Five solved challenges, writeups reconstructed from session traces and independently re-verified: recomputed offline, or replayed against a local test instance, rather than taken on faith.
Reverse-engineering an undocumented 16-byte binary telemetry record format.
Breaking ECDSA via a Hidden Number Problem lattice attack on a biased nonce.
Two-time-pad keystream recovery from a stream cipher that never advances its counter.
The AES-GCM Forbidden Attack: forging an authenticated tag from a single reused nonce.
Geolocating a hillside church from a single unlabeled photograph.