Cipher-Structure-Aware Variational Quantum Cryptanalysis: A Reversible Public-Diagnostic Framework
Abstract
We introduce a cipher-structure-aware variational framework for key recovery from public data in reduced block ciphers. Public S-box differential constraints and candidate-key-dependent inverse-round residuals are converted into phase separators through reversible compute-phase-uncompute circuits. The principal separator is a hybrid DDT construction that combines pairwise and synchronized multi-pair differential constraints before residual refinement. The construction is specified by public functions and does not require a key-indexed phase table in the physical circuit. We formalize the public-instance model, prove one-sided completeness of the structural diagnostics, and derive a conditional lower-tail bound for false-key diagnostic gaps under an explicitly stated sub-Gaussian moment condition. This statistical statement concerns the diagnostic landscape, not convergence of a finite-depth QAOA optimizer. On ten independent random three-pair instances of 16-bit simplified AES, an 18-layer Hybrid-DDT schedule reaches a mean public-consistent-key probability of 0.529785, with values from 0.388892 to 0.770937, ranks the correct key first in every run, and has largest observed false-key probability 0.008723. The result is a reduced-cipher mechanism study, not an attack on full AES.
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BibTeX
@misc{li2026cipherstructureaware,
title = {{Cipher-Structure-Aware Variational Quantum Cryptanalysis: A Reversible Public-Diagnostic Framework}},
author = {Xi Li},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2609.28493},
eprint = {2609.28493},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2609.28493},
}
RIS
TY - UNPB
TI - Cipher-Structure-Aware Variational Quantum Cryptanalysis: A Reversible Public-Diagnostic Framework
AU - Xi Li
PY - 2026
DA - 2026/09/01
PB - arXiv
DO - 10.48550/arxiv.2609.28493
UR - https://arxiv.org/abs/2609.28493
AB - We introduce a cipher-structure-aware variational framework for key recovery from public data in reduced block ciphers. Public S-box differential constraints and candidate-key-dependent inverse-round residuals are converted into phase separators through reversible compute-phase-uncompute circuits. The principal separator is a hybrid DDT construction that combines pairwise and synchronized multi-pair differential constraints before residual refinement. The construction is specified by public functions and does not require a key-indexed phase table in the physical circuit. We formalize the public-instance model, prove one-sided completeness of the structural diagnostics, and derive a conditional lower-tail bound for false-key diagnostic gaps under an explicitly stated sub-Gaussian moment condition. This statistical statement concerns the diagnostic landscape, not convergence of a finite-depth QAOA optimizer. On ten independent random three-pair instances of 16-bit simplified AES, an 18-layer Hybrid-DDT schedule reaches a mean public-consistent-key probability of 0.529785, with values from 0.388892 to 0.770937, ranks the correct key first in every run, and has largest observed false-key probability 0.008723. The result is a reduced-cipher mechanism study, not an attack on full AES.
ER -