What systems and services can be used when implementing user registration logic?

• Authentication and Authorization System:
  • OAuth 2.0 / OpenID Connect
  • JWT (JSON Web Tokens)
  • Standard libraries and frameworks (e.g., Spring Security for Java, ASP.NET Identity for .NET, Passport.js for Node.js)
• User Database:
  • Relational DBs (PostgreSQL, MySQL, SQL Server)
  • NoSQL DBs (MongoDB, Cassandra)
• Email Sending Service (email confirmation):
  • SendGrid
  • Mailgun
  • Amazon SES
• SMS Sending Service (phone number confirmation):
  • Twilio
  • Nexmo (now Vonage API)
  • Sinch
• Password Hashing System:
  • Bcrypt
  • Argon2
  • Scrypt
• Service to prevent automated registrations (bot protection):
  • Google reCAPTCHA
  • hCaptcha
• Logging System:
  • ELK Stack (Elasticsearch, Logstash, Kibana)
  • Splunk
  • Grafana Loki
• Monitoring System:
  • Prometheus + Grafana
  • Datadog
  • New Relic
• Secrets Manager (for storing API keys, DB passwords):
  • HashiCorp Vault
  • AWS Secrets Manager
  • Azure Key Vault

Example registration logic using email confirmation and password hashing:

// Example implementation in Java using Spring Security and Bcrypt
public void registerUser(User user) {
    // 1. Hash the password
    String hashedPassword = passwordEncoder.encode(user.getPassword());
    user.setPassword(hashedPassword);

    // 2. Generate email verification token
    String verificationToken = UUID.randomUUID().toString();
    user.setVerificationToken(verificationToken);
    user.setEnabled(false); // User is inactive until confirmation

    // 3. Save user to DB
    userRepository.save(user);

    // 4. Send verification email with link
    emailService.sendVerificationEmail(user.getEmail(), verificationToken);
}