
Andrei Stoian developed advanced GPU-accelerated cryptographic features and robust CI workflows for the zama-ai/tfhe-rs repository, focusing on scalable, high-performance homomorphic encryption. He engineered CUDA-based keyswitching and polynomial multiplication, enabling dynamic GPU usage and batch processing for machine learning workloads. Andrei improved reliability through deterministic multi-GPU testing, memory safety enhancements, and error handling, leveraging C++, Rust, and CUDA. His work included refactoring build systems, integrating static analysis, and optimizing benchmarking pipelines for accurate performance assessment. By strengthening documentation, parameter management, and developer tooling, Andrei delivered maintainable, efficient solutions that improved runtime stability and developer productivity across heterogeneous hardware environments.
April 2026 — zama-ai/tfhe-rs. Delivered enhancements to GPU testing and runtime robustness, focusing on reliability, efficiency, and developer velocity. Key features and fixes improved CI feedback loop and resource handling, aligning with business goals of faster iteration and stable GPU pipelines.
April 2026 — zama-ai/tfhe-rs. Delivered enhancements to GPU testing and runtime robustness, focusing on reliability, efficiency, and developer velocity. Key features and fixes improved CI feedback loop and resource handling, aligning with business goals of faster iteration and stable GPU pipelines.
March 2026 (2026-03) – TFHE-rs (zama-ai/tfhe-rs) monthly summary focusing on business value and technical excellence. Progress highlights: - GPU Benchmarking Improvements: Implemented parsing of results from scheduled runs and updates to PBS benchmarks, enabling Grafana-driven visibility and more reliable performance assessments. - CUDA Backend Versioning and Release Quality: Added semantic versioning checks to CI for the CUDA backend and relaxed dependency constraints to reduce integration friction while preserving release integrity. - CUDA Backend Error Handling and Correctness Fixes: Enforced CUDA runtime API error conformance and corrected the compatibility check for GPU LWE ciphertext cleartext multiplication, improving correctness and runtime reliability. - Semgrep Rules for CUDA Release Ordering: Updated rules to ensure proper release ordering in CUDA functions, reducing release risk and audit overhead. Impact and value: - Increased reliability of benchmarking pipelines and observability for performance-sensitive workloads. - Higher release quality with improved CI checks and smoother dependency management. - Stronger correctness guarantees for CUDA backend operations, lowering production risk. Technologies and skills demonstrated: - GPU benchmarking workflows, Grafana data ingestion, PBS benchmarks - CI/semver checks, dependency management for CUDA backend - CUDA runtime API conformance and cryptography correctness - Semgrep static analysis and release hygiene - Cross-team collaboration and code quality improvement
March 2026 (2026-03) – TFHE-rs (zama-ai/tfhe-rs) monthly summary focusing on business value and technical excellence. Progress highlights: - GPU Benchmarking Improvements: Implemented parsing of results from scheduled runs and updates to PBS benchmarks, enabling Grafana-driven visibility and more reliable performance assessments. - CUDA Backend Versioning and Release Quality: Added semantic versioning checks to CI for the CUDA backend and relaxed dependency constraints to reduce integration friction while preserving release integrity. - CUDA Backend Error Handling and Correctness Fixes: Enforced CUDA runtime API error conformance and corrected the compatibility check for GPU LWE ciphertext cleartext multiplication, improving correctness and runtime reliability. - Semgrep Rules for CUDA Release Ordering: Updated rules to ensure proper release ordering in CUDA functions, reducing release risk and audit overhead. Impact and value: - Increased reliability of benchmarking pipelines and observability for performance-sensitive workloads. - Higher release quality with improved CI checks and smoother dependency management. - Stronger correctness guarantees for CUDA backend operations, lowering production risk. Technologies and skills demonstrated: - GPU benchmarking workflows, Grafana data ingestion, PBS benchmarks - CI/semver checks, dependency management for CUDA backend - CUDA runtime API conformance and cryptography correctness - Semgrep static analysis and release hygiene - Cross-team collaboration and code quality improvement
February 2026 monthly summary for zama-ai/tfhe-rs GPU backend work. Highlights include feature delivery for GPU LUT generation, enhanced GPU backend robustness and crypto FFI safety, and the introduction of CI linting for CUDA code. These efforts improved reliability, correctness of cryptographic paths, and overall code quality with automated checks.
February 2026 monthly summary for zama-ai/tfhe-rs GPU backend work. Highlights include feature delivery for GPU LUT generation, enhanced GPU backend robustness and crypto FFI safety, and the introduction of CI linting for CUDA code. These efforts improved reliability, correctness of cryptographic paths, and overall code quality with automated checks.
Concise monthly summary for 2026-01 covering key features, bugs fixed, and impact for zama-ai/tfhe-rs. Highlights: 1) GPU memory safety and testing improvements; refined CI filters to focus on relevant high-level API and core crypto GPU tests, improved memory error detection accuracy, and addressed leaks with enhanced error reporting in Valgrind-based tests. 2) TFHE CUDA LUT generation refactor; replaced direct LUT calls with generate_and_broadcast to boost efficiency, structure, and maintainability. 3) GPU backend robustness improvements; strengthened thread safety in GPU memory pool setup and added modulus checks for cryptographic operations to ensure compatibility and better error handling. Impact: improved reliability, faster issue resolution, and stronger GPU cryptographic workflow. Technologies: GPU memory safety testing, Valgrind-based testing, CUDA backend, mutex/thread safety, cryptographic parameter validation, code refactoring.
Concise monthly summary for 2026-01 covering key features, bugs fixed, and impact for zama-ai/tfhe-rs. Highlights: 1) GPU memory safety and testing improvements; refined CI filters to focus on relevant high-level API and core crypto GPU tests, improved memory error detection accuracy, and addressed leaks with enhanced error reporting in Valgrind-based tests. 2) TFHE CUDA LUT generation refactor; replaced direct LUT calls with generate_and_broadcast to boost efficiency, structure, and maintainability. 3) GPU backend robustness improvements; strengthened thread safety in GPU memory pool setup and added modulus checks for cryptographic operations to ensure compatibility and better error handling. Impact: improved reliability, faster issue resolution, and stronger GPU cryptographic workflow. Technologies: GPU memory safety testing, Valgrind-based testing, CUDA backend, mutex/thread safety, cryptographic parameter validation, code refactoring.
2025-11 Monthly Summary: Delivered GEMM-based keyswitching for LWE ciphertexts in tfhe-rs to enable batch processing and scalability. Implemented temporary buffers and updated core routines to support the new method, laying the groundwork for higher throughput in large cryptographic workloads. Initiated benchmarking to quantify latency improvements and guide further optimizations. This work enhances performance and scalability for TFHE-based services.
2025-11 Monthly Summary: Delivered GEMM-based keyswitching for LWE ciphertexts in tfhe-rs to enable batch processing and scalability. Implemented temporary buffers and updated core routines to support the new method, laying the groundwork for higher throughput in large cryptographic workloads. Initiated benchmarking to quantify latency improvements and guide further optimizations. This work enhances performance and scalability for TFHE-based services.
2025-10 — Focused on stabilizing the GPU coprocessor path in zama-ai/tfhe-rs. Delivered a robust fix to the GPU coprocessor installation workflow that corrects npm dependency installation and ensures host contracts deploy and compile reliably, stabilizing GPU benchmarks. This improves reliability of GPU-enabled crypto workloads and enhances benchmarking repeatability, enabling faster, more accurate performance assessments and customer-facing reporting.
2025-10 — Focused on stabilizing the GPU coprocessor path in zama-ai/tfhe-rs. Delivered a robust fix to the GPU coprocessor installation workflow that corrects npm dependency installation and ensures host contracts deploy and compile reliably, stabilizing GPU benchmarks. This improves reliability of GPU-enabled crypto workloads and enhances benchmarking repeatability, enabling faster, more accurate performance assessments and customer-facing reporting.
September 2025 — zama-ai/tfhe-rs: Multi-GPU backend and testing improvements delivering reliability, performance visibility, and deterministic validation across GPUs. Key features delivered - Multi-GPU Backend and Benchmarking Enhancements: Consolidated CUDA stream management, improved cross-GPU synchronization, enhanced benchmarking workflow for manual-dispatch and instance selection, and added a dedicated fake multi-GPU debug mode to accelerate development and validation across GPUs. Commit highlights include: 1dcc3c8c898cfebe243f82a9bbe458e9990b96ce, 87c0d646a4bfadcf0bf3b39f6ba7fb323e27cfcf, 30938eec74408b037aae5ffc2af352471d7658fa, 0604d237ebbe42675519071733c7170e14556292. - Deterministic GPU Testing and Reliability Improvements: Introduced seeded RNG for GPU device selection and operation sequencing to ensure deterministic GPU tests, updating executor types and setup to support reproducible test runs. Commit: 73de886c074959b45e049a59bbf0944dd46002f4. Major bugs fixed - Fixed issues related to coprocessor benchmarking under GPU workloads, contributing to more stable and repeatable benchmark results. (Evidence: commit fix(gpu): coprocessor bench) Overall impact and accomplishments - Increased reliability and predictability of multi-GPU tests and benchmarks, enabling faster performance tuning, more confident release planning, and reduced debugging time. Supports scalable validation across GPUs and clearer benchmarking signals for optimization. Technologies and skills demonstrated - GPU programming patterns: CUDA stream consolidation, multi-GPU synchronization, and fake multi-GPU debugging workflows - Benchmark design and reproducibility: seeded RNG for deterministic tests and updated executors for stable runs - Cross-GPU validation tooling and development enablement
September 2025 — zama-ai/tfhe-rs: Multi-GPU backend and testing improvements delivering reliability, performance visibility, and deterministic validation across GPUs. Key features delivered - Multi-GPU Backend and Benchmarking Enhancements: Consolidated CUDA stream management, improved cross-GPU synchronization, enhanced benchmarking workflow for manual-dispatch and instance selection, and added a dedicated fake multi-GPU debug mode to accelerate development and validation across GPUs. Commit highlights include: 1dcc3c8c898cfebe243f82a9bbe458e9990b96ce, 87c0d646a4bfadcf0bf3b39f6ba7fb323e27cfcf, 30938eec74408b037aae5ffc2af352471d7658fa, 0604d237ebbe42675519071733c7170e14556292. - Deterministic GPU Testing and Reliability Improvements: Introduced seeded RNG for GPU device selection and operation sequencing to ensure deterministic GPU tests, updating executor types and setup to support reproducible test runs. Commit: 73de886c074959b45e049a59bbf0944dd46002f4. Major bugs fixed - Fixed issues related to coprocessor benchmarking under GPU workloads, contributing to more stable and repeatable benchmark results. (Evidence: commit fix(gpu): coprocessor bench) Overall impact and accomplishments - Increased reliability and predictability of multi-GPU tests and benchmarks, enabling faster performance tuning, more confident release planning, and reduced debugging time. Supports scalable validation across GPUs and clearer benchmarking signals for optimization. Technologies and skills demonstrated - GPU programming patterns: CUDA stream consolidation, multi-GPU synchronization, and fake multi-GPU debugging workflows - Benchmark design and reproducibility: seeded RNG for deterministic tests and updated executors for stable runs - Cross-GPU validation tooling and development enablement
August 2025: Focused on stability, correctness, and developer productivity in the zama-ai/tfhe-rs repository. Delivered GPU backend error handling enhancements, CI/build workflow improvements, and performed minor codebase polish. These changes improve runtime reliability, reduce CI build times, and enable better profiling and debugging for CUDA paths.
August 2025: Focused on stability, correctness, and developer productivity in the zama-ai/tfhe-rs repository. Delivered GPU backend error handling enhancements, CI/build workflow improvements, and performed minor codebase polish. These changes improve runtime reliability, reduce CI build times, and enable better profiling and debugging for CUDA paths.
In July 2025, GPU-focused CI enhancements and CUDA backend hardening were delivered for the tfhe-rs project, driving faster GPU benchmarking, improved issue detection, and cleaner build signals across the GPU software stack.
In July 2025, GPU-focused CI enhancements and CUDA backend hardening were delivered for the tfhe-rs project, driving faster GPU benchmarking, improved issue detection, and cleaner build signals across the GPU software stack.
June 2025 monthly summary for zama-ai/tfhe-rs. Focused on strengthening GPU-related build performance, test reliability, CI efficiency, and developer documentation. Key initiatives and outcomes below.
June 2025 monthly summary for zama-ai/tfhe-rs. Focused on strengthening GPU-related build performance, test reliability, CI efficiency, and developer documentation. Key initiatives and outcomes below.
April 2025 monthly summary for zama-ai/concrete-ml: Delivered a targeted dependency upgrade of Concrete-ML Extensions to 0.1.9, aligning licenses and lockfiles to improve consistency, stability, and access to library bug fixes and improvements. This work reduces drift between components and supports smoother downstream integration and CI.
April 2025 monthly summary for zama-ai/concrete-ml: Delivered a targeted dependency upgrade of Concrete-ML Extensions to 0.1.9, aligning licenses and lockfiles to improve consistency, stability, and access to library bug fixes and improvements. This work reduces drift between components and supports smoother downstream integration and CI.
January 2025 monthly summary focused on enhancing runtime configurability and maintainability through flexible parameter management and clear documentation. Delivered a new dictionary-based parameter loading path for TFHE parameters and added comprehensive provenance documentation for a CUDA GEMM kernel, improving traceability and onboarding for future work. No critical bugs reported or fixed this month; primary value came from more robust configuration, test coverage, and documentation that supports lean deployments and easier cross-repo collaboration.
January 2025 monthly summary focused on enhancing runtime configurability and maintainability through flexible parameter management and clear documentation. Delivered a new dictionary-based parameter loading path for TFHE parameters and added comprehensive provenance documentation for a CUDA GEMM kernel, improving traceability and onboarding for future work. No critical bugs reported or fixed this month; primary value came from more robust configuration, test coverage, and documentation that supports lean deployments and easier cross-repo collaboration.
Month: 2024-12 — Focused on delivering performance improvements in tfhe-rs by enabling GPU-accelerated packing of keyswitch data. The work involved refactoring CUDA kernels, removing an unnecessary fast-path check, and using optimized host routines to reduce latency and memory overhead. Delivered as a single feature with clean, reviewable changes that enhance cryptographic throughput on GPU-powered workloads.
Month: 2024-12 — Focused on delivering performance improvements in tfhe-rs by enabling GPU-accelerated packing of keyswitch data. The work involved refactoring CUDA kernels, removing an unnecessary fast-path check, and using optimized host routines to reduce latency and memory overhead. Delivered as a single feature with clean, reviewable changes that enhance cryptographic throughput on GPU-powered workloads.
November 2024: Delivered GPU-accelerated cryptographic operations in tfhe-rs with runtime CUDA availability checks, enabling dynamic GPU usage for ML workloads. Implementations include a fast-path keyswitch packing optimized for ML, circulant-matrix based GPU polynomial multiplication, and a runtime CUDA device availability check to gracefully fallback when GPUs are unavailable. These changes unlock substantial performance improvements in ML inference workloads and improve scalability across heterogeneous hardware.
November 2024: Delivered GPU-accelerated cryptographic operations in tfhe-rs with runtime CUDA availability checks, enabling dynamic GPU usage for ML workloads. Implementations include a fast-path keyswitch packing optimized for ML, circulant-matrix based GPU polynomial multiplication, and a runtime CUDA device availability check to gracefully fallback when GPUs are unavailable. These changes unlock substantial performance improvements in ML inference workloads and improve scalability across heterogeneous hardware.

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