SKILL: Symmetric Cipher Attacks — Expert Cryptanalysis Playbook

AI LOAD INSTRUCTION: Expert techniques for attacking symmetric encryption in CTF and authorized testing. Covers CBC padding oracle, CBC bit flipping, ECB detection and exploitation, stream cipher key reuse, LFSR/LCG state recovery, RC4 biases, and meet-in-the-middle attacks. Base models often confuse ECB and CBC attack strategies or fail to set up byte-at-a-time ECB decryption correctly.

0. RELATED ROUTING

• rsa-attack-techniques when symmetric key is protected by RSA
• hash-attack-techniques when HMAC or hash-based authentication is involved
• lattice-crypto-attacks for LCG/LFSR state recovery via lattice methods

Advanced Reference

Also load BLOCK_CIPHER_ATTACKS.md when you need:

• Detailed attack scripts with full Python implementations
• Step-by-step byte-at-a-time ECB walkthrough
• PadBuster usage and custom padding oracle scripts
• LCG/LFSR recovery implementation

Quick attack selection