Why Building Your Own Authentication Is Harder to Maintain Than to Write

Writing a basic login system is quick, but keeping it secure over time is where the real cost lies. Password hashing settings must be periodically raised as hardware improves, which requires an upgrade path for existing hashes. Data protection keys expire and rotate, and losing them makes protected data permanently unreadable. Token-based systems add certificates with their own expiry and rotation needs, and OAuth security guidance such as RFC 9700 evolves, so implementations can fall out of line without code changes. The article argues that frameworks like ASP.NET Core Identity are reasonable foundations, while the ongoing maintenance burden remains even when using them.