SCITT: Supply Chain Integrity, Transparency and Trust

A Framework for Securing Modern Software Supply Chains

Abstract

The increasing complexity of software supply chains has created unprecedented security challenges, as demonstrated by high-profile attacks like SolarWinds and Log4Shell. Supply Chain Integrity, Transparency and Trust (SCITT) emerges as a comprehensive framework designed to create an immutable, transparent ledger for software supply chain artifacts and attestations. This whitepaper examines SCITT's architecture, security model, and interoperability features, demonstrating how it addresses critical gaps in current supply chain security approaches while maintaining compatibility with existing tools and workflows.

1. Introduction

Modern software development relies on complex supply chains involving multiple parties, from open-source contributors to commercial vendors. Each component may pass through numerous hands before reaching production systems, creating opportunities for compromise at every stage. Traditional approaches to supply chain security rely on point-in-time verification and trust relationships that can be exploited by sophisticated attackers.

SCITT provides a standardized framework for creating tamper-evident, publicly verifiable records of claims about software artifacts throughout their lifecycle. By establishing a cryptographically secured, append-only registry of attestations, SCITT enables organizations to make verifiable statements about their software while allowing consumers to independently verify these claims and trace complete component histories.

2. Technical Architecture

2.1 Core Components

SCITT's architecture consists of four primary components:

Transparency Service: The central registry that maintains an append-only log of all claims. This service provides cryptographic receipts proving that claims have been registered at specific points in time.

Claims: Signed statements about software artifacts, including but not limited to Software Bills of Materials (SBOMs), vulnerability reports, build provenance, and security assessments. Claims are format-agnostic, allowing integration with existing standards.

Receipts: Cryptographic proofs issued by the Transparency Service confirming that a claim has been registered. These receipts enable offline verification without accessing the service.

Verifiers: Entities that validate claims and their associated receipts to establish trust in software components before deployment or use.

2.2 Cryptographic Foundation

SCITT builds upon established cryptographic standards, primarily CBOR Object Signing and Encryption (COSE) for signature formats. This ensures compatibility with existing public key infrastructure while providing flexibility for future cryptographic algorithms. The framework uses hash chains similar to certificate transparency logs, creating an immutable record that makes tampering immediately detectable.

3. Relationship to Blockchain Technology

While SCITT shares fundamental concepts with blockchain technology, it represents a specialized application optimized for software supply chain metadata rather than general-purpose transactions.

3.1 Shared Principles

Both SCITT and blockchain systems implement:

• Immutable append-only logs where historical records cannot be altered

• Cryptographic linking between entries to ensure temporal ordering

• Transparent verification allowing any party to audit the complete history

• Decentralization potential through federated architectures

3.2 Key Differentiators

Unlike traditional blockchains, SCITT:

• Eliminates consensus overhead: No proof-of-work or proof-of-stake mechanisms required

• Enables efficient scaling: Designated transparency services operated by trusted organizations

• Separates storage and verification: Federated registries can reference each other without full replication

• Optimizes for specific use cases: Designed specifically for software attestations rather than financial transactions

This specialized approach makes SCITT more energy-efficient and performant while maintaining the security guarantees essential for supply chain integrity.

4. Security Benefits

4.1 Non-Repudiation and Accountability

Once an organization registers a claim about their software, the cryptographic receipt creates an undeniable record. This accountability mechanism ensures that malicious actors cannot quietly inject compromised components or retroactively alter their attestations after a breach is discovered.

4.2 Tamper-Evidence and Forensic Capabilities

SCITT's cryptographic receipts provide temporal proof of when specific claims existed, enabling precise forensic analysis. Security teams can definitively determine what was known at any point in time, identifying exactly when and where compromises occurred in the supply chain.

4.3 Attack Prevention and Detection

SCITT addresses several critical attack vectors:

Supply Chain Injection: Unauthorized modifications become immediately visible due to missing or invalid SCITT registrations from legitimate sources.

Dependency Confusion: Internal packages can be cryptographically distinguished from public packages through issuer verification.

Time-of-Check/Time-of-Use: Cryptographic receipts ensure the verified version matches the deployed version.

Retroactive Tampering: The append-only nature prevents attackers from covering their tracks by modifying historical records.

4.4 Policy Enforcement

Organizations can implement automated security policies that verify multiple conditions before allowing software deployment:

• Presence of required attestations (SBOMs, vulnerability scans)

• Signatures from authorized entities

• Build provenance from approved CI/CD systems

• Compliance with regulatory requirements

These policies can be enforced programmatically across organizational boundaries, creating a transparent trust framework.

5. Interoperability and Integration

5.1 Format-Agnostic Design

SCITT's architecture accepts any serializable content type, enabling seamless integration with existing tools and standards:

• SPDX and CycloneDX for software composition

• In-toto and SLSA for build provenance

• Custom formats for proprietary security assessments

• Industry-specific compliance attestations

This flexibility allows organizations to adopt SCITT without abandoning their current toolchains or workflows.

5.2 Federation Capabilities

Multiple SCITT instances can interoperate through claim references, enabling:

• Cross-organizational trust without centralization

• Industry-specific registries that maintain autonomy

• Geographic distribution for performance and compliance

• Gradual adoption across supply chain participants

5.3 Standardized APIs

SCITT employs standard HTTP REST APIs with COSE signatures, ensuring:

• Language-agnostic integration

• Minimal modification to existing tools

• Consistent verification regardless of claim format

• Simplified adoption across diverse ecosystems

6. Implementation Considerations

6.1 Deployment Models

Organizations can choose from several deployment approaches:

Public Registries: Industry-wide transparency services operated by trusted entities Private Registries: Internal services for proprietary software and sensitive attestations Hybrid Models: Selective publication based on confidentiality requirements Federated Networks: Interconnected registries sharing trust relationships

6.2 Performance and Scalability

SCITT's design prioritizes efficiency:

• Lightweight claim registration process

• Offline verification capabilities

• Distributed caching of receipts

• Selective synchronization between registries

These characteristics enable SCITT to scale to global software supply chains without creating performance bottlenecks.

6.3 Migration Strategies

Organizations can adopt SCITT incrementally:

1. Begin with high-value or high-risk components

2. Integrate with existing CI/CD pipelines

3. Gradually expand coverage across the software portfolio

4. Establish federation with supply chain partners

7. Future Directions

The SCITT framework continues to evolve through the IETF standardization process. Key areas of development include:

• Enhanced privacy features for sensitive attestations

• Improved federation protocols for cross-registry trust

• Integration with emerging software identity standards

• Automated policy languages for complex trust requirements

8. Conclusion

SCITT represents a fundamental advancement in software supply chain security, providing the transparency and accountability necessary for modern software ecosystems. By combining the immutability of blockchain-inspired architectures with the efficiency required for practical deployment, SCITT offers a path toward comprehensive supply chain integrity.

The framework's format-agnostic design and standardized APIs ensure that organizations can adopt SCITT without disrupting existing workflows, while its cryptographic foundation provides the security guarantees necessary to detect and prevent sophisticated supply chain attacks. As software supply chains continue to grow in complexity, SCITT's transparent trust model becomes increasingly critical for maintaining security at scale.

References

• IETF SCITT Working Group. "Supply Chain Integrity, Transparency and Trust." Internet Engineering Task Force. https://datatracker.ietf.org/wg/scitt/about/

• SCITT Architecture Internet-Draft. "An Architecture for Supply Chain Integrity, Transparency, and Trust." https://datatracker.ietf.org/doc/draft-ietf-scitt-architecture/

• Microsoft Corporation. "SCITT Confidential Consortium Framework Ledger Implementation." https://github.com/microsoft/scitt-ccf-ledger

• SCITT Community. "SCITT API Emulator Reference Implementation." https://github.com/scitt-community/scitt-api-emulator

• Internet Engineering Task Force. "CBOR Object Signing and Encryption (COSE)." RFC 8152. https://datatracker.ietf.org/doc/html/rfc8152

• Cybersecurity and Infrastructure Security Agency. "Software Supply Chain Security Guidance." https://www.cisa.gov/software-supply-chain-security

• SCITT Receipts Format Specification. "SCITT Receipts." https://datatracker.ietf.org/doc/draft-ietf-scitt-receipts/

• Package URL Specification. "A minimal specification for purl." https://github.com/package-url/purl-spec

• Supply-chain Levels for Software Artifacts. "SLSA Framework." https://slsa.dev/

• OpenSSF Sigstore Project. "A new standard for signing, verifying and protecting software." https://www.sigstore.dev/