Fundamental Limitations of Post-Quantum Cryptographic Architectures

TL;DR

This paper critically examines the fundamental theoretical and physical limitations of lattice-based post-quantum cryptography, questioning its claimed unconditional security against quantum attacks.

Contribution

It provides a comprehensive analysis across multiple domains showing that current assumptions and physical models challenge the notion of unconditionally post-quantum security.

Findings

Provisional complexity assumptions remain vulnerable to future quantum algorithms.

Injected noise does not guarantee permanent information erasure in cryptographic schemes.

Quantum error correction and learning models can potentially extract secret information.

Abstract

Modern lattice-based cryptography, particularly the learning with errors paradigm, relies on injecting artificial noise to secure data against quantum adversaries. This study systematically examines the theoretical and physical boundaries of this noise-reliant model across four interconnected domains: computational complexity, information-theoretic thermodynamics, quantum error correction, and quantum learning theory. Starting from the algorithmic foundation, our analysis notes that these frameworks rely on provisional complexity-theoretic assumptions that remain vulnerable to future quantum algorithmic advancements. Furthermore, by translating this cryptographic mechanism into physical thermodynamics, we illustrate that intentionally injected discrete Gaussian noise does not equate to the permanent erasure of information. Because the structural integrity of the cryptographic secret remains preserved within the ciphertext, advanced quantum error correction protocols and quantum learning models can efficiently extract the underlying mathematical kernel. Ultimately, we suggest that while lattice-based cryptography provides a robust transitional alternative, definitively classifying these frameworks as unconditionally post-quantum represents a premature classification relying on transient physical bottlenecks rather than impenetrable theoretical boundaries.