Cryptography based on Landauer's principle

Quantum cryptography turns to its advantage the apparent pessimism of the no-cloning theorem: It exploits a physical property of information to make communication theoretically secure against adversaries having unbounded computing power. Such overturn has also been realized (to achieve various cryptographic primitives) with other physical restrictions such as bounded storage, noisy channels, and the no-signalling principle of special relativity. We add to the list here the second law of thermodynamics — to which not much glamour has been attached before.

We define a theoretical model — a classical-information world in which exponentially large randomized memories are accessible, and reversible computation is effortless, but free energy is severely limited — and present in its context an information-theoretically secure protocol for 1-out-of-2 oblivious transfer. Its security follows directly from Landauer’s principle (which states that the erasure cost of 1 bit of information is at least kB T ln 2 J/K). Oblivious transfer is an important cryptographic primitive because it can be used as a subroutine to achieve any multi-party computation task securely.