Individual skill

symmetric-cipher-attacks

Symmetric cipher attack playbook. Use when exploiting block cipher mode weaknesses (CBC padding oracle, ECB cut-and-paste, bit flipping), stream cipher key reuse, or meet-in-the-middle attacks.

knowledge/hack-skills/skills/symmetric-cipher-attacks/SKILL.md

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# 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](../rsa-attack-techniques/SKILL.md) when symmetric key is protected by RSA
- [hash-attack-techniques](../hash-attack-techniques/SKILL.md) when HMAC or hash-based authentication is involved
- [lattice-crypto-attacks](../lattice-crypto-attacks/SKILL.md) for LCG/LFSR state recovery via lattice methods

### Advanced Reference

Also load [BLOCK_CIPHER_ATTACKS.md](./BLOCK_CIPHER_ATTACKS.md) when you need:
- Detailed attack scripts with full Python implementations