Even strong mathematical algorithms can be broken if implemented incorrectly. This brief reviews common coding mistakes in cryptographic operations.
1. Reusing Initialization Vectors (IV)
Many block ciphers require a random Initialization Vector (IV) to ensure the same plaintext encrypts to different ciphertexts. If a developer uses a static or predictable IV, patterns emerge in the ciphertext, allowing observers to recover the plaintext data.
2. Padding Oracle Vulnerabilities
When decrypting block cipher data, the application checks if the block padding is correct. If the application returns different error codes for “invalid padding” vs “incorrect decryption key,” it leaks key details. An attacker can use these oracle leaks to decrypt ciphertext block-by-block without possessing the private key.
3. Insufficient Entropy (Weak Keys)
Key generators rely on pseudo-random number generators (PRNG). If the generator does not draw from a strong hardware entropy pool, the keys will be predictable and vulnerable to factorization attacks.