-way process that transforms data of any size into a fixed-size string of characters (a hash value or digest). It's irreversible; you cannot get the original data back from its hash.
They serve different purposes!
Symmetric Encryption
Symmetric encryption uses the same secret key for both encrypting and decrypting data. It's fast and efficient, making it suitable for encrypting large amounts of data.
Common algorithms include AES (Advanced Encryption Standard). The key must be kept secret and securely exchanged between parties.
Node.js Symmetric Encryption
Node.js's built-in crypto module allows us to perform symmetric encryption. Here's an example using AES-256-CBC, a strong symmetric algorithm.
Note: In a real application, the encryption key should be securely generated and stored (e.g., in environment variables) and the IV should be random for each encryption.
const crypto = require('crypto');
// IMPORTANT: In production, generate this key securely and store it safely!
const ENCRYPTION_KEY = 'averysecretkeyforencryption123456'; // Must be 32 bytes for AES-256
const IV_LENGTH = 16; // For AES-256-CBC, IV is 16 bytes
function encrypt(text) {
const iv = crypto.randomBytes(IV_LENGTH);
const cipher = crypto.createCipheriv(
'aes-256-cbc',
Buffer.from(ENCRYPTION_KEY, 'utf8'),
iv
);
let encrypted = cipher.update(text, 'utf8', 'hex');
encrypted += cipher.final('hex');
// Store IV with encrypted data (e.g., as 'iv:encryptedData')
return iv.toString('hex') + ':' + encrypted;
}
function decrypt(text) {
const textParts = text.split(':');
const iv = Buffer.from(textParts.shift(), 'hex');
const encryptedText = textParts.join(':');
const decipher = crypto.createDecipheriv(
'aes-256-cbc',
Buffer.from(ENCRYPTION_KEY, 'utf8'),
iv
);
let decrypted = decipher.update(encryptedText, 'hex', 'utf8');
decrypted += decipher.final('utf8');
return decrypted;
}
const message = 'Sensitive data for storage.';
console.log('Original:', message);
const encryptedMessage = encrypt(message);
console.log('Encrypted:', encryptedMessage);
const decryptedMessage = decrypt(encryptedMessage);
console.log('Decrypted:', decryptedMessage);Asymmetric Encryption
Asymmetric encryption, also known as public-key cryptography, uses a pair of keys: a public key and a private key.
- Public key: Can be shared with anyone. Used for encryption.
- Private key: Must be kept secret. Used for decryption.
If you encrypt data with someone's public key, only they can decrypt it with their private key. This is slower than symmetric encryption but crucial for secure communication and digital signatures.
Hashing for Passwords
When storing user passwords, NEVER encrypt them. Instead, always hash them. If an attacker gains access to your database, they would ideally only find irreversible hashes, not decryptable passwords.
A good hashing algorithm for passwords should be:
- One-way: Impossible to reverse.
- Collision-resistant: Extremely unlikely for two different inputs to produce the same hash.
- Slow: Deliberately designed to be computationally intensive to deter brute-force attacks.
Salting Passwords
To further enhance password security, we use salts. A salt is a unique, random string added to a password before it's hashed.
Why use salts?
- Prevents Rainbow Table Attacks: Without salts, attackers could pre-compute hashes for common passwords (rainbow tables).
- Unique Hashes: Even if two users have the same password, their salted hashes will be different.
The salt is usually stored alongside the hash.
Bcrypt for Password Hashing
bcrypt is a widely recommended library for hashing passwords in Node.js because it's designed to be slow and integrates salting automatically.
It handles generating a unique salt and performing multiple rounds of hashing (controlled by saltRounds, a work factor) to make brute-force attacks more difficult.
const bcrypt = require('bcrypt');
async function runBcryptExample() {
const password = 'mySecretPassword123';
const saltRounds = 10; // A higher number means more processing time
console.log('Original Password:', password);
// Hash the password with a generated salt
const hashedPassword = await bcrypt.hash(password, saltRounds);
console.log('Hashed Password:', hashedPassword);
// Compare a candidate password with the stored hash
const isMatch = await bcrypt.compare(password, hashedPassword);
console.log('Password Match (correct):', isMatch);
const wrongPassword = 'wrongPassword';
const isWrongMatch = await bcrypt.compare(wrongPassword, hashedPassword);
console.log('Password Match (wrong):', isWrongMatch);
}
runBcryptExample();Securing Data in Transit (TLS/SSL)
While encryption and hashing protect data at rest (stored in a database), it's equally important to protect data while it's moving between systems (data in transit).
TLS/SSL (Transport Layer Security/Secure Sockets Layer) protocols provide encryption for network communication. When you visit a website using HTTPS, your browser and the server use TLS/SSL to encrypt all data exchanged, preventing eavesdropping and tampering.
Check Your Understanding
Which of the following statements about encryption and hashing are TRUE?
Recap: Data Protection
Great job! You've learned the fundamentals of data encryption and hashing:
- Encryption protects sensitive data, making it reversible with a key.
- Hashing provides one-way transformation, ideal for password storage and data integrity.
- Symmetric encryption uses a single key, while asymmetric encryption uses public/private key pairs.
- Always use strong, salted hashing (like bcrypt) for passwords.
- TLS/SSL secures data in transit over networks.
Implementing these practices is vital for building secure Node.js applications!
Perguntas Frequentes
A aula “Criptografia e Hashing de Dados” é grátis?
Sim — o texto completo de “Criptografia e Hashing de Dados” é grátis para ler aqui na web. Para praticá-la interativamente (um editor de código integrado e um tutor de IA 24/7) e desbloquear o restante do curso de Node.js Backend Development Bootcamp, atualize para CoddyKit PRO. O curso de Node.js Backend Development Bootcamp inclui 4 aulas no total.
O que vou aprender em “Criptografia e Hashing de Dados”?
Aprenda a criptografar dados confidenciais armazenados e em trânsito e a usar técnicas adequadas de hashing para senhas de usuários. Você pratica Node.js Backend Development Bootcamp com código prático que executa diretamente no navegador, e um tutor de IA 24/7 responde suas dúvidas enquanto trabalha na aula.
Preciso ter experiência prévia para começar Node.js Backend Development Bootcamp?
Nenhuma experiência prévia é necessária. Node.js Backend Development Bootcamp no CoddyKit é estruturado para alunos iniciantes até avançados, então você pode começar aqui ou desde o início e aprender no seu ritmo. Esta é a aula 3 de 4.
Quanto tempo leva a aula “Criptografia e Hashing de Dados”?
A maioria das aulas CoddyKit leva cerca de 5–10 minutos. Cada uma é compacta e interativa, então você faz progresso constante e retoma exatamente de onde parou entre web e app.
Posso escrever e executar código nesta aula de Node.js Backend Development Bootcamp?
Sim. Cada aula de Node.js Backend Development Bootcamp inclui um editor de código integrado, então você escreve e executa código real direto no navegador e recebe feedback de IA instantaneamente — nenhuma configuração local necessária.
Todas as aulas deste curso
- Entendendo os 10 Principais Riscos da OWASP
- Práticas de Codificação Segura em Node.js
- Criptografia e Hashing de Dados
- Limitação de taxa e proteção contra força bruta