Cryptographic Implementation Mistakes Questions

Common errors and anti patterns when using cryptography in applications and infrastructure. Topics include choosing weak or broken primitives for hashing or encryption, improper use of cipher modes, reusing initialization vectors or nonces, hardcoded or poorly managed keys, weak or predictable randomness, incorrect certificate validation, lack of forward secrecy, improper key rotation and lifecycle management, and insecure custom cryptography. Candidates should be able to explain why each mistake is dangerous and describe secure alternatives and best practices for key management, library selection, secure configuration, and secure handling of secrets.