> For the complete documentation index, see [llms.txt](https://docs.optimumsec.xyz/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.optimumsec.xyz/coding/security-driven-development.md).

# Security-Driven Development

Similar to how Test-Driven Development (TDD) focuses on writing tests before the actual code, SDD prioritizes the identification and mitigation of potential security vulnerabilities and correctness issues throughout the development process. While fully adopting all the principles of SDD might be considered heavy or even overkill for many development teams, even implementing them partially can have a significant positive impact on the overall security and reliability of the smart contract.

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## Key principles of Security-Driven Development (SDD):

1. [**Threat Modeling First**](https://github.com/optimumsec/the-complete-guide-to-securing-web3-protocols/blob/main/coding/actor-based-threat-modeling.md): Begin by identifying potential attack vectors and security risks in the contract’s intended functionality.
2. **Security-Driven Specifications**: Define explicit security and correctness requirements, such as invariants, access control rules, and critical state transitions.
3. **Write Security Tests Before Code**: Develop comprehensive tests to validate these requirements, including unit tests, property-based tests, and fuzz tests.
4. **Iterative Development with Security in Mind**: As the code evolves, continuously revisit and refine threat models and add new security tests.
5. **Automated and Manual Auditing**: Integrate static analysis tools and conduct periodic manual code reviews.
6. **Formal Verification**: For critical components, use formal verification tools to mathematically prove correctness against the defined specifications.


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