Cryptography and Cryptanalysis | High-Performance Experimental Laboratories

A technical research platform dedicated to the exploration of cryptographic primitives and the implementation of advanced cryptanalytic attacks. This repository serves as an engineering workbench for testing high-throughput stream ciphers, stochastic key recovery, and algebraic state reconstruction.

🚀 Laboratories Overview

Laboratory 01: Substitution Cryptanalysis
Modular statistical environment for substitution ciphers utilizing n-gram frequency distributions and Chi-Square divergence testing to quantify linguistic similarity.

Laboratory 02: Classical Cipher Suite
Automated brute-force engine for Caesar and Affine ciphers implementing the Extended Euclidean Algorithm and result-pattern orchestration for explicit error handling.

Laboratory 03: Heuristic Key Recovery
Stochastic cryptanalysis workbench utilizing Metropolis-Hastings and Simulated Annealing with Unsafe hot-path optimizations—achieving a 99.5% reduction in execution time (from 100s to 519ms).

Laboratory 04: LCG State Reconstruction
Known-plaintext attack implementation targeting Linear Congruential Generators, leveraging arbitrary-precision arithmetic to solve systems of linear congruences.

Laboratory 05: LFSR & GF(2) Solvers
Stream cipher analysis framework featuring a zero-allocation Gaussian elimination solver over $GF(2)$ optimized with 64-bit word-packing and stackalloc buffers.

Laboratory 06: Geffe Correlation Attack
Divide-and-conquer statistical attack suite targeting non-linear Geffe combiners through Pearson Rho correlation coefficients to recover internal states in sub-linear time.

Laboratory 07: Trivium SIMD & Cube Attack
High-throughput Trivium implementation leveraging AVX2 SIMD parallelization (8-stream) and algebraic Cube Attacks—reaching peak throughput of 70 Gbps.

🏗️ Technical Highlights

High-Performance Compute: Extensive use of Span<T>, stackalloc, and Unsafe pointer arithmetic to achieve zero-allocation in cryptographic hot paths.
Vectorization: Implementation of AVX2 intrinsics to parallelize stream cipher state updates, processing 8 independent streams in 256-bit registers.
Advanced Cryptanalysis: Application of stochastic (MCMC) and algebraic (Cube Attack) methods to break ciphers without exhaustive key searches.
Compilation Strategy: Systematic use of Native AOT (PublishAot) to ensure predictable execution latency and minimal memory footprint.

🛠️ Tech Stack & Runtime Environment

Languages: C# 13, C# 14
Runtimes: .NET 9.0, .NET 10.0
Numerical Core: System.Numerics.BigInteger, Custom Xoshiro256 PRNG
Low-Level Tools: AVX2 SIMD Intrinsics, System.Runtime.CompilerServices.Unsafe, and stackalloc
Deployment: Native AOT for self-contained, high-performance binaries

🧪 Quality & Standards

Validation: All implementations verified against Known Answer Tests (KAT) or through Monte Carlo simulations to ensure statistical reliability.
Optimization Principles: Focus on cache locality, branchless programming, and zero-allocation in execution "hot loops".
Architecture: Adherence to Vertical Slice and Layered DDD-Lite principles to maintain modularity in performance-critical kernels.

🙋‍♂️ Author

Kamil Fudala

⚖️ License

This project is licensed under the MIT License.

FreakyF/Cryptography-And-Cryptanalysis