OOBI (Out-of-Band Introduction) Protocol

Identity Protocol

A formal protocol specification (IETF Internet-Draft) defining a mechanism for introducing KERI Autonomic Identifiers (AIDs) to witness, watcher, and service endpoints via URL-based out-of-band exchanges. An OOBI is a URL pairing an AID with a network endpoint (IP address or URL) that can provide or cache the associated KERI Key Event Log (KEL). OOBIs enable KERI participants to bootstrap identifier discovery without a centralized directory, allowing any party with the OOBI URL to locate and verify another party's key state.

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Details

License Open specification (IETF I-D); reference implementations in KERI Python (keripy) and Rust (keri-core) under Apache-2.0
Dev Status 🟢 Active
Dev Status Detail Released (implemented in production KERI tooling including KERIA, keripy, and the WebOfTrust reference implementations; IETF Internet-Draft active)
Owner Samuel M. Smith (spec author); IETF Internet-Draft (draft-ssmith-oobi); KERI community
Governing Body IETF (Internet-Draft draft-ssmith-oobi) | None (single specification author; KERI community)
Governing Body - List
  • Internet Engineering Task Force
Country USA (Samuel M. Smith)
Start Year 2021
Stack Language-agnostic (IETF specification); implemented in Python (keripy / KERIA), TypeScript (signify-ts), Rust; HTTP URLs as the OOBI format
Funding Community / DARPA (KERI ecosystem funded partly by DARPA and DIF grants; OOBI spec funded as part of KERI development)
Funding - List
  • Decentralized Identity Foundation
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: OOBI (Out-of-Band Introduction) ProtocolThis tool in the centre and the things it is directly related to. Each line names the kind of relationship.OOBI(Out-of-Ban…ACDC (Authentic Chained Data Containers) (Basis for, Based on, Protocol spoken by, Speaks protocol)ACDC(Authentic C…KERI (Basis for, Based on, Conforms to, Identifies via, Interoperates with, Speaks protocol)KERIDIDs (Conforms to, Identifies via)DIDsDecentralized Identity Foundation (Funded by)DecentralizedIdentity Fou…did:scid (Required by)did:scidDIDComm (Speaks protocol)DIDCommInternet Engineering Task Force (Standardized at, Stewarded by)InternetEngineering…KERI Suite (Member of suite)KERI Suite
  • ACDC (Authentic Chained Data Containers) (Tool): Basis for, Based on, Protocol spoken by, Speaks protocol
  • KERI (Tool): Basis for, Based on, Conforms to, Identifies via, Interoperates with, Speaks protocol
  • DIDs (Tool): Conforms to, Identifies via
  • Decentralized Identity Foundation (Organization): Funded by
  • did:scid (Tool): Required by
  • DIDComm (Tool): Speaks protocol
  • Internet Engineering Task Force (Organization): Standardized at, Stewarded by
  • KERI Suite (Suite): Member of suite

Open in Graph Explorer

Use Case Domains

Identity & Trust

Affordances

Trust graph portability Sovereign identity

Identity Protocol Attributes

Origins KERI ecosystem bootstrap (designed to solve KERI's identifier discovery problem — KERI AIDs are self-certifying but need a mechanism for parties to locate each other's key event logs without a central directory)
Database N/A (OOBIs point to endpoints that serve KELs; no database defined by the OOBI spec itself)
Query Language HTTP URL resolution (OOBI is a URL; resolution fetches KEL from specified endpoint via HTTP GET)
Data Formats OOBI URL (format: scheme://host:port/oobi/{AID}/{role}/{eid}); KERI CESR (Composable Event Streaming Representation) for KEL data returned by endpoints
Mobile Support Library-level (any HTTP client; QR code OOBI sharing common in mobile KERI wallet implementations)
Web Support Yes (OOBI URLs are HTTP/HTTPS; web-based KERI wallets resolve OOBIs via standard HTTP)
Native Apps Library-level (embedded in KERI wallet applications; QR code OOBI sharing in mobile wallet UIs)
Terms Free / Open standard (IETF Internet-Draft; Apache-2.0 reference implementations)
Funding - List
  • Decentralized Identity Foundation
Funds Unknown (part of broader KERI ecosystem funding; not separately itemized)
Based On KERI (Key Event Receipt Infrastructure) — OOBI is the bootstrap/discovery mechanism for KERI identifiers; HTTP URL format; CESR (Composable Event Streaming Representation) for KEL data
Governing Body - List
  • Internet Engineering Task Force
Permissions Key-based (OOBI is an open URL; AID key control governs what can be done with the discovered identity)
Authentication & Identity KERI AID-based (OOBI introduces a KERI AID to its endpoint; authentication is via KERI key event log verification, not OOBI itself)
Storage Model N/A (OOBI points to endpoints; storage is at the KERI witness/watcher infrastructure level)
Interoperability KERI ecosystem (OOBI is specific to KERI AID discovery; compatible with any KERI-conformant implementation)
Data Portability Full portability (OOBIs can be exchanged out-of-band via any channel — QR code, email, chat, NFC — enabling key state discovery independently of platform)
Governance & Decision Making Community / IETF process (IETF Internet-Draft; community-governed; Sam Smith as spec author)
Protocol Maturity / Standardization IETF Draft (active IETF Internet-Draft draft-ssmith-oobi; implemented in production KERI tooling; not yet published as RFC)
Identity Standards KERI (Key Event Receipt Infrastructure); W3C DID (KERI AIDs can be expressed as DIDs); CESR (Composable Event Streaming Representation)
Identity Standards - List
DID Methods Supported did:keri (KERI AIDs as DIDs; OOBI is the discovery mechanism for did:keri resolution)
DID Methods Supported - List
Key Management Delegated to KERI (OOBI locates the key event log; KERI manages key rotation, pre-rotation, and recovery via the KEL)
Credential Types N/A (OOBI is a discovery/bootstrap protocol; credential types defined at KERI/ACDC layer)
Credential Types - List
Verification Method Key event log verification (OOBI URL leads to KEL; cryptographic verification of key binding performed by KERI resolver, not OOBI itself)
Privacy Features Minimal (OOBI URLs may expose AID and endpoint; out-of-band exchange (QR code, direct link) limits exposure; no ZKP features)
Authentication Methods QR code scanning (common OOBI exchange mechanism in wallets); Deep linking (OOBI URL passed via any channel); HTTP GET resolution
Revocation Mechanism N/A (OOBI is a discovery URL; revocation handled at KERI key event log level)
Agent Types Supported Any KERI-identified entity: Humans (individuals), Organizations, Services/APIs, Devices/IoT
Wallet/Client Types SDK/Library integration (keripy, signify-ts, KERIA server); QR code exchange in mobile wallets
Recovery Mechanisms N/A (recovery handled at KERI level via key event history and pre-rotation)
Compliance / Regulations Unknown (IETF Internet-Draft; no specific regulatory compliance addressed)
Credential Exchange Protocols KERI/ACDC (Authentic Chained Data Containers); compatible with DIDComm via KERI DID method
Credential Exchange Protocols - List
Trust Framework Cryptographic verification only (OOBI points to KEL; trust established through KERI key event log cryptographic verification; no external trust anchor)
Cost Model Free (open IETF Internet-Draft; open source implementations)
Censorship Resistance Hybrid (OOBI URLs depend on endpoint availability; multiple OOBIs can be provided for same AID via different witnesses/watchers; resilient via multi-witness architecture)

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
Funded by
  • Decentralized Identity Foundation
Identifies via
Member of suite
  • KERI Suite
Speaks protocol
Standardized at
  • Internet Engineering Task Force
Stewarded by
  • Internet Engineering Task Force
Interoperates with
Basis for
Protocol spoken by
Required by