The_Electroconvulsive_Cipher

The machine hiccupped.

The records show the treatment completed — but not cleanly. Thirty sessions logged. Fifteen went the full course. The other fifteen stopped a round early.

Something slipped between the shocks.

The ECT unit encrypts all patient treatment records using a legacy block cipher. A malfunction introduced single-bit errors into a batch of ciphertexts.

The treatment logs, the faulty outputs, and the encryption unit itself have been recovered.

The errors are the vulnerability. Biham and Shamir figured it out in 1997.