Specification for encoding CBOR (and Gordian Envelopes) as plain-text URIs that are also QR-code-friendly. Provides a typed URI scheme (ur:type/...), Bytewords minimal encoding for ASCII safety, multipart sequencing (MUR) for data exceeding single-QR capacity, and Luby Transform fountain codes that allow an animated QR sequence to begin at any frame and tolerate missing frames. Widely adopted across the Bitcoin self-custody ecosystem (Sparrow Wallet, Foundation Devices Passport, Keystone, etc.) for airgapped PSBT signing and seed/key transmission. Supports both bare URs (single CBOR data items) and Envelope-wrapped URs (recommended for richer use cases). Sub-specs include MUR (Multipart UR), Bytewords encoding, and a registry of UR types and CBOR tags
LicenciaBSD-2-Clause Plus Patent License — bc-ur (C++), URKit (Swift), bc-ur-rust, @ngraveio/bc-ur (JavaScript), and multiple third-party implementations
Estado de Desarrollo 🟢 Activo
Detalle del Estado de DesarrolloReleased — production; widely adopted in Bitcoin wallet ecosystem; reference libraries in C++, Swift, Rust, TypeScript, JavaScript, Python, Java
PropietarioBlockchain Commons LLC (not-for-profit benefit corporation founded by Christopher Allen, April 25, 2019; Berkeley, California). Specification authors: Wolf McNally, Christopher Allen
Órgano de Gobierno Blockchain Commons LLC (not-for-profit benefit corporation; CBOR tags registered in the IANA registry)
PaísUSA (Berkeley, California)
Año de Inicio 2020
StackReference libraries: C++ (bc-ur), Swift (URKit), Rust, TypeScript, plus third-party Java (Sparrow Wallet) and Python (Foundation Devices) implementations
FinanciamientoBlockchain Commons donations and patron sponsorships
OrígenesBlockchain Commons; designed initially for airgapped PSBT (Partially Signed Bitcoin Transaction) transmission
Base de Datos N/A — encoding specification, not a storage system
Lenguaje de Consulta N/A — encoding specification
Formatos de DatosCBOR (deterministic, via dCBOR for Envelope-wrapped URs); Bytewords minimal encoding (base-32 ASCII subset compatible with QR alphanumeric mode and URI syntax); type-prefixed UR scheme (ur:seed/, ur:psbt/, etc.)
Edición Colaborativa en Vivo N/A — encoding specification
Edición de Texto Enriquecido N/A — encoding specification
Soporte MóvilYes — primary use case is mobile QR-based airgap transmission
Soporte WebYes (JavaScript and TypeScript libraries)
Compatibilidad con la Web SemánticaUR types provide self-describing data tagging; not RDF-semantic but enable interoperable interpretation of binary cryptographic data across implementations
Madurez del Protocolo / EstandarizaciónProduction-ready; widely adopted across the Bitcoin self-custody ecosystem; CBOR tags registered in IANA registry; revised April 2025 (BCR-2020-006 v2 types and tags)
Tipo de Vocabulario / OntologíaType registry (BCR-2020-006) of UR types and CBOR tags maintained by Blockchain Commons (registered in IANA CBOR Tags Registry); covers seed, hdkey, psbt, output-descriptor, sskr, envelope, xid, and others
Patrón de UsoAirgapped data transmission (especially PSBT signing); QR-encoded transport of seeds, keys, descriptors, Envelopes; hardware-wallet-to-coordinator communication; multi-party ceremony coordination
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