Information-theoretic one-bit unclonable encryption

Can one-bit private-key encryption be efficient, perfectly correct and information-theoretically unclonable after key disclosure? The target is a one-time n-qubit construction for which two separated receivers both recover the bit with probability at most 1/2+O(2^(-n/2)).

Why it matters and what counts as progress

Why it matters: It seeks exponentially small joint-recovery advantage while combining unconditional security with an efficient construction.

What counts as progress: Reduce cloning advantage while retaining efficient, perfectly correct encryption and unconditional security, or extend the guarantee beyond a one-bit message.

How the problem developed

23 Jul 2026 · Reported solution [1]
Prabhanjan Ananth, Seyoon Ragavan and Amit Sahai The authors posted their one-bit unclonable-encryption result; the paper gives an efficient, perfectly correct Pauli-eigenstate scheme with both receivers’ success at most 1/2+O(2^(−n/2)) after key disclosure.
4 Oct 2026 · Revised manuscript [2][3]
Ananth, Ragavan and Sahai The revised preprint documents the merged result and a Lean formalization of the construction and security bound.

AI contribution

Unconditional Unclonable Encryption

Prabhanjan Ananth, Seyoon Ragavan, Amit Sahai

Ananth, Ragavan and Sahai give efficient, perfectly correct, one-time private-key encryption of one bit using a random nonidentity phase-free n-qubit Pauli and a random eigenstate. After key disclosure, both separated receivers recover the bit with probability at most 1/2+O(2^(−n/2)) against information-theoretic attacks.

AI involvementAI-led

ImportanceNotable

Technical verificationFormal (Lean 4 + human)

Human understandingFull