Cryptography without Long-Term Quantum Memory and Global Entanglement

2025-04-30

AI Summary

This work addresses the challenge of constructing quantum cryptographic primitives without long-term quantum memory or global entanglement. We propose a novel paradigm based on classical queryable oracles and semi-quantum tokens. Methodologically, our constructions rely solely on short-duration quantum operations, locally independent noise assumptions, and lightweight quantum hardware—enabling short-lived semi-quantum one-time programs, RAM obfuscation, long-lived one-time programs, and copyright protection. Our key contributions are: (i) the first provably secure constructions of RAM obfuscation and long-lived one-time programs under the strict constraints of no long-term quantum memory and no global entanglement; and (ii) a dramatic reduction in requirements for quantum coherence time and gate fidelity, with error tolerance introducing only logarithmic overhead. All schemes are rigorously proven secure and designed for near- to mid-term noisy intermediate-scale quantum (NISQ) devices.

Technology Category

• Machine Learning: Quantum Machine Learning
• Search and Optimization: Learning to Search
• Computer Vision: Adversarial Attacks & Robustness

Application Category

• Security and Privacy: Applications of cryptography
• Search and Retrieval-Augmented AI: Retrieval-Augmented Generation (RAG) and multi-modal RAG
• Economics, Online Markets and Human Computation: Economic aspects of blockchain and cryptocurrencies

Abstract

We show how oracles which only allow for classical query access can be used to construct a variety of quantum cryptographic primitives which do not require long-term quantum memory or global entanglement. Specifically, if a quantum party can execute a semi-quantum token scheme (Shmueli 2022) with probability of success $1/2 + delta$, we can build powerful cryptographic primitives with a multiplicative logarithmic overhead for the desired correctness error. Our scheme makes no assumptions about the quantum party's noise model except for a simple independence requirement: noise on two sets of non-entangled hardware must be independent. Using semi-quantum tokens and oracles which can only be queried classically, we first show how to construct a"short-lived"semi-quantum one-time program (OTP) which allows a classical sending party to prepare a one-time program on the receiving party's quantum computer. We then show how to use this semi-quantum OTP to construct a semi-quantum"stateful obfuscation"scheme (which we term"RAM obfuscation"). Importantly, the RAM obfuscation scheme does not require long-term quantum memory or global entanglement. Finally, we show how RAM obfuscation can be used to build long-lived one-time programs and copy-protection schemes.

Problem

• Construct quantum cryptography without long-term quantum memory
• Build cryptographic primitives using classical query oracles
• Enable secure one-time programs without global entanglement

Innovation

• Uses classical query access oracles
• Implements semi-quantum token schemes
• Avoids long-term quantum memory requirements