era_connect 0.1.0

Air-gapped ERA hardware wallet SDK: UR/QR linking and signing for EVM, Bitcoin (+ LTC/DOGE/DASH/BCH), Solana, Tron, TON, Cardano, Sui, Cosmos and XRP. Headless, zero-I/O.

era_connect

Put the ERA air-gapped hardware wallet behind a Dart or Flutter wallet. The device never touches a cable or a radio: sign requests leave your app as animated QR frames, signatures come back the same way.

Account linking and transaction signing for eleven chain families — EVM (all networks), Bitcoin, Litecoin, Dogecoin, Dash, Bitcoin Cash, Solana, Tron, TON, Cardano, Sui, Cosmos and XRP.

• Headless. You render the QR and own the camera; this package owns every byte of the protocol — BC-UR fountain encoding, the Keystone-compatible registry, the CBOR layouts, the reply checks.
• Pure Dart. No plugins, no dart:io in the library. Flutter on every target, plus CLI and web.
• Zero I/O. No network calls, ever. Nothing leaves the process.
• No keys, ever. The device signs; this package builds requests, reads replies and derives public addresses. There is no signer here to misuse.
• Hardened where it matters. A scanned QR is attacker-controlled input, so it is treated that way: bounds precede allocations, the scanner refuses hostile frames, every reply must echo its request id, and compressed replies inflate under a hard ceiling.

Install

dart pub add era_connect

Sixty seconds to a signature

import 'package:era_connect/era_connect.dart';

final era = EraConnect(EraConnectConfig(origin: 'MyWallet')); // shown on device

// 1. LINK — scan the device's "connect" QR once.
final scanner = era.scanner(
    UrScannerOptions(expectedTypes: ['crypto-multi-accounts']));
// feed camera frames: scanner.receivePart(text) until scanner.isComplete
final accounts = era.parseAccounts(scanner.result());

final evm = accounts.evm()!;
evm.deriveAddress(0); // 0x… — derived locally, no device round-trip

// 2. SIGN — build the transaction with your chain tooling, hand over the bytes.
final request = era.evm.generateSignRequest(EvmSignRequestProps(
  signData: rawRlpBytes,
  dataType: EvmDataType.transaction,
  path: evm.pathFor(0),
  xfp: evm.xfp,
  chainId: 1,
));

// 3. DISPLAY — animate the request as QR frames.
final animated = request.toAnimated();
// render animated.nextFrame() on a timer (~125 ms per frame)

// 4. SCAN the reply. The request-id echo is enforced for you.
final replyScanner = request.scanner();
// feed camera frames …
final signature = replyScanner.parse();

// 5. VERIFY before broadcasting — see package:era_connect/verify.dart

Full walkthrough: doc/getting-started.

Chain support

Ten modules cover eleven families — Litecoin, Dogecoin and Dash ride the Bitcoin module, since the device signs them through the same PSBT flow.

Chain	Signing	Library
EVM (all networks)	transactions, personal_sign, EIP-712	package:era_connect/evm.dart
Bitcoin	PSBT v0; messages (script types depend on firmware)	package:era_connect/btc.dart
Litecoin, Dogecoin, Dash	the Bitcoin PSBT flow with a coin id	package:era_connect/btc.dart
Bitcoin Cash	structured envelope, FORKID sighash, CashAddr	package:era_connect/bch.dart
Solana	transactions (incl. versioned), off-chain messages	package:era_connect/solana.dart
Tron	any contract — the raw raw_data is what gets signed	package:era_connect/tron.dart
TON	BoC root-hash signing, TON Connect proofs	package:era_connect/ton.dart
Cardano	witness sets, soft-derived vkey binding	package:era_connect/cardano.dart
Sui	intent-message signing, local address derivation	package:era_connect/sui.dart
Cosmos (~35 zones incl. Ethermint)	Amino, Direct, ADR-036	package:era_connect/cosmos.dart
XRP	the XRP Toolkit ur:bytes convention	package:era_connect/xrp.dart

package:era_connect/era_connect.dart re-exports all of it behind the EraConnect facade. The per-chain libraries exist so an app that signs one chain does not import ten.

Verify before you broadcast

The reply's request-id echo proves which request was answered. package:era_connect/verify.dart proves what was signed — it recomputes the digest, checks the signature against the key the request named, and compares the returned transaction with the one you sent.

import 'package:era_connect/verify.dart';

final check = verifyEvmSignature(/* … */);
if (!check.ok) throw StateError(check.reason!);

On two paths there is no request id at all — Bitcoin PSBT and XRP — so the content check is the only binding you have. Verification is mandatory there, not advisory. Details in doc/advanced/verification.md.

Documentation

• Getting started — five pages, install to verified signature
• Chain guides — one per family: props, replies, verification, broadcasting
• Verification · QR tuning · Flutter integration · Key-derivation calls · WalletConnect
• API reference: the dartdoc on pub.dev

Security

Found a flaw? Please report it privately — see SECURITY.md.

License

Apache-2.0 — see LICENSE and NOTICE.