2024-12 Monthly Summary: Focused on hardening AES-NI inline assembly across Mbed TLS components to ensure correct code generation and secure cryptographic operations across diverse compilers and optimization levels. Implemented rigorous XMM register clobber and constraint specifications and propagated fixes across two repositories, with updated changelogs to reflect the improvements. Spearheaded cross-repo coordination between Mbed-TLS/mbedtls-framework and zephyrproject-rtos/mbedtls to deliver consistent, reliable cryptographic behavior in production builds.

Monthly work summary for 2024-11 focused on reliability, correctness, and maintainability of AES-NI ECB paths across two open-source TLS projects. Key fixes and code-quality improvements completed in November: Key features delivered and major fixes: - Zephyr Project: Fixed AES-NI ECB inline assembly clobber to prevent data corruption by adding '0' and '1' to the clobbered registers list in mbedtls_aesni_crypt_ecb. Commit 98910a143790aec0c09a1e86b32704af285eb89e. - Mbed-TLS/mbedtls-framework: Corrected clobber tracking in mbedtls_aesni_crypt_ecb by adding explicit clobbers for xmm0, xmm1, memory, and condition codes. Commit 0abc1ce1eadb335304ca63f6460467eff129e7a1. Overall impact and business value: - Prevented data corruption and subtle misbehavior in AES-NI ECB paths, increasing reliability and security of cryptographic operations. - Improved compiler optimizations and predictability by making clobber usage explicit, reducing risk of regressions across varied toolchains. - Achieved cross-repo consistency in inline-assembly practices, simplifying future maintenance and audits. Technologies and skills demonstrated: - C, inline assembly, and AES-NI integration - Correct clobber semantics, register tracking, and compiler interaction - Debugging and verification of low-level cryptographic code - Cross-project collaboration and knowledge sharing across repositories