Worked on expanding cryptographic test coverage for the GMP extension in the schneems/php-src repository, focusing on validating the behavior of gmp_pow with large, cryptographic-sized numbers. Developed comprehensive tests that included demonstrations of basic finite field arithmetic and Diffie-Hellman key exchange, ensuring robust handling of edge-case numerical scenarios. Leveraged PHP and the GMP extension to enhance the reliability and security posture of cryptographic operations by enabling earlier detection of regressions. Emphasized thorough testing practices to improve traceability and maintainability within the codebase, contributing a focused feature that strengthens the correctness of cryptographic-number handling without introducing new bug fixes.