bc_ur_dart 0.1.28

A dart plugin for Uniform Resources(URs) decode/encode. URs are URI-encoded CBOR structures developed by Blockchain Commons.

bc_ur_dart

A pure Dart implementation of the Uniform Resources (UR) protocol and common crypto-wallet UR registry models. UR is a CBOR-based, fragmentable QR protocol used by cold wallets for account export, transaction signing, and signature return flows.

Features

• Encode and decode single-part and multipart UR strings.
• Decode and generate CBOR-backed signing/account models for:
  • BTC PSBT and GSPL signing
  • ETH signing requests and signatures
  • Solana, TRON, Cosmos, BCH, ALPH, SC, and Keystone-compatible chain payloads
  • crypto-hdkey, crypto-account, and crypto-multi-accounts
• Explicit malformed UR/CBOR errors for model parsing. Invalid model payloads fail closed instead of relying on raw Dart cast errors.

Examples

The monorepo contains a Flutter demo at:

examples/bc_ur_dart_demo

This package itself is pure Dart, so package verification still uses dart test.

Installation

dependencies:
  bc_ur_dart: ^0.1.26

Quick Start

import 'package:bc_ur_dart/bc_ur_dart.dart';

final ur = UR.decode(
  'ur:bytes/hdeymejtswhhylkepmykhhtsytsnoyoyaxaedsuttydmmhhpktpmsrjtgwdpfnsboxgwlbaawzuefywkdplrsrjynbvygabwjldapfcsdwkbrkch',
);

final encoded = ur.encode();
final fragment = ur.next();

final decoder = UR();
final complete = decoder.read(fragment);

Error Handling

Use UR parsing as two separate validation layers:

• Transport validation: UR.decode() and UR.read() validate UR text, ByteWords, sequence, and fragments.
• Semantic validation: model factories such as EthSignRequestUR.fromUR() and CryptoHDKeyUR.fromUR() validate CBOR shape, required fields, and nested registry items.

Every chain model's decoder fails closed on malformed input, throwing URException subclasses — InvalidTypeURException for a wrong UR type and InvalidCborURException for bad CBOR shape / missing required fields — rather than raw ArgumentError, RangeError, or Dart cast errors. Application scan flows can therefore catch all parse failures via on URException at the completed-UR boundary and stop the signing flow. (Encode-side helpers that build requests still throw ArgumentError for programmer errors such as mismatched list lengths.)

Development

This is a pure Dart package.

dart format path/to/changed_file.dart
dart analyze
dart test

Do not use flutter test for this package. Avoid broad formatting; format only files you intentionally changed.

License

MIT