Hunt Agent Crypto Weaknesses

Agents sometimes expose crypto as tools — encrypt, decrypt, sign, verify, mint tokens. Weak algorithms (ECB), missing authentication (no MAC), predictable keys/IVs, or a decrypt oracle turn the crypto tool into an auth-bypass / secret-extraction primitive. In enterprises this is session/API-token minting and document encryption behind a copilot.

Where This Lives / Attack Surface Signals

• Tools: encrypt, decrypt, create_token, sign, verify, hash, generate_key.
• Agent mentions a mode (ECB/CBC/CTR/GCM) or "block size"/"padding".
• Token format documented in the system prompt / a *_info tool.
• Tool prepends/appends user input to a secret before encrypting.
• Encrypt-only or decrypt-only availability → an oracle.

Crown Jewel Targets

Forged auth/session tokens → account/admin takeover; byte-at-a-time recovery of an appended secret; padding-oracle decryption of protected ciphertext.

Characterize First

1. Algorithm details — "what cipher, mode, block size, padding?"
2. Token/ciphertext format — structure and where user input sits.
3. Block behaviour — send 0/1/15/16/17 bytes; count output blocks (find the 16-byte AES boundary).
4. Oracle direction — can you encrypt? decrypt? verify? Each enables different attacks.