Calculating encryption schemes’ theoretical security guarantees eases comparison, improvement. Most modern cryptographic schemes rely on computational complexity for their security. In principle, they can be cracked, but that would take a prohibitively long time, even with enormous computational resources. There is, however, another notion of security — information-theoretic security — which means that even an adversary with unbounded computational power could extract no useful information from an encrypted message. Cryptographic schemes that promise information-theoretical security have been devised, but they’re far too complicated to be practical. In a series of papers presented at the Allerton Conference on Communication, Control, and Computing, researchers at MIT and Maynooth University in Ireland have shown that existing, practical cryptographic schemes come with their own information-theoretic guarantees: Some of the data they encode can’t be extracted, even by a