lowRISC/opentitan
Nov 2024 – Sep 2025
8 Months active
Languages Used
AssemblyCC++RustPythonBazelBUILDStarlark
Technical Skills
C ProgrammingC/C++Code RefactoringCryptographyDriver DevelopmentEmbedded Systems
Yi-Hsuan Deng
PROFILE
Yi-hsuan Deng
Yihang Deng contributed to the lowRISC/opentitan repository by engineering robust firmware, build, and security infrastructure for embedded systems. He developed modular ROM and boot security features, optimized certificate handling, and improved memory safety through dynamic configuration and linker scripting in C and Bazel. His work included refactoring toolchain flag management, enhancing test automation with Python and Hjson, and integrating source-based code coverage using LLVM. By addressing critical bugs and expanding test coverage, Yihang enabled more reliable, maintainable, and auditable firmware builds. His technical depth is evident in the seamless integration of cryptography, build systems, and low-level programming throughout the project.
Overall Statistics
Feature vs Bugs
85%Features
Repository Contributions
68Total
Bugs
4
Commits
68
Features
23
Lines of code
7,219
Activity Months8
Your Network
4235 people
Work History
September 2025
8 Commits • 6 Features
Sep 1, 2025September 2025 monthly summary focusing on reliability, modularity, and coverage instrumentation across the lowRISC/opentitan repository. Delivered updates to test configuration, Bazel-based build and coverage tooling, and cryptographic operation safety, enabling faster CI feedback and improved observability.
8 Commits • 6 Features
Sep 1, 2025September 2025 monthly summary focusing on reliability, modularity, and coverage instrumentation across the lowRISC/opentitan repository. Delivered updates to test configuration, Bazel-based build and coverage tooling, and cryptographic operation safety, enabling faster CI feedback and improved observability.
September 2025
August 2025
6 Commits • 3 Features
Aug 1, 2025August 2025 monthly summary for opentitan: Delivered core improvements in firmware configurability, memory safety, and ROM test coverage. Implemented Dynamic Firmware Configuration System using Bazel variables and dynamic linker/script configurations to consolidate slot management and reduce hard-coded addresses, enabling easier maintenance across firmware builds. Fixed a critical memory safety issue in SRAM provisioning by adding a stack/BSS boundary check, preventing overflow and improving robustness. Expanded test coverage for OTP-driven ROM behavior with end-to-end tests for clock jitter switches and for OTP-controlled debug information, and extended CRT test suite with corner-case trapping and an illegal-instruction fault handler. These changes enhance reliability and maintainability across builds. Commits include: ddedbfe8b6a955a4ab2073e4b43726d0f6962b77; 535c83a375ca2ecf9792e87185a402adeb14a91a; 98087420e536f7e6e3e62c2540a777bb199cea6f; d55f82b2973b3c0cfad258c12ac0c7ebd0032e36; 22b82b7a41449d579f6487af603505b1c6fdb80f; 38bdc708ab5e183188a6f506c2972e7239002128.
August 2025
6 Commits • 3 Features
Aug 1, 2025August 2025 monthly summary for opentitan: Delivered core improvements in firmware configurability, memory safety, and ROM test coverage. Implemented Dynamic Firmware Configuration System using Bazel variables and dynamic linker/script configurations to consolidate slot management and reduce hard-coded addresses, enabling easier maintenance across firmware builds. Fixed a critical memory safety issue in SRAM provisioning by adding a stack/BSS boundary check, preventing overflow and improving robustness. Expanded test coverage for OTP-driven ROM behavior with end-to-end tests for clock jitter switches and for OTP-controlled debug information, and extended CRT test suite with corner-case trapping and an illegal-instruction fault handler. These changes enhance reliability and maintainability across builds. Commits include: ddedbfe8b6a955a4ab2073e4b43726d0f6962b77; 535c83a375ca2ecf9792e87185a402adeb14a91a; 98087420e536f7e6e3e62c2540a777bb199cea6f; d55f82b2973b3c0cfad258c12ac0c7ebd0032e36; 22b82b7a41449d579f6487af603505b1c6fdb80f; 38bdc708ab5e183188a6f506c2972e7239002128.
July 2025
11 Commits • 4 Features
Jul 1, 2025July 2025 performance summary for lowRISC/opentitan focused on increasing test automation, debugging capabilities, and cryptographic validation for OTBN. Delivered consolidated OTBN testing and simulation tooling, extended DMEM memory loading capabilities, and enhanced simulator observability. Expanded P-256 cryptography test coverage, and implemented a critical endianness fix to improve numeric correctness across simulations. These efforts bolster validation throughput, reduce verification risk, and demonstrate strong engineering discipline across testing, debugging, and cryptographic verification.
11 Commits • 4 Features
Jul 1, 2025July 2025 performance summary for lowRISC/opentitan focused on increasing test automation, debugging capabilities, and cryptographic validation for OTBN. Delivered consolidated OTBN testing and simulation tooling, extended DMEM memory loading capabilities, and enhanced simulator observability. Expanded P-256 cryptography test coverage, and implemented a critical endianness fix to improve numeric correctness across simulations. These efforts bolster validation throughput, reduce verification risk, and demonstrate strong engineering discipline across testing, debugging, and cryptographic verification.
July 2025
March 2025
18 Commits • 2 Features
Mar 1, 2025March 2025 monthly summary for lowRISC/opentitan: Key security hardening, attestation refinements, and release tooling enhancements. Delivered boot-time security hardening and attestation handling updates, plus ROM_EXT imm_section refactor, version stamping, and release tooling. Improved build/test hygiene, reproducible releases, and auditability with commit-stamped artifacts and standardized naming.
March 2025
18 Commits • 2 Features
Mar 1, 2025March 2025 monthly summary for lowRISC/opentitan: Key security hardening, attestation refinements, and release tooling enhancements. Delivered boot-time security hardening and attestation handling updates, plus ROM_EXT imm_section refactor, version stamping, and release tooling. Improved build/test hygiene, reproducible releases, and auditability with commit-stamped artifacts and standardized naming.
February 2025
14 Commits • 3 Features
Feb 1, 2025February 2025 (lowRISC/opentitan) focused on strengthening security, reducing firmware size, and improving build maintainability. Delivered integrated ROM_EXT boot hardening, optimized DICE/CWT certificate handling, and a more modular build system. Addressed a critical build dependency issue to stabilize CI and production pipelines. Result: stronger security posture, smaller footprint, more reliable builds, and scalable certificate/variation support.
14 Commits • 3 Features
Feb 1, 2025February 2025 (lowRISC/opentitan) focused on strengthening security, reducing firmware size, and improving build maintainability. Delivered integrated ROM_EXT boot hardening, optimized DICE/CWT certificate handling, and a more modular build system. Addressed a critical build dependency issue to stabilize CI and production pipelines. Result: stronger security posture, smaller footprint, more reliable builds, and scalable certificate/variation support.
February 2025
January 2025
1 Commits • 1 Features
Jan 1, 2025January 2025 monthly summary for lowRISC/opentitan: Key feature delivered: Toolchain optimization flag handling refactor implementing mutual exclusion between -Os and -Oz and introducing constraints/arguments to manage optimization levels, leading to more predictable, robust toolchain configurations. Major bugs fixed: none reported this month. Overall impact and accomplishments: Increased build stability and reliability, reduced risk of misconfiguration in toolchain flags, enabling repeatable builds for downstream targets. Technologies/skills demonstrated: toolchain flag management, constraint design for configuration options, disciplined commit usage and repository alignment with OpenTitan standards.
January 2025
1 Commits • 1 Features
Jan 1, 2025January 2025 monthly summary for lowRISC/opentitan: Key feature delivered: Toolchain optimization flag handling refactor implementing mutual exclusion between -Os and -Oz and introducing constraints/arguments to manage optimization levels, leading to more predictable, robust toolchain configurations. Major bugs fixed: none reported this month. Overall impact and accomplishments: Increased build stability and reliability, reduced risk of misconfiguration in toolchain flags, enabling repeatable builds for downstream targets. Technologies/skills demonstrated: toolchain flag management, constraint design for configuration options, disciplined commit usage and repository alignment with OpenTitan standards.
December 2024
3 Commits • 1 Features
Dec 1, 20242024-12 monthly summary for lowRISC/opentitan: Delivered ROM Extension Build Optimization and Stability to reduce firmware size and preserve version metadata; fixed RNG polling loop to ensure data_ready condition based on RND_STATUS bit0. These work items improve image size, reliability, and RNG correctness, with clear business value in firmware efficiency and system safety.
3 Commits • 1 Features
Dec 1, 20242024-12 monthly summary for lowRISC/opentitan: Delivered ROM Extension Build Optimization and Stability to reduce firmware size and preserve version metadata; fixed RNG polling loop to ensure data_ready condition based on RND_STATUS bit0. These work items improve image size, reliability, and RNG correctness, with clear business value in firmware efficiency and system safety.
December 2024
November 2024
7 Commits • 3 Features
Nov 1, 2024November 2024 monthly summary for lowRISC/opentitan: delivered security, reliability, and reuse improvements across the ROM and DICE stack, with attention to cross-SKU boot consistency and maintainable architecture. Key features included DICE and certificate handling modernization, an immutable ROM extension boot order, and relocation of the ePMP library to a common drivers area. A critical bug fix addressed DICE page ID handling to ensure correct boot-time behavior. The work strengthens security posture, reduces ROM footprint, and improves reuse and build stability.
November 2024
7 Commits • 3 Features
Nov 1, 2024November 2024 monthly summary for lowRISC/opentitan: delivered security, reliability, and reuse improvements across the ROM and DICE stack, with attention to cross-SKU boot consistency and maintainable architecture. Key features included DICE and certificate handling modernization, an immutable ROM extension boot order, and relocation of the ePMP library to a common drivers area. A critical bug fix addressed DICE page ID handling to ensure correct boot-time behavior. The work strengthens security posture, reduces ROM footprint, and improves reuse and build stability.
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Quality Metrics
Correctness92.4%
Maintainability90.8%
Architecture90.6%
Performance85.0%
AI Usage20.0%
Skills & Technologies
Programming Languages
AssemblyBUILDBazelBzlCC++HjsonMakeMakefileMarkdown
Technical Skills
AssemblyBackend DevelopmentBazelBazel Build SystemBuild SystemBuild System ConfigurationBuild System ManagementBuild SystemsC PreprocessorC ProgrammingC/C++Certificate GenerationCode CleanupCode CoverageCode Instrumentation
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