License: Creative Commons Attribution 4.0 International license (CC BY 4.0)
When quoting this document, please refer to the following
DOI: 10.4230/LIPIcs.ITCS.2023.87
URN: urn:nbn:de:0030-drops-175900
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Morimae, Tomoyuki ; Yamakawa, Takashi

Proofs of Quantumness from Trapdoor Permutations

LIPIcs-ITCS-2023-87.pdf (0.7 MB)


Assume that Alice can do only classical probabilistic polynomial-time computing while Bob can do quantum polynomial-time computing. Alice and Bob communicate over only classical channels, and finally Bob gets a state |x₀⟩+|x₁⟩ with some bit strings x₀ and x₁. Is it possible that Alice can know {x₀,x₁} but Bob cannot? Such a task, called remote state preparations, is indeed possible under some complexity assumptions, and is bases of many quantum cryptographic primitives such as proofs of quantumness, (classical-client) blind quantum computing, (classical) verifications of quantum computing, and quantum money. A typical technique to realize remote state preparations is to use 2-to-1 trapdoor collision resistant hash functions: Alice sends a 2-to-1 trapdoor collision resistant hash function f to Bob, and Bob evaluates it coherently, i.e., Bob generates ∑_x|x⟩|f(x)⟩. Bob measures the second register to get the measurement result y, and sends y to Alice. Bob’s post-measurement state is |x₀⟩+|x₁⟩, where f(x₀) = f(x₁) = y. With the trapdoor, Alice can learn {x₀,x₁} from y, but due to the collision resistance, Bob cannot. This Alice’s advantage can be leveraged to realize the quantum cryptographic primitives listed above. It seems that the collision resistance is essential here. In this paper, surprisingly, we show that the collision resistance is not necessary for a restricted case: we show that (non-verifiable) remote state preparations of |x₀⟩+|x₁⟩ secure against classical probabilistic polynomial-time Bob can be constructed from classically-secure (full-domain) trapdoor permutations. Trapdoor permutations are not likely to imply the collision resistance, because black-box reductions from collision-resistant hash functions to trapdoor permutations are known to be impossible. As an application of our result, we construct proofs of quantumness from classically-secure (full-domain) trapdoor permutations.

BibTeX - Entry

  author =	{Morimae, Tomoyuki and Yamakawa, Takashi},
  title =	{{Proofs of Quantumness from Trapdoor Permutations}},
  booktitle =	{14th Innovations in Theoretical Computer Science Conference (ITCS 2023)},
  pages =	{87:1--87:14},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-263-1},
  ISSN =	{1868-8969},
  year =	{2023},
  volume =	{251},
  editor =	{Tauman Kalai, Yael},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{},
  URN =		{urn:nbn:de:0030-drops-175900},
  doi =		{10.4230/LIPIcs.ITCS.2023.87},
  annote =	{Keywords: Quantum cryptography, Proofs of quantumness, Trapdoor permutations}

Keywords: Quantum cryptography, Proofs of quantumness, Trapdoor permutations
Collection: 14th Innovations in Theoretical Computer Science Conference (ITCS 2023)
Issue Date: 2023
Date of publication: 01.02.2023

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