Provenance

What is Provenance?

Software provenance refers to comprehensive metadata that documents the origin, authorship, and complete history of a software artifact's creation. Provenance information answers critical questions about software artifacts: Who created it? When was it built? What source code was used? What build system created it? What dependencies were included?

Like a chain of custody in physical evidence handling, software provenance establishes an unbroken chain of accountability throughout the software supply chain, enabling consumers to verify the authenticity and integrity of the software they use.

Components of Software Provenance

Comprehensive provenance metadata typically includes:

1. Source Information

   • Repository URL
   • Commit hash or version tag
   • Branch information
   • Source code integrity hashes

2. Build Details

   • Build system identification
   • Build configuration
   • Build environment information
   • Timestamp of build
   • Builder identity (person or system)

3. Dependency Information

   • Complete list of dependencies
   • Versions of dependencies
   • Sources of dependencies
   • Dependency integrity verification

4. Artifact Details

   • Artifact hash (e.g., SHA-256)
   • Digital signatures
   • Artifact format and type

5. Post-Build Information

   • Distribution channel
   • Deployment details
   • Verification records

Why is Provenance Important?

Provenance is vital for software supply chain security because it:

• Enables Verification - Allows consumers to verify the authenticity of software
• Supports Auditing - Provides evidence for compliance and security audits
• Facilitates Incident Response - Helps identify affected systems when vulnerabilities are discovered
• Prevents Tampering - Makes unauthorized modifications to software detectable
• Builds Trust - Establishes confidence in the software supply chain
• Enhances Traceability - Links artifacts back to their source and creation process

Provenance Standards and Tools

Several emerging standards and tools support software provenance:

SLSA (Supply-chain Levels for Software Artifacts)

A security framework that defines increasing levels of supply chain security, with provenance as a key component. SLSA provenance is a metadata format that describes how an artifact was built.

Sigstore

An open-source project providing tools for signing, verifying, and tracking software artifacts:

• Cosign - Tool for container signing
• Rekor - Transparency log for software artifact metadata
• Fulcio - Free certificate authority for code signing

in-toto

A framework that cryptographically verifies each step in the software supply chain through a series of "links" that document actions performed on software artifacts.

Attestations

Signed statements about artifacts that make specific claims about properties or processes.

Implementing Provenance

To implement robust software provenance:

1. Generate Build Provenance - Configure CI/CD systems to automatically generate provenance during builds
2. Sign Artifacts - Use cryptographic signing to verify artifact authenticity
3. Store Provenance Securely - Maintain tamper-proof records of provenance information
4. Verify Provenance - Implement checks that validate provenance before deployment
5. Standardize Formats - Use standard formats like SLSA provenance for interoperability
6. Automate Verification - Build automated systems to check provenance during deployment