Top Cryptographic Misuse Patterns

Electronic Codebook (ECB) mode encrypts each block independently with the same key. Identical plaintext blocks produce identical ciphertext blocks. The classic demonstration is the "ECB penguin": encrypting a bitmap image with ECB preserves the block-level structure of the image, making the penguin outline clearly visible in the ciphertext. ECB mode provides no semantic security and should never be used for any practical encryption purpose.

Implementing cryptographic primitives from scratch is one of the most dangerous practices in software development. Cryptography requires perfect correctness under adversarial conditions: a subtle timing leak, an off-by-one error in padding, or a misunderstanding of security requirements can create exploitable vulnerabilities indistinguishable from correct behavior in normal testing. Even expert cryptographers make implementation mistakes; application developers should use well-audited libraries exclusively.