I'm happy to see the unclonable encryption problem solved;...
Henry Yuen@henryquantum
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Jul 25, 2026
~1 min read
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I'm happy to see the unclonable encryption problem solved; Prabhanjan Ananth and Amit Sahai report their findings, with the help of the UCLA harness (link below). This was a challenge for the quantum crypto community for the last 6 years.
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Paper: scirate.com/arxiv/2607.215…
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Unclonable encryption allows you to encrypt your messages into qubits, such that only one person can decrypt the message -- even if you broadcast the secret key to the entire world. The ciphertext, in other words, is not copyable, because it's a quantum state.
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The challenge in the community was to argue that there exist secure unclonable encryption schemes. The original beautiful paper of Broadbent and Lord (arxiv.org/abs/1903.00130) in 2020 showed a scheme that satisfied "search security".
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The challenge was to show a scheme satisfying "indistinguishability security", which is a stronger notion. This was a notorious problem in the area that stumped many researchers in quantum crypto.
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In some sense, we only had one bullet in the gun, and that was the monogamy of entanglement analysis of Tomamichel, Fehr, Kaniewski, and Wehner (arxiv.org/abs/1210.4359). ChatGPT, apparently found a different way of analyzing unclonable encryption that did not reduce to TFKW.
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What times we live in!