Sidetree Specification

Sidetree is a protocol for creating scalable Decentralized Identifier (DID) networks that can operate on top of any existing decentralized anchoring system. The protocol enables creation and management of decentralized identifiers without requiring centralized authorities or trusted third parties.

Key features:

• Layer 2 Protocol that works with various anchoring systems (Bitcoin, Ethereum, etc.)
• Deterministic State Resolution through cryptographically-signed operations
• Scalable Architecture using Content-Addressable Storage (CAS)
• Self-Certifying Identifiers through cryptographic key binding
• Eventually Strong Consistency model for DID state changes

Core Technical Components:

1. File Structures:

   • Core Index Files: Contains create, recover, and deactivate operations
   • Provisional Index Files: Contains update operations and chunk file references
   • Chunk Files: Contains the actual DID state data
   • Proof Files: Contains cryptographic proofs for operations

2. Operation Types:

   • Create: Initial DID creation
   • Update: Modify DID state/document
   • Recover: Restore control using recovery key
   • Deactivate: Permanently disable DID

3. Protocol Features:

   • Commitment Scheme for secure key revelation
   • JSON Web Signatures for operation authentication
   • Conflict-Free Replicated Data Types (CRDTs) for state management
   • Content-Addressable Storage for data distribution

Implementation Requirements:

1. Anchoring System Integration:

   • Must support deterministic transaction ordering
   • Must provide immutable transaction history
   • Must enable reference anchoring of operation batches

2. Network Components:

   • Sidetree Nodes: Process operations and maintain DID states
   • CAS Network: Distributes operation data files
   • Anchoring System: Provides chronological ordering

3. Security Considerations:

   • Cryptographic proof verification
   • Key commitment scheme validation
   • Operation signature verification
   • State conflict resolution

4. Interoperability Features:

   • W3C DID specification compliance
   • JSON-LD context support
   • DID Resolution protocol alignment
   • Versioning support for protocol evolution

Current Adoption:

• Implemented by Microsoft in ION
• Used by Transmute in enterprise solutions
• Adopted by several DIF member organizations
• Multiple test networks operational

The protocol is maintained by the Decentralized Identity Foundation and continues to evolve through community contributions and implementation feedback.