Flutter Takes a Leap Towards Enhanced Security with SLSA Compliance

Flutter Takes a Leap Towards Enhanced Security with SLSA Compliance

Flutter 3.10 ships with SLSA Level 1 compliance

In the fast-paced digital world, ensuring the security and integrity of software is of paramount importance. With the increasing frequency and sophistication of cyber-attacks, developers and organizations are continually seeking ways to bolster their security practices. In this pursuit, the Software Bill of Materials (SBOM) has emerged as a crucial framework for promoting transparency and accountability in the software supply chain. Recently, Flutter, Google's popular open-source UI software development toolkit, announced its new compliance with the Supply chain Levels for Software Artifacts (SLSA), marking a significant milestone in enhancing the security posture of Flutter apps.

What is SLSA?

SLSA, which stands for Supply chain Levels for Software Artifacts, is a framework developed by Google to establish a set of security requirements and best practices for software supply chains. It is designed to create a transparent and robust software supply chain ecosystem, safeguarding software components from potential security threats. SLSA has multiple levels, each representing an increasing level of security rigour.

  • SLSA Level 1: The first level focuses on establishing a strong foundation for security. It requires the use of a formalized Bill of Materials, ensuring that all components in the supply chain are listed. Additionally, it enforces that the software is built with well-defined and reproducible build processes.

  • SLSA Level 2: Level 2 builds upon the foundations laid in Level 1 and introduces stricter security measures. At this level, software suppliers are required to cryptographically sign the provenance of each software artifact in the supply chain. This cryptographic signing enables consumers to verify the authenticity and integrity of the artifacts they receive, reducing the risk of tampering or unauthorized modifications during distribution.

  • SLSA Level 3: Level 3 further enhances security by enforcing the principle of "defence-in-depth." It requires the adoption of hardware-based security measures, such as hardware-backed cryptographic signing and verification. Hardware security mechanisms provide an additional layer of protection against attacks, making it significantly more challenging for adversaries to compromise the software supply chain.

Flutter's Journey to SLSA Compliance

Flutter has emerged as one of the leading frameworks for building high-quality, cross-platform applications. With its ever-growing popularity, the Flutter team recognized the need to fortify its security practices to inspire even greater confidence among developers and end-users.

The journey to achieve SLSA compliance was a collaborative effort involving the Flutter development team, the broader open-source community, and security experts. The process commenced with a comprehensive audit of Flutter's supply chain, identifying potential areas of improvement and addressing any vulnerabilities.

One of the core components of SLSA is the implementation of a Software Bill of Materials (SBOM). Flutter tackled this requirement by creating a structured and standardized SBOM that lists all the software components and dependencies used in the framework. This SBOM acts as a critical reference point for developers and users to understand the software's composition and any potential security implications.

To achieve higher levels of SLSA compliance, Flutter had to introduce additional security measures. This involved implementing cryptographic signing of software artifacts at Level 2 and adopting hardware-based security mechanisms at Level 3. These measures significantly reduce the risk of supply chain attacks and ensure that software consumers can trust the authenticity and integrity of the artifacts they receive.

Benefits of Flutter's SLSA Compliance

Flutter's compliance with SLSA brings forth numerous benefits for developers, organizations, and end-users alike:

  1. Enhanced Security: SLSA compliance ensures that Flutter apps are built with robust security practices, safeguarding users from potential threats and vulnerabilities.

  2. Trust and Transparency: By adhering to SLSA's principles, Flutter provides transparency into its supply chain, building trust among developers and users.

  3. Reduced Risk of Supply Chain Attacks: The cryptographic signing of artifacts and hardware-based security mechanisms make it exceedingly difficult for malicious actors to tamper with Flutter's software components.

  4. Industry Leadership: Flutter's commitment to SLSA compliance sets an example for other software projects, encouraging the industry to prioritize security in software development.

  5. Future-Proofing: As software security threats evolve, SLSA compliance ensures that Flutter remains resilient against emerging challenges.


Flutter's compliance with SLSA is a significant achievement that demonstrates its dedication to improving the security of its software supply chain. By embracing the SLSA framework, Flutter takes a proactive approach to fortifying its software against potential attacks, ensuring that its vast community of developers can build and deploy applications with greater confidence. As the digital landscape continues to evolve, initiatives like SLSA become increasingly vital to creating a secure and trustworthy software ecosystem.

Flutter's commitment to security sets a strong example for other software projects, encouraging the broader tech industry to prioritize security at every step of the development process. With SLSA compliance now in place, Flutter is undoubtedly positioned to deliver even more secure and reliable experiences for its users; especially considering they indicated they wanted to pursue Level 2 back in March 2023 in their article about achieving Level 3 compliance in the Cocoon engine.

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