Worked on enhancing DER signature parsing within the tkhq/sdk repository, focusing on backend development and cryptography using TypeScript. Addressed a critical bug by tightening length validation and clarifying error messages, which reduced the risk of misparsing signatures. Expanded the test suite to cover invalid encodings and edge cases related to padding, ensuring that correct DER semantics were preserved throughout. Delivered these improvements through a structured four-commit process, maintaining compatibility with existing cryptographic workflows. The work emphasized robust error handling and comprehensive testing, resulting in more resilient downstream services and clearer diagnostics for developers working with cryptographic signature parsing.