ECC Protocol & Implementation Attacks — Curveball, ProSign 3, Checkpoint, Digestive, No Random No Bias

cryptohack

Task: five CryptoHack ECC protocol/implementation challenges (ECDSA, ECDH, invalid-curve, CurveBall). Solution: attacker-controlled generator (CVE-2020-0601), tiny-nonce ECDSA key recovery, invalid-curve small-subgroup ECDH with CRT+sign resolution, ECDSA digest-truncation + JSON duplicate-key, and short-nonce Hidden Number Problem via LLL lattice.