Related-Key Attack
The related-key attack assumes the adversary can access encryption oracles under multiple related keys (with known relations), exploiting key-schedule weaknesses to distinguish the cipher.
Purpose
It evaluates cipher security under weakly related key schedules and poses real threats to key-agreement protocols (e.g., WPA2).
Mechanism
Key pairs (K, K+Δ) are constructed so round-key differences are predictable, and keys are recovered along differential characteristics. Related-key differential weaknesses were once found in the AES-256 key schedule.
Use cases
- AES-256 key schedule evaluation
- WPA2 TKIP attacks
- Key-agreement protocol security