Trust Spanning Protocol

Identity Protocol

Specification for the protocol at the center of the ToIP hourglass model — the "trust spanning" layer (Layer 2) intended to be "to digital trust what IP is to digital data." Facilitates secure, message-based communication between endpoints with potentially different identifier types (W3C DIDs, KERI AIDs, URNs, etc.), as long as those identifiers are based on public-key cryptography with a verifiable trust root. Provides three core properties: authenticity (mandatory), confidentiality (optional), and metadata privacy (optional, against correlation attacks). Verifiable identifiers (VIDs) form authentic relationships via TSP messages serving as virtual trust channels

Community
Links
Visit Website See this tool in the graph Suggest an edit

Details

License Spec: open under ToIP IPR framework; Rust open-source reference implementation hosted at OpenWallet Foundation (sponsored by Futurewei, Gen, Accenture); Python implementation by Sam Smith / Web of Trust community
Dev Status 📝 Draft
Dev Status Detail Implementers Draft — vs1.0 Experimental Rev 2; first official version target 1.0.0 upon spec release
Owner Trust Over IP Foundation (project of Linux Foundation Decentralized Trust); developed by the Trust Spanning Protocol Task Force (TSPTF) within the Technology Stack Working Group
Governing Body ToIP / LF Decentralized Trust (Trust Spanning Protocol Task Force, within the Technology Stack Working Group)
Governing Body - List
  • Trust Over IP Foundation
Country International (Linux Foundation; global membership)
Start Year 2023
Stack Specification only; reference implementations in Rust (Futurewei/Gen/Accenture-sponsored implementation at OpenWallet Foundation) and Python (Web of Trust GitHub community); CESR (Composable Event Streaming Representation) proposed as encoding format
Funding Trust Over IP Foundation member contributions; reference implementation funded by OpenWallet Foundation Premier members (Futurewei, Gen, Accenture)
Last Investigated Jul 1, 2026

Topology view

This tool in the centre and the things it is directly related to. Each line names the kind of relationship.

Topology view: Trust Spanning ProtocolThis tool in the centre and the things it is directly related to. Each line names the kind of relationship.TrustSpanning Pr…DIDComm (Based on, Speaks protocol)DIDCommFirst Person Project / Network (Basis for, Conforming implementations, Protocol spoken by)First PersonProject / Ne…KERI (Based on, Conforms to)KERIACDC (Authentic Chained Data Containers) (Composes with)ACDC(Authentic C…DIDs (Conforms to)DIDsOpenID for Verifiable Credentials (OpenID4VC) (Conforms to, Speaks protocol)OpenID forVerifiable C…Keyring (Protocol spoken by)Keyringp2p-trust-stack (Protocol spoken by)p2p-trust-st…Real Life Trust Protocol (RLTP) (Protocol spoken by)Real LifeTrust Protoc…Trust Over IP Foundation (Stewarded by)Trust OverIP Foundation

Open in Graph Explorer

Use Case Domains

Identity & Trust

Affordances

Trust graph portability Sovereign identity

Identity Protocol Attributes

Origins ToIP TSPTF — design synthesized from four overall proposals submitted by Sam Smith, Daniel Hardman, Wenjing Chu, Michael Herman (early 2023)
Database N/A — TSP is a transport-layer trust spanning protocol; persistence is implementation/application concern
Query Language N/A — TSP is message-oriented (Direct Mode endpoint-to-endpoint, Routed Mode via intermediaries); query patterns belong at higher ToIP layers
Data Formats TSP messages with VID_String length-prefixed identifiers; supports DID and URN syntaxes (extensible)
Mobile Support Designed to be lightweight enough for mobile and constrained devices; transport-agnostic so messages can run over Bluetooth, HTTP, or other transports suitable for mobile
Web Support Transport-agnostic — designed to be carried over any transport (HTTPS, DIDComm, raw sockets)
Native Apps Implementation-dependent; reference Rust and Python libraries are embeddable in native apps; expected wallet integrations via OpenWallet Foundation reference implementation
Terms Open standard, free to implement (under ToIP IPR framework requiring contributor membership)
Funds Unknown — ToIP/LF Decentralized Trust funded by member dues; specific TSPTF budget not separately published; four years of cumulative person-hours invested by ToIP members and sponsoring organizations (Futurewei, Gen, Accenture)
Based On W3C DIDs (DID method-agnostic); KERI Autonomic Identifiers (AIDs); IETF URN spec (RFC 8141); public-key cryptography
Governing Body - List
  • Trust Over IP Foundation
Permissions Out of scope for TSP itself — permission and authorization semantics belong at higher ToIP layers
Authentication & Identity VID-rooted — endpoints identified by Verifiable Identifiers (DIDs, AIDs, or URN-based PKC identifiers)
Storage Model N/A — transport protocol; storage of messages, keys, and credentials is implementation concern at higher layers
Interoperability Designed as a "spanning layer" for maximum interoperability across decentralized digital trust infrastructure; can bridge centralized, federated, and decentralized identifier architectures
Data Portability High — VIDs and TSP-channel relationships are portable across transports and ecosystems; any VID type can communicate with any other VID type through the spanning protocol
Governance & Decision Making ToIP TSWG governance — open weekly meetings, consensus-driven, IPR-protected under LF Decentralized Trust; cross-organization collaboration with DIF, Hyperledger, OpenWallet Foundation, W3C Credentials Community Group; Implementers Drafts iterated through public review
Protocol Maturity / Standardization Implementers Draft (current); pre-1.0; Rust and Python reference implementations in development
Identity Standards W3C DIDs, KERI AIDs, ToIP Technology Architecture Specification
Identity Standards - List
DID Methods Supported Any (method-agnostic by design)
Key Management Per VID system (DID method or KERI key event log)
Credential Types N/A at the spanning protocol layer — credentials are exchanged at higher ToIP Layer 3 Trust Tasks (DIDComm-style credential exchange, OpenID4VC, etc.)
Credential Types - List
Verification Method Cryptographic verification using keys associated with senders VID
Privacy Features Optional confidentiality (encryption); optional metadata privacy (anti-correlation measures)
Authentication Methods Mandatory authenticity via cryptographic signatures rooted in VID
Revocation Mechanism Underlying VID system's revocation — KERI key rotation events, DID document update, X.509 CRL/OCSP — TSP itself does not define revocation, deferring to the VID's trust root
Agent Types Supported Humans, institutions, devices, AI agents — TSP April 2025 white paper explicitly extends to AI and human trust interactions
Wallet/Client Types Implementation-dependent — expected wallet integrations via OpenWallet Foundation reference implementation; KERI-style agent infrastructure compatible
Recovery Mechanisms Underlying VID system's recovery — KERI rotation events, DID rotation, X.509 reissuance — TSP itself does not define recovery
Compliance / Regulations Designed to support eIDAS, EUDI Wallet, and GLEIF (Global Legal Entity Identifier Foundation) use cases; GLEIF actively participating in TSPTF
Credential Exchange Protocols TSP is not a credential exchange protocol itself; credential exchange protocols including DIDComm subprotocols and OpenID4VC can run over TSP
Credential Exchange Protocols - List
Trust Framework Layer 2 of ToIP four-layer stack; complemented by TRQP (Layer 1) for trust registry queries; supports any governance framework above it
Cost Model Free — open standard, royalty-free implementation under ToIP/LF Decentralized Trust IPR
Censorship Resistance Strong — transport-agnostic, messages can traverse any underlying transport without prior assumption of trust; Routed Mode supports intermediary-mediated circumvention

Relationships

How this tool connects to other tools and organizations, from relationships reviewed by the OpenHaven data steward. They describe how projects connect, not how good they are.

Based on
Conforms to
Speaks protocol
Stewarded by
  • Trust Over IP Foundation
Composes with
Basis for
Conforming implementations
Protocol spoken by