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intermediate Phase · Backend Security

Password Security

Implement secure password policies, storage, and reset flows.

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Password Security

Password Policy

Rule Description
Minimum length 8+ characters
Complexity Mix of types
No common passwords Check against breached lists
No reuse Prevent reusing last N passwords

Storage Rules

  1. Always hash (BCrypt/Argon2)
  2. Unique salt per password
  3. Never log plaintext passwords
  4. Never return passwords in API responses

Key Points

  • Understanding Password Security is essential for production systems
  • Always consider scalability and maintainability
  • Test thoroughly before deploying to production
  • Monitor performance and set up alerting

Common Patterns

  1. Validation: Always validate input at the boundary
  2. Error Handling: Use structured error responses
  3. Logging: Log key events for debugging
  4. Testing: Unit, integration, and load tests
  5. Documentation: Keep docs updated with code changes

Password Best Practices

Policy Requirements

  • Minimum 8 characters
  • Mix of character types
  • Check against breached passwords
  • No personal information

Storage

  • Use bcrypt/scrypt/Argon2
  • Unique salt per password
  • Appropriate cost factor
  • Never store plaintext

Reset Flow

  1. Verify user identity
  2. Generate single-use token
  3. Send via secure channel
  4. Token expires in 1 hour
  5. Invalidate all existing sessions

Key Points

  • Understanding Password Security is essential for production systems
  • Always consider scalability and maintainability
  • Test thoroughly before deploying to production
  • Monitor performance and set up alerting

Common Patterns

  1. Validation: Always validate input at the boundary
  2. Error Handling: Use structured error responses
  3. Logging: Log key events for debugging
  4. Testing: Unit, integration, and load tests
  5. Documentation: Keep docs updated with code changes

Practice Problems

0 / 3 solved
Implement Password Security

Design and implement a solution for Password Security in a backend system. Consider scalability, error handling, and production readiness.

Solution 
// Password Security implementation
// Key aspects: validation, error handling, logging, testing

public class PasswordSecurity {
    // Production-ready implementation
}
Password Security Edge Cases

Identify and handle edge cases for Password Security. What happens under high load, with invalid input, or during failures?

Solution 
// Edge case handling:
// 1. Null/empty input -> validation
// 2. High load -> rate limiting, queuing
// 3. Failures -> retries, circuit breaker
// 4. Concurrent access -> locks, idempotency
Password Security Testing Strategy

Write a testing strategy for Password Security. Include unit tests, integration tests, and performance tests.

Solution 
// Test plan:
// - Unit: 80% coverage target
// - Integration: API contracts
// - Performance: latency, throughput
// - Chaos: failure injection

Quiz

1. Minimum recommended password length?

Question 1 options

2. Never do what with passwords?

Question 2 options

3. What is a common mistake when implementing Password Security?

Question 3 options

Flashcards

Question

Minimum password length?

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Answer

8+ characters

Question

Never log?

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Answer

Plaintext passwords

Question

Password Security best practices

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Answer

Follow SOLID principles, write clean code, test thoroughly, document decisions, and monitor in production.

Revision Notes

Key Takeaways

  • 1. Enforce password policies
  • 2. Always hash with BCrypt/Argon2
  • 3. Never log or return plaintext passwords
  • 4. Check against breached password lists

Interview Tips

  • • Implement password policies
  • • Know storage rules

Cheat Sheet

Password Security

  • Length: 8+ chars
  • Hash: BCrypt/Argon2
  • Never: log or return plaintext
  • Check: breached password lists