Table of Contents
Fetching ...

On Split-State Quantum Tamper Detection and Non-Malleability

Thiago Bergamaschi, Naresh Goud Boddu

TL;DR

The paper advances quantum tamper-detection by showing that a multipartite quantum encoding across at least $3$ shares enables tamper-detection against split-state tampering with bounded entanglement, a feat impossible for classical codes. It provides a concrete 3-split tamper-detection code with constant rate and inverse-subexponential error in the bounded-storage regime, built from quantum-secure non-malleable extractors and unitary 2-designs. Beyond the code itself, the authors develop a blueprint to turn these codes into tamper-detecting secret sharing schemes and establish links to quantum encryption/authentication, highlighting how tamper-detection naturally implies a form of encryption of shares. They also connect their constructions to leakage-resilient secret sharing and to non-malleable quantum encryption notions, yielding a framework that unifies tamper-resilience, secret sharing, and encryption in the quantum setting. The work raises open questions about optimal capacity, LOCC tamper-detection, and extensions to quantum secrets, while providing concrete building blocks for tamper-detecting quantum cryptographic primitives with practical rate and security guarantees.

Abstract

Tamper-detection codes (TDCs) are fundamental objects at the intersection of cryptography and coding theory. A TDC encodes messages in such a manner that tampering the codeword causes the decoder to either output the original message, or reject it. In this work, we study quantum analogs of one of the most well-studied adversarial tampering models: the so-called $t$-split-state tampering model, where the codeword is divided into $t$ shares, and each share is tampered with "locally". It is impossible to achieve tamper detection in the split-state model using classical codewords. Nevertheless, we demonstrate that the situation changes significantly if the message can be encoded into a multipartite quantum state, entangled across the $t$ shares. Concretely, we define a family of quantum TDCs defined on any $t\geq 3$ shares, which can detect arbitrary split-state tampering so long as the adversaries are unentangled, or even limited to a finite amount of pre-shared entanglement. Previously, this was only known in the limit of asymptotically large $t$. As our flagship application, we show how to augment threshold secret sharing schemes with similar tamper-detecting guarantees. We complement our results by establishing connections between quantum TDCs and quantum encryption schemes.

On Split-State Quantum Tamper Detection and Non-Malleability

TL;DR

The paper advances quantum tamper-detection by showing that a multipartite quantum encoding across at least shares enables tamper-detection against split-state tampering with bounded entanglement, a feat impossible for classical codes. It provides a concrete 3-split tamper-detection code with constant rate and inverse-subexponential error in the bounded-storage regime, built from quantum-secure non-malleable extractors and unitary 2-designs. Beyond the code itself, the authors develop a blueprint to turn these codes into tamper-detecting secret sharing schemes and establish links to quantum encryption/authentication, highlighting how tamper-detection naturally implies a form of encryption of shares. They also connect their constructions to leakage-resilient secret sharing and to non-malleable quantum encryption notions, yielding a framework that unifies tamper-resilience, secret sharing, and encryption in the quantum setting. The work raises open questions about optimal capacity, LOCC tamper-detection, and extensions to quantum secrets, while providing concrete building blocks for tamper-detecting quantum cryptographic primitives with practical rate and security guarantees.

Abstract

Tamper-detection codes (TDCs) are fundamental objects at the intersection of cryptography and coding theory. A TDC encodes messages in such a manner that tampering the codeword causes the decoder to either output the original message, or reject it. In this work, we study quantum analogs of one of the most well-studied adversarial tampering models: the so-called -split-state tampering model, where the codeword is divided into shares, and each share is tampered with "locally". It is impossible to achieve tamper detection in the split-state model using classical codewords. Nevertheless, we demonstrate that the situation changes significantly if the message can be encoded into a multipartite quantum state, entangled across the shares. Concretely, we define a family of quantum TDCs defined on any shares, which can detect arbitrary split-state tampering so long as the adversaries are unentangled, or even limited to a finite amount of pre-shared entanglement. Previously, this was only known in the limit of asymptotically large . As our flagship application, we show how to augment threshold secret sharing schemes with similar tamper-detecting guarantees. We complement our results by establishing connections between quantum TDCs and quantum encryption schemes.
Paper Structure (339 sections, 290 theorems, 700 equations, 55 figures, 3 tables, 44 algorithms)

This paper contains 339 sections, 290 theorems, 700 equations, 55 figures, 3 tables, 44 algorithms.

Key Result

theorem thmcountertheorem

For every $n\in \mathbb{N}$, $\gamma\in (0, \frac{1}{20})$, there exists a quantum tamper detection code secure against the 3-split-state tampering model $\mathsf{LO}_{\Theta(\gamma n)}^3$, of blocklength $n$, rate $\frac{1}{11} - \gamma$, and error $2^{-n^{\Omega(1)}}$.

Figures (55)

  • Figure 1: The Quantum Split-State Tampering Model, $t=3$Boddu2023SplitState. A (possibly entangled) message $M$ is encoded, and subsequently tampered with using quantum channels $U, V, W$, jointly with an entangled state on registers $E_1, E_2, E_3$.
  • Figure 2: Quantum TDC against $\mathsf{LO}^{t+1}$.
  • Figure 3: A "Tamper-Detecting" Secret Sharing Scheme
  • Figure 4: Clifford Twirling with Side Information.
  • Figure 5: $t$-split-state tampering model for $t=3$.
  • ...and 50 more figures

Theorems & Definitions (585)

  • theorem thmcountertheorem: 3-Split Tamper Detection Codes
  • theorem thmcountertheorem: Tamper-Detecting Quantum Secret Sharing
  • theorem thmcountertheorem: Tamper-Detection Codes Encrypt their Shares
  • definition thmcounterdefinition: Quantum Non-Malleable Codes Boddu2023SplitState
  • definition thmcounterdefinition: Schatten $p$-norm
  • definition thmcounterdefinition: Trace distance
  • definition thmcounterdefinition
  • definition thmcounterdefinition: Conditioning
  • definition thmcounterdefinition
  • definition thmcounterdefinition: The Schmidt Number, Terhal1999SchmidtNF
  • ...and 575 more