EPEX: A Zero-SRAM Matrix-Free Expansion Engine for Embedded Post-Quantum Cryptography | Zenodo
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Published June 18, 2026
| Version 1
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EPEX: A Zero-SRAM Matrix-Free Expansion Engine for Embedded Post-Quantum Cryptography
Authors/Creators
Wartenberg, Tom
Description
EPEX — Embedded Procedural Expansion Engine — is an independent cryptographic engineering research artifact focused on one practical question:
Can public LWE-style matrix coefficients be generated on demand, without persistently storing the matrix in embedded SRAM?
EPEX explores a matrix-free expansion layer for Regev-style Learning With Errors (LWE) research on highly resource-constrained embedded targets. Instead of materializing a public matrix A as a static memory object, EPEX derives coefficients procedurally through a deterministic, coordinate-seekable expansion function based on a compact 16-bit ARX permutation.
This release is a Zenodo technical documentation snapshot, not a production cryptographic library and not a fully buildable GitHub repository.
What this archive contains:
• A complete technical documentation chain for the EPEX v1 research prototype
• Architectural rationale and lineage from the original EchoPulse permutation research
• A matrix-free LWE-style coefficient-generation model
• Empirical statistical distinguishability reports
• Cortex-M4F target footprint profiling and embedded-resource analysis
• Structural defect discovery, remediation, and re-validation
• Phase 5 / Phase 5R repair documentation
• Phase 6 residual-structure and SMT-based analysis
• Current-status and residual-risk assessment
• Forward-looking 32-bit scaling roadmap and architecture levers
Core milestone:
EPEX demonstrates a documented path from a materialized LWE toy baseline toward a procedural, matrix-free coefficient generator with zero persistent public-matrix storage and a very small embedded target footprint.
The most important part of this release is not a claim of production security. It is the transparent engineering lifecycle:
Design → Baseline → Matrix-Free Transition → Embedded Profiling → Structural Breaks → Repair → Re-Validation → Residual-Risk Assessment → Future Scaling Roadmap
Key documented results:
• Persistent public-matrix storage removed in the tested matrix-free configuration
• Deterministic coordinate-seekable coefficient generation
• Empirical statistical validation under the documented test suites
• Cross-compilation and footprint profiling for a bare-metal ARM Cortex-M4F target profile
• Documented remediation of earlier structural defects, including dead upper seed bits and coordinate aliasing
• Explicit residual-risk documentation instead of hidden or overstated security claims
Important limitations:
• EPEX v1 is a research prototype, not production cryptographic software
• The current parameter set is intentionally small: n=m=32, q=256
• No formal cryptographic security proof is claimed
• The internal 16-bit ARX core imposes birthday-bound limitations
• Security depends on the observed diffusion behavior of the 6-round ARX permutation
• The 32-bit extension is a roadmap direction, not part of the deployed v1 implementation
• The archive does not contain a complete production-ready KEM or a full Cargo workspace
Intended audience:
• Embedded cryptography researchers
• Post-quantum cryptography engineers
• LWE / lattice-based cryptography reviewers
• Resource-constrained security architects
• R&D teams evaluating memory-minimal PQC implementation strategies
Recommended entry points:
• 00_EPEX_README_Zenodo.pdf
• 01_EPEX_Executive_Introduction.pdf
• 02_EPEX_Master_Technical_Reference.pdf
• EPEX_Framework_Full_Documentation_Archive.zip
Disclaimer:
This project is not production-ready cryptographic software and must not be used to protect real-world secrets without independent peer review, formal parameterization, security analysis, implementation hardening, and complete integration testing.
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0.1.EPEX.executive_instruction.pdf
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0.1.EPEX.executive_instruction.pdf
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0_EPEX_Master_Technical_Reference.pdf
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1.5.EPEX.README.V1.pdf
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EPEX.FRAMEWORK.zip
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